Suspension specialists can tell many interesting examples from practice, but I will have to limit myself to just a short story about why harder is not always tenacious, and softer is not always more comfortable. The operation of the car's suspensions is not at all as simple as it seems at first glance. They perform many functions that are not readily apparent. I will try to briefly mention the main ones.
In general, many books have been written about the work of pendants, and most of them are very thick. I will try only to outline the main points "on top" in order to fit into the format of an informative article.
Why you can't do without a suspension
Even very flat roads actually bend in many directions, and the Earth itself bears little resemblance to an endless plane. And for all four wheels to touch the surface, they must be able to move up and down. In this case, it is highly desirable that the running surface of the wheel adjoins the surface with its entire width at any position of the suspension. So cars with stiff and short-travel suspensions are practically doomed to poor grip, because one of the wheels will always be unloaded.
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Why Suspension Must Have Compression Stroke
For all wheels to contact the road, it is not at all necessary that the suspension can be compressed, it is enough that the wheels can only move downward. But when the car moves in corners, lateral forces arise that tend to tilt the car. If at the same time one side of the car can rise, and the other cannot lower, the center of gravity of the car will strongly shift towards the loaded wheel, which in turn will cause many negative consequences.
First of all, even greater unloading of the inner wheel in relation to the rotation and an increase in the roll moment due to the movement of the center of gravity upward relative to the center of the suspension roll (about it below). And, of course, if the wheels do not have a compression stroke, then even a small unevenness under one of the wheels should cause the body to move, moving all the other wheels down with all the associated energy costs for lifting and a decrease in wheel traction. Which, to put it mildly, is not very comfortable. It is also destructive for the body and suspension parts. In general, the suspension must be balanced, with compression and rebound travel for proper operation.
Why does the car roll in corners
Since we have already decided that the car's suspension should be and has the ability to move up and down, then, purely geometrically, a certain point is formed, a center around which the car body rotates when it rolls. This point is called the roll center of the vehicle.
And the sum of the inertial forces acting on the car in a corner is just applied to its center of mass. If it coincided with the center of the roll, then there would be no roll in the corner, but it is usually located much higher, and the result is a heeling moment. And the higher the roll center is, the lower the center of gravity, the smaller it is. On special racing structures like Formula 1 cars, the center of gravity is placed below the roll center, and then the car can roll in the opposite direction, like a boat on water.
Actually, the location of the roll center depends on the suspension design. And automotive engineers learned how to "raise" it higher by changing the design of the levers, which in theory could get rid of rolls not only low sports cars, but also high enough. The problem is that the suspension, designed to provide an "unnaturally raised" roll center, copes well with body tilt, but it does not do well with the main task of damping bumps.
Why the suspension needs to be soft
It is quite obvious that the softer the suspension, the less the change in the position of the body when hitting an unevenness and during roll the load is less distributed between the different wheels. This means that the grip of the wheels with the road does not deteriorate and energy is not spent on moving the center of mass of the machine up and down. Well, have we found the perfect formula? But, unfortunately, not everything is so simple.
First, the suspensions have limited compression strokes, and they must be coordinated with the change in axle load when the car is loaded with passengers and luggage, and with the load arising from cornering and unevenness. Suspension that is too soft will compress so hard when cornering that the wheels on the other side will lift off the ground. So the suspension must prevent the compression travel from being exhausted on one side and the wheel from hanging out on the other.
It turns out that being too soft a suspension is also bad ... The best option is a relatively small range of "softness", after which the suspensions become stiff, but adjusting such a structure is more difficult, the higher the difference between the hard and soft parts.
With any redistribution of the load between the wheels, there is a deterioration in the overall adhesion of the wheels to the road. The fact is that additional loading of some wheels does not compensate for all losses during unloading of others. And in the case of hanging unloaded wheels, the increase in grip on the loaded side does not compensate for even half of the losses.
In addition to a general deterioration in grip, this also leads to a deterioration in handling. They fight this unpleasant factor by changing the inclination of the rolling plane of the wheel relative to the road - the so-called camber. As a result of constructive measures aimed at programming the camber change during the roll of the machine, it is possible to compensate for the change in wheel grip under lateral loads in a reasonable range and thereby make the machine easier to control.
Why do you have to make the suspension stiffer on sports cars?
The controllability of the car is extremely negatively affected by any changes in the angles of the suspension when the car rolls and delays in responses to control actions due to a shift in the center of gravity. This means that you have to make the suspensions stiffer so that the rolls decrease when cornering.
The last resort is a powerful stabilizer lateral stability- torsion bar, which prevents the wheel from moving one axle relative to the other. But this is not the most The best way... Yes, it improves the situation with changing the wheel alignment angles in a turn, but it relieves the load on the inner wheel in relation to the turn, and overloads the outside one. It's a little better to just make the suspension stiffer. This has a greater impact on comfort, but not as much to relieve the inner wheel.
Considerable importance of shock absorbers
In addition to elastic elements, gas or liquid shock absorbers are also present in the car's suspension - elements responsible for damping suspension vibrations and outputting the energy that the car spends on moving the center of mass. With their help, you can correct all the suspension reactions to compression and rebound, because the shock absorber can provide much more rigidity in dynamics than a spring. Moreover, its stiffness, in contrast to the springs, will be very different depending on the suspension travel and the speed of its movement.
Of course, a completely soft shock absorber will not be able to fulfill its main task - damping vibrations, the car will simply sway after passing through an unevenness. And installing a very stiff one will create an effect similar to installing a very stiff spring that does not want to compress and thereby increases the load on the wheel and relieves everyone else. But fine tuning will help reduce roll in corners and help the springs, reduce body swoop during acceleration and braking, and at the same time not interfere with the wheels of passing small irregularities. And, of course, do not allow "breakdown" of the suspensions when driving through hard irregularities. In general, they affect the behavior of the machine no less than the stiffness of the springs.
A little about comfort and vibration frequencies
It is clear that a car without a suspension would have zero comfort, because all minor irregularities from the road would be transmitted directly to the riders. Brr. But if the suspension is made very soft, then the situation will not be much better - the constant buildup is also extremely bad for people. It turns out that a person does not tolerate vibrations with a small amplitude and high frequency from a rigid suspension, as well as with a large amplitude and low frequency from a soft one.
