Most shock absorbers are supplied without bump stops or special boots. Such products not only increase the service life of shock absorbers, but also their efficiency. Many car enthusiasts do not know what exactly bump stops are needed for, otherwise called compression stroke buffers, and how to choose them. In this material, we will look at the structure and operating principle of fenders, and will also figure out how to determine their wear and choose a new spare part if the old one fails.
How to check silent blocks?
A flat mount will be required for diagnosis. This will allow you to determine how badly these parts are worn. Using the mount, the lever will move in the longitudinal and transverse directions. If there is play or damage, then the front suspension silent blocks are to blame for the knocking.
Sometimes the levers can be collapsible. Then you can replace it with a silent block. To do this, the lever is dismantled, and then, using a special mandrel, the part is squeezed out. It is advisable to lubricate the new silent block before installation. The seating surface must also be cleaned. After installation, the knocking should stop.
Steering
Even for experienced service engineers from numerous car repair shops, finding the cause of extraneous knocking noises is a serious problem. Many people immediately recommend replacing the shock absorber strut. Here it is, new, on the car, and the strange knocking noise in the front suspension on small bumps has not gone away. The car owner goes to another service center, but there they offer him to replace the support bearing, but even after that the knocking noise does not disappear.
When diagnosing the front suspension, experienced car owners begin checking with the steering system.
The main causes of vibration in the steering wheel
Among the popular reasons that cause a slight knock in the front suspension on small bumps is a large gap between the steering rack and gear. This is the result of wear and tear. To make an accurate diagnosis, it is recommended to pull the steering rods up and down. At the same time, carefully observe the movement of the rod. If she doesn't move, then she's fine. If the rod dangles, then most likely the bushings are worn out.
If the rack turns, then the accurate diagnosis is a large gap in the engagement. But this problem can be easily eliminated by tightening this very rail. Also, when pulling the steering rod, you may notice broken or overly worn bushings securing the steering rods to the steering rack.
Another possible cause of knocking is the steering joint. Testing this hypothesis with both hands will be quite difficult. You'll need a friend's help. The assistant must turn the steering wheel very quickly and sharply, and the car owner must grasp the hinge in such a way as to hold the hinge itself, its body and finger. If there is wear, you can feel the play. Then suspension repairs will not be necessary in the near future, and you will only have to buy and replace the hinge bushing.
Excursion to the manufacturers
Along with buying a new damper and boot, it makes sense to also buy a new shock absorber bushing. The trio of these products is designed to increase the service life of shock absorbers and increase their resistance to impacts. When choosing spare parts, you should also take into account the manufacturer. Bumpers can be found both in the assortment of large manufacturers of rubber-metal products and from packers. Dampers and anthers from:
- Sachs (Germany);
- Masuma (Japan);
- Monroe (USA);
- Boge (Germany);
- SAT (China).
Analogues with good affordability are offered by RBI (Taiwan), Lynxauto (Japan), BCGuma (Ukraine), Febi (Germany). It is worth noting that if large manufacturers of shock absorbers produce shock absorbers themselves, including at factories in the countries of registration, then small parts and consumables, such as boots and bump stops, are usually produced by factories in Asian countries. As practice has shown, the difference in quality can be significant. The same dust protection kits collect both positive and negative reviews, while the quality of the German company's shock absorbers impresses most buyers.
Upper rack support
This can also cause knocking in the front suspension over small bumps. On car forums, the topic dedicated to this knock is very popular. The reasons are different for everyone. In attempts to combat this annoying sound, car owners go through the entire suspension, but often the knock remains.
One possible cause is the upper strut support. It consists of a rubber part as a damper and a bearing. If this rubber element has lost its elasticity, then this is the cause of this extraneous knock that all drivers struggle with. In order to find out for sure whether this is so, measure the gap between the limiter and the support. In most cars this is easy to do, but in some models this unit may be closed. If measurements show that the gap is more than 10 mm, then the support must be urgently replaced. However, this gap is not always uniform. When measuring, it is recommended to focus on the average figure. It is worth checking this support carefully: on many cars this sound appears only on one side.
Classification of fenders
Despite the simple design, bump stops can be different. Due to the fact that load damping indicators must be different for different vehicle operating conditions, manufacturers produce bump stops of several classes. Externally similar products may belong to one of the following classes:
- Standard;
- For the track;
- For sports cars;
- For a comfortable ride.
