Damped knocking under braking
03-28-2014, 08:25 AM
#27
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2004 W203 270CDI
I'm not certain I know what you think of.
Can you please show me a picture of that?
Is it the four rubbers that steering rack is mounted on?
If those are bushings, then where are the bolts?
Can you please show me a picture of that?
Is it the four rubbers that steering rack is mounted on?
If those are bushings, then where are the bolts?
03-28-2014, 08:47 AM
#29
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2004 W203 270CDI
Thank you very much.
I just found out about these two threads, they helped too:
1. Replacing steering rack bushings ... must I remove the rack?
2. knocking noise when i turn the steering wheel
I have the same symptoms as those guys. I will order now all 4 bushings. Is there something else I should consider?
Also, I'm trying to understand this post but my English is not so good, if someone can translate to something easier to understand I'd be grateful.
I just found out about these two threads, they helped too:
1. Replacing steering rack bushings ... must I remove the rack?
2. knocking noise when i turn the steering wheel
I have the same symptoms as those guys. I will order now all 4 bushings. Is there something else I should consider?
Also, I'm trying to understand this post but my English is not so good, if someone can translate to something easier to understand I'd be grateful.
I read a TSB about this for which no remedy exists yet.
Cause:
Torsion of the hydro-mount in the strut rod.
When maneuvering, the hydro bushing end stop plug can collide with the inside of the outer sleeve.
In isolated cases, this surface can exhibit pinpoint wear depending on the operating conditions of the vehicle. This wear is caused by the end stop plug resting against the outer sleeve during braking maneuvers.
As the end stop plug slides over the damaged area, fluctuations in friction pairing occur which cause the knocking/creaking noises.
Note:
The noise can generally be reproduced by driving a figure-8 in reverse. If the noises occur during this maneuver, the steering gear is not the cause of the problem and must not be replaced.
Remedy:
No remedy exists at present time
Cause:
Torsion of the hydro-mount in the strut rod.
When maneuvering, the hydro bushing end stop plug can collide with the inside of the outer sleeve.
In isolated cases, this surface can exhibit pinpoint wear depending on the operating conditions of the vehicle. This wear is caused by the end stop plug resting against the outer sleeve during braking maneuvers.
As the end stop plug slides over the damaged area, fluctuations in friction pairing occur which cause the knocking/creaking noises.
Note:
The noise can generally be reproduced by driving a figure-8 in reverse. If the noises occur during this maneuver, the steering gear is not the cause of the problem and must not be replaced.
Remedy:
No remedy exists at present time
Last edited by Meca; 03-28-2014 at 08:50 AM.
04-15-2014, 05:59 PM
#31
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2004 W203 270CDI
OK, so finally, after a year, the problem is solved...
It was the steering rack bushings:
Besides them, we also changed all control arm bushings and sway bar bushings, the car feels very smooth now, like new!
Thanks everyone for the help, I really appreciate it.
It was the steering rack bushings:
Besides them, we also changed all control arm bushings and sway bar bushings, the car feels very smooth now, like new!
Thanks everyone for the help, I really appreciate it.
04-15-2014, 08:03 PM
#32
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2007 C230SS; 2014 ML350 BT
Glad you got it sorted out! The steering rack bushings are not particularly robust on these cars. Had my whole entire steering rack and bushings replaced at just under 60K miles. They are worn out again and need to be replaced and I just hit 123K miles
12-12-2014, 02:12 PM
#34
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2004 W203 270CDI
It's been...how much, 8 months since I installed new bushings ?
What do I do now?
Buying new bushings every 8 months is out of the way. I don't get it, how can this fail so much?
Is there any other version of these bushings? Maybe of some other, more durable material ?
Also, I don't know if I'm imagining or what, but I think my car pulls slightly to the right, even after the alignment. Any hints on that ?
12-12-2014, 04:58 PM
#35
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Maybe a front suspension rebuild should be part of the 'A' service? ... 
I just replaced my rack bushings a few months ago and it made a difference. That last bit of steering pull-to-the-right disappeared. There is still something loose in the rack, but I haven't checked the inner or outer tie rods yet so I'm hoping it is one of those vs internal rack play.
You said 8 months only? What brand parts have you been getting? I bought Lemfoerder control arms and sway bar links, an MB sway bar (with molded on bushings), and Corteco strut, motor and transmission mounts.