To create comfortable conditions for passengers, it is necessary to coordinate the stiffness of springs, shock absorbers and tires so that on the most popular surfaces for this car, the oscillation frequency of passengers and the level of acceleration remain within comfortable limits.
The frequency and amplitude of suspension vibrations are also important in another aspect - the natural resonance frequencies of the vehicle-suspension-road system should not coincide with the possible frequencies of control actions and disturbances from the road. So the task of the designers is also to bypass dangerous modes as far as possible, because in the event of resonance, you can turn the car over, and lose control, and simply break the suspension.
So what should be the suspension?
Paradoxically, the softer the suspension, the better the grip. But at the same time, it should not allow strong rolls and changes in the contact patch of the wheels with the road. The worse the roads, the softer the suspension needs to be in order to get good traction. The lower the coefficient of grip of the wheels, the softer the suspension should be. It would seem that the installation of an anti-roll bar can solve the problem, but no, it also has its negative features, it makes the suspension more "dependent" and reduces the suspension travel.
So tuning the suspension remains a matter for true craftsmen and always requires a lot of time for field tests. Many factors are intricately intertwined and, by changing one parameter, you can worsen both handling and ride smoothness. And not always a stiff suspension makes a car faster, while a soft suspension makes it more comfortable. A change in the stiffness of the front and rear suspension relative to each other and even the slightest change in the characteristics of the stiffness of the shock absorbers. I hope this article will help you to be more careful about the choice of accessories for suspensions and prevent rash experiments.
Not only characteristics such as smooth operation and handling of obstacles, but also your safety while riding, depend on the correctly selected spring and competent settings of the shock absorber. Modern shock absorbers have a decent amount of adjustments, and many are simply afraid to twist them. Hopefully this article will help you figure out what's going on with your rear shock and make your suspension even better! A shock absorber is one of the elements of any bicycle suspension. There are many types of shock absorbers - air and spring, with and without a stable platform, but the principle of operation of the basic settings remains the same. We will return to them a little later (for example rear shock absorber Fox DHX 5), but for now, let's talk about the main characteristics of the shock absorber and the spring.
What is written on the shock absorber?
Each shock absorber has 2 parameters - the length along the axes and the stroke of the rod. Let's consider them using the example of a shock absorber with the following parameters: 8.75x2.75 (1 inch = 2.54 cm = 25.4 mm) The first number is the length along the axes in inches. It is measured in the center of the holes into which elements (bolts or axles) are inserted to rigidly fix it in the frame. (in millimeters, it turns out 222.2 mm) The second number is the stroke of the rod. Also measured in inches. This value shows how many millimeters the rod fits into the damper body. (70 mm is obtained in millimeters). Both values are very important. Each frame is designed for a given shock absorber length. When installing a shock absorber of greater or lesser length, the geometry changes (most often for the worse) - the angle of the fork falls over or sharpens, the carriage is overestimated or underestimated. Suspension smoothness, progressiveness and linearity change, and, in rare cases, due to changes in shock absorber operation, frame or shock absorber breakage occurs. The travel of the suspension directly depends on the stroke of the rod. Let me remind you that the suspension travel is the distance that rear wheel vertically from the state when the shock absorber is fully extended to the state when the shock absorber is fully compressed (when the stem is recessed to the very end). It should be noted that sometimes shock absorbers with the same length along the axes have different rod lengths. Example: 8.75x2.8 and 8.75x2.5.
If the frame is designed for a 2.8 rod stroke, and you put a shock absorber with a rod length of 2.5 (with the same length along the axes of both), then the suspension travel will be reduced while the geometry of the bike remains unchanged. When installing a shock absorber with a rod stroke exceeding the native value, mechanical damage to the frame parts may occur in the event of a suspension breakdown. Another example is the same stroke along the axes for different shock absorber lengths. Example: 8.75x2.8 and 9.0x2.8. In this case, the suspension travel remains virtually unchanged, but the geometry changes.
Tip: use exactly the shock absorber recommended by the manufacturer. If the market does not have the required sample, then choose something as close as possible to this value... From my own experience, I will say that the length along the axes should not differ from the native one by a value of ± 5 mm, and the stroke of the rod should not be more than 3-5 mm.
Spring.
The spring can be titanium or steel. Unlike auto and motorcycle suspensions, the springs on bicycles are always linear, without changing the thickness of the coils along the entire length. There are 5 parameters in the spring - stiffness, recommended stroke, length, inner and outer diameters. Stiffness is measured in lbs / inch², which means pounds / square inch. In most cases, this value is in the range from 200 to 700 in increments of 50 (rarely - 25). The recommended stroke is the shock absorber stroke for which the spring is designed. Most often it is written on shock absorbers: 400x2.8 The first value is stiffness, the second is the recommended stroke. The length of the spring is primarily dependent on the recommended stroke. The larger it is, the longer the spring. Also, the length increases with increasing stiffness, because the turns increase in diameter, but the distance between them does not.
The inner diameter depends on the landing pad and the shock absorber washer that holds the spring. It is worth noting that two seemingly identical springs can differ in inner diameter (for example, Fox Vanilla before 2006 and Fox DHX have different spring seats, respectively, the springs will be different). In addition to accurately positioning the spring in the grooves of the shock absorber washers, there must be sufficient distance from the spring coils to the shock absorber housing. Otherwise, the spring will start rubbing the body. The outer diameter, in fact, depends on the same as the inner one. However, different spring manufacturers make springs from different materials. For this reason, the thickness of the coils may exceed the standard value for a native spring. She, in one case, may simply not fit between the tank and the body, and on the other, start wiping the tank.
