New Suspension rebuild. Problem with rear of car

nordicmatter · 19 Feb 2017

Hi James

Been thinking about this today and my money is on the shocks and springs. As you have gone this far I would consider changing them for new, as you don't have electronically adjustable suspension the cost isn't that bad and they are all over EBay. The dampers have a large input in to supporting the weight of the rear of the car, I once removed pasam suspension from an early 997 I had and kept the original springs. The ride was shockingly hard yet with the pasam shocks it was too soft.

I suspect the shocks are un matched due to wear.

Mark

wizard993 · 19 Feb 2017

Shocks could be causing your issue but before you change them stick it into a Kwik-fit with the Hunter laser wheel alignment machine. They will charge you about 100-120 quid to do the toe-in, cambers etc. Most of these guys know exactly what they are doing and the initial check is usually free so nothing to lose. Best put it all back to stock geo settings for now.

911's can feel as if it's the back-end that's at fault when in fact the front can also be out and cause the car to feel strange/unstable.

If your new suspension is firmer then you should expect the back end to hop a bit more/become a bit more lively on a-road undulations.

If it's still mis-behaving(lateral weaves) then focus on the rear shocks.

These cars are VERY sensitive to even slightly worn suspension parts, GEO mis-alignments and wheel/tyre issues.

Harv · 19 Feb 2017

James

As you have already had alignment done at 9e then I seriously doubt that QF will help much, and also they would have spotted anything that was waaaay off in the specs (I agree that centre gravity is probably a good way forwards). Oh those 964rs engine mounts are great, I've fitted mine :thumb:

You said that you stripped the whole suspension down front and rear, what state were the strut top mounts in? Just wondering if one of those maybe worn or loose, missing a shim, washer etc.

I had a mk4 golf with vague handling but the give away was the occasional creaking/clunking and that was a loose locking nut on the rear shock to top mount.

Hope you manage to nail this soon, sounds like it's really fighting you.

Jamesx19 · 19 Feb 2017

Cheers for all your replies

I think that the general consensus is leading toward the dampers, which I agree with. Also there are some good arguments toward looking at the front dampers as being as crucial to the rear handling as the rear dampers.

Good to know the 964RS mounts are good.

I agree with Harv. I'm happy with the Geo by 9e, and looking at the settings, they are pretty much the same as a standard Geo. The toe settings are standard, with the Rear being 1.5 deg neg camber and the front 40' neg camber.

C of G is unfortunately several hundred miles away! Though Balance motorsport is nearby so I'll give them a call and see is they can dyno them.

If one is shot, then that would create asymmetric movement. If they are all OK........... Well I'm not sure if I know where to go after that!

Thanks all again for your thoughts

Griffter · 20 Feb 2017

Op, thanks for reporting back. It sounds like the wheels and tyres are ok then ðŸ™‚
I'd still check them on the car though, in case you can detect any discrepancy with the hub or bearing.

Alternative thought: driveshaft/cv joint wear?

forever · 20 Feb 2017

Why did you not just ask 9E? They are the experts and would be able to help....

skinny_monkey · 20 Feb 2017

Another vote for dampers. If it was the other stuff you'd expect it to be more constant and not just set off with bumps. You just need one to be knackered to mess the car up. Also I have learnt that on some types you should only operate them the correct way up...

Jamesx19 · 20 Feb 2017

Hi,

Griffter - Looked at those. They actually look like they have been replaced at some point as they still have a white Part sticker attached to each. I may have to investigate them further if changing the dampers doesn't work.

Skinny_monkey - I'm ordering up some Bilstein B8's tonight

£950... Lets hope they are the issue!

Forever - Good point, but right now I'm happy (ish) to spend money on parts, and hoping not to have to spend money on diagnosis. Also, any garage will give an opinion, then try to rectify the fault based on their theory. Much as you all have helped me with on this thread already. On the day, 9e thought it may be dampers anyway.

Cheers James

Mike! · 28 Feb 2017

Sent my car to Porsche for a 4 wheel alignment where the said they couldn't do it due to control arms being so worn at the camber bolt it would take adjustment. So I replaced the rear control arms and now the car feels like it driving on ice. The rear end is extremely unstable and wobbles/jerks and you can hear the rear wheels slide on gravel, I couldn't go above 20mph.

I adjusted the camber bolt to the middle and its way better but still really unstable. From looking at the wheel it looks like it has lots of toe in and negative camber. I suspect due to the toe in the wheels are acting like screws and driving the wheels inward to the point where it's bending the strut and eventually overcomes the grip on the other wheel leaking to the jerk and pops straight again. Driving a little faster and it's not as bad, assume the tyres are shearing against the tarmac rather than griping and jerking at low speeds.

Total nightmare, and I've not notice my rear strut is leaking badly where I can physically see a huge wet patch all over the driveshaft/ARB after 300m of driving, probably related.

maldren · 28 Feb 2017

I'm amazed that Porsche didn't point out the leaking strut!!!