Oh yeah -- have you replaced your motor and tranny mounts yet? They make a difference as well.
I just replaced my rack bushings a few months ago and it made a difference. That last bit of steering pull-to-the-right disappeared. There is still something loose in the rack, but I haven't checked the inner or outer tie rods yet so I'm hoping it is one of those vs internal rack play.
You said 8 months only? What brand parts have you been getting? I bought Lemfoerder control arms and sway bar links, an MB sway bar (with molded on bushings), and Corteco strut, motor and transmission mounts.
Oh yeah -- have you replaced your motor and tranny mounts yet? They make a difference as well.
12-12-2014, 05:30 PM
#36
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I just replaced my rack bushings a few months ago and it made a difference. That last bit of steering pull-to-the-right disappeared. There is still something loose in the rack, but I haven't checked the inner or outer tie rods yet so I'm hoping it is one of those vs internal rack play.
You said 8 months only? What brand parts have you been getting? I bought Lemfoerder control arms and sway bar links, an MB sway bar (with molded on bushings), and Corteco strut, motor and transmission mounts.
Oh yeah -- have you replaced your motor and tranny mounts yet? They make a difference as well.
You said 8 months only? What brand parts have you been getting? I bought Lemfoerder control arms and sway bar links, an MB sway bar (with molded on bushings), and Corteco strut, motor and transmission mounts.
Oh yeah -- have you replaced your motor and tranny mounts yet? They make a difference as well.
I changed almost everything in the front end and I always hear something more rattling.
Brand of the bushings... I think Lemforder or MB. Everything was ordered from MB parts dealer.
All motor and tranny mounts were replaced when I purchased the car, 2 years ago. This is driving me mad.
12-13-2014, 12:32 AM
#37
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The A service is the basic oil change service ... about once a year
I'm really surprised the bushings would appear to not be lasting anywhere near as long the second time around. I hope MB doesn't supply inferior parts for their replacement parts vs factory install. My guess would be that it's yet again something else in there that hasn't been touched yet. Either that, or your auto mechanic didn't torque some bolts correctly and they're allowing some shifting of suspension parts.
As I mentioned, I'm still chasing down that last bit of play/noise in the front suspension. I'm also starting to think I'm just getting overly sensistive to the noises ... maybe I should test drive a new car just to calibrate my senses ...
I'm really surprised the bushings would appear to not be lasting anywhere near as long the second time around. I hope MB doesn't supply inferior parts for their replacement parts vs factory install. My guess would be that it's yet again something else in there that hasn't been touched yet. Either that, or your auto mechanic didn't torque some bolts correctly and they're allowing some shifting of suspension parts.
As I mentioned, I'm still chasing down that last bit of play/noise in the front suspension. I'm also starting to think I'm just getting overly sensistive to the noises ... maybe I should test drive a new car just to calibrate my senses ...
12-13-2014, 09:20 AM
#38
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The A service is the basic oil change service ... about once a year
I'm really surprised the bushings would appear to not be lasting anywhere near as long the second time around. I hope MB doesn't supply inferior parts for their replacement parts vs factory install. My guess would be that it's yet again something else in there that hasn't been touched yet. Either that, or your auto mechanic didn't torque some bolts correctly and they're allowing some shifting of suspension parts.
As I mentioned, I'm still chasing down that last bit of play/noise in the front suspension. I'm also starting to think I'm just getting overly sensistive to the noises ... maybe I should test drive a new car just to calibrate my senses ...
I'm really surprised the bushings would appear to not be lasting anywhere near as long the second time around. I hope MB doesn't supply inferior parts for their replacement parts vs factory install. My guess would be that it's yet again something else in there that hasn't been touched yet. Either that, or your auto mechanic didn't torque some bolts correctly and they're allowing some shifting of suspension parts.
As I mentioned, I'm still chasing down that last bit of play/noise in the front suspension. I'm also starting to think I'm just getting overly sensistive to the noises ... maybe I should test drive a new car just to calibrate my senses ...
The car is serviced according to service book, I don't know about front suspension rebuilding, but I've changed almost everything in the front end.
Shocks, bushings, control arms, steering rods, all the accompanying bits and pieces, etc.