Is it possible to put a 400x3.0 spring on an 8.75x2.8 shock absorber? It is possible, provided that the length of the spring does not exceed the maximum length between the fully unscrewed washer and the bottom pad. If the length of the spring exceeds this value, and it must be compressed to install the spring, then its use is highly discouraged. The use of such a spring can ultimately tear off the lower pad of the shock absorber, plus, in case of any separation of the rear wheel from the ground, the stem cover, oil seal, body and the stem itself bear an increased load, because the spring is constantly compressed. In addition, a 400x.3.0 spring weighs more than a 400x2.8 spring. Is it possible to put a 400x2.5 spring on an 8.75x2.8 shock absorber? It is forbidden. Because the stroke of the spring rod is less than the stroke of the shock absorber rod, then when the suspension is fully triggered, the spring coils will close together and then the pad and the shock absorber washer will be destroyed with possible destruction of the rod. Let's note one more point. The stiffer the spring, the thicker its coils. Because the distance between the turns must remain unchanged in order to avoid contact of the turns (described above), then the length of the spring and the outer diameter increase.
In our practice, there was a case that a 500x2.5 spring fit perfectly into a shock absorber, and an 850x2.5 spring exceeded the permissible outer diameter. When choosing a spring, you should be guided by the following parameters: - the recommended stroke of the spring rod must be either the same as in the shock absorber, or exceed by a small value; the seat of the pad and the washer. The spring should not touch the shock absorber body during operation - the spring with the outer part of the coils should not come into contact with the reservoir
Shock absorber setting (for exampleFOXDHX 5.0)
-selection of the required spring rate
-settingBottom-Out
-selection of pressure in the tank
- rebound adjustment
-adjustmentProPedal
Frames with different types Suspensions work differently and even with the same rider weight, spring rates can vary by 50,100 or even 200 pounds. The work of the shock absorber also plays a significant role. Many manufacturers in the technical manual for frames have a table of the necessary settings. However, on the one hand, they will not suit every rider, on the other hand, they all ride in different ways.
Spring rate... This is one of the main parameters of the shock absorber. Sag is the most important indicator when choosing a spring. When you get on the bike, the suspension is compressed to a certain amount. For freeride and downhill, it ranges from 25 to 40% (on average 1/3). What is a sag? Sag = shock absorber extended length / full stroke,% With a stroke of 70 mm, a sag of 25 mm is about 1/3 How is it easiest to measure? Measure the length of the shock absorber along the axles in mm with the suspension fully extended. Suppose we have it 222 mm. The stroke is 70 mm. Sit on the bike (it is better to stand on the pedals with your elbows slightly on the handlebars). Ask a friend to measure the distance between the shock absorbers. For example, it will be 195 mm. Subtract the value obtained (195 mm) from the length of the shock absorber (222 mm). 222-195 = 27 mm. This is the amount by which the shock absorber has compressed. Sag = 27/70 * 100% = 38.5% Our sag was 38.5%. To increase it, put a softer spring so that the shock absorber compresses under your weight by a greater amount. To reduce the sag, place the spring stiffer. With a little experience with spring selection, I would recommend choosing a spring for a sag of 33%. What does sag affect? It will be most understandable if you imagine a flat road and a hole in it. When the rear wheel hits the hole, because the spring is compressed under your weight, the wheel will go down as much as the sag and work the hole. Spring too soft. Sag-> 50%. At each hole, the wheel will fall too much, which, on the one hand, will, of course, improve control over the track, and on the other, it will slow down the bike. If too soft spring the shock absorber will constantly break through, which will entail the destruction of both itself and the frame. The spring is too stiff. Sag<20%. Каждая кочка будет отдаваться в педали, ухудшится контроль за трассой, хоть и прибавиться стабильности (но только на ровных участках, где нужно много крутить).
CustomizationBottom-Out... This adjustment is the blue cap on the reservoir. Changes the volume of the air chamber. When the shock absorber is operating, oil moves from the main chamber to the reservoir. The fewer obstacles in the path of the oil, the more linear and smoother the shock absorber will work. Bottom-Out allows you to adjust the progressiveness of the shock. Fully unscrewed, the shock will operate linearly from start to finish. When the adjustment is fully tightened, a progression will begin in about the last third of the stroke. Why is it needed? All tracks have both small and large obstacles. Small obstacles need soft and smooth handling; large obstacles need hard and progressive handling. If you are jumping drops, turn the adjustment until the shock stops pushing through. Note that the Bottom-Out setting does not in any way affect the action of the shock absorber in 2/3 of the initial travel - it remains the same soft. The bottom line is this - twist to the value at which the shock absorber will not break through. However, if you do not jump drops, or there are no large obstacles on the track, on which the shock absorber works for the entire travel, then twist the adjustment until the shock absorber begins to break through. The more smooth ride the suspension has, the better. But remember - it doesn't have to break through. It is necessary to find the ratio at which it will work most beneficially for a given situation.
Tank pressure selection. The pressure in the reservoir should be between 125-200 Psi. Pressure too low (<125 Psi) ухудшит работу, начнутся провалы в подвеске. Слишком высокое (>200 Psi), the pressure will also worsen the performance, the suspension will become too stiff, and the chance of shock absorber destruction will also increase (from increased load on the oil seals and the rod to the explosion of the reservoir). Basically, the pressure in the reservoir is approximately equal to the change in compression. At low pressure, the shock absorber works most smoothly, it handles bumps better. At high pressure, its work becomes tougher, it is more difficult for the oil to flow through all the holes, to some extent it begins to dull on bumps and break through less. Remember one important thing - if you pumped up to 125 Psi with the Bottom-Out fully twisted, and decided to unscrew the Bottom-Out, then the pressure in the tank will drop below the minimum. Also, when the Bottom-Out is completely unscrewed and the pressure is 200 Psi, when the Bottom-Out is tightened, the pressure will exceed the allowable value. My advice is to deflate the shock first, then adjust the Bottom-Out and then re-inflate. Bottom line: Tank pressure depends on how you ride. Love harder - the pressure is higher, softer - the pressure is lower. 4.Adjustable rebound. Rebound is the time during which the shock absorber returns from the compressed state to the uncompressed state. Drive a lot over bumps - bounce faster, jump drops a lot - slower. If the rebound is too slow, the shock absorber will not have time to unclench to handle the next bump. If it is too fast, it will toss the wheel with a significant deterioration in traction. Remember to bounce slower on drops - if you rebound quickly, the suspension will throw you over the handlebars upon landing, which often results in broken arms, collarbone and concussions. On the trails, in my opinion, the rebound adjustment on the shock absorber rather than on the fork is crucial. Despite the fact that there are always a huge number of obstacles on the track, bounce 1-3 clicks slower than the optimal value. This will add stability.
