Bushes on rear lower suspension arms

[beej]

Howdy folks,

I can feel increased lateral movement at the back of the car depending on road bumps, thick paint on lane changes, and so on. Last year's MOT test [sorry, don't know what this annual check is called in the USA] brought out that the bushes on the rear lower suspension arms, both sides of the car, were deteriorating.

My local guy wants to replace the arm as well as the bush, with the OEM part (probably 996.341.053) costing £250/$400 each. I didn't ask the dealer yet.

Yet poly bushes seem to be available on their own. But would that do the job, or do I risk replacing the deteriorating bushes only to find there's still a bit of a shimmy at the back of the car?

Thanks if you more experienced guys have an opinion :)

[ericinboca]

Howdy folks,

I can feel increased lateral movement at the back of the car depending on road bumps, thick paint on lane changes, and so on. Last year's MOT test [sorry, don't know what this annual check is called in the USA] brought out that the bushes on the rear lower suspension arms, both sides of the car, were deteriorating.

My local guy wants to replace the arm as well as the bush, with the OEM part (probably 996.341.053) costing £250/$400 each. I didn't ask the dealer yet.

Yet poly bushes seem to be available on their own. But would that do the job, or do I risk replacing the deteriorating bushes only to find there's still a bit of a shimmy at the back of the car?

Thanks if you more experienced guys have an opinion :)

If the local guy is right in identifying the bushings are worn out, then just changing the bushings is likely to make dramatic improvement. The aftermarket bushings tend to be stiffer than the rubber used by the factory, though. The stiffer bushings improve the feel you will have under load, but also deteriorate ride. (My track car has solid aluminium bushings and spherical bearings, transferring a ton of road noise, harshening the ride, but giving me amazing response and feel.)

New control arms come with bushings already in them.

He may be saying he wants to replace the whole arms because of labor costs involved in changing the bushings - it might be a wash between changing bushings on old arms and replacing arms; or he might not think you want the stiffer aftermarket bushings.

Either way, he has to take the arms off. Replacing the arms, he takes the old ones off, and installs new ones. To change the bushings, he takes the old arms off, presses out the old bushings, presses in new, and then reinstalls the arms. Extra labor. See what I mean?

Also changing the whole arm reduces the number of come backs he has - same reason a lot of shops change the rotors at the same time they change pads.

[ivangene]

are there details as to how he checked them to determin they were bad? That would be useful. If you know they are bad, replace them with OEM is good unless you have wanted "more" out of your car and are willing to loose some things to get it. Be careful, its a slippery path :)

[beej]

I've got no more details. Thanks for the advice - it seems the right thing to do is get the arm not just a poly replacement for the bushes, so I've gone and got "OEM-equivalent" replacements for £130 each rather than £250 that the dealer wants. Booked in for the repair next week.

Many thanks!

[beej]

While the lower wishbones were being fitted, some problems were found, so I'm having to replace the control arm (996.341.043 which is #17 on PET sheet 501) as well as the eccentric screw (what a great name for a part! 996.331.217) which has had to be drilled out :(

The control arms I've found at an affordable price online, but had to go to Porsche for the eccentric screw. I'm buying pairs as I want both sides of the car done. You might find the 996 screw has been deleted so using the 997 screw instead.

I've never had to pay 17 pounds for a screw before... :)

Edited December 8, 2009 by beej

[beej]

Just to end this, in case it helps anyone else: picked up the 996 today and the engineer showed me the parts he replaced. The rear suspension parts, AFAICT from 11 years of history never replaced before, the rubber bushes were certainly deteriorated and he showed the passenger side wishbone had play in it which was resulting in a clunk on bumps, and presumably the shimmy at the rear.

He also showed part of the chassis (or sub-frame?) where it had cracked when he was trying to remove the eccentric screw which had over 11 years... become "as one" with the suspension. He'd drilled it out and then hit it with a hammer, and that had cracked the sub-frame itself. Cast aluminium isn't infinitely strong!

Looked for the PET part of that chassis part to share the knowledge, but didn't find it. Under the engine mount somewhere :)

[greerj1]

Were you able to source the bushings separately from the wishbone, control arms etc?

Thanks:

James Greer

[geoff]

Were you able to source the bushings separately from the wishbone, control arms etc?

I'm trying to track down a suspension squeak, and have asked on several boards. I still haven't isolated the squeak, but if you look at http://www.boxstersp...indpost&p=32552 the replacement part numbers for the lower control arm are listed. elephantracing.com also has replacement bushings for the stock lower control arm. If I can ever figure out what part is making the squeak, I'll know what part(s) to replace

[beej]

Hi James,

Not OEM replacement bushes, no.

But I did keep costs down by finding OEM quality parts on eBay!

(I had poly bushes on a previous car but didn't like the firmness)

Beej