Rear suspension "granch"

[RDM]

With the engine out and all that rear suspension just hanging out there naked and a week or so to kill before rebuild parts arrive, it seemed only natural to try to solve another problem.

When driving over a speed bump (or 2x4 put in the driveway for testing purposes), my rear suspension makes a loud squeak/scrape noise on both sides, going both up and down. It's more common with large displacement, and it's more common when the car is cold. Rear sway bar bushings look new.

Two tidbits, perhaps unrelated, perhaps not: The torsion bar cover bushings were replaced this summer. The noise started after the car was up on jackstands for several weeks.

Below are some pictures of the driver's side pieces. Anything jump out as odd? Any suggestions as to what to do to resolve this problem? Bushings to replace? Lubricate? Something else?

This will continue to be a street driven car, so the solution needs to be quiet and comfortable.

Thanks,

Dru

[Flieger]

If you disconnect the drop links for the rear sway bar you can move it by hand and confirm they are not making the noise (or maybe they are).

Did you only do the torsion bar cover bushings, not the ones that go on the spring plate inside the torsion tube? What kind of bushings?

You say it was on jack stands for a couple weeks. That would allow the rubber to flow into a shape that it is not in during driving, when the weight of the car is on it. Therefore, there might be a gap between the torsion bar and bushing if the rubber is old. In which case the bar would twist inside the rubber and make noise. The bar is supposed to be held tight to the rubber such that the rubber works in shear- the rubber itself twists and there is no relative motion between bar and rubber or tub and rubber.

And if you only did the outer bushings then I could see that the two would not be aligned after sitting on jack stands. Either way the noise would probably go away after a couple weeks.

If you used polyurethane bushings (black plastic) then you need to lubricate them to attempt to quiet them down.

[javadog]

Some of the aftermarket rubber spring plate bushings make this type of noise. I'd probably start there. As long as you have it apart, I'd probably replace all the bushings. Try looking at the ones made by Elephant Racing.

JR

[zippy_gg]

Originally Posted by RDM

Maybe not a big deal but the parts diagram for my 86 Carrera shows a washer on both sides of the lower shock mount connecting to the trailing arm.
Your model year might be different though...
(part #9)

[Porchdog]

My car has had a similar symptom for years. Only when cold, only over large displacement bumps.

Long ago a shop replaced the rear torsion bar bushings - that didn't stop the noise.

[RSTarga]

you need new rubber bushings on everything. The elephant rubber are closest to original.

[Jdub]

I agree that you absolutely should replace all bushings. Droplinks, shocks, and related. A suspension rebuild will transform the car - you will be amazed.

[david.avrahami@]

The noise you are describing is most likely from the sway bars and the associated bushings...I replaced both and the noise disappeared.

[RDM]

I watched the Elephant video on removal of spring plate bushings Shouldn't the rubber piece of this part be glued to the spring plate, as their video shows? Rotation there would happen over large bumps, and could cause substantial noise.




The other thing I noticed is that Pelican says that the shocks should have two cone-shaped rubber pieces on them, and mine has one donut-shaped rubber piece. The shocks are green Bilstiens.

[Craig_D]

Originally Posted by RSTarga

you need new rubber bushings on everything. The elephant rubber are closest to original.

I agree with this. Your rubber looks like it owes you nothing, and should be replaced.

[zippy_gg]

Originally Posted by Craig_D

I agree with this. Your rubber looks like it owes you nothing, and should be replaced.

+1 The rubber should be glued as you found out.

[RDM]

Originally Posted by Craig_D

I agree with this. Your rubber looks like it owes you nothing, and should be replaced.

Originally Posted by zippy_gg

+1 The rubber should be glued as you found out.

Originally Posted by RSTarga

you need new rubber bushings on everything. The elephant rubber are closest to original.

Thank you for your feedback. So I've read the Elephant product descriptions, and I'm left with three questions.

Are the PolyBronze truly as quiet and comfortable as rubber bushings?

Are they worth the cost for a street-driven car?

Are they a permanent fix?

[Flieger]

Originally Posted by RDM

Thank you for your feedback. So I've read the Elephant product descriptions, and I'm left with three questions.

Are the PolyBronze truly as quiet and comfortable as rubber bushings?

Are they worth the cost for a street-driven car?

Are they a permanent fix?

No, get the rubber ones.

[RSTarga]

agree, stay with rubber

[RDM]

This project is proceeding at a leisurely pace, as I have lots of kids and lots of life and an engine rebuild going on now also.

OK, so further teardown reveals… the cover looks crappy. Rust and general unpleasantness inside.



Which makes the rubber look ugly as well



And yet, when cleaned up the rubber looks new. Again. The suspension has been gone through and refreshed in the not-too-distant past.



So, pulling the spring plates reveals… more unglued rubber. The rubber that should be glued to the spring plate is comfortably wedged into the torsion bar tube.



So could the noise problem come from the not-correctly-glued sping plate bushings? And is the solution to pull the spring plates, reglue the bushings, lubricate the covers, and call it good, or am I missing something? The bushings do all look really fresh.

If so, what is the right glue? What is the right lubricant? And what is the right coating to keep my spring plate bushing covers clean and unrusted?

[zippy_gg]

Since these rubber bushings were improperly installed and of unknown source I would replace them with new rubbers from ER and follow proper procedures; peace of mind is priceless, and you don't want to to the job twice.

[Jdub]

Whatever lubricant, be sure it will not attack the rubber. Silicone grease is okay for this purpose.

There is some discussion if the gluing of the bushing is even required. I believe the OEM solution was to vulcanize the rubber to the assembly. You might get away with just a thorough cleaning and tactical grease application.

[E Sully]

Do not use any lubricant on the covers or rubber bushings. It goes on with a little liquid soap. The noise you hear may be from the rubber shifting because it was greased. The rubber bushings are meant to twist, not slide.
Elephants site shows the installation.
http://www.elephantracing.com/documents/911-2290003-2290004rubber-spring-plate-bushing-instructions.pdf

[RDM]

Originally Posted by E Sully

Do not use any lubricant on the covers or rubber bushings. It goes on with a little liquid soap. The noise you hear may be from the rubber shifting because it was greased. The rubber bushings are meant to twist, not slide.
Elephants site shows the installation.
http://www.elephantracing.com/documents/911-2290003-2290004rubber-spring-plate-bushing-instructions.pdf

Do you mean "twist not slide" like attached on both ends? To attach the bushings inside and out (twist not slide) would turn them into a supplemental torsion bar. I used to think they should work that way, but on reflection I don't think a rubber bushing can take that much of a twist angle and stay in one piece long-term.

And Elephant's instructions include soap (a lubricant, though probably not as long-term as silicone grease). Hmm….

[E Sully]

Yes, twist and add to the springing. There are quite a few threads on this forum regarding that. Same as the rubber bushings on the front arms. There is a reason no grease fittings are installed and no lubrication is mentioned in the maintenance section of the manual. Soap is not a long term lubricant, it lasts long enough for installation, not long term lubrication.
Read posts #9, 16 from Chuck Moreland, Elephant Racing.
Neatix spring plate bushing glue