AdjustmentProPedal... Whatever suspension you have, the shock absorber will still swing when pedaling. Why is this happening? Human legs cannot pedal at the same speed and balance as a motorcycle engine. The low RPM of the crankset cranks makes the suspension squeeze each time you press the pedal. Due to this, part of the energy is lost for the buildup. For this, there is a ProPedal adjustment, which prevents swinging. It has 15 positions, from fully off to fully on. It would seem - why is it needed at all, is it possible to turn it on once to isolate the buildup? No. Despite assurances from Fox that activating the adjustment will not affect shock performance, this is not the case. The harder you twist the ProPedal, the worse the shock absorber begins to handle bumps, a slight knock appears. Therefore, you need to look for a compromise between reducing the buildup and working out the suspension of the bumps. If the track is long and easy, where you need to twist a lot, Propedal can be turned on from 10 to 15 clicks. If the track has a lot of bumps and turns, do not use Propedal for more than 8 clicks. Bottom line: Propedal position depends on the track. Find a compromise between rocking and bumping. Of course, ideally, the shock should be tuned for each track, and the understanding of what the settings should be comes only with experience. Do not be afraid to once again climb into the suspension and twist some kind of twist - the main thing is to remember what you did and immediately check how the bike's behavior has changed. Good luck with your setup!
Text: Arsen "Bars-Zerwick" Khanbekyan
Photo: Fox Shox
What springs are better to put car owners are wondering when faced with the choice of these elements and the improvement of suspension performance. The selection will depend on the length, overall diameter, steel diameter, stiffness, spring shape, manufacturer's brand. Therefore, in order to choose the best option, it is necessary to analyze all the listed factors. And also decide on the goal - to carry passengers or bags of potatoes ...
Springs replacement signs
There are four main signs that a spring needs to be replaced.
Roll the machine to one side
It is checked visually when the machine is on a level surface, without load. If the body is skewed to the left or right side, the springs need to be replaced. Likewise with forward / backward roll. If before that the car stood on the surface level, and now its front or rear part in a calm state has dropped significantly down, then new springs must already be installed.
However, there is one caveat when the spring may not be to blame. In the design of VAZ-classic cars (models from VAZ-2101 to VAZ-2107), a so-called glass or seat is provided in the upper part of the spring. The spring rests against it with its upper part.
Often, in old cars, during a long operation, the glass falls through, which leads to a distortion of the entire structure. For diagnostics, it is necessary to dismantle the spring from the sagging side of the machine, remove the rubber cushion and inspect the glass itself. Most often, such a breakdown occurs from the front wheels, especially the left. However, this also occurs on the rear suspension.
Extraneous noise in the suspension
The noise can be very different - clank, rumble, thud. This noise appears on the slightest irregularities in the road, even small pits or bumps. Of course, ideally, you need to perform a full diagnosis and check of ball, steering rods, rubber bands. However, if the listed elements are in working order, then it is necessary to check the shock absorber springs.
Often the reason for the clanking or rattling sounds from the suspension lies precisely in the broken spring. This usually happens at some loop. Less often - the spring splits into two parts. However, in the latter case, the roll of the car body will appear.
Metal fatigue
The concept of "metal fatigue" means that during operation the spring loses its properties and, accordingly, does not work normally. This is usually true for the extreme / extreme loop. So, the very end of the spring, with considerable effort, hits the penultimate coil. As a result of this, two flat workings are mutually formed on their surface. That is, the bar from which the spring is made becomes not round in cross section, but slightly flattened on one side. It can be found both above and below.
As a rule, such spring elements do not hold the suspension, and the car sags, and also very gently "bounces" in the pits. In this case, it is advisable to install a new spring. And the sooner the better. This will protect other suspension elements and make the ride more comfortable.
Rear spring problems
Checking an unloaded machine may not always give the correct answer to the question of whether the springs need to be replaced. The fact is that over time, the rear of the car sags in case of congestion. And then, on bumps, wheel arches or mud flaps strikes against the road. In this case, additional diagnostics are needed.
If the springs have burst, then they need to be replaced. When they are simply "tired", while you buy new ones, you can use the so-called spacers or thickened rubber bands, which are installed under the spring seats in the "glass". Installation of spacers will cost much less, and will solve the problem of a low landing of the car, that is, increase the ground clearance.
As for the front springs, the same procedure can be done with them, but this will significantly increase the suspension stiffness. This leads not only to discomfort while driving, but also to an increase in the load on the "glasses", because of which they can simply burst. Therefore, it is up to the car owner to decide whether or not to install thickened spacers in the front.
What to look for when choosing
There are several factors to consider when choosing springs.
Rigidity
Rigidity affects not only the comfort while driving in the car, but also when the load on other elements of its chassis system. Soft springs are more comfortable to ride, especially on poorly paved roads. However, it is undesirable to put them on a car that often transports significant loads. Conversely, stiffer springs are best used on vehicles designed to carry heavy loads. This is especially true for rear shock absorbers.
In the context of rigidity, one more situation is relevant. Often, when buying new springs (especially for VAZ-classics), a pair of identical springs included in one set may have different stiffness. Naturally, this leads to the fact that the car tilts to the right or left. It is almost impossible to check them when buying them, so there are two ways to solve the problem.
The first is to install the spacers mentioned above. With their help, you can level the ground clearance of the machine and achieve uniform suspension stiffness. The second way is to buy better quality springs, usually from trusted manufacturers, usually foreign ones.
Stiffness is a physical quantity that in springs depends on the following parameters:
- Bar diameter... The larger it is, the more and the rigidity. However, here you need to take into account the shape of the spring and the diameter of the bar from which each turn is made. There are springs with variable overall diameters and bar diameters. More about them later.
