Uprated Rear Suspension

[Wurzel 16]

Just a scrounge for opinions really.

 

I really fancy sorting the handling out for minimal cost (SCB Phase two will have to wait).

 

The car has been lowered 40mm at the front with the rear to match so that could be lots more. It's currently running standard Bilstein shocks which I understand will need to be changed fairly soon although the fronts are doing remarkably well considering.

 

My question is, do I fork out on uprated torsion bars (standard 205 rear beam) or just the ARB or both?

 

My own opinion is to simply uprate the ARB to prevent roll as the suspension/shocks at the rear seem hard enough as it is. I don't want it skipping around corners!

 

Would I HAVE to uprate the front ARB as well to match or could I live with it for a while? My aim is to convert to the 309 set up but finding a rear beam (fudged or otherwise) is rare and I would have to buy new front wishbones just for peace of mind.

 

Anyone with uprated bars or even the now legendary 309 setup (still not sure why?) you opinions are more than welcome.

 

Thanks in advance

 

Nick

[Adi 0]

The torsion bars and rear roll bar do seperate jobs but work together to provide roll stiffness so reducing roll in a corner.

 

The torsion bars are an uncoiled spring.......so by uprating the torsion bars will not only make the rear ride abit stiffer at the rear.......but makes the rear tyre spend a longer amount of time in contact with the ground........so producing more grip.

 

If just the anti roll bar is fitted....and it is too stiff......then when going round corners....if you hit any bumps with the outside rear wheel.....the rear end will indeed hop.

 

It is a case of balancing the torsion bars and roll bar.

 

You could try and find a slightly thicker rear roll bar and fit it. See what you think of the balance. If it hops at all round corners and on bumps.....the torsion bars will have to be uprated slightly as well.

 

If the roll is reduced but the rear too twitchy....then that is time to start uprating the front roll bar etc.

[Wurzel 16]

Cheers Adi,

 

Just the sort of info I was after.

[Miles 331 1 Cars]

I must disagree there after my many years of playing around with the set up on my Race car, Best thing to do (In my experance) is to Have the biggest ARB on the back and even disconnect the front one to help turn in, I run 26mm Torsion bars and a 28 or 30mm ARB which for circuit works fine, But road use a bit too much so I would just go the ARB route.

[Guest dead205]

Wheres the best place to get uprated anti roll bars and torsion bars?

 

cheers

 

mark

[cybernck 402 1 Cars]

309 gti beam is so popular as you get a bit thicker torsion bars, thicker ARB, as well as a wider track for a little money.

 

 

only place to get them afaik is peugeot sport. unless sbc can get them from another source...

[Wurzel 16]

The only place I've seen them for sale is directly from Pug sport through main dealers or Pugspares website who I suspect, source them from the same place.

 

ARB's are £150 plus vat and delivery.

 

Probably wait out until the 309 beam comes along. Then again, I could always sell on the ARB as I should imagine it will be a desired item.

 

I agree with Miles though, I remember reading that stiffer suspension on the average road can be a limiting factor rather than an advantage. I just want to stop the body roll slightly at the rear and make the car handle better, maybe at the cost of ride comfort.

[Adi 0]

playing around with the set up on my Race car,

 

Race car........no bumps. Roads......lots of bumps.

 

If you just raise the roll bar stiffness.....it can start to do the job of the spring. Then it will start to hop round corners when hitting bumps.

 

To get rid of this....you have to raise the spring rate. In this case....that is the torsion bar.

 

disconnect the front one to help turn in

 

IMO I would never diconnect the front roll bar. For the front end to be stable and be consistant on turn in....the roll centre needs to be stable. The idea is to make the rear stiffer than the front. Not the front weaker than the rear. By having the front roll bar.....that keeps the roll centre more stable and therefore a consistant feel and placement of the front end. Then the rear roll stiffness is raised.

[Wurzel 16]

I understand that road and track are very different environments.

 

Not too sure how the ARB would act like a spring though if the rate were too high? I expect it will come to me after I've thought about it a bit more.

 

Taking the front ARB off during some rally stages and maybe track stages is fairly common, at least on 205's. I would expect that the front spring rates would be greater though.

[Adi 0]

Not too sure how the ARB would act like a spring

 

Both torsion bars and roll bar provide resistance on the rear arms. The roll bar is connected to the other rear arm where the torsion bar is connected to the axle frame.

If the roll bar becomes too stiff it is the one that provides most resistance in bump and therefore lifts the inside rear wheel.....making the rear end hop.

 

Taking the front ARB off during some rally stages

 

Again different set up.......you don't want too much lateral movement on loose surfaces. The roll bars will provide most lateral movement......so therefore either weaker roll bars are used......or none at all at either end.

 

Taking the front ARB off during track stages is fairly common

 

What removing the front roll bar does is increase the roll distribution at the rear.

So therefore the car will turn in better and generally be more nervous.

But the total roll resistance is still the same. A better method would be to leave the front roll bar connected and increase the rear roll stiffness...therefore decreasing the total roll.

 

That is what I am doing currently on the rear of a 206. There isn't a large enough rear roll bar made to fit through the tube. So I'm having to design an adjustable bar that is connected to the chassis....then connected to the rear arms. That will give greater rear roll stiffness at the rear....so making the balance better.....but also increase the total roll resistance with the front roll bar connected.

[red 0]

I run the standard rear torsion bars with a 23mm ARB cotrolled by 2nd hand Bilstein Tarmac shocks and group N rubbers on the arms, you could go to solid mounts but I think that would be to far for a rd car as they work fine, with a front wheel drive car I think you'll find it nearly impossible to keep the inside rear wheel on the ground when driving hard, this is lowered 25mm rear and 30mm front, the front is a Bilstein Streetline kit still going strong with Bridgestone SO3's on the 4 corners.

 

Regards Russ.....

Edited August 23, 2003 by red

[saveloy 8]

I would go the ARB route. I have standard torsion bars,but use a 24mm rear ARB. AVO adjustables all round & group N bushes. This set up works a treat. Roll is minimal on the road & I have never had cause to describe it as twitchy. The car reacts like it always has,but at higher cornering speeds than a standard car. In a straight line it remains comfortable,since the rear spring rate has not been altered. However,on very bumpy roads,the ARB can come into play on the straights,in that it will twist & add an element of ride harshness. The ARB route means eating the cake.

[Wurzel 16]

Thanks for all the replies guys, definately some things to think about there.

 

When I changed to the Grp N rear mounts and renewed the cross beam bushes, it made a marked difference. Admittedley, the rear mounts were knackered.

 

ARB seems the cheapest compromise still giving good gains. Piece of piss to do as well so if I don't like it I can take it off again without too much trouble. Can't see that happening though.

 

Might save up and get myself some tarmac spec billies as well.

 

You never know, a 309 gti Beam may come along.