Now I got problem with front discs, which I bought several months ago and already had to do turning on them because they bend (I'm not driving fast or braking heavily). Now they've bent again.
Combine that with constant front end problems and dashboard rattlings (which seem to appear and go away randomly) and I'm getting really
Do you perhaps know where to find torque requirements for these rack bushings, I'd like to check them just to be sure?
3 days ago we tried them "by hand" and they were tightened alright.
Last edited by Meca; 12-13-2014 at 09:23 AM.
12-13-2014, 11:03 AM
#39
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Meca, reading your posts it almost seems that you have been getting fake Chinese parts. Looks like it's a common practice in some countries. Are you buying parts at the official MB dealer or some MB 'reseller'? Dealer usually also gives a 1 year warranty, so you may try to remove the rack bushings and have them replaced if they are worn...
12-15-2014, 01:58 PM
#41
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Thanks guys...
Well, they shouldn't be of questionable quality.
Parts come from a certified MB parts dealer.
I'll have to investigate further, maybe something else is causing rack bushings to wear out prematurely.
Well, they shouldn't be of questionable quality.
Parts come from a certified MB parts dealer.
I'll have to investigate further, maybe something else is causing rack bushings to wear out prematurely.
12-16-2014, 12:01 AM
#42
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Have you determined that the rack bushings are worn out after 8 months? If you replace them again, please take a photo to show us.
On my car, the worn rack bushings allowed for the rack to move side-to-side slightly when there was pressure on the steering system. So when the crown of the road leaned to the right, the car would veer to the right, and vice versa. Replacing the bushins removed that. I don't know if you have the same symptoms as me ... I just find it hard to believe that these bushigns would wear out so quickly, when the others lasted several years.
On my car, the worn rack bushings allowed for the rack to move side-to-side slightly when there was pressure on the steering system. So when the crown of the road leaned to the right, the car would veer to the right, and vice versa. Replacing the bushins removed that. I don't know if you have the same symptoms as me ... I just find it hard to believe that these bushigns would wear out so quickly, when the others lasted several years.
12-16-2014, 09:07 AM
#43
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Have you determined that the rack bushings are worn out after 8 months? If you replace them again, please take a photo to show us.
On my car, the worn rack bushings allowed for the rack to move side-to-side slightly when there was pressure on the steering system. So when the crown of the road leaned to the right, the car would veer to the right, and vice versa. Replacing the bushins removed that. I don't know if you have the same symptoms as me ... I just find it hard to believe that these bushigns would wear out so quickly, when the others lasted several years.
On my car, the worn rack bushings allowed for the rack to move side-to-side slightly when there was pressure on the steering system. So when the crown of the road leaned to the right, the car would veer to the right, and vice versa. Replacing the bushins removed that. I don't know if you have the same symptoms as me ... I just find it hard to believe that these bushigns would wear out so quickly, when the others lasted several years.
I think my car slightly pulls to the right in general, because recently I found a part of the road that's slightly leaned to the left, and it kept going straight.
I asked a guy from MB dealership, and the bushings he sold me are original Mercedes.
I'm trying to think of what could cause bushings to wear out prematurely. I just don't know about this stuff enough to come to conclusion, that's why I spend days and days in mechanic workshops, driving myself and others nuts, and overall looking like a nut case.
But this problem is something I have to listen to every day, they don't.
12-16-2014, 10:14 AM
#44
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There is really nothing that could wear out the rubber that quickly. Those bushings have metal cores with bolt collars so you cannot squish the rubber any more than they allow. The rubber itself should last several years under normal weather conditions.
You said you had a new rack installed that included factory-installed bushings? That should theoretically rule out improper insertion of the bushings into the steering rack mounting tabs. Tearing the rubber during insertion seems about the only thing that could possibly have happened.
You said you had a new rack installed that included factory-installed bushings? That should theoretically rule out improper insertion of the bushings into the steering rack mounting tabs. Tearing the rubber during insertion seems about the only thing that could possibly have happened.
12-16-2014, 10:19 AM
#45
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No, the rack isn't new.
Previous owner had 18" wheels on the car.
I'm starting to suspect that something's wrong with the rack itself.
Lately I noticed something new. Driving straight, and moving the wheel slightly from left-right and vice versa reveals some kind of wobbling.
