Low Speed (Autosolo) ARB Question FWD
Discussion
Hi all
(First caveat, I have no understanding of suspension. It’s a black art)
I have a little 205 gti for Autosolo’s. On the original spec suspension there’s a lot of body roll and under steer.
I believe that the usual rule is to increase the rear arb, to increase the front grip.
However, I’ve also spotted online people saying that the front arb increases turn in stability.
Therefore, bearing in mind the intended use (low speed but rapid change of direction) the exam question is, will it be worth putting on a thicker front arb (cheap as chips) in isolation? Or increase the thickness of both (the rear option is several times the price of the front.
The other thing to mention is that I also now have some adjustable Avo shocks / springs to fit. So do I make that change first and see how I get on?
Any constructive comments gratefully received.
Cheers
(First caveat, I have no understanding of suspension. It’s a black art)
I have a little 205 gti for Autosolo’s. On the original spec suspension there’s a lot of body roll and under steer.
I believe that the usual rule is to increase the rear arb, to increase the front grip.
However, I’ve also spotted online people saying that the front arb increases turn in stability.
Therefore, bearing in mind the intended use (low speed but rapid change of direction) the exam question is, will it be worth putting on a thicker front arb (cheap as chips) in isolation? Or increase the thickness of both (the rear option is several times the price of the front.
The other thing to mention is that I also now have some adjustable Avo shocks / springs to fit. So do I make that change first and see how I get on?
Any constructive comments gratefully received.
Cheers
From my experience of building and setting up a 205 for hillclimbing:
Roll is not necessarily your enemy if you can get some camber (1-2 degrees). This can be done with adjustable top mounts or 309 wishbones.
You really don't want to be stiffening up the front end too much for low speed twisty stuff unless you're running a decent LSD. The amount of traction you get out of a corner is dictated by the traction of the inside front wheel, which obviously reduces the stiffer you go.
My theory (which seemed to work) with FWD hatches is to set the front end up to get the best traction / turn in, then use the rear end to adjust the balance. A lot of people set the car up with springs, TBs and dampers to work in the wet with no rear ARB, then fit one to bias the balance forward in the dry.
I would hazard a guess that the AVOs will be too stiff for Autosoloing. Check what spring rates are on them, but I wouldn't go any stiffer than 160lb/in on the front end.
Roll is not necessarily your enemy if you can get some camber (1-2 degrees). This can be done with adjustable top mounts or 309 wishbones.
You really don't want to be stiffening up the front end too much for low speed twisty stuff unless you're running a decent LSD. The amount of traction you get out of a corner is dictated by the traction of the inside front wheel, which obviously reduces the stiffer you go.
My theory (which seemed to work) with FWD hatches is to set the front end up to get the best traction / turn in, then use the rear end to adjust the balance. A lot of people set the car up with springs, TBs and dampers to work in the wet with no rear ARB, then fit one to bias the balance forward in the dry.
I would hazard a guess that the AVOs will be too stiff for Autosoloing. Check what spring rates are on them, but I wouldn't go any stiffer than 160lb/in on the front end.
McSwerve II said:
Hi all
(First caveat, I have no understanding of suspension. It’s a black art)
I have a little 205 gti for Autosolo’s. On the original spec suspension there’s a lot of body roll and under steer.
I believe that the usual rule is to increase the rear arb, to increase the front grip.
However, I’ve also spotted online people saying that the front arb increases turn in stability.
Therefore, bearing in mind the intended use (low speed but rapid change of direction) the exam question is, will it be worth putting on a thicker front arb (cheap as chips) in isolation? Or increase the thickness of both (the rear option is several times the price of the front.
The other thing to mention is that I also now have some adjustable Avo shocks / springs to fit. So do I make that change first and see how I get on?
Any constructive comments gratefully received.
Cheers
(First caveat, I have no understanding of suspension. It’s a black art)
I have a little 205 gti for Autosolo’s. On the original spec suspension there’s a lot of body roll and under steer.
I believe that the usual rule is to increase the rear arb, to increase the front grip.
However, I’ve also spotted online people saying that the front arb increases turn in stability.
Therefore, bearing in mind the intended use (low speed but rapid change of direction) the exam question is, will it be worth putting on a thicker front arb (cheap as chips) in isolation? Or increase the thickness of both (the rear option is several times the price of the front.
The other thing to mention is that I also now have some adjustable Avo shocks / springs to fit. So do I make that change first and see how I get on?
Any constructive comments gratefully received.
Cheers
I suspect if you add more front roll-stiffness you'll end up spinning-away what power you have via the inside wheel (at low speeds and so low gears). More rear roll stiffness does work on FWD cars for better traction but to a degree it only holds-down the inside front by making the rear too stiff and ready to lift-off oversteer. Pick your poison carefully.
Anecdote: I've had several fast saabs. On the GM900 turbos, a stiffer rear antiroll helps traction immensely (once you have the factory rack bush problem fixed); it would also do lift-off overstter like a giant Mini (fun - but slow) Compare that with the original 900Ts, for which the fastest set-up is to leave the rear alone and to disconnect the front AR bar! More roll; but more consistent grip also.
It's grip you want - the roll doesn't matter so long as it doesn't actually detract as a poster above noted. There must be some more specialist 205/track knowledge out there to tap. Good luck - it sounds like fun
ETA: in something as light as the 205 perhaps it could be worth a (free) play with tyre pressures F:R. Just an idea.
Anecdote: I've had several fast saabs. On the GM900 turbos, a stiffer rear antiroll helps traction immensely (once you have the factory rack bush problem fixed); it would also do lift-off overstter like a giant Mini (fun - but slow) Compare that with the original 900Ts, for which the fastest set-up is to leave the rear alone and to disconnect the front AR bar! More roll; but more consistent grip also.
It's grip you want - the roll doesn't matter so long as it doesn't actually detract as a poster above noted. There must be some more specialist 205/track knowledge out there to tap. Good luck - it sounds like fun
ETA: in something as light as the 205 perhaps it could be worth a (free) play with tyre pressures F:R. Just an idea.
Edited by Huff on Monday 2nd April 19:24
Hi
My 106 Rallye S1 has torsion bars from a 106GTI on the rear and a front ARB from a cooking 106 1.0 Graduate (thinner). Slitghtly stiffer front springs at std ride height. Works well for tarmac road rallying.
I did two autosolos for fun (not really my bag). I disconnected the farb. Turn in and traction brilliant. Famous Peugeot lift off oversteer available at 20mph. This. Throttle controlled swing of the back end is a lot faster and flowing than trting to apply handbrake turn methods.
If you are really after an autosolo set up, thw first thing I'd suggest is remove one of your farb droplinks and go try the car round the cones. I think you'll be surprised how good it is.
Peter
My 106 Rallye S1 has torsion bars from a 106GTI on the rear and a front ARB from a cooking 106 1.0 Graduate (thinner). Slitghtly stiffer front springs at std ride height. Works well for tarmac road rallying.
I did two autosolos for fun (not really my bag). I disconnected the farb. Turn in and traction brilliant. Famous Peugeot lift off oversteer available at 20mph. This. Throttle controlled swing of the back end is a lot faster and flowing than trting to apply handbrake turn methods.
If you are really after an autosolo set up, thw first thing I'd suggest is remove one of your farb droplinks and go try the car round the cones. I think you'll be surprised how good it is.
Peter
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