Bouncy Rear End

[gti_al 1]

Had a thread going about this, but can't post there as it has been archived. http://forum.205gtidrivers.com/index.php?s...c=80954&hl=

 

Uni has finished, started again, finished again and started again and i haven't looekd at this. It is doing my head in now though, as the car rides really badly. I know the best solution is to raise it, but i don't want to do that yet.

 

Just wondering if i can get away with new standard dampers at this height, or do i really need something uprated? I just want it to be comfortable and ride reasonably... it surges badly now so the last thing i need is encouragement to go faster around corners. It is a road car which i am trying to get comfortable and quick, with reasonable manners

 

I plan on trying nick's ideas with the bumpstops, but will only have time to get it in the garage and apart once, so will do the dampers at the same time. So, should i try new 205 or 306 shocks, or some konis or something? They won't end up costing much different, but i haven't liked konis in the past.

 

This is how it sits now

[welshpug 1,657]

if its on standard torsion bars I would personally stick to O.E, part number 5206 K6, which is the part number for the 205 AND 306 GTi.

[gti_al 1]

if its on standard torsion bars I would personally stick to O.E, part number 5206 K6, which is the part number for the 205 AND 306 GTi.

 

that was what i was hoping. The height won't cause problems?

[Dan Ingram 1]

I think the problem is that its upside down, try turning it over and it should drive much better

 

On a serious note mine is sat about the same as yours and I'm running standard torsion bars and new OE dampers and it drives spot on. Theres still plenty of travel and it only bottoms out if you really give it some over a big bump.

[gti_al 1]

That sounds good. I only had that pic from yesterday handy too... that is chris's (casnell). Being a rally person, i suspect it being upside down isn't a big deal...

 

Have you done anything with your bumpstops? We are finding they behave quite strangely once lowered, but it seems you guys aren't having the same issues. It would make more sense just to raise it, but i like it where it is.

[Dan Ingram 1]

Nope I've not touched the bumpstops. I wouldn't think it was a good idea, they are there for a reason.

[Tom Fenton 1,541]

Looks to me like it is simply too low at the back, compared to the front.

[boombang 2]

Nope I've not touched the bumpstops. I wouldn't think it was a good idea, they are there for a reason.

 

Conversely, the bumpstops are there to give a buffer once the suspension is at the end of it's designed travel for the standard spec.

 

On this basis, during normal suspension operation on a lowered car with standard length bumpstops, you are losing say 30-40mm of that designed travel and instead replacing it with no suspension. Bear in mind that the suspension arm could be moving with some force at the time it hit the bumpstop, it can create a dangerous situation.

 

I went out as a passenger in a 205 Gti at Donnington many moons ago, which was compliant and balanced until suspension was heavily loaded up. Then it became erratic and hard to control - was simply that the arm was touching the bumpstop and giving effectively no suspension whatsoever. The owner was on about spending a small fortune on changing his suspension setup for another.

 

We went back into the pits, I had a look over the car and saw standard length bumpstops well worn from lots of contact. 30 seconds later with a hacksaw blade and the car was transformed - cut the bumpstops down to about halfway and it saved him a small fortune.

[GLPoomobile 958]

My old 1.9 beam was as low as that, if not a touch lower. Didn't give me any problems, but then I was missing the bump stop on one side, might have even been missing both, I can't remember. But then I fitted the beam on my next 1.6 and I'm sure that did have the bump stops in place and it was not a problem on that car either.

 

My current one is higher but I find the ride horribly bouncy on the Koni shocks that it has (previous 1.6 and 1.9 had standard shocks).

[Dan Ingram 1]

Conversely, the bumpstops are there to give a buffer once the suspension is at the end of it's designed travel for the standard spec.

 

On this basis, during normal suspension operation on a lowered car with standard length bumpstops, you are losing say 30-40mm of that designed travel and instead replacing it with no suspension. Bear in mind that the suspension arm could be moving with some force at the time it hit the bumpstop, it can create a dangerous situation.

 

I went out as a passenger in a 205 Gti at Donnington many moons ago, which was compliant and balanced until suspension was heavily loaded up. Then it became erratic and hard to control - was simply that the arm was touching the bumpstop and giving effectively no suspension whatsoever. The owner was on about spending a small fortune on changing his suspension setup for another.

 

We went back into the pits, I had a look over the car and saw standard length bumpstops well worn from lots of contact. 30 seconds later with a hacksaw blade and the car was transformed - cut the bumpstops down to about halfway and it saved him a small fortune.

 

Do standard rear shocks have an internal bump stop then? I thought they are there to stop the shock bottoming out and smashing itself to bits?

[gti_al 1]

Looks to me like it is simply too low at the back, compared to the front.

 

In an ideal world i'm sure the rear is too low... realistically though, i just can't be bothered pulling it apart again. It actually handles well, and the difference won't be the cause of the bouncy rear. I could raise it up again, but that will involve getting cold, dirty and i just can't see it happening. I can just give it to a mechanic to do the shocks though, and be fairly sure they can't stuff it up. I realise it won't handle like at the standard height, but that is ok. I just want to try and calm the back end down a bit

 

I agree on the konis too. I really don't like them, and can't see the point in doing half a job... it either seems like you upgrade properly to something really good, or leave it standard.

 

I guess now the question is whether cutting the bumpstops is likely to damage the dampers. I like nick's idea on this front... it makes sense that if the bumpstop had some give it would still do its job, but be more progressive

Edited August 4, 2008 by gti_al

[pug_ham 244 3 Cars]

Do standard rear shocks have an internal bump stop then? I thought they are there to stop the shock bottoming out and smashing itself to bits?

No, the only bumpstops for the rear shocks are those fitted to the shell. I think even with the beam lowered 30mm the rear shocks are still likely to bottom out.

 

I've killed two rear shocks with my beams lowered 30-40mm in the last two years (a koni on my GTi & an oe one on my STDT). Admittedly neither of these were brand new when I fitted them.

 

I think cutting the rear bumpstops down slightly on a lowered car is a good move. I've got some new ones to fit to my car & I intend to trim at least 15mm off the end before I fit them to give me slightly more suspension travel to allow for the fact its now lowered before I hit them.

 

Graham.