Weird ! Fishtail on acceleration/deceleraltion - PeachParts Mercedes-Benz Forum

zorin · #1 12-07-2003, 10:54 PM

Hello all,
1988 260E - 200K miles

For the past week or so I have noticed that when I accelerate or decelerate, even though the road is dry , the car sort of fishtails slightly. i.e. I slam the gas pedal to accelerate, the rear slightly throws to one side. I take my foor off the gas pedal to decelerate
and the same thing happens . It's as if one of the rear wheels hesitates or has a delay.

It's a scary feeling when you're on the highway and this happens.

Could it be a bad CV joint, a bad differential or loose control arms?
Please help.

Thanks

psfred · #2 12-07-2003, 11:01 PM

Bad torque links on the rear suspension. Replace both sides.

In fact, probably want to do the "kit" thing from BuyMBParts (I think they are the ones) -- all eight links for something like $250.

MB's multi-link rear suspension design uses flexing bushings -- the steel core is bolted up tight, and the rubber flexes on both ends to add spring effect. Very nice, but the rubber can deteriorate, and when it does, usually on the torque link (upper diagonal one), the toe on the rear wheel changes rather significantly on both acceleration and deceleration. This causes the rear end of the car to steer. Very uncomfortable.

Check the rear subframe and diff mounts while you are in there, chances are they need to be replaced, too. Mine certainly do -- I'm collecting parts and intend to remove the rear subframe for the work.

Peter

zorin · #3 12-07-2003, 11:08 PM

Thanks Peter. I will do that.
Will I need wheel alignment once I replace the torque links?

sbourg · #4 12-08-2003, 10:08 AM

Check the condition of the rubber bushes on your rear links. If they aren't crumbling or otherwise in obvious condition of advanced deterioration, it would be a premature expenditure to replace everything now. Look first for a loose attachment bolt - all it takes is one to cause squirrely handling, and there are a lot of them back there.

Steve

psfred · #5 12-08-2003, 06:33 PM

The bolts would have to be VERY loose to cause trouble, and I'd not expect them to get that way anyway.

Very likely to be links, right age and milage.

Peter

zorin · #6 12-19-2003, 04:51 AM

I have ordered the parts. I will keep you posted after I replace the Torque Links.

Thanks.

sbourg · #7 12-19-2003, 02:20 PM

Quote:

Originally posted by psfred
The bolts would have to be VERY loose to cause trouble, and I'd not expect them to get that way anyway.

Very likely to be links, right age and milage.

Peter

Apparently it hasn't happened to you - it has to me. One bolt, slightly loose, very squirrely handling. Handling has been flawless ever since I tightened it.

This is much more likely than all the bushings failing, since onset was quick, according to the poster.

Steve

psfred · #8 12-19-2003, 02:30 PM

Worth a check, but my torque link(s) failed abruptly -- I dodged something on the road late one night (turned out to be a tree branch with leaves, but looked solid at the time), and immediately got a "loose" rear end. I think the rubber tore when I jerked the car around.

I've got new links for the left side (did the right ones this summer), since I still have some looseness back there, but on the left rather than the right side. Definite sloppyness in handling with wet or icy road surface.

All the bolts were rusted down solid, took quite a bit of effort to get them loose!
Peter

zorin · #9 04-05-2004, 11:14 PM

I replaced the torque links with the new ones couple of months ago but that did not help. Ever since then I have been trying to figure out the problem. All the other bolts and links at rear seem OK.

Last week I suspected the Differential , so I lifted both rear wheels and started the engine and put the gear on Drive. Only the driver side rear wheel was turning. I tried to move the passenger side rear wheel by hand but the driver side was still turning much faster. I suspected the seized break caliper. I opened the caliper on the passenger side and cleand and lubricated it. After I assembled the break caliper I did the same test and this time both wheels were truning on "D". The problem disappeared for few days only to re-appear again. I thought the break has seized again but I lifted the rear of the car and both wheels were turning OK on "D".

The differential is NOT a "limted slip" one. I have changed the Diff oil twice in the last few months (Hypoid C 80W90) .

The symptom remains: accelerate from cruising, the front of the car jerks to the right, lift foot off the gas pedal, the front of the car jerks to the left before it straightens out, as if one rear wheels moves at a different speed than the other one momentarily.

I can not determine for sure if it is the differential that is causing the problem, and visibily nothing wrong with the shafts at either side.

Any help would be appriciated.

Thanks.

sbourg · #10 04-06-2004, 12:21 AM

If only one wheel were receiving power, the other one should still force the car to track properly. Mistracking under acceleration is almost certainly caused by a change in rear steering angle from a loose attachment - either deteriorated bush or loose bolt. Make certain too that your rear sway bar plastic links are there and attached at both ends. This could cause a similar problem under very abrupt maneuvers. Of course, check the rear subframe mounts for failure too.

Steve

Freestyler · #11 04-06-2004, 01:35 AM

Would it be insulting to ask you if you checked the tire pressure?
Low pressure in one of the rear tires can cause this very behaviour.

Freestyler

sajecw · #12 04-06-2004, 01:35 AM

My rear tie rods were loose when the alignment guy forgot to tighten them. I thought someone hit me from the side the first time it happened.

At first I though it was a bad rear or bushing, but it was loose bolts.

Go over everything with a gun, because I thought they were fine under visual inspection.

william rogers · #13 04-06-2004, 01:52 AM

grease gun?

William Rogers..........

sajecw · #14 04-06-2004, 01:54 AM

Quote:

Originally posted by william rogers
grease gun?

William Rogers..........

No, I meant to say impact gun. Although grease would may the problem quiter.

I am not saying I have the same car, but the problem was so simple and we thought the worst.

haasman · #15 04-06-2004, 02:07 AM

Zorin

I am wondering if you are looking for the problem at the wrong end. Check the front suspension, but specifically you pitman arm bushings.

If you can, get someone to gently rock the front wheel (holding it at the nine and three o'clock position while you put your hand on the pitman arm bushing area and see if you have movement.

Also a good time to check the rest of the tie-rods etc.

Is your steering dampener in good shape?

Haasman