- Spring outer diameter... Other things being equal, the larger the diameter, the lower the stiffness.
- Number of turns... The more there are, the lower the rigidity. This is because the spring will bend along its vertical axis. However, here you need to consider additional parameters. In particular, a spring with a small number of turns will have a small stroke, which is unacceptable in many cases.
Length
The longer the springs are, the greater the vehicle's clearance will be. For each specific car model, the corresponding value is directly indicated in its technical documentation. In some cases, the length of the front and rear springs will be different. In the best case, the manufacturer's recommendations should be adhered to. Departure from them is possible only for tuning or in the case of using a car for cargo transportation.
Coil parameters
The general name in this case means the diameter and the number of turns. The overall stiffness of the spring depends on these two parameters. By the way, some models of springs have an uneven shape with turns of different diameters. In particular, with narrow turns at the edges, and wide in the middle.
However, such turns also have different diameters of the metal bar. So, the large diameter coils in the middle of the spring are made from a large diameter bar. And the extreme small turns are from a small diameter bar. Large rods work on large irregularities, and small ones, respectively, on small ones. However, due to the fact that small rods are made of thinner metal, they tend to break more often.
These springs are mostly original, that is, those that were installed from the factory. They are more comfortable to ride, but their resource is lower, especially with constant driving on bad roads. Non-original springs are usually made from a bar of the same diameter. This reduces the ride comfort of the vehicle, but increases the overall spring life. In addition, such a spring will be cheaper, since it is technologically easier to manufacture it. What to choose in this or that case - everyone decides for himself.
Types
All damping springs are divided into five basic types. In particular:
- Standard... These are springs with the characteristics specified in the machine manufacturer's recommendations. They are usually intended for use in urban environments or in limited off-road conditions.
- Reinforced... They are usually used on vehicles designed to carry large loads. For example, in options where the base model of the car is a sedan, and the reinforced version is a van or a pickup truck with a cargo compartment in the back.
- With the rise... Such springs are used to increase the vehicle's ground clearance.
- Underreporting... With their help, on the contrary, they reduce the ground clearance. This changes the dynamic characteristics of the machine as well as its handling.
- With variable stiffness... These springs provide a comfortable ride in various road conditions.
The choice of one or another type of springs depends on the operating conditions of the machine and the recommendations of the manufacturer.
Springs for shock absorbers VAZ
According to the statistics provided by the service station, most often domestic car owners of VAZ cars are concerned about the problem of replacing shock absorber springs, both of the so-called "classics" (models from VAZ-2101 to VAZ-2107) and front-wheel drive models (VAZ 2109, 2114).
Most of the springs for Zhiguli, Samar, Niv are produced directly at the Volzhsky Automobile Plant. However, there are other manufacturers as well. In this case, a trademark is applied to the springs or a third-party tag is attached. Please note that the original springs made at VAZ are more technologically advanced.
The fact is that one of the final stages in the manufacture of springs, in particular for the rear part of the suspension, is the application of a protective epoxy coating to the surface of the spring. The front springs may only be coated with a special black enamel based on chlorinated rubber. And only the manufacturer VAZ applies a protective epoxy material to the rear springs. Other manufacturers simply apply enamel to both the front and rear springs. Accordingly, it is preferable to buy original VAZ springs.
The last step in the manufacture of automotive springs is to control their quality and rigidity. All manufactured products pass through it. Those springs that fail the test are automatically rejected. The rest are divided into two classes, depending on the tolerance field. If the tolerance field is positive, then such a spring belongs to class A in terms of load. When a similar field is minus, then to class B. In this case, the springs of each class have a corresponding color designation - a strip of a certain color is applied on the outer strip.
The division into the above classes (and their color gradation) was adopted due to the fact that the stiffness of all finished springs will differ, albeit slightly. Therefore, strictly speaking, if you want to put a stiffer spring, then your choice is class A, if a softer one, then class B. At the same time, the difference in their stiffness can be insignificant, in particular, from 0 to 25 kilograms of load.
The color coding and technical data of the springs produced at VAZ are shown in the table.
| Spring | Model | Bar diameter, in mm, tolerance is 0.5 mm | Outer diameter, mm / tolerance | Spring height, mm | Number of turns | Spring color | Stiffness class | Marking color |
|---|---|---|---|---|---|---|---|---|
| Front | 1111 | 10 | 94/0,7 | 317,7 | 9,5 | black | - | - |
| 2101 | 13 | 116/0,9 | 360 | 9,0 | black | A-standard | Yellow | |
| B-soft | Green | |||||||
| 2108 | 13 | 150,8/1,2 | 383,5 | 7,0 | black | A-standard | Yellow | |
| B-soft | Green | |||||||
| 2121 | 15 | 120/1,0 | 278,0 | 7,5 | black | A-standard | Yellow | |
| B-soft | Green | |||||||
| 2110 | 13 | 150,8/1,2 | 383,5 | 7,0 | black | A-standard | Red | |
| B-soft | Blue | |||||||
| 2141 | 14 | 171/1,4 | 460,0 | 7,5 | Gray | - | - | |
| Back | 1111 | 10 | 100,3/0,8 | 353,0 | 9,5 | Gray | - | - |
| 2101 | 13 | 128,7/1,0 | 434,0 | 9,5 | Gray | A-standard | Yellow | |
| B-soft | Green | |||||||
| 2102 | 13 | 128,7/1,0 | 455,0 | 9,5 | Gray | A-standard | Red | |
| B-soft | Blue | |||||||
| 2108 | 12 | 108,8/0,9 | 418,0 | 11,5 | Gray | A-standard | Yellow | |
| B-soft | Green | |||||||
| 21099 | 12 | 110,7/0,9 | 400,0 | 10,5 | Gray | A-standard | Red | |
| B-soft | Blue | |||||||
| 2121 | 13 | 128,7/1,0 | 434,0 | 9,5 | Gray | A-standard | White | |
| B-soft | Black | |||||||
| 2110 | 12 | 108,9/0,9 | 418,0 | 11,5 | Gray | A-standard | White | |
| B-soft | Black | |||||||
| 2141 | 14 | 123/1,0 | 390,0 | 9,5 | Gray | - | - |
Traditionally, VAZ springs of class A are marked in yellow, and class B in green. However, as you can see from the table, there are exceptions. First of all, this applies to station wagons - VAZ-2102, VAZ-2104, VAZ-2111. Naturally, these machines are equipped with stronger springs.
