replacement rear shocks thumping

I have an '02 Jetta TDI that I had replaced the original rear shock absorbers with the gas charged KYB GR 2 shocks. Now anytime that the rear of the car hits a bump, it has a thumping action, instead of dampening the bump. Gets to be annoying while driving over long stretches of rough roads. Wondering if anyone has run into this and what can be done to remedy this problem? The OEM shocks with 165,000 miles on them, worked better than the replacements.

Thanks in advance for any solutions for this problem.

KYB has a bad reputation here, FWIW. I haven't used them myself.
Were the shock mounts replaced or were old parts reused?

I don't have any bother with mine, are you 100% sure you put the top mounts in the right way round? My mate put his in the wrong way round and it was thumping too.

How many miles and how are rear axle beam bushings?

Often overlooked when it seems like a shock or mount (like I did the first time).

It's really important to follow the correct procedure when installing the rear mounts. you need to preload the rear suspension before torqueing down the mount bolts.

How can they be put in the wrong way? I'm disappointed with my rear bilstein sports, though the issue with them is a lot of bouncing.

The rear strut top bushes fit in upside down, like the lower top one upside down then the top one upside down. If you do that then it leaves like a good 0.5 -1 inch of play so anytime you hit a bump it makes a knock. This isn't a wind up either, my mate really did put his in the wrong way round and ended up with this exact problem and it's free to check.

Seatman: The European models must have a different upper shock mount than those in the States. The ones that I have seen, are a cast aluminum mount that can only be tightened to the shock threads in one way---it can't go on any other way.

Dieselfueler: By preloading, I'm assuming you are moving the axle beam upward (to approx. ride height), before tightening the lower mounting bolt?---Perhaps this is causing the thumping, I did tighten the shock when it was fully extended.

Thanks,
SP55

The preload is mainly to insure that the top mount is seated correctly I usually tighten the top mount bolts finger tight then use a floor jack under the rear to compress the rear beam the do the final torque to the mount bolts

Is it a klunk? If so then I would agree that it must be something loose with the top mounts. Unless the bottom bushing is missing, that is the only place for any slop.

Also, I was able to change my rear shocks with the rear tires on ramps. If you are not changing the springs it can be done.

I did not put a person in the back, but did have a full tank of fuel and a bunch of tools in the back.

sp55 said:

Seatman: The European models must have a different upper shock mount than those in the States. The ones that I have seen, are a cast aluminum mount that can only be tightened to the shock threads in one way---it can't go on any other way.
Thanks,
SP55

Click to expand...

Sorry my mistake, I'm going on about the Mk3 which is different.

Regarding the shocks though, I get no knocking from my kyb's, I was getting a knocking at the front which ended up being the strut top bush even though there was no visible reason for it. That was on the front but mine are different too, just wondering if it's possible the mountings are causing the problem on the rears in this case though.

This may be kind of obvious to most, but I thought I would share it just in case....

With the A4 rear shock mount, on one side there are 2 mounting holes:

http://www.metalmanparts.com/product.sc?productId=240&categoryId=33

When I did my suspension overhaul last sprint, the right rear was the last I did, and was probably getting tired. On my test drive, I was getting a clunk coming from the right rear when going over a bump.

When I got home and took a look at everything, I saw that I had the mounting bolt going through that lower hole on one side. Quick change of the bolt to the right hole, and all was good.

I know it might be obvious to most, but worth taking a quick look?

I had another thought on this. My Bilsteins came with a new nut and washer on the shock shaft. The original mounting did not use a washer, so I did not install it.

If you did instal the washer, I suppose it cound contact the metal shock mount body if the rubber deflected enough.