Unfortunately, many car parts sellers do not specify which class a particular bump stop belongs to. Things are better in stores that work closely with manufacturers of rubber and rubber-metal products. If the full characteristics are not indicated anywhere, you can classify them yourself according to the following criteria:
- Standard bumpers. Same geometry and rigidity as standard dampers. The material in most cases is rubber;
- Road bumpers. Medium rigidity and thickness of the bridges, dense boot;
- Bump stops for sporty driving. High rigidity and large thickness of jumpers;
- Bump stops for a comfortable ride. Softness and a large number of thin bridges.
The bump stops for the front and rear shock absorbers are somewhat different, but sellers usually know where they are installed and can clarify. We only note that the front buffers are somewhat stiffer and stronger than the rear ones, since they take additional load. Requirements for the life of the front buffers, their resistance to temperature and chemical influences, are also more stringent, which is due to greater loads on the product (the front part of the car is heavier, since the engine is located in it).
Worn support bearing
These sounds appear in the same way as with an inelastic damper, but they are sharper and much louder. In order to make an accurate diagnosis in this case, it is necessary to remove the stand. It is recommended to take into account one rather interesting feature that is inherent in such breakdowns: bearing wear is always uneven. So, maximum wear is where it is constantly located when the car is driving straight. If after turning the steering wheel the knocking noise disappears for a while, then it is definitely a support bearing.
There is also another diagnostic method. It is quite old, but effective. You will need an assistant again. The second person should rock the machine up and down. At this time, the driver should feel the shock absorber rod with his hand. The knock will be transmitted to this rod.
Another possible reason is that the nut on the upper support is loosely tightened, sometimes this happens.
Spherical bearing
On car forums, in topics dedicated to this knock, a variety of reasons for knocking in the front suspension are discussed. Ball joints are one popular reason. One can say even more - this is a classic among all possible sources of extraneous knocks.
But there is one peculiarity here. On front-wheel drive cars, knocking noises from ball joints are very rare. It is more typical for classic VAZ models.
Thus, a worn joint can cause sharp vibrations when crossing small irregularities in the road. It is quite easy to diagnose this malfunction - pull the front wheel in a transverse direction. Naturally, it is advisable to lift the car for this. Beginners may confuse play in the ball joint with wheel bearing movements. In this case, the assistant must hold the brake before pulling the wheel, this will eliminate the hub play.
Sometimes an extraneous knock can be caused by a real trifle - check the rubber boots. Hinges cannot last long if the protective cover is torn.
Rack
Very often, knocking in the front suspension on small bumps is attributed to this particular unit. In reality, the stand is the source of knocking in very, very rare cases. But it’s worth checking, because this is a very important unit.
A heavily worn, very weak strut, even if it has not yet leaked, can cause shocks. When the car moves and the wheels fall into a hole, the rebound force of this strut is not enough, and it is not able to prevent the spring from straightening. The stand shoots the wheel down. When the wheel either touches the hole or hangs in the air, it stretches to its maximum. There will be a blow in both the first and second cases.
Conclusion
Shock absorber bumpers are an excellent option for modifying the suspension, if, of course, they have not yet been installed on your car. If you experience inconvenience when driving on poor-quality surfaces and are concerned about the life of your shock absorbers, we strongly recommend that you consider installing bump stops and strut boots. You can choose from both the assortment of large foreign companies and local manufacturers of rubber products for the secondary market of automotive parts. The cost of a high-quality dust protection kit usually does not exceed $60, and the bumpers from such a kit can last up to several years. We also recommend taking several spare boots.
Rack diagnostic methods
There are a lot of methods. The classic one is to swing the body down, and it should smoothly rise to its normal position and stop. If everything is so, then the rack is working.
It happens, although quite rarely, that the strut makes extraneous sounds due to its internal problems, for example, the nut that holds the piston has become unscrewed. However, this does not cause knocking. When driving, the car sways and controllability decreases. In this case, replace the strut and repair the suspension.
Various shock absorber breakdowns are the consequences of its improper use. The oil in these systems must have a special specific viscosity, which also depends on the air temperature. Having warmed up the engine, the driver immediately takes off, but the oil in the rack has not warmed up. If it’s frosty outside, then the viscosity in the stand is too high. In this case, thin and very fragile parts fail.