Many motorists are interested in the question, can springs from station wagons be installed on sedans or hatchbacks? In fact, it depends on the goal pursued. If it consists in the fact that to increase the ground clearance due to the fact that the body began to sag with aging, then an appropriate replacement can be performed. If the car owner wants to increase the carrying capacity of the car in this way, then this is a bad idea.
Reinforced springs can lead to gradual deformation of the body, and, therefore, premature failure of the machine.
The color gradation of the springs may vary from manufacturer to manufacturer. The same is with geometric dimensions. In terms of color, traditional yellow can be replaced by red and / or similar brown. In more rare cases, white is used. It is the same with green, which can be replaced by blue or black.
As for the diameter of the spring bar, it can be different from different manufacturers. And some (for example, "Phobos", which will be discussed below) generally make springs from a bar of different diameters on one product. Therefore, it is important to select the overall height and outer diameter of the spring.
There are several typical types of VAZ springs that are installed on various models of this manufacturer. Let's consider them in more detail:
- 2101 ... This is a classic version for VAZ-classics, that is, for rear-wheel drive sedans.
- 21012 ... These springs are unique and non-standard. In general, they are similar to 2101, but are made from a larger diameter bar, which is why they are more rigid. They were originally intended for installation on the right front side in export right-hand drive vehicles. Similar springs were installed on both sides of the front suspension in vehicles with special equipment.
- 2102 ... These are springs for station wagon cars (VAZ-2102, VAZ-2104, VAZ-2111). They are increased in length.
- 2108 ... These springs are installed on front-wheel drive VAZ vehicles with eight-valve engines. The exception is VAZ-1111 "Oka". There is another version 2108 in export performance. They are color-coded. So, the front springs are marked in white and blue, and the rear ones are in brown and blue. Accordingly, it is better to ride with them only on good roads. They are not intended for domestic roads, so it is better not to use such springs.
- 2110 ... These are the so-called "European" springs intended for the installation of machines intended to be exported. In particular, for cars VAZ 21102-21104, 2112, 2114, 21122, 21124. Please note that these springs have low stiffness and are designed for operation on smooth European roads. Accordingly, for bumpy domestic roads, it is better not to buy them. Including, you do not need to install them if the car is supposed to be often used for off-road driving or on dirt country roads.
- 2111 ... Such springs are installed on VAZ-2111 and VAZ-2113 cars.
- 2112 ... Designed for installation on the front part of the suspension of cars VAZ-21103, VAZ-2112, VAZ-21113.
- 2121 ... Springs are installed on all-wheel drive "Niva", including VAZ-2121, VAZ-2131 and other modifications.
Springs for VAZ 2107
Ideally, it is recommended to install original VAZ 2101 springs for the "seven". However, if you want to improve aerodynamics and increase steering sensitivity, you can put more rigid samples. For example, from the station wagon VAZ-2104. This is recommended only for relatively old cars. This should not be done to increase the carrying capacity. By the way, if you do this, you will need to cut off one coil from the spring for the VAZ-2104.
Springs for VAZ 2110
Traditionally, original 2108 springs are installed on the front suspension of the "tens" with an eight-valve engine, and 2110 euros - on the rear. Their characteristics will ensure the optimal behavior of the machine both on asphalt surfaces and on unpaved roads.
If the car is equipped with a 16-valve engine, then stronger springs are installed on the front suspension - 2112. On the rear - the same 2110 euros. The exception is the VAZ-2111.
Selection by catalog
On modern cars, in most cases, the choice of shock absorber springs occurs in electronic catalogs. The technical documentation clearly indicates the spring model, its full name, characteristics, dimensions, load capacity, and so on. Therefore, if the car owner does not want to change anything in the suspension, but only replace the part with a new one, then there is nothing difficult in choosing.
However, in some cases, car owners, for whatever reason, want to replace the spring with a stiffer or softer one. Then you need to pay attention to the following parameters:
- Manufacturer. Genuine springs (especially on VAG machines) can have a wide range of stiffness. And non-original springs do not have such an assortment.
- Spring type. In particular, their marking, including color.
- Rigidity. It will most likely differ from the original one (depending on the number of turns and their diameter).
After specifying the model of the springs used on the Internet, you need to clarify the VIN-code by which you can buy a spring in an online store or at a regular outlet.
Suspension Springs Rating
Which auto springs are better? There is no unequivocal answer to this question, and there cannot be, since there is a huge variety of them with differences, both in technical parameters and in manufacturers. The following is a list of ten good and most popular spring manufacturers, whose products are ubiquitous on the domestic auto parts market.
LESJOFORS
The full name of the company is LESJOFORS AUTOMOTIVE AB. It is one of the oldest and largest companies producing springs, shock absorbers, springs in Europe. The company has eight manufacturing plants in Sweden, and one each in Finland, Denmark and Germany. The company owns the trademarks LESJOFORS, KILEN, KME, ROC, under which springs are also produced.
LESJOFORS springs are of very high quality. They are made of high-quality high-carbon spring steel, covered with a protective layer on top (phosphating), and painted with powder paint. All this allows you to maintain the performance of the springs for many years. In addition, all springs are subject to quality and performance control. The range of produced springs is about 3200 items. The reviews are mostly positive, because even there are few fakes. The only drawback is the high price.
Kilen
In the fall of 1996, the German company Kilen was acquired by the aforementioned LESJOFORS. Until that time, both of them were direct competitors. Accordingly, the Kilen trademark is owned by LESJOFORS. Kilen springs are of high quality and durability. The manufacturer claims that the products it produces have a resource twice that of the original VAZ springs. Reviews of car owners, in general, confirm this statement. Therefore, these springs are recommended for purchase not only to the owners of domestic VAZs, but also to other cars for which the company produces springs. The price is adequate.
