Torsion bar advice

[Jacob]

I am thinking of upgrading the rear torsion bars to 26mm. Have any of you already done this and if so what have been the noticeable benifits?

I am using my car more for trackdays (plan to do at leat 3 this year + visit to the ring[]) - should I jusy by-pass the 'stop gap' and go for the 22/29mm set up

 

[Guest]

9M run this "fast road" set-up on Colin's 3.2. It's just turbo t-bars and leave the front alone. The turbo t-bars are only 1mm bigger but the spring rate is the third power of the diameter so its a big enough change to notice. I personally think the cheaper way to get to a similar place is to put on a 22mm rear anti roll bar. It does much the same thing in so far as it dials a little understeer out and makes the rear work a fraction harder. If you want to replace spring plate bushes then you might as well do torsion bars though.

As you probably know, I have 22/29s and ran them with Bilstein HDs for a good year or so. It very livable in terms of ride handling. I am now on custom valved race Bilsteins and the difference is massive. The ride is seriously hard and you steer around bumps, manhole covers and potholes. This is the right shock valving for the spring rates and should be killer on the track but its antisocial in its harshness - though monoball strut mounts do not help either. So, the message is, that if you compromise the track performance and run soft shocks it's OK for daily use but if you do it properly its a real step towards track toy only. I think that the US guys running 23/33s etc who say the ride is "just fine" must have much better roads than us or run softer than ideal shocks.

Best advice is ask yourself what you want the car to eventually be - track toy, fast road etc - and do it once and right with that goal in mind.

 

[bruceb]

I've just had the 26mm torsion bars fitted with what can best be described as tarmac rally spec Bilsteins and the later carrera anti roll bars.

It a massive improvement over the standard set up I had on my SC with the Bilstein HD's. I use the car mainly for trackdays but did not want to compromise the road manners to much. The car is stiffer on the road but certainly not harsh. On the track its just great with much better control over the bumps and under braking.

It still understers a little but I am quite happy with that as the car feels safe at all times. Its not the ultimate trackday setup but as a compromise I thinks it works well

 

[Jacob]

I guess I will use my car as a fast road set up and occasional 'track toy' I had never really contemplated changing the rear anti roll bar first or even at all. Incidentally, what is the standard size of the rear anti roll bar?
So now I have 3 choices....... (although I think the 22/29 set up may be a little extreme for what I need)

 

[bruceb]

For the 87 car you already have the largest OEM Porsche rear anti roll bar fitted which is 21mm dia IIRC.

Larger bars aftermarket bars are available from most tuning shops. It certainly cheaper to fit the ARB first and see if you like the difference. Torsion bar changes are labour intensive and require complete geometry setups for the rear, hence the costs can be quite high.

One thing not mentioned so far are the shocks, Its really important that these are in good condition before doing any upgrades and it would be worth checking the condition of the ones fitted already.

 

[Jacob]

Cheers Bruce

What is the best DIY way to see if the shocks are in good working order?

 

[bruceb]

Jacob

I would take it along to a Porsche specialist for a check, the cars are too stiff for the wing bounce test. It might be worth getting a couple of opinions just to make sure unless you have total faith in your local shop