Thick oil may also not be related to the weather. Sometimes excessively thick liquid is poured into shock absorbers. This is done to increase the resistance force and so that the oil does not “run away”. But as a result, stability and controllability deteriorate, because hard does not mean good.
More information about the device and purpose
Spare parts for hafei princip
Rear drum brake pads
1.6 DA476Q
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Axle shaft (drive) front left 1.6 DA476Q
Car suspension shock absorbers are designed to absorb impacts that could be transmitted to the body while driving over uneven surfaces. In shock absorbers, the rod and oil seal suffer the most. It is not difficult to increase their service life - it is enough to solve the problem of strong shocks that are transmitted to the main components of the shock absorber. This can be done in several ways, but the simplest and most practical is to install a bumper . It not only softens impacts, but also protects products from sand, dirt and water. The bumper, otherwise called a buffer, is made of:
- Polyurethane foam. This is a fairly elastic material and products made from it can withstand strong impacts;
- Silicone. Soft material, resistant to aggressive chemical compounds and temperature changes;
- Rubber. Quite hard and not very durable, but cheap material. Doesn't absorb shocks well enough, but still gets the job done.
The bump stop is a corrugated product made of one of the above materials, in the center of which there is a hole through which the shock absorber rod is threaded. The buffer limits the stroke of the rod, dampens and partially redistributes the loads that are perceived by the rod and pistons of the shock absorber. In fact, this element helps the springs, which also absorb shocks and prevent the metal parts of the shock absorber from colliding with each other. Most models of fenders are equipped with an additional removable boot , which protects the product from the effects of pollutants, chemicals, abrasive materials, etc.
The bumpers without anthers resemble an accordion that folds under mechanical stress. In some cases, they are reduced to one link and this means that the shock absorber absorbs a strong impact. In such conditions, the bump stops wear out quickly and last a little longer than the life of the shock absorber, i.e. on average about 70-80 thousand kilometers. Hard fenders with high-quality anthers can have such a resource. Soft products with a large number of jumpers last less.
Brakes as a source of knocking
Sometimes sounds coming from the suspension are actually coming from the brakes. It happens that a car enthusiast has checked everything and replaced everything that can be replaced. The front suspension layout has already been learned by heart, but the knocking was still there.
To make a diagnosis, you need to move. If the knocking noise disappears when braking, and when the pedal is released, it resumes again, then the brake pads are to blame. The same problems can occur after installing new pads.
If the car is knocking, do not rush to repair the chassis. Perhaps the extraneous sound is caused by a completely different reason. In this case, only a complete diagnosis can help. It may be enough to replace the front suspension silent blocks and the sound will disappear forever.
I was tormented by a knocking sound (whooping) in the area of the front pillars (It doesn’t seem to be very audible and the sound is not clanging, but so unpleasant… … … …
The knocking appeared on bumps at low speeds. At higher speeds, due to the noise of the wheels and engine, the knock was not audible.
The entire front was covered. Everything seems to be normal. The mileage is only 20 thousand. The stands are dry.
I accidentally came across a comment - “the front anthers are knocking.” I googled the question and found several answers.
I also decided to try to eliminate the knocking noise.
I took off the front wheel. Later it turned out that you don’t have to remove the wheel, but simply jack up the car.
When lifting the car, the boot rises up. Underneath it I found a bunch of small pebbles and dirt. They probably also added noise.
Looking up, you can see the gap between the boot and its seat.
At the bottom, the boot is also thicker than the shock absorber, about a centimeter.
This is the reason for the knocking (noise).
In the video you can clearly hear that the boot is knocking (strongly) when moving up and down. And it makes a little noise when rocking left and right.
We pull the boot down with both hands and it jumps off its seat.
The blue arrow shows the ring (thickening) on which the boot is held. The red arrow shows the gap in which the boot moves up and down and knocks.
Take a piece of foam rubber and cut out a seal like this.
We push it into the boot seat.
We push the boot into place (you'll have to sweat).
The boot should fit tightly, the foam does not allow it to dangle (move).
Just in case, the gap between the boot and the seat was covered with the remains of the aquarium sealant.
