S3 Sprinting Springs?

[ianl]

I’m looking for some advice on spring rates for my 1991 S3. The car was fitted with Avo adjustable dampers and spring platforms for the previous owner by Wedge 2 years ago. As the springs now appear to have relaxed and the ride height is too low at the front I have attempted to raise the platforms. Unfortunately the aluminium platforms are seized to the damper bodies and I have had to strip the lot down and cut off the collars to be replaced by new ones (Ordered yesterday p.m. from Avo and arrived this morning – impressed!).
When I stripped the parts fitted by Wedge I found that the springs would appear to have been mistakenly swapped front to rear on the RH front and LH rear. Can’t see any part numbers or rate markings on the springs but they were sized as follows:
RH Front 288mm free length 12 full coils 12mm wire 2.25” ID
LH Front 278mm free length 11 full coils 13mm wire 2.25” ID
RH Rear 288mm free length 12 full coils 12mm wire 2.25” ID
LH Rear 278mm free length 11 full coils 13mm wire 2.25” ID
Thought it felt a bit odd!
I intend to try a few sprints later in the year (work permitting) and would like to carry on using the Avo dampers. I appreciate that there may well be better alternatives but as I already have the Avo's I will use them as a starting point. Having trawled the excellent Pistonheads archives I’m considering going stiffer on the springs along the same lines as Paceracing and GreenV8S i.e. 650lbs/in 10.5” long fronts and 400 lbs./in 10.5” long rears. Am I right in assuming that the above springs are more than double the original rates? Having watched Pete at Curborough I was impressed with his V8S’s progressive breakaway at the rear and relative lack of roll going through the kink. My S3 is only used for fun so I’m happy to trade some ride comfort for more predictable handling and less roll. The other alternative is to powder coat and re fit the original springs from Wedge to the correct ends which I assume means the 13mm wire diameter (higher rate?) on the front and see how it goes.
Other intended mod’s are:
Polly bushes or solid bearings on the ARB.
Re set camber. Not sure what to yet?
205-55-15 Bridgstones or I may try Toyo T1-S
Tower View brake upgrade and roll over bar
And possibly Poly bushes on the wishbones and trailing arms.
All suggestions gratefully accepted.
Ian L

[shpub]

First question:

Which class are you intending to compete in?
Standard production means you keep the springs and everything else as standard but can retain the AVOs and fit a roll bar.

Beyind that and you are in B6 along with Pete and myself.

Steve

[ianl]

I’d like to be able to experiment with the car’s spec, as to me that is half the fun. So I will have to play at the big boys end of the playground. To be honest my self-preservation instinct and lack of driving skill will probably mean I wouldn’t be competitive in either class.

[GreenV8S]

quote:I’m looking for some advice on spring rates for my 1991 S3. The car was fitted with Avo adjustable dampers and spring platforms for the previous owner by Wedge 2 years ago. As the springs now appear to have relaxed and the ride height is too low at the front I have attempted to raise the platforms. Unfortunately the aluminium platforms are seized to the damper bodies and I have had to strip the lot down and cut off the collars to be replaced by new ones (Ordered yesterday p.m. from Avo and arrived this morning – impressed!).
When I stripped the parts fitted by Wedge I found that the springs would appear to have been mistakenly swapped front to rear on the RH front and LH rear. Can’t see any part numbers or rate markings on the springs but they were sized as follows:
RH Front 288mm free length 12 full coils 12mm wire 2.25” ID
LH Front 278mm free length 11 full coils 13mm wire 2.25” ID
RH Rear 288mm free length 12 full coils 12mm wire 2.25” ID
LH Rear 278mm free length 11 full coils 13mm wire 2.25” ID
Thought it felt a bit odd!
I intend to try a few sprints later in the year (work permitting) and would like to carry on using the Avo dampers. I appreciate that there may well be better alternatives but as I already have the Avo's I will use them as a starting point. Having trawled the excellent Pistonheads archives I’m considering going stiffer on the springs along the same lines as Paceracing and GreenV8S i.e. 650lbs/in 10.5” long fronts and 400 lbs./in 10.5” long rears. Am I right in assuming that the above springs are more than double the original rates? Having watched Pete at Curborough I was impressed with his V8S’s progressive breakaway at the rear and relative lack of roll going through the kink. My S3 is only used for fun so I’m happy to trade some ride comfort for more predictable handling and less roll. The other alternative is to powder coat and re fit the original springs from Wedge to the correct ends which I assume means the 13mm wire diameter (higher rate?) on the front and see how it goes.
Other intended mod’s are:
Polly bushes or solid bearings on the ARB.
Re set camber. Not sure what to yet?
205-55-15 Bridgstones or I may try Toyo T1-S
Tower View brake upgrade and roll over bar
And possibly Poly bushes on the wishbones and trailing arms.
All suggestions gratefully accepted.
Ian L

