Torsion Bar Size

[driversdomainuk 8]

Hi

 

I am running a front 22mm ARB and a rear 25mm ARB

 

 

I am changing my rear TBs now, and want to know if it would be ok to go for 25mm TB - I am aware most tend to drop a couple of mm (i.e 23mm TB with 25mm ARB) but as I use the car for hillclimb and hardly ever on the road, would going for 25mm TB/25mm ARB work or would 24mm give better results.

 

cheers

[Rippthrough 98]

Hi

 

I am running a front 22mm ARB and a rear 25mm ARB

I am changing my rear TBs now, and want to know if it would be ok to go for 25mm TB - I am aware most tend to drop a couple of mm (i.e 23mm TB with 25mm ARB) but as I use the car for hillclimb and hardly ever on the road, would going for 25mm TB/25mm ARB work or would 24mm give better results.

 

cheers

 

 

You might find you want to go down an arb size if going stiff on the torsion bars, after all, it's only a patch for having soft bars in the first place.

Edited April 17, 2007 by Rippthrough

[petert 587]

Provided you have a cage, 23mm TB and 25mm ARB is generally accepted as the optimum rear setup for track work in the dry. Unbearable on the road for any length of time.

Edited April 17, 2007 by petert

[smckeown 1]

I assume that's 205 size peter, for 309 they would be slightly stuffer like mine.

 

I'm no expert on what suspension would be needed for track vs hilclimbing, but wouldnt the terminal speeds be lower and some of the bends tighter ? (of course both circuits and hilclimbs vary in their configuration). So would Would you want a slightly softer setup for a hilclimb vs track ?

 

Am sure some of the experienced hilclimbers on here can add their thinking on this

[driversdomainuk 8]

Provided you have a cage, 23mm TB and 25mm ARB is generally accepted as the optimum rear setup for track work in the dry. Unbearable on the road for any length of time.

 

 

I have a 10 point welded in cage....so why should i NOT go for a 24mm TB..?

[petert 587]

Go for it then, but remember stiffness increases to 4th power.

eg

 

19^4=130321 mm4

 

23^4=279841 mm4 (210% stiffer than 19mm)

 

24^4=331776 mm4 (250% stiffer than 19mm, 18% stiffer than 23mm)

 

Regardless of the type of event (so long as its tar we're talking about) the aim is to keep the front wheels on the ground. So if you've got the torsional rigidity provided by the roll cage you can dial in as much stiffness in the rear as you can bear. Different in the wet however. That's my thoughts on the subject, others may differ!

[Rippthrough 98]

Go for it then, but remember stiffness increases to 4th power.

eg

 

19^4=130321 mm4

 

23^4=279841 mm4 (210% stiffer than 19mm)

 

24^4=331776 mm4 (250% stiffer than 19mm, 18% stiffer than 23mm)

 

Regardless of the type of event (so long as its tar we're talking about) the aim is to keep the front wheels on the ground. So if you've got the torsional rigidity provided by the roll cage you can dial in as much stiffness in the rear as you can bear. Different in the wet however. That's my thoughts on the subject, others may differ!

 

 

Personally Id push the tb's right up, then bring the arb size down to regain some grip.

[SPGTi 2]

Is there a problem with the rear setup at the moment ? If so what is it ? Are you changing because it is the limiting factor in decreasing your times ? The Koni suspension is basically a "fast road" kit, would your funds be better spent in getting height adjustable coilovers with a range of springs, or if regs allow with remote cannisters ? Height adjustable would allow corner weighting adjustments to get the car set up better.

 

Just a few ideas

 

Steve

[driversdomainuk 8]

Is there a problem with the rear setup at the moment ? If so what is it ? Are you changing because it is the limiting factor in decreasing your times ? The Koni suspension is basically a "fast road" kit, would your funds be better spent in getting height adjustable coilovers with a range of springs, or if regs allow with remote cannisters ? Height adjustable would allow corner weighting adjustments to get the car set up better.

 

Just a few ideas

 

Steve

 

 

After getting the Tran-x diff, soft yoko tyres and fat front and rear arb I thrashed by PB time by 3 sec on practice day...I want to get quicker still....and am finding there is still a bit too much of a body roll on some corners - I want it to be totally flat on the corners.

Edited April 18, 2007 by driversdomainuk

[SPGTi 2]

After getting the Tran-x diff, soft yoko tyres and fat front and rear arb I thrashed by PB time by 3 sec on practice day...I want to get quicker still....and am finding there is still a bit too much of a body roll on some corners - I want it to be totally flat on the corners.

 

I understand that but what I am getting at is :

 

Is the it the rear end that is really a problem ? I presume that you are running the std Koni springs upfront, which are probably only 160lb/in. I would assume that at the moment esp. in the damp/wet you will have a tendency to oversteer, so stiffening up the rear even more will make this worse. In another thread you have spoke about getting 300lb springs (which you will have to have made), will the damper be effective with this increased poundage ? The dampers have an important part to play esp when you start making everything very stiff.

I have driven pugs with std setup, Koni kit, Bilstein coilovers (PTS) and Proflex. With the only difference being the dampers and if I had the money Proflex would be on every car I own, it is awesome, I never realised dampers could make so much difference.

 

Do you get people to video your runs, this will help hilight where you have problems esp if you also video the front runners to compare.

 

Maybe find a "setup" specialist as at the moment I think everything is guesswork (well it is by me anyway ) as you have probably found the "easy" seconds, now it gets more difficult.

 

best of luck

 

Steve

[driversdomainuk 8]

I understand that but what I am getting at is :

 

Is the it the rear end that is really a problem ? I presume that you are running the std Koni springs upfront, which are probably only 160lb/in. I would assume that at the moment esp. in the damp/wet you will have a tendency to oversteer, so stiffening up the rear even more will make this worse. In another thread you have spoke about getting 300lb springs (which you will have to have made), will the damper be effective with this increased poundage ? The dampers have an important part to play esp when you start making everything very stiff.

I have driven pugs with std setup, Koni kit, Bilstein coilovers (PTS) and Proflex. With the only difference being the dampers and if I had the money Proflex would be on every car I own, it is awesome, I never realised dampers could make so much difference.

 

Do you get people to video your runs, this will help hilight where you have problems esp if you also video the front runners to compare.

 

Maybe find a "setup" specialist as at the moment I think everything is guesswork (well it is by me anyway ) as you have probably found the "easy" seconds, now it gets more difficult.

 

best of luck

 

Steve

 

Hi Steve,

 

I am running standard Konis up front, but am considering swopping for coil overs and 275/300 lb springs - if you read my other post I have put forward a few quesitons there as I am unsure about these spring sizes etc..

 

In reply to your question, the back end is not really a problem, I am just trying to make the car as stiff as possible

[smckeown 1]

I'm very happy with my stiff rear, it's very planted indeed, lots of grip even when hitting the curbs.

 

you can see pics of my front and rear and through the corners at anglsey. You can still see there's plenty of front compression with 275lbs with standard arb

 

http://www.track-monkey.co.uk/2058v_trackdays.htm

[SPGTi 2]

Have a look at this article. They might help you decide what dampers you need and then how to try and set them up (hard bit) along with different spring rates, TBs and ARBs

 

Thorney

 

 

 

 

Maybe in the local library

 

Competition car suspension

 

Steve

[petert 587]

If you go too big on the front bar you'll keep the tyre(s) off the ground. Better to increase the front to 300-325 and go back to the std. front bar. I've got 340lb springs on mine and I'm going to experiment with no front bar.