How Stiff Should It Be?

[niklas 1]

I'm using 23mm torsion bars and 25mm antiroll bar and my question is, how stiff should it be?

Should it be possible to by hand rock the rear a few centimetres (like 1 or 2 cm) ??

I'm not really sure my rear beam is as healthy as it should be, and if it ain't then I don't know the cause...

 

I'm using LEDA coilovers in the front with 275 lbs/in springs and it's pretty stiff!

It doesn't feel right to have a rear end being quite a lot softer than the front

[Jonmurgie 2]

Do you mean you can move it 1 or 2cm with NO rear shocks attached or with rear shocks?

 

If it's with the rear shocks attached then it probably due to them being soft... if it's without them attached then I would say that's normal

[niklas 1]

Do you mean you can move it 1 or 2cm with NO rear shocks attached or with rear shocks?

 

If it's with the rear shocks attached then it probably due to them being soft... if it's without them attached then I would say that's normal

 

Hrmm I'd rather like the torsion bars being a bit stiffer than they are today, than having to rely on shocks doing the torsion bars' work.

Which I thought was the point with using 23 mm torsion bars!

Edited August 15, 2006 by niklas

[tom_m 0]

bounce stiffness isn't everything on the rear... if its too stiff it will just skip from bump to bump losing you grip and stability. its the roll stiffness that counts in corners, and you can't really check that by hand

[Butler 0]

What does it drive like? Are you suffering from understeer?

 

There's not more weight in the back of a stripped 205, so don't need it to be rock hard as long as you have enough roll stiffness.

[smckeown 1]

you won't get understeer by stiffening up the rear on a FWD car, based on the books i've read. As tom says it wil lbe less compliant on bump surfaces, even on bumpy circuits. My mega stiff rear is still very balanced, no understeer or understeer.

[niklas 1]

What does it drive like? Are you suffering from understeer?

 

Yes, that is exactly the problem. I haven't driven any other 205 with stiffened up rear so nothing to compare to. But I kind of expected something more than this, it feels just wrong. Not alive so to speak. Turn-in is lazy, you really have to force it in..

 

Obviously, it's a track car I'm on about so whether it can cope with poor and uneven b-roads is hardly of any interrest!

[niklas 1]

Noone with any fruitful input?

[veloce200 3]

Noone with any fruitful input?

 

The solid beam mounts remove the tail happy antics of the car. Have you been on track yet? You'll be grateful it feels the way it does through a very fast bend!

Try some more toe-out if it won't get the arse end out!

[Jonmurgie 2]

When I went from standrd rear beam to the 23mm/25mm setup (seans old beam) the transformation was AMAZING on track... it was a little stiffer on the road but it wasn't until I was out on track that the car just felt soooooo much more planted and the back end was a 1000 times more stable.

 

Everyone else with this setup has raved about it so I find it odd your not liking it?!

[tom_m 0]

When I went from standrd rear beam to the 23mm/25mm setup (seans old beam) the transformation was AMAZING on track... it was a little stiffer on the road but it wasn't until I was out on track that the car just felt soooooo much more planted and the back end was a 1000 times more stable.

 

Everyone else with this setup has raved about it so I find it odd your not liking it?!

 

agreed, even just going to 21/23 (another of sean's old beams! )on the road i noticed the difference.

 

maybe your looking at the wrong end nik? an uber stiff front end will make a FWD understeer like crazy

Edited August 16, 2006 by tom_m

[niklas 1]

Ah interresting

 

Veloce: The solid mounts have absolutely changed the confidence in the rear end, it's not as "unreliable" as before. And yes, I enjoy this greatly as it makes me cooler going through the fast bends.

I've been out on track for two different occasions with this car, both wet and dry

 

Jonmurgie: Yes, but did the rear end go from "alive and passively steering but unreliably twisty" to "dead as a fish, happily tailing along"?

 

tom_m: I'm running coilovers in the front with 275 lbs/in springs, which I doubt should be too stiff. I know many cases where people are racing with stiffer front ends and they seem to enjoy their car more than I do

 

Maybe I should describe the car in question a little further:

It's a bog standard XU9JAZ 122bhp with worn engine maxing out at 180 km/h but that doesn't really concern me for the moment

Front setup is LEDA coilovers with 275 lbs/in springs, Rally design eccentric top mounts setup for max camber and 309 gti track control arms with new OE standard bushes.

Rear setup is 23/25, LEDA shocks and solid beam mounts.

Ride height is not really setup, it's as low as possible in the front and probably a little higher than it should be in the rear.

Front toe is not really setup well either, but it's probably around zero toe which is not my aim. I'm aiming for around 2-3 mm toe-out.

Tyres are Potenza RE540S 195/55.

[Butler 0]

What is actually the problem? Are you saying that you rear beam isn't as stiffer as you expected 23mm bars and 25mm arb to be?

[Jonmurgie 2]

I htink he's saying his rear end used ot be alive and passively steering but unreliably twisty but now it's dead as a fish, happily tailing along which doesn't sound right at all...?!

[Butler 0]

Right. I'd fit new, but standard beam mounts then, easy to do.

[niklas 1]

I htink he's saying his rear end used ot be alive and passively steering but unreliably twisty but now it's dead as a fish, happily tailing along which doesn't sound right at all...?!

 

Exactly!

Surely your car, Jon, must provide a lot better turn in than a standard gti? How is the car behaving mid-corner and on corner-exit compared to a standard gti?