Both Jason and I have very aggressively set up cars. A setup like this isn't suitable for all people, it's a compromise that happens to suit our driving. SO I would be cautious about simply copying this setup, you need to work towards a setup that suits *you* and the way *you* use the car. For example, with stiffer springs there is less traction on poor surfaces, and the car responds quicker to steering and braking inputs (which means the driver then has to respond quicker to stay in control). Also, changing the springs and dampers can have a very dramatic effect on the balance on the car. I did the sums to ensure I didn't upset the balance too much, and I've tweaked it a couple of times since that first big change to suit the power and grip I have, and my driving style. Can't tell you off-hand what those rates you proposed will do to the balance, although I can do a rough estimate if you want if you tell me what size anti-roll bar you have currently. But given the relatively low price of springs I'd suggest you make several incremental changes rather than one huge one. Amongst other things this gives you time to get used to the eyeball-rattling ride quality!

BTW I assume those standard springs are progressive rate with four turns nearly coil bound at normal ride height? This increases the effective spring rate by 50%.

Don't forget to grease the spring seat adjuster threads when you reassemble so it doesn't seize up again!

Cheers,
Peter Humphries (and a green V8S)

[Paceracing]

An S3 probably runs in class B6 anyway, provided the rules haven't changed since I stopped sprinting in 1999. The Y2K weight rule change outlawed the V6 'S' cars because of the weight being registered as less than 1000 KG's. The V8S should be OK as it is about 1060 KG's according to Autocar. This probably only applies to the Southern Championships though and was done to annoy Elsie drivers.

Regarding the changing of the springs but retaining the old dampers, this could have disasterous consequences to the cars' handling. Stiff springs which are under damped will result in the car oscillating over bumps and can be very dangerous. Another effect is that braking is less efficient with poor or underdamped springs (next time you are in Quick Fit read the wall charts). Conversly, over damped springs cause 'crashing' and when braking, the front wheels will skip. Another affect of over damping is the 'jacking' effect where the spring is prevented from returning the car to the original ride height, and the car jacks down on the suspension.
The trick is to get it all balanced, which is why we use adjustable dampers. A final point is that even though the dampers are adjustable, the valves may still not be suited to the springs so you have to get them re-valved to suit the spring rates!
Technical isn't it?


Jas

>> Edited by Paceracing on Tuesday 12th March 16:26

[ianl]

Thanks for all the replies.
I think I will refit the progressive springs to the right ends of the car and try a few changes once I have a baseline to work from.
Pete, if you could do the sums on the above springs with my current (standard) 25mm diameter ARB I’d be very interested to know the results.
I will be re-setting the camber angles once all the bits are re powder coated and back together. Could anyone suggest a good starting point to begin experimenting from?
Thanks
IanL

[GreenV8S]

quote:Pete, if you could do the sums on the above springs with my current (standard) 25mm diameter ARB I’d be very interested to know the results.

So that's 650lbs fronts and 400 lbs./in rears with a 25mm bar?

quote:
I will be re-setting the camber angles once all the bits are re powder coated and back together. Could anyone suggest a good starting point to begin experimenting from?

I would start the fronts somewhere between -1.5 deg and -2 deg for a reasonable road setup. More if you are going for maximum cornering grip, but you will definitely notice the kick-back and tramlining. Rears are not easily adjustable and I'd leave them alone for now. Bear in mind the camber will change every time you change the ride height, and there are lots of factors that limit the ride height.