The same as when brake discs are bent and create vibrations while you drive/brake, but here it wobbles a bit while going slowly in the straight line and only for a starting few cm's when turning the wheel from "center" position to either side.
I wonder if bent discs have something to do with it.
Previous owner had 18" wheels on the car.
I'm starting to suspect that something's wrong with the rack itself.
Lately I noticed something new. Driving straight, and moving the wheel slightly from left-right and vice versa reveals some kind of wobbling.
The same as when brake discs are bent and create vibrations while you drive/brake, but here it wobbles a bit while going slowly in the straight line and only for a starting few cm's when turning the wheel from "center" position to either side.
I wonder if bent discs have something to do with it.
12-16-2014, 10:42 AM
#46
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Sorry, somewhere in the thread I thought I saw a note about replacing the rack.
So, if the bushing were installed by force that could potentially rip the rubber. Sounds like a low probability of that happening, but you never know ...
If the rack is original, then I wouldn't rule that out. I am still working on that last bit of play inside my steering system, I haven't touched the inner or outer tie rod ends so I am hoping it is them and not something inside the rack.
Warped rotors are never fun. I would suggest just replacing them. MB might use Balo brand rotors ... I bought Zimmerman for my car -- including rear drilled rotors for the sportier look -- and they have held up well for the last two years with no warping.
So, if the bushing were installed by force that could potentially rip the rubber. Sounds like a low probability of that happening, but you never know ...
If the rack is original, then I wouldn't rule that out. I am still working on that last bit of play inside my steering system, I haven't touched the inner or outer tie rod ends so I am hoping it is them and not something inside the rack.
Warped rotors are never fun. I would suggest just replacing them. MB might use Balo brand rotors ... I bought Zimmerman for my car -- including rear drilled rotors for the sportier look -- and they have held up well for the last two years with no warping.
12-16-2014, 01:14 PM
#47
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If you find what was causing problems on your car, let me know. Maybe it's similar to my problem.
I can get new original Mercedes rotors for $230 here (both, front). Don't know about other brands.
I can get new original Mercedes rotors for $230 here (both, front). Don't know about other brands.
12-17-2014, 09:19 AM
#48
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Hmm I just noticed something.
An hour ago, I was coming at a U-turn and had to do it quickly because there were cars incoming.
I approached a U-turn, hit brakes, then turned my steering wheel all the way to the left. While turning it, something was knocking down there.
So, it was a combination of braking+turning the wheel.
Any hints ?
An hour ago, I was coming at a U-turn and had to do it quickly because there were cars incoming.
I approached a U-turn, hit brakes, then turned my steering wheel all the way to the left. While turning it, something was knocking down there.
So, it was a combination of braking+turning the wheel.
Any hints ?
12-17-2014, 10:55 AM
#49
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For me, the remote knocking sound was the control arms ... I had to replace both upper and lower before they went away. I replaced the struts along with the uppers, and there was still some knocking after that, so I know it wasn't the struts. Once I replaced the lower control arms that knocking stopped.
Another potential culprit is the sway bar links ... I looked back through the thread and you never mention replacing them (you mention bushings but not links).
Sway bar links are known to cause knocking noises on many makes of cars.
I haven't had this particular issue since I replaced my links early on when I started replacing suspension parts, but if you have not replaced them on your car then that is something I would look at.
Another potential culprit is the sway bar links ... I looked back through the thread and you never mention replacing them (you mention bushings but not links).
Sway bar links are known to cause knocking noises on many makes of cars.
I haven't had this particular issue since I replaced my links early on when I started replacing suspension parts, but if you have not replaced them on your car then that is something I would look at.
12-17-2014, 10:58 AM
#50
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Another thing I just thought of -- hopefully not in your case -- is if the mechanic tightened the control arm bushing bolts with the load off the suspension, he would be tightening the bushings to the car at the wrong angle, and when you lowered the car the bushings would be stretched (10+ degrees of angle) and could fail prematurely under normal use.
You might be able to tell by just taking a close look at the rubber in the bushing to see if it looks twisted, stretched, cracked.
You might be able to tell by just taking a close look at the rubber in the bushing to see if it looks twisted, stretched, cracked.
Last edited by jkowtko; 12-17-2014 at 06:29 PM.
