Low profile tyres for competition use

[MartinD]

Hi all,
I am buying new tyres for sprint and hillclimb use in UK and I am thinking of getting some 175x50x13 Yokos, A539s. Normally low profile is good on a track car, but does this hold true for an Elan Sprint using Tony Thompson springs and dampers (110 / 150 lb springs). I still get a lot of body roll on track and I was wondering if more tyre compliance would be preferable, maybe 60 or 70 profile. I notice most race elans use a higher profile, but is this due to historic rules rather than choice. My only tyre requirement is list 1a in the blue book, which is basically road tyres.
So anyone competitors used 50 profile rubber on their car to good or bad effect ?

Regards Martin

[toomspj]

We use 60 profile yokohamas (A048) for historic roadsports in HSCC because the rules don't allow us to use lower profile tyres.

I don't think changing tyre profile is likely to affect body roll - that's going to be influenced more by ride height, anti roll bar diameter and damper settings. I guess I'd opt for going to a lower ride height and stiffening up the anti roll bar for a car that is used on the road.

If you're using it predominantly on the track you could go way harder on the spring rate - say 300# front and 180# rear, but it will be quite harsh on the road. If you turn up the bump settings on your s/absorbers that will give you an unpleasant ride

[johnaspencer]

Paul is correct that the TTR springs though a big improvement on standard spec are totally inadequate for track work. Tony provided me with 325 rating which go over his dampers at the front and 175 for the back. It might be worth changing the platforms at the back to adjustable height and using narrower springs to allow wider wheels.

If you have not already discovered this with 5J and especially 5.5J wheels you need to take something off the lower wishbone nuts otherwise you will be machining the inside of your rims.

Yokoham Advan 048s are fantastic.

Consider uprating to a 26R front anti-roll bar.

The car is then stiff enough for the track but will be horrid on the normal road.

[MartinD]

Hi,
Thanks for the comments, I have now done about four sprints at Curburough (my local track) on the setup and the car feels great to drive, very chuckable and the tyres are great with the profile not being a problem, although gearing is very low . But as can probably see from the picture, there is too much body roll, which I was expecting. My next step will be either 250 front 150 rear springs or the 26R anti roll bar, money permitting.

Cheers
Martin

[gino1]

Hi Martin,

On one of my Elans I have the standard springs and dampers on the front and 160Lb on the rear with Koni adjustables.
I am running 185 x 60 x 13 A048's (Brilliant!) and the larger 26R anti roll bar.
You will have a significant change and lose that lean on every bend with just the larger roll bar.

Gino Milano
Italy

[johnaspencer]

I did the anti-roll bar first, tried a trackday at Silverstone, and then uprated the springs. The latter made a bigger change to body roll but ruined the ride on country / urban roads.

One other point is bumpsteer and suspension geometry. I still don't understand bump steer fully but had it done by a local race prep company with laser guided everything. Probably the best money I have spent pound for pound.

Finally before moving from sprint or hillclimb to track think about a good classic car instructor. Also most trackdays have brake, turn and apex cones set up for modern Caterhams, Elises etc which handle quite differently to an Elan. A session with a guru will reinforce this point.

Good luck!

[rgh0]

If you want to use the car for both road and track days then a moderate spring upgrade to say 150# front and 110# rears and a 7/8 inch roll bar should do and is a good compromise

If it is only for racing and you like it hard and your tracks are smooth and you are not worried that handling in the wet will be a real handful go to 250# to 300# fronts and 150# to 175# rears.

175 / 60 Yoko A048 or Dunlop DZ3G work well with these set ups

cheers
Rohan