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-   -   Two bushing-related questions (unable to answer with search...) (http://forums.pelicanparts.com/porsche-911-technical-forum/470174-two-bushing-related-questions-unable-answer-search.html)

500_19B 04-21-2009 06:53 AM

Two bushing-related questions (unable to answer with search...)
 
I believe I have a squeaking bushing issue in the rear, which is not all that surprising. Both the spring plates and sway bar are on the originals I believe.

I have ruled out the squeak being in the interior as I completely removed the interior as part of a restoration (new carpets, re-dyed leather etc.) and even with all the panels etc. out, the squeaking persists. Here are my questions that I have been unable to answer through searching:

1) When I bounce any of the four corners up and down, with the car parked in the garage, I cannot hear squeaking… Is it possible that suspension bushings can squeak on the road, but not while stationary? I am surprised, and a little concerned that I cannot hear anything…

2) When I bounce the rear of the car vigorously (by putting most of my 180 pounds on the rear bumper pads) I can hear (and feel) an audible “clunk”. Could this be my torsion bar cap hitting the bushing cover? Or is there a more likely culprit.

FWIW, this is my torsion cap/bushing cover on the passenger side. Close, but still some clearance. On the other side, it appears there is no clearance…

http://i15.photobucket.com/albums/a3...a/P1030227.jpg

I appreciate everyone taking the time to look at my questions, thanks!

P.S. I intend to do a complete suspension overhaul (bushings, tie rods, ball joints etc) but hope to defer it to the winter as I have spent a huge amount this year on other things. What I am trying to do is identify what is causing my noises and evaluate whether it is even OK to live with it for the summer.

Chuck Moreland 04-21-2009 08:23 AM

Those spring plate bushing could certainly be the cause.

When under load while driving, the bushing compresses more than you jumping on the bumper. Likely enough to cause metal/metal contact based on the picture. Those are highly deformed.

500_19B 04-21-2009 09:28 AM

Thanks Chuck,

I imagine you've seen zillions of these, so if you feel they are highly deformed in relation to what's out there, then I guess I need to reconsider how quickly I do this job and how far I go...

tonythetarga 04-21-2009 10:03 AM

I agree with Chuck, but you should also look at the sway bar bushings. You might disconnect the rear bar or remove it and see if the clunk goes away. The sway bar bushings are an easier replacement than the spring plates.
Another point I wanted to make is that the'bounce on the bumper' test doesn't work with these cars. The "spring" is a steel bar that twists (torsion bar) and the shock just dampens the recoil. Your 180 lbs won't do much as you found out.
If you choose to redo the spring plate bushings, do the front a-arm bushings up front at the same time, as well as both sway bar bushing sets. You'll be fresh and ready to go after the alignment and corner balance.

burgermeister 04-21-2009 11:59 AM

You can swap the spring plates side-to-side if the rubber is still in decent shape. Then the fat part of the rubber will be on top and the skinny part on the bottom. After a few weeks, it will be evened out. Works quite well.

+1 on checking the swaybar bushings.

500_19B 04-21-2009 01:25 PM

I have been thinking, and right now I am leaning towards a temporary fix to get me through a couple of thousand summer miles: Swapping the spring plates as mentioned, rotating the control arm bushings and replacing the sway bar bushings. When I go to Chuck's site and start thinking about all the things I want to do (bushings, shocks, ball joints, tie rods etc) I realize I can't do it quite yet. Also, when I put the new spring plate and control arm bushings on, I want to get things re-plated, powder coated etc. So, for me the temporary fix followed by the right fix may be the way to go. I will obviously have to spring for two alignments going this route though...

Thank you for all the answers, each one has been informative.

RKC 04-21-2009 01:30 PM

If there is a "clunk" you should also wiggle the sway bar - if it wiggles from pushing on it with your toe (car on the ground), it is probably the bracket. Original brackets crack easily (an updated, stronger one can be welded in). Had this happen a year or two ago.

RWebb 04-21-2009 01:42 PM

but... your idea has you doing a nasty job twice - I'd do it once and be done. Cut down on items that can be done later w/o redo'ing others.

tonythetarga 04-21-2009 03:09 PM

Quote:

Originally Posted by RWebb (Post 4619991)
but... your idea has you doing a nasty job twice - I'd do it once and be done. Cut down on items that can be done later w/o redo'ing others.

++1. You should just get new neatrix spring plate bushings and put them in. The hard part is indexing the torsion bars, which you have to do anyway just to swap sides. The neatrix bushings are cheap and will last you many more years. One corner balance and one alignment only (that's where the $ is if you do the bushings and torsion bar settings yourself). Many of us have done this as DIY and it is doable with research, questions, a level floor and an angle gauge.

Chuck Moreland 04-21-2009 08:27 PM

I would agree that it is a short sighted to swap worn spring plates side to side. You still have to do a corner balance/alignment when you are done. And that goes about $600 +/- if it's done properly.

Why skrimp on the parts when you can get proper rubber bushings for a measly $70 from pelican here:
http://www.pelicanparts.com/cgi-bin/smart/more_info.cgi?pn=ERMP-2290003&catalog_description=Elephant%20Racing%20Ru bber%20Spring%20Plate%20Bushing%20Set%20Of%20Four% 2C%20%39%31%31%2F%39%31%31%20Turbo%20%28%31%39%36% 38%2D%38%39%29

And swapping sides only solves half the problem. Yes, it flips the 'fat' side of the bushing to the bottom, but it leave an undersized bushing in place.

And undersize bushings will slip to accomodate the rotation, when they should be deforming to accomodate rotation by design. I'll grab a picture to make my point.

Chuck Moreland 04-21-2009 08:42 PM

http://forums.pelicanparts.com/uploa...1239165145.jpg

The pic above is from a current thread. Notice the bushing is not just deformed, it has worn away. Especially on the left hand side.

Once the bushing has deformed, it becomes loose in the torsion tube / cover plate. It then begins to slide instead of deforming to accomodate rotation (as designed).

Once the sliding begins, the bushing is toast. Wear becomes rapid, as shown. Corner balance slides all over the place.

Flipping the bushing to the opposite side addresses half the problem, at best. The "savings" vs new rubber bushings seems trivial compared to the labor and follow on cost of corner balance and align.

500_19B 04-22-2009 05:51 AM

OK, I am convinced!!

Yesterday afternoon I ordered the ER spring plate bushings and rear sway bar bushings. I will do that work first (and re-plate the spring plates) and then I will order the ER rubber control arms bushings and ball joints for the front later in the summer and do that. Finally, I will do the rest (shocks, tie rods, wheel bearings and semi-trailing arm bushings) over the winter. Still have two alignments to contend with though... Is it possible to get a bare-bones "street-OK" alignment as an intermediate step after the first phase of work and then spring for the detailed corner-balance/alignment later? I know I sound like a cheapskate...

jonbot 04-22-2009 08:19 AM

Check and make sure the three bolts that attach the spring plate to the banana arm are tight, as well as your camber and toe alignment bolts. I had a squeek for a while, very similar in characteristics to what you describe, and it turned out the alignment shop didn't tighten these bolts properly, or at all! :eek: Once I tightened them up, the squeek went away.

RWebb 04-22-2009 08:26 AM

yes - and many can do the align themselves


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