OSR too low. Dampers or torsion bar failed?

[nick9one1]

Another post from me!

Today I've noticed the OSR is 1" lower than the NSR.
I measured all round the car from floor to wheel arch top,
Fronts are the same as each other, OSR is roughly the same again, but NSR is 1" higher.

I've not noticed the difference before.. which means it possibly has only just happened?!
Could the OSR damper has failed, causing it to drop? or is it possible that the rear height adjustment has just slipped that side?

I took the wheel off to have a look but didn't notice anything obvious, the damper 'looked' ok and wasnt leaking. And the height adjustment bolt/plate didn't look like they had moved.

I could just alter the rear heights using the eccentric bolts to level it out, but I don't really want to do that if there is another cause for it being uneven.

 

[chrisg]

Hiya

I'm no expert on these things, but I don't believe the shocker actually adds to the ride height per se (could be wrong). Got to be worth checking on the lower side that the shocker hasn't come undo at either end.

I would check that the axle is properly located on both sides and nothing has 'slipped' where it locates into the body.

It's also possible (although unlikely) that the plates have slipped on one side hence the 1" difference - there is adjustment of up 1" on these. These eccentric bolts are usually done up very tight and rusted tight on most cars.

Good luck, let us know what the cause is once you find it !

 

[colin944]

Don't worty perfectly normal.Mine was the same it's just the drivers side settles more over the years from having only driver in car . Really easy to fix just need to reindex the driverside torsion bar in order to get them level again.

 

[bmnelsc]

ORIGINAL: colin944

Don't worty perfectly normal.Mine was the same it's just the drivers side settles more over the years from having only driver in car . Really easy to fix just need to reindex the driverside torsion bar in order to get them level again.

I would have thought that a torsion bar adjustment would be required to get it back to level but it does raise an interesting question. If the torsion bar on one side has developed a sag (either the bar has a permanent twist slightly off from the original spline orientation or the bar has weakened so that the weight of the car now twists the bar enough for a 1" sag) then what about the "spring rate" in that torsion bar? IMHO it must be different than before (probably weaker) and must be different from the other side which has not sagged.

I just don't see how re-indexing (to factory spec) would put it back to level as you coming off the same anchor points. If the bushings are worn and you replace them (to take out the settled spot on the bush) then it would make sense (to me).

 

[Jonny944CS]

As a first port-of-call, I would also have a close look at the bushes.

Part #5 in particular.

 

[nick9one1]

Thanks, I'll take the wheel off tonight and check the bushes.

 

[colin944]

Part no 5 is the mount that I am always banging on about.If you change to poly bushes uprated shocks etc and don't change no5 then you won't get the full benifit of all your hard work.Also unless part 5 had broken it would not give you a big drop.The torsion bars do sag after a long time,but the only way to rectify this is to replace with new bars.

 

[nick9one1]

Is it possible to purchase part 5 in polyurethane?

 

[colin944]

The simple answer is no.They can only be bought from Porsche as far as I am aware.I tried to get these elswhere but ended up buying from Porsche.But I still think you will have to reindex you rear end to solve the problem.When I did my car I totaly removed the back end including the fuel tank as I was doing a full refurb.I split the spring plates and cleaned them up and replaced all the bushes in the process.Putting the rear suspension back together is not a difficult task,its just a question of getting the spring plate angles right.

 

[Neil Haughey]

Its only the Koni dampers that have a spring effect to them but even then its only a small effect.

OP check under there asap because the worst case is that one of your rear suspension mountings has corroded through and detached itself from the body shell. Not the end of the world though and certainly not unheard of, we had to have our torsion bar tube hangers remade on our 968 due to corrosion that wasn't actually that bad (cost 600 quid including reproofing the seams back there). However any corrosion in these areas is a very real and pressing safety issue.

 

[bmnelsc]

The bushes that are most likely to contribute to a sag (as well as worn torsion bars) are the integral bushes on the trailing arm. There is a large rubber bush on the trailing arm where it goes into the torsion bar carrier and another on the other side where the trailing arm "socket" goes through the body mount.

There are poly-bronze bushing kits available to replace these. Elephant Racing has them as well as Pelican Parts. Not sure if Porsche parts are available for not....

 

[pauljmcnulty]

OP check under there asap because the worst case is that one of your rear suspension mountings has corroded through and detached itself from the body shell. Not the end of the world though and certainly not unheard of, we had to have our torsion bar tube hangers remade on our 968 due to corrosion that wasn't actually that bad (cost 600 quid including reproofing the seams back there). However any corrosion in these areas is a very real and pressing safety issue.

Good point. It's also where the seat belts mount so worth an urgent look.

 

[Jonny944CS]

ORIGINAL: bmnelsc

The bushes that are most likely to contribute to a sag (as well as worn torsion bars) are the integral bushes on the trailing arm.  There is a large rubber bush on the trailing arm where it goes into the torsion bar carrier and another on the other side where the trailing arm "socket" goes through the body mount.

There are poly-bronze bushing kits available to replace these.  Elephant Racing has them as well as Pelican Parts. Not sure if Porsche parts are available for not....

Good point regarding the internal bushes Bruce. Over here they are around £500 for the pair from an OPC [&:]

Am I correct in saying that you can peform a visual check on the integral bushes by looking at the concentricity between the swing plate spigot and the aluminium body mount? Large differences side to side could point to an issue.

 

[Neil Haughey]

I had a look at mine recently just as part of a visual check over, its very difficult to see anything of those bushes themselves however yes I guess you can look and see if the torsion bar spring plate (strut in PET) part is sitting nicely with the tube. A small amount out at that point would of course be amplfied at the wheel. I believe the bushes get squeezed and go oval over time but I really can't see how this could suddenly happen. My S2 was a little unenven several years back but it got like that gradually over a long period of time and was a little uneven right from when I got it in 11 years ago.

 

[colin944]

On a 944 the two rubber doughnuts on the spring plate are bonded on to the spring plates.On a vw they are not. You can use vw polybushes for the spring plates but you have to burn off the origionals first.I replaced mine with ones from a VW I think it was a type 3 they are poly.I am lucky to have a vw aircooled guru near me and we worked through all the different ones until we got the right size.If you are in any doubt then talk to the guys at pro 9 and they will sell you the right ones.Mine cost me £16 for all 4.Just goes to show the difference between vw and porsche aftermarket parts.
However I cant see any wear in these bushes causing you car to sag.They are only there to keep the springplates located.Poly or broze will only hold then tighter in than standard rubber.

 

[Neil Haughey]

Certainly not in such a way that one side ends up 1" low I would have thought. The torsion bars do of course sag over time, on our 968 the back is a little low but its still pretty even and handles fantastically well regardless. This still looks like something has broken free to me if its suddenly happened and that picture has been taken with the car on flat ground.

 

[colin944]

I agree that if it happened suddenly then something has gone pop.However most will sag over time and some just sag to one side.Mine was like that but I never really noticed it until I was following my own car in another car.Long story butmy brother in law was driving with me following in his car.

 

[nick9one1]

I haven't got round to investigating this properly, but..

I believe it did happen suddenly, although I might be wrong. I've only owned the car about a month and have only just noticed.
There isn't any noise i.e. knocking/crashing from the rear. I've tried bouncing the back quarter by pressing down on the spoiler and it feels exactly the same as the other side. The drive doesn't feel any different either.

hopefully this points to sagging of the torsion bar, but I guess when I get the wheel off I'll find out!