MisterCorn · 28 Feb 2017

Mike! said:
Sent my car to Porsche for a 4 wheel alignment where the said they couldn't do it due to control arms being so worn at the camber bolt it would take adjustment. So I replaced the rear control arms and now the car feels like it driving on ice. The rear end is extremely unstable and wobbles/jerks and you can hear the rear wheels slide on gravel, I couldn't go above 20mph.

I adjusted the camber bolt to the middle and its way better but still really unstable. From looking at the wheel it looks like it has lots of toe in and negative camber. I suspect due to the toe in the wheels are acting like screws and driving the wheels inward to the point where it's bending the strut and eventually overcomes the grip on the other wheel leaking to the jerk and pops straight again. Driving a little faster and it's not as bad, assume the tyres are shearing against the tarmac rather than griping and jerking at low speeds.

Total nightmare, and I've not notice my rear strut is leaking badly where I can physically see a huge wet patch all over the driveshaft/ARB after 300m of driving, probably related.

I assume you had the alignment done after changing the arms? Do you have a printout from it?

MC

Harv · 28 Feb 2017

Going off OP's issue...

Did you replace the camber adjust bolts (fitting new ones with lots of copper slip?).

It's not something you can do at home by trial and error. The cars suspensions is very adjustable.

Rear toe setting should be set at 0 or as near damn it, and the rear camber something like -1.5deg. The trick really is getting both sides exactly the same.

I'd take it to somewhere with hunter or beissbath alignment system.

@OP have you gotten any further with your issue?

Jamesx19 · 28 Feb 2017

Hi Harv,

The Bilstein B8 dampers have been delivered, and I have some new nuts from Porsche as the new one's on the camber bolts have now been undone and tightened a few times!

Looking to fit on Thurs/Fri so I can update then.

Interested in Mike! account.

Mike! what control arms did you fit? Did you the work or someone else? and as MisterCorn asks did you have alignment done?

If any body else has fitted Meyle control arms recently I'd be interested to hear what their results are.

My Geo was:

FL Toe +3' / Camber - 48' FR Toe +3' / Camber - 48'
RL Toe + 9' / Camber - 1 deg 40' RR Toe +10' / Camber - 1 deg 42'

Harv · 28 Feb 2017

James

Sounds good.

I think I've read that the rear toe shouldn't exceed +8' as that can make handling twitchy so definitely try and have that dialled back to as near 0 if possible and try running -1.5 deg camber as stated.

Really interested to hear the outcome on this.

Consider Elite at Horsham if you are based south of London :thumb:

Mike! · 28 Feb 2017

maldren said:
I'm amazed that Porsche didn't point out the leaking strut!!!

The strut was bone dry before fitting the lower control arms/test drive

MisterCorn said:
I assume you had the alignment done after changing the arms? Do you have a printout from it?

MC

This issue is immediately after changing the arms when I drove the car only to the end of the street, I cant get it to Porsche to get the alignment done as its can't be driven. The alignment I had attempted to be done before from Porsche is what revealed the worn control arm (not the toe arm, see below).

Jamesx19 said:
Hi Harv,

Interested in Mike! account.

Mike! what control arms did you fit? Did you the work or someone else? and as MisterCorn asks did you have alignment done?

If any body else has fitted Meyle control arms recently I'd be interested to hear what their results are.

I fitted Meyle arms also. Brand new pair. Seems dimensionally the same when side by side but didn't measure them as there is only one type right? So I couldn't have bought the wrong ones?

Anyway, went to have another look. Removed the wheel and checked the toe control arm and the bushing is shot at it was set for max toe in. I adjusted it but it just turns and the arm barely moves as the bushing rubber all cracked.

I called Porsche and spoke to the chap who attempted the alignment before. He confirmed it was the control (coffin) arm that was worn when adjusting the camber but didnt notice the toe arm (probable didnt get that far). I told him that the the old control arm popped out fine but I had to pull the hub towards teh front of the car to get the ball joint in then jack it up to get the tuning fork to allign with the arm. I assume this was normal as I only had one corner of the ground and would have been fighting the ARB but he said it should still be in alignment and fit up without having to pull anything into place.

He went to ask some other techs at Porsche but they are all stumped and can;t explain why the car would do that after a control arm change, even if the settings were way out as the standard adjustment range isn't extreme enough.

He did mention that there was a bracket/or washer which keeps the camber bolt from loosening/rotating during driving. I mentioned I have the recess in the subframe where the head of the eccentric bolt is housed and adjusted, and a keyed eccentric washer and nut at the other end. He seemed to think something was missing (certainly the same set up from befroe and on both sides). He had a 997 which is similar on the ramp and was going to sent me a pic but nothing as of yet. Still a mystery.

New Suspension rebuild. Problem with rear of car

nordicmatter

New member

wizard993

Donnington

Harv

Suzuka

Jamesx19

Hockenheim

Griffter

Hockenheim

forever

Monza

skinny_monkey

Montreal

Jamesx19

Hockenheim

Mike!

Silverstone

maldren

Albert Park

MisterCorn

Fuji

Harv

Suzuka

Jamesx19

Hockenheim

Harv

Suzuka

Mike!

Silverstone

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