car STILL pulls to the left, running out of things to replace!
 

The car is a 1987 420SEL. I have: had the front rotors turned, replaced front pads, replace front rubber hoses, and replaced the front calipers with professionally rebuilt ones. What else could cause it to pull? It is VERY sharp. You have to turn the wheel quite a ways to the right to keep from doing a 180! Both front wheels seem to have equal heat/dust on the rims after driving. Could one piston being bad in the RR caliper cause it to pull very bad? It does it even on light braking, so I figured it would definitely be in the front.
Could a problem like this be an ABS thing? The light isn't on, and it seems to work whenever it's needed. This problem seemed to just start up one day and has gotten slowly worse over time. I want to try and disable the ABS, but I coudn't find a fuse, and I didn't know what relay it is. I didn't think it would help, but I just wanted to try and knock the off the list of possibilities, since I'm running out of other things to replace.
Thanks
David

Have you checked tire pressure? Have you had the alignment checked?

Sixto
95 S420
87 300SDL

The car's had an allignment, and the tires are about 3,000 miles old. I don't think one of thopse even being slightly off could cause it to pull as bad as it is.
Thanks
David

Master cylinder (one of 2 systems failing), deteriorated front subframe mounts, worn idler arm bushes, and lots of other stuff you may have checked but not mentioned.

Steve

you may have tried this already, but have you switched the front wheels? My car was pulling to the right even after a proper alignment and various components replaced. Switched the fronts over and boom- straight tracking. The car still follows the road camber but I hear this is a normal trait with Merc steering.

Its very difficult to help answer a question like this when anything in the front end may cause a pull and even some things in the rear end may cause your car to drive crooked. Sometimes the problems are related.

Has the front end been checked for worn parts? Pushing and pulling the tire at 12 & 6, 3 & 9 o'clock ? Have the bushings and upper controls been checked for wear? Have the tires been swapped side to side (tires can pull very badly) ?

Throwing parts at a problem is frustrating.

I agree with brian it may have nothing to do with your brakes. My tie rods are worn and I pull to the right when braking, I am having then changed next week.

Tire pressure difference will surprise you especially with a Benz. Mine is so sensative that a 1 pound difference on either side will cause the car to drift. Eleminate that possiblity by making sure the pressure is equal on both sides and at the right setting.

First, keep in mind that if the car pulls to the right, then the left rear brake may be the problem, or if it pulls left it could be the right rear brake. Also remember that it may not be a problem with one brake not working, but another working too good.
A trick I have been using for years is find a dirt road, hard dirt field, grass field, etc. Then do a semi-panic stop on one of these serfaces. After you stop, get out and look at the tire tracks left in the dirt. An outside observer also helps. Look for signs of brakes not enguaging at the same time, or not at all, or possibly one brake locked up sooner than the rest of them.
I think you get the idea. When you find one brake not working like the others, you know where to start.

Bad bushings on the rear controls arms does this too -- however, it will steer the OTHER way on acceleration.

I'd take a look at the track rod bushings. If one is bad, that wheel will move back on braking and cause steering geometry changes.

Peter

We have checked the front-end for worn parts. Every once in awhile I hear a slight clunk noise when hitting a pot hole at slow speeds, so I think it will need ball joints. Everything else looked pretty good actually. Idler arm, tie-rods, etc were really good. If it were the subframe mounts would the car really pull really bad?
Thanks
David

Sbourg, I thought the master cylinder is dual-circuit? It controls front and back, not left to right. Are there any kind of proportioning valves in the front? When we bled the brakes, each side seemed to have equal rpessure coming out of the screw. I know that's not a very scientific statement. Are you saying I should rotate them front-back, or left-right?
Thanks Again
David

David:

Clunk on bumps is a bad track rod to body bushing.

Peter

Could this be a master cylinder or perhaps an ABD pump? I wouldn't think that this would have anything to do with that system though, becasue when ABS systems are down, brakes work fine, just not ABS.
Thanks
David

Sounds to me like a guide rod mount. Visual inspection of bushes is difficult, often they look fine but when you take them apart it is obvious they are very worn.

Check tire pressures, rotate wheels and get another alignment if it hasn't been done since the problem was occuring.

If you can't diagnose this further then a trip to an experienced mech is in order.

Matt.

How do I test the guide rod mounts? I am now thinking that also, because on my way home tonight it was making this very loud "pop" noise at the slightest bumps while moving slowly. It didn't seem to do it very much over maybe 30-35? It is coming from the left and it sounds as if it were right under my feet or just in front of them.
Thanks
David

The origin of sounds can be pretty deceptive.

I would suggest taking the car in to get it professionally checked out, probably cost you an hour or so for someone familiar with W126's to diagnose the problem.

Once you know what's wrong there's write-ups on here for pretty much every piece of front end work.

Matt.

David, what kind of tires did you put on? Did you notice the pulling when you changed to these new tires? I have seen certain brands of tires (Goodyear Aquatread comes to mind) that defied all attempts at alignment on my W123. Different tires solved the problem instantly.

I'm not saying this is your problem, just wondering if you can correlate the addition of your (relatively) new tires and the onset of this pulling problem.

On our 190E it is front/back, but many other vehicles I have worked on used a cross-control split.

Worn bushes anywhere in the front suspension outside the sway bar will flex excessively under braking load, and this will change suspension geometry, and thus steering direction.

Steve

After your comments about professional techs and being "ripped off" I've pretty much ignored you.


Now I read this and see you have fallen into the trap of tossing parts at it instead of fixing it.


Maybe now you understand the benefits of training, experience and competence.










BWWWAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA AAAAAAAAAAAAAA!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!


I hope you wallet survives the repairs needed to fix the car.



Joe

I never said anything about professional techs. I just don't like one in particular one in town, that's all. I have great respect for mechanics, guess what I do? My uncle's also a mechanic, just not one of those mercedes type people.
Besides, replacing calipers on a 17 year old car with almost 200k miles isn't a bad idea. Nor is replacing the rubber hoses that accompany them since it's pretty standard.
Thanks
David