Lemforder
Lemforder springs are supplied as original spare parts for many vehicles around the world. Accordingly, the company is considered one of the world leaders in their production. Often, such springs are installed on expensive foreign cars, that is, they are presented in the premium sector. Accordingly, they cost a lot of money.
As for the quality, it is at its best. However, in some cases, it is noted that either a fake or a marriage is rarely found. But such cases are few. Such expensive springs are recommended for installation on foreign business and premium class cars.
CS Germany
Springs CS Germany belong to the middle price range and to the middle quality segment. Produced in Germany. A good option in terms of value for money, recommended for European cars. The reviews are mostly positive.
Koni
The springs produced under the Koni trademark are distinguished by a high service life. The manufacturer produces a wide range of springs for various vehicles. An interesting feature is the fact that many spring models can be adjusted in terms of stiffness. It is done using a special adjusting "lamb". As for the price, it is usually above average, but does not come close to the premium class.
BOGE
A large number of different suspension elements, including springs, are produced under the BOGE brand. They belong to the premium class, are of high quality and at a high price. Marriage is extremely rare. Recommended for installation on machines of European manufacturers. The reviews are mostly positive.
Eibach
Eibach springs are among the highest quality and most durable springs on the market. Over time, they practically do not sag and do not lose rigidity. They can definitely be recommended to all car owners, for whose cars there are suitable springs. The only conditional drawback of these spare parts is their high price.
SS20
All SS20 springs are 100% quality according to the manufacturer. This is ensured by the fact that during mechanical testing of new products, the springs are selected in pairs. That is, a pair of springs will be guaranteed to have the same mechanical characteristics. Firm CC20 produces its springs using two technologies - cold and hot winding, both overstated and understated.
K + F
Kraemer & Freund is also one of the leaders in the production of various spare parts, including springs for cars and trucks. The company supplies its products to both the primary and secondary markets. The range of products sold has about 1300 items, and is constantly expanding. Genuine K + F springs are of high quality but cost a lot.
TEVEMA
The Polish company TEVEMA produces shock absorber springs for the European and Asian markets. The products of this company are often used by owners of cars produced in 1990-2000s. They are excellent replacements for original spare parts. At the same time, the cost of new springs is approximately two to three times lower than that of the original ones. Reviews of the springs are mostly positive.
The spring manufacturers listed above belong to the middle class, that is, they produce fairly high-quality products at a relatively inexpensive price. Therefore, they are popular. However, there are two more classes of manufacturers. The first is premium manufacturers. Their products are of extraordinary quality, and their original products are installed on expensive business and premium class foreign cars. For example, such manufacturers include Sachs, Kayaba, Bilstein. They have almost no drawbacks, only the high price of their springs makes them look for a cheap alternative.
Another segment of firms under whose brands springs are produced is the budget class. This includes a lot of companies. For example, Tekhtime, PROFIT, Maxgear. The price of such springs is quite low, however, their quality is appropriate. Such companies do not have their own production facilities, but only pack cheap and variable quality springs purchased somewhere in China. For example, rejected during testing at some of the more well-known enterprises. However, there are a number of cheap springs that can still be used and which have received a lot of positive feedback.
But among the budget springs there are some pretty good options. These include.
Any part of the car is tested before a new car brand goes into mass production. The suspension has been adjusted to improve operating conditions and driving safety. These adjustments are made by the manufacturer. They are average values and are intended for driving on public roads.
The driving style of each car owner is different. This dictates the different requirements that drivers place on their cars. There are two inversely proportional criteria that designers try to average. This is the smoothness of the suspension and handling. Unfortunately, the high performance of one of them drastically reduces the performance of the other. Therefore, depending on what exactly needs to be increased, a certain tuning of the suspension is made.
Installation of springs
The spring plays a key role in driving and maneuvering. For better handling, stiffer springs must be chosen as they are able to respond more quickly to constantly changing forces. Any component manufacturer specifies the degree of spring stiffness and provides a choice according to this parameter. An external sign of a reinforced spring is the marking on the outside of the coil in the form of a green or blue strip. If the marking is not applied, then you should pay attention to the diameter of the rod. Larger diameter means more rigidity. If the spring consists of two sections with different coils, then this is a direct sign of excellent controllability.
Several manufacturers specialize in sports springs and offer products in different price ranges.
Installation of shock absorbers
Combining stiff springs and standard shock absorbers is not only pointless, but also wasteful. High vibration frequency and low amplitude can quickly damage stock equipment. In order to effectively damp the resulting vibrations, a rigid shock absorber is needed. Gas models have these properties. Since the classic two-pipe oil shock absorber has one significant drawback - oil foaming under intense loads, the one-pipe gas version will be the best solution to improve handling.
The work of a rigid spring with a gas shock absorber provides timely compression and rebound, which leads to improved grip of the wheels with the road surface. When cornering at high speed, the body of the car is less prone to roll. During acceleration and braking, it is possible to get rid of the "pecks" characteristic of a soft suspension. All this affects the information content of the steering wheel and the sharpness of control.
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As in the case of springs, branded manufacturers have stood out, producing shock absorbers with high technical performance.
Rack supports
This unit affects handling only in two cases: if the shock absorber is pivotally attached to the support and the support allows you to change the angle of the castor. In the first case, such supports are not installed on production cars, and the second will be described below. However, car owners prefer to install supports from leading manufacturers, because high-quality vibration absorption is also combined with good handling.
Wheel alignment
As it was said at the very beginning, the collected elements into a single node will not yet give the expected result of the work. To achieve certain indicators of vehicle handling, it is necessary to adjust three parameters - wheel alignment angles.
Castor angle
The castor angle can be defined as the angle of deviation of the axis of rotation of the wheel from the vertical passing through its center. Without specially modeled animation, it is difficult to imagine the influence of the castor angle on the behavior of the car. The designers note that this angle must be different from zero for the steering system to self-center after the force stops (when exiting the turn). A larger angle contributes to more efficient steering return. But in parallel with this, the turning radius and the effort for maneuvering increase. In technical terms, the castor angle allows for an increased range of camber adjustment, which affects the area of adhesion of the wheel to the road. However, many manufacturers do not provide the ability to adjust the pivot axis by setting the optimum angle at the factory.
