Rear end clunk

[500ESpain]

Hi, guys

I have a clunk at the rear end. It happens mostly when I lift off the throttle and then accelerate again. It also happens when shifting from R to D with foot on the brake. I was thinking about differential mountings and/or rear subframe bushes or maybe too much play on the halfshafts. What do you think?

 

[gsxr]

I agree, check the diff mounts, subframe bushings, and flex discs on the driveshaft. It's not likely to be the halfshafts (axle shafts).

 

[Glen]

Agree...differential bushings first.

 

[500ESpain]

Thanks, guys. I forgot to tell you that I've already changed all the rubber in the driveline (flex discs, center bearing housing). Was the first thing I did with no success.

I'm not doing the job myself because I don't have a lift but is it a difficult job to do (especially the subframe bushings) for an average mechanic? Is there anything I should change too while doing these jobs?

 

[gerryvz]

You may want to change the rubber bushings at the tops of each rear strut where it bolts to the car. These get compressed and brittle with age and wear, and are a very often overlooked "chassis rubber" piece that I am always harping on about. They are extremely inexpensive and a pretty easy DIY job to replace. There are two rubber pieces per strut - a top and a bottom piece.

This has been known to cause frustrating clunking that otherwise has no known remedy.

Cheers,
Gerry

 

[500ESpain]

Thanks! I've read your posts about this item but I'm not quite sure where are exactly located. I understand they are where the springs meet the body, is that correct? If I'm right, I`ll need a spring compressor or is it easier than that? I'm a little bit lost. Thanks again!

 

[gerryvz]

You can see the parts I mentioned, rubber buffers, at #23 and #29 in the diagram below.

The part numbers are as follows, and you need TWO of each:

124 326 03 68
201 326 18 68

You don't need a spring compressor. Basically you just need to unbolt the rear struts from inside the car (at the top) and replace the buffers.

I believe there is more about this here:

http://500e.com/forums/showthread.php?t=299
http://www.500ecstasy.com/forums/showthread.php?t=2843
http://www.500ecstasy.com/forums/showthread.php?t=4703
http://www.500ecstasy.com/forums/showthread.php?t=3218

Cheers,
Gerry

 

[500ESpain]

So simple as that? Unbolt the strut an replace the bushings? No need to ift the car an decompress the strut?

Thanks again for you valuable knowledge!

 

[gsxr]

To replace the upper bushing, from inside the trunk, you don't have to lift the car.

To replace the lower bushing, you need to lift the car and decompress the strut, and support the lower control arm while removing the strut from the top hole in the body.

 

[gerryvz]

Yes, the rear end of the car has to be off the ground (or at least that particular wheel). It's best to lift the entire rear end and then depressurize the SLS system in order to make it easy to hand-compress the struts. You can depressurize the system perhaps by cracking one of the lines going into the nitrogen cells after you lift up the rear end. Just be sure to catch any fluid that drips in a cup, and have a bit of extra fluid on hand to replace. There shouldn't be much that drips though.

The bottom rubber pieces take MUCH more abuse than the top ones and thus are more imperative to replace.

Cheers,
Gerry

 

[500ESpain]

Understood, thanks!!

 

[gerryvz]

Did you ever fix this issue of the rear-end clunk? What part(s) did it require?

Cheers,
Gerry

 

[500ESpain]

Unfortunately I've been experimenting more trouble with the car and I've been incredibly busy with personal stuff so this went to the end of the list.

I bought all the rubber but I have no time to replace it right now. I had the same problem in my '84 300D so I replaced the diferential and rear subframe mounts with very little improvement. Then I replaced the rods from the sway bar to the control arm a couple of days ago. It's MUCH better now. It was an easy and quick job and only 24 euro in parts. I will replace the bar bushigs next to check if the problem is completely solved.

I'm sorry but the progress with the 500 is very slow. I will keep you updated anyway.

Thanks!

 

[500ESpain]

Finally I had some time and I replaced the rods. I would say that the problem is 80% fixed so next job is to replace the rest of of rear axle rubber. Replacing the rods is incredibly easy and it improved a lot not just my problem but the ride quality as well.

Easy steps:

- Jack up the car and remove wheels.
- Remove LCA plastic cover.
- Remove the bolts (13mm lower, 17-19 upper)
- Replace the rods
- On the right side I had to jack up the suspension a little bit to take out the rod.

Thanks again for the interest.