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Simon TR4a
06-22-2006, 09:32 AM
I have been following a discussion on another forum about the new Hoosier Speedster tyres (tires) which are becoming popular in Triumph and Porsche 356 circles.
A claim was made that Dick Stockton, a TR4 racer got readings of 1.3 to 1.4g in the corners on "data aquisition" equipment.Most vintage racers don't have any way of getting this kind of data, and I assume it was a G Tech meter or similar, and possibly 10% optimistic.
Even allowing for that, this still sounds like a fantastic figure for a car on treaded vintage-legal tyres with 7 or 8 heat cycles in them.
I realise a skidpad with a 200 ft diameter will not give as high figures as a corner with a 500-600 ft radius, like some of those at Watkins Glen, but isn't this getting close to the figures Can-Am cars got back in the 60's with huge slicks?

Anyone have any data, or opinions?
Simon, (tormented in Toronto.)It would have been better if I could say Puzzled in Pittsburgh!

billspohn
06-22-2006, 11:23 AM
No data, no informed opinions, but I tend to be skeptical - I'd believe maybe 1.00 on new slicks........

Monkeywrench
06-22-2006, 03:19 PM
Hi Alan,

It was I who posted that data. The data machine that we used was a DAQ unit. It was out of one of our crew members Spec Miata. You are right, we do believe it is optomistic, but from car to car, it was about .1 g's greater than the Spec Miata at the same track in similar conditions. You also have to keep in mind that Dick is a very accomplished race car driver. 1965 DP Runoffs Pole, multi Northeast SCCA Divisional champion, numerous track records, 2nd BP 1970 Runoffs, etc. If there is anyone that can drive on the ragged edge it is him. We're going to have him drive the Spec Miata in a few weeks, not only just for fun, but to also gain some back to back data between drivers.

But yes, we do belive it is very optimistic, the idea of stating that was to show how it compared with a Spec Miata, which with a mid pack National driver was doing approx. 1.2 g's through the corner with that particular DAQ unit. I hope this clears this up, that posting was a bit rushed anyhow, lol. Cheers..

-Bob

PS: for anyone not familiar with the Hoosier Speedster, it's a sticky DOT legal radial tire with some "vintage" tread. It's been approved by most vintage sanctioning bodies.

Simon TR4a
06-22-2006, 03:30 PM
Thank you, Bob, I am hugely impressed with that kind of number, considering the constraints in vintage racing; the narrow track and simple suspension of the TR4.
Whatever the absolute figure, the comparison with a Miata is a real testimony to his driving; I have tried to keep up with those things at Shannonville, unsuccessfully!
Thanks for the additional information.
Simon.

Hap Waldrop
06-22-2006, 08:08 PM
Hey Bob, how ya doing. For what it's worth, those are about the same numbers we see on SCCA production cars with cantilever slicks. Bob it would be intesresting to put this system on a cantilever slick shod car like a SCCA prod car and see what kind of numbers you record. What kind of numbers did you see on the vintage car with other tires?

Monkeywrench
06-22-2006, 10:59 PM
Sorry Simon (not Alan)

Though the suspension on the car isn't a full blown SCCA spec unit, it ain't all stock, and is very well sorted (still SVRA legal though). As you know we are trying to dial out some understeer, but with the understeer we're having it is not going to change ultimate grip (ie: lateral g's), just when he can get on the power..

Hi Hap,

It would be interesting to what numbers that, that daq unit (I forget the brand) will read on a slick shod car, obviously for comparisions sake. Also this is a bit like comparing dyno numbers, as you well know, they all don't read the same; some high, some low.

We didn't get any other recordings on any other tires. We would have liked to, but time constraints and a wheel leaking issue kept us from doing that.

-Bob

We'll be back up at the Glen for the US Zippo GP. Try to make it and stop by and say "Hi" if you do.