Next, cut out a piece of sound insulation 15 centimeters long.
Glue it around the shock absorber. We deliberately leave a gap of one centimeter. The gap is necessary for air circulation in the boot when it is compressed and unclenched.
For Shumka, the boot is pulled tightly and does not dangle left and right)
I tried to tighten the boot on the Shumka with a tie. The boot is vacuumed, air flows poorly. Off-road, it will simply burst when squeezed sharply. I removed the screed.
Today I drove around the area, over bumps and holes - the knocking noise was gone!
Time will tell how long the knocking will go away... ...
PS Something like this! Don't switch - there will be a continuation...
Replacing rear shock absorber bump stops (A4, Tour)
07 Nov 2012 |
Repair | Kudrik | Discuss Having discovered a small tear on the bump stop of the rear shock absorber during the next wheel change, it was decided to change it.
To replace you will need:
1J0 512 131 — Bump stop for vehicles with PPD, original.
I used 77 01 59 from Elastogran, it costs 2 times less, I would initially rate the quality as 4, they are a little stiffer than the original ones, and the funniest thing is: I ordered 2 pieces, they received 2 bump stops slightly different in rigidity. The instructions say to replace all the nuts and bolts, I only replaced the self-locking nuts, the ones that secure the shock absorber to the beam.
Just in case of numbers, here are the dimensions that are written in ETKA 7.0 update 371:
N 103 041 02 — Shock absorber nut M10x1
N 102 861 10 — Lower fastening nut M10;
N 905 173 04 — lower fastening bolt М10х75х45;
N 906 484 02 — Bolt for fastening the upper support to the body M10x35;
You will also need:
- Combination key 16;
- Ratchet;
- Head 1/2 by 16;
- 6 key with open jaw;
- The key is 16 Z-shaped (the angle must be 75 degrees, a smaller one will not fit);
- Ratchet extension;
- Ideally, a torque wrench (I didn’t have one);
- Car stands;
- And a standard set that is included with the car.
First of all, it is necessary to follow SAFETY PRECAUTIONS. Do not crawl under the car if it is only standing on a jack; always place a reliable support that will not fall, at least place the wheel that was removed under the threshold. Do not keep your head in the same plane as the wrench you are using to tighten the nut. Don't take on a job unless you feel confident that you can finish it. Only the person performing the work bears full responsibility for the work and its consequences; this article is for informational purposes and only gives tips on how to make the subject more convenient and correct.
Initially, we put the car on the handbrake, in 1st gear and place a “shoe” under the diagonally opposite wheel. Raise the car to a height sufficient to remove the wheel and place it on a stand. Then remove the wheel and remove the ABC sensor wire mount from the body.
Unscrew the upper shock absorber mount (2 bolts).
We unscrew the lower shock absorber mount, hold it on one side, and twist it on the other.
Then we pull the beam down and take out the shock absorber strut.
Remove the cap by prying it off with a flat screwdriver. Unscrew the nut that secures the shock absorber and the upper support. To do this, hold the rod against turning with a 6 wrench and turn the nut with a Z-shaped wrench. I first moistened the nut with WD-40.
Removes the bump stop with the plastic bulb.
Let's look into this whole thing. To do this, pull the bumper out of the support and out of the plastic flask. And we collect everything with new parts. In order to press the bumper into a plastic flask, you need to twist it at an angle downwards in the direction of the special hole.
Then we put everything back together. We assemble the stand and screw it into place. It is important that the final tightening of the lower support must be done on a loaded suspension; to do this, we jack up the petal in which the spring rests. As always, there were some problems: I had a licked thread on the lower shock absorber mounting to the beam. I temporarily unscrewed it with an ordinary M10x80 bolt and a self-locking M10 nut, and put a washer in just in case. Now I’ll order a new normal bolt and nut, and everything will be fine. I spent 1.5 hours, but this was on the condition that I was doing it for the first time, some things put me in small dead ends (for example, pressing the support into a plastic flask and pyramids needs a little modification, otherwise it would be under the standard places if you put both a jack and a stand at the same time , it’s inconvenient), well, I had to take pictures and sometimes get distracted. In general, I think that it’s quite possible to do it in 40 minutes, and without rushing.
07 Nov 2012 | Repair | Kudrik | Discuss
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