3000M competition spring rates

[rsh]

Can anyone suggest suitable spring rates for a track only car, road use limited to driving to and from events. Lots of advertisers have 'uprated springs' but nobody is prepared to share numbers if you're not buying. Am currently running around 200lbs front and rear with 1" bar up front. Will source springs locally as freight costs prohibitive.

[GreenV8S]

quote:
Can anyone suggest suitable spring rates for a track only car, road use limited to driving to and from events. Lots of advertisers have 'uprated springs' but nobody is prepared to share numbers if you're not buying. Am currently running around 200lbs front and rear with 1" bar up front. Will source springs locally as freight costs prohibitive.

Since springs are relatively cheap, you could start by measuring the existing springs and stiffen them up by say 20 % all round, and keep going up until you reach a compromise you like between ride comfort and body control. You will need care to maintain the car's handling balance if you go far from standard, but the calcs for this are quite simple. At the same time, you will need to play with the wheel geometry and tyre pressures to suit the new spring rates. Although I could happily throw numbers at you based on what suits me in the V8S I think this would be the wrong answer as you need to set the car up to suit you and your driving preferences.

To give you a rough idea, my guess is that you will end up somewhere around 300 lb/in wheel rate all round, which depending on your suspension geometry might be around 600 lb/in spring rate. But I would need to know more about the suspension geometry to confirm that. In any case I'd suggest you make several small changes rather than one big one and get the rest of the car set up to suit.

Cheers,
Peter Humphries (and a green V8S)

[davidy]

Talk to Adrain Venn at Exactly TVR (see oily pages), he can probably suggest the best set up for track work, he did mine on a track-day Taimar, but too a secret recipe (I know what they are but he asked me not to divulge!!), they were great especially with Leda Shock Absorbers.

Beware of going too hard on the rear as you may crack the rear uprights when kerb hopping!!

davidy

[davidy]

Forgot to say

Best improvement came from Corner Weighting the car with a simulated driver (ie you). This made a dramatic improvement in handling and gave me a lot more confidence as a driver (enabled over 100mph through Cramer Curves at Donington Park!!). Probably best money I spent on the car.

Davidy

PS Can say that my car was quite a bit stiffer than yours!!

[rsh]

Any new contributions on the spring rate topic ? Have been through every TVR web page and forum on the planet and still can't crack the cone of silence when it comes to what the definitive spring rate for 3000m track use is. Let's have some fresh numbers, even the front/rear ratio would be a great start. The truth is out there ... someone will crack ...

Kiwi Rod

[19560]

I hope you're still with us. The general consensus seems to be a front to rear ratio of 4:3. I would think that 400 at the front and 300 at the rear would be a good starting point. Julian is running that on his S at the moment. I have a friend with the Leda set up who uses his car for everyday transport. It has 190 springs all round and is too soft for the track. The Tasmin racers (a third weight increase over an M) are using 800 to 900 lb/in springs. Ian Bannister was using springs in excess of 300 in his yellow Vixen IIRC. Good luck.

[rsh]

Thanks for the update Jonathan, feedback from other sources agrees with your 4:3 ratio, they suggested 350lbs:250lbs. Prior to this had tried 300lbs:200lbs but too soft at rear so currently 300lbs:250lbs for next race meeting. Looks like I'm heading in the right direction.

Kiwi Rod

[19560]

Your iterations do seem to be heading in the right direction. Note that the Leda system uses much thinner springs and is designed to be used with front and rear anti roll bars (the front is a lot larger.) The 350/250 seems to be a reasonable set up for a fast road car but may still be slightly too soft for racing. I am not surprised that you found 200 at the rear too soft for racing. Will 300/250 tend to suffer a little with oversteer and tempt you to soften the rear shock absorbers too much to compensate? It could be fun finding out. (With a 400/300 or stiffer set up you may need something to protect your teeth on the way to the track.)