Probable causes? Car drifts left when braking- requires countersteer to keep straight. Have a 94 E320 Starmark coupe 75K miles. Factory techs unable to find cause and have reviewed front:1)rotors- measured ok no glazing but sanded anyway, 2)pads- measured no glazing but sanded and switched left to right, 3)front suspension- ok, 4)tires balanced- wear and tread ok,
5)suspension alignment-ok 6)bled brake lines
Ideas on possible causes? thanks and great site-fad

Do passenger cars have the equivalent of a race car's "brake bias" dial? Like maybe an "equalization" valve, or something? What about your right side brake line path -- could it be "plugged" such that the left side grabs harder than the right? Is there a way to check the caliper braking "force" that's applied to the rotors?

How about the rear tracking rod or pulling strut bushings?

I know this doesn't solve your problem, just throwing a few more questions out there so maybe we can all benefit from the answer(s).

Brian

Hey, no offense I assure you, but if it's a Starmark car make THEM figure it out!!! That's what the warranty's for, eh?

For starters (and I know it sounds obvious), ensure front tire pressure isa uniform. From there I'd start perhaps by rebuilding the calipers...something's causing disproportionate braking force, and I find a hydraulic line an unlikely cause especially in a '94 car. From there I really don't know, but htere's no apportioning valve I'm aware of.

Good luck and please post your resolution

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Best regards, Michael
'92 500E
'88 300TE

[QUOTE]Thanks Michael and Brian16V.
I've given the car to the factory techs 3x this month to help me fix this problem. Early this week it was escalated to the shop foreman and has said that unless the cause(s)can be isolated-he can not proceed with a Starmark warranty repair or customer paid repair and is not willing to just start replacing parts in hopes of solving it. He stated that he has done everything he knows of to isloate/locate the cause- short of arbitrarily replacing calipers, rotors,lines, bushings. I accepted the car back yesterday- mystery still unsolved. I do trust the integrity of the factory techs but may be resigned to live with the drift.



[This message has been edited by -fad (edited 02-29-2000).]

You shouldn't have to live with anything....something's wrong and it's their obligation to fix it. It didn't drift when it left the assembly line, so it shouldn't now! If the local tech can't ID the problem, ask that they contact the regional tech support person...or you'd be more than happy to do so on their behalf. Do NOT settle...something's wrong and it needs to be fixed. In an emergency situation, your condition poses a risk that NO MBZ tech would ever want to see out on the road.

Stay with it and let us know.

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Best regards, Michael
'92 500E
'88 300TE

An easy thing you can do yourself is to rotate that front left tyre to another corner and see what happens. You shouldn`t have to live with this on a Benz. Mine is an 88 w124 and I can take my hands of the steering wheel and stop in a straight line and nothing has been replaced since factory. The drag link will be done for the first time next month I mean come on....
Yal


[This message has been edited by yal (edited 02-29-2000).]

Similar thing happened to my '90 300se except it drifted right under braking. I replaced the front shocks and bushes and it was ok after that. The previous shocks seemed ok but I guess the shock on the right had a little more wear than the left one. You can't really tell the conditions of the shocks just by looking at them. Hope this helps.

Kevin
'70 280sl 5spd
'90 300se
'98 E320

I had that problem once on my 81 300d. It turned out to be a rear brake problem, sticky caliber. My car stops from any speed perfectly straight..don't settle.

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Mark B

81 300D

-fad,

Michael and yal both made good suggestions. I think I would move the tire myself, because tires are probably not covered under your warranty. If they were to do a lot of work and found that it was the fault of a tire, you would be in a bad situation.

After ensuring that the tire is not the problem, take Michael's advice and call the regional MB representative. Be persistent and don't take any nonsense. I went through an intermittent problem with an M-B dealer once. It only showed up occasionally, I finally got the regional rep involved who had them drive the car until the problem showed itself. They fixed it. Had I not gone over their heads to the rep, I would never have gotten any satisfaction from that particular dealership. I believe that most dealers will be persistent and find your problem. But there are a few who just want to make some flimsy excuse to get you out the door so they can go home to supper.

Check the tire and then don't take any guff. I'll bet you worked hard for the money you paid them, occasionally they have to work hard to satisfy their customers. Life's tough.

Good Luck,

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Larry Bible
'84 Euro 240D, 516K miles
'88 300E 5 Speed
Over 800,000 miles in
Mercedes automobiles

Thanks for your strong support-it's really appreciated. I have certainly worked hard for this vehicle and purposefully sought out the best Starmark (travelled to S.Cal from SF to test 7 '94-'95 E320 coupes)and paid a premium for this one expecting the best. I'll approach this problem doing what I can do first and then raise the balance of the possible causes with our "higher source". I'll post resolution so we'll all expand the knowledge database.
tks-fad

tks-fad

Apologies for the tardy follow-up.

The problem was fixed by changing the front brake pads.

Although the pads were at 50% wear, it seemed to be the easiest and most cost effective attempt on my part to eliminate possible causes.

I believe factory authorized service did try their best to diagnose the cause of the pulling (after numerous times of not being able to verify complaint). However, we came to a point where service would not just "start replacing parts without diagnosing it as the cause of the problem".

FYI- attempts to cure pulling prior to changing pads included: 1) exchanging brake pads- left to right, 2) hand sanding front rotors, 3) inspecting all calipers of proper functioning, 4) front end alignment, 5) tire balancing and rim inspection for bending/ damage, & 6)brake system bleeding

-fad

Maybe pads were contaminated
 

I know if you even get a small amount of brake fluid on the pads, the brake will tend to grab the rotor. Oil, on the other hand, does the opposite by allowing the rotor to slip. I used to have terrible brakes on my car. New pads all around made a vast improvement. I think the PO must have driven the car through a gushing oil well or something because all of the pads were oily and were equally poor at braking. Or mabe it had something to do with the once massive oil leaks that the car came with.:rolleyes:

Gary

I have another theory. It could be that one of your calipers has a bad piston/bore. The piston could be meeting with resistance in the bore and thus causing it not to apply the same pad to rotor pressure as the opposite side. By replacing the pads, you moved the piston further up into the bore of the caliper, thus remedying the problem. If later in the life of the pads the problem arises again and you don't find any source of contamination, I would suspect the caliper.

Q is right on target!
 

Q took the words right out of my mouth (or is that 'off my keyboard'?). This seems to be the case, and the problem is VERY likely to recur when the piston travels down the bore again as the pads wear. I hope that your car is still covered by the warranty at that time, otherwise, I would force the issue NOW.