The modern car industry is distinguished by the ability to regulate castor. For this, front-wheel drive models are provided with shims on the struts. Adding one puck increases the angle by 19 minutes. The maximum deflection of the pivot axis is 3 degrees. But by installing the SS20 strut supports, you can achieve better results. Experiments with this parameter should be carried out in a special service, since changing it will entail a readjustment of the camber angle.
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The plane of the wheel should not be strictly vertical, as this will play a cruel joke when driving through irregularities and cornering. Camber is the angle between the plane of the wheel and the vertical plane. It is considered positive if the top of the wheel protrudes outward and negative inward. When cornering, the body will certainly begin to roll, which means that the wheel for better grip must change its plane relative to the vertical. This is only possible with negative camber. Some car brands do not provide for setting this parameter, others have their own specific indicators. If it is not possible to visit the service, then by any means and means you should achieve a negative camber setting of 15 degrees. Although this angle will provoke more intense tire wear, it will provide good handling at high speeds.
Toe angle
The toe angle is plotted relative to the direction of travel. If the planes of the wheels intersect in front of the car, then the angle is positive. A negative angle is bad for handling. The manufacturer recommends adhering to the normal position with allowable amendments. However, to increase the car's responsiveness to steering turns, the toe angle is made for 10-15 minutes in the positive direction. This setup is not devoid of a negative moment - uneven tire wear.
Considering all the options for increasing controllability, it is impossible to highlight the best option, since any design change or change in settings has its drawbacks. These procedures are mainly used by racing enthusiasts. They can afford to drastically overestimate the handling parameters to the detriment of comfort and the resource of parts. Judging by the reviews of car owners, tuning the suspension for everyday driving should be done on 1-2 points.
Distinguish between vertical, longitudinal and lateral rigidity of suspensions.
The vertical stiffness of the suspension should provide the required smoothness of the vehicle. Its value can be assigned according to the known value of the vehicle mass per axle and the required natural vibration frequency of the sprung mass according to the formula:
Front suspension weight,;
f is the natural frequency of oscillations, we take f= 1 Hz;
The total stiffness of the suspension (2 wheels), taking into account
stiffness of tires.
From the resulting total suspension stiffness, it is easy to distinguish the stiffness of the suspension itself:
Selecting the required suspension travel
For driving on an uneven road with a normalized micro-profile, in principle, (a large dynamic suspension compression stroke is not required. According to the results of calculations of the car's movement, even on a broken dirt road, the standard deviation of the suspension travel is no more than 20 mm. Then, according to rule 3a, it is enough to have a stroke compression 3 * 20 = 60 mm. At the same time, when driving over single irregularities in a corner or when braking, a greater travel may be required. The suspension travel must be large enough to ensure certain roll angles. Practice shows that for cars with a track of about 1400 mm, it is necessary to have a compression stroke from the state of full load of at least 70 mm and a rebound stroke from a state of loading by 1 driver not less than 50 mm. For a larger track, a larger suspension travel is required. ; S comp = 70 mm - compression stroke; S? = 210 mm - total suspension travel.
Let us construct the characteristics of the suspension by the known values of the sprung mass in the two extreme states of loading and by the stiffness of the suspension.
The elastic characteristic built in this way does not provide the required dynamic coefficient of the suspension. The usual value is K d = 2 for vertical loads. In addition, at the full rebound stroke, the wheel has a force of 1400 N (140 kgf). Without additional elastic elements, the suspension will "punch", and shocks on the "pickups" will also be felt. To avoid them, we introduce additional elastic elements.
The point of inclusion of the compression buffer must be determined empirically. However, although the long compression buffer provides smoother turn-on, it usually has limited performance. The soft suspension, which is required to provide a good ride, results in excessive roll when the vehicle is turning. To reduce the roll in the suspension, elastic elements are used - anti-roll bars. A feature of the stabilizer is that with the same suspension stroke, it does not develop additional effort, but is included in the work only with a different stroke. Lack of stabilizer - it increases the stiffness of the suspension when hitting an obstacle with one wheel.
Longitudinal and lateral stiffness of the suspension
Suspension stiffnesses must be large enough to maintain vehicle handling and to reduce the space required for the wheel arches. At the same time, in order to ensure smooth running, these stiffnesses cannot be too large.
Non-linear characteristics are desirable.
We accept: C x = 12 * C z = 12 * 32465.7 = 389588.3 N / m; C y = 12 * C z = 90 * 32465.7 = 2921912.2 N / m.
Suspension angular stiffness
Must be large enough to prevent excessive body roll when cornering.
Maximum permissible roll according to GOST R = 7 ° at 0.4 g. In fact, for conventional passenger cars, it is between 2 and 4 °. Let's take 4 °.
Let's calculate the angular stiffness (total):
Where kg is the sprung mass;
We distribute the resulting total angular stiffness along the axes. For rear-wheel drive vehicles C per / C back = 1.3. With lane = 20900. This distribution is associated with the desire to get some understeer and the position of the roll axis. The exact values and distribution of angular stiffness are obtained during the fine-tuning of the vehicle.
Suspension damping
Suspension damping has a significant effect on vehicle vibrations. The damping force depends on the deformation rate of the suspension. Typically, the relative vibration damping factor is used to estimate damping:
K p - damping per wheel, N / cm; C zп - suspension stiffness (1 wheel), N / m; m p - sprung mass per wheel.
relative damping should be 0.25 ... 0.30. An important role for ensuring wheel vibrations without taking off from the road is played by the value of the relative damping of wheel vibrations.
С zk - wheel stiffness, N / m;
Kf - coefficient of wheel stiffness increase, depends on the cord material in the belt, k f = 1.05.
K k - own damping of the tire, K k = 30 N / cm;
m K - unsprung weight per wheel; it includes the entire mass of parts that make a full stroke with the wheel and S part of the mass of the levers, one end of which is fixed to the body.
