GT40s.com - View Single Post - What causes heavy steering at racing speeds

Kalun D · 06-21-07, 11:36 PM

""Scrub Radius is not far from that of your car Trevor, yours 110mm, mine 114mm.""

Too much scrub radius. Should be less than 25mm. 0 is optimum. As light as these cars are in front, if the steering is heavy there's problems.

It is hard to find an upright that gives you zero scrub with a 235 Halibrand tire wheel setup, and 255 is worse. One reason I scratch built mine.

My setup.

4 deg King pin
3 deg Caster
3 deg Ackerman
0 camber
20mm scrub
235's
2.7 turn 240Z rack
13 in steering wheel

easy to park, good turn radius
one handed steering at any speed
tracks nice, light and quick like a go kart.

If changing uprights is too much trouble, Frank Catt's setup may be the way to go.

06-21-07, 11:36 PM	#135 (permalink)
Kalun D Kalun_D 5 Tenths Join Date: Dec 2003 Location: Seattle GT40: Scratch build Posts: 593 Rep Power: 11	Re: What causes heavy steering at racing speeds ""Scrub Radius is not far from that of your car Trevor, yours 110mm, mine 114mm."" Too much scrub radius. Should be less than 25mm. 0 is optimum. As light as these cars are in front, if the steering is heavy there's problems. It is hard to find an upright that gives you zero scrub with a 235 Halibrand tire wheel setup, and 255 is worse. One reason I scratch built mine. My setup. 4 deg King pin 3 deg Caster 3 deg Ackerman 0 camber 20mm scrub 235's 2.7 turn 240Z rack 13 in steering wheel easy to park, good turn radius one handed steering at any speed tracks nice, light and quick like a go kart. If changing uprights is too much trouble, Frank Catt's setup may be the way to go. Last edited by Kalun_D; 06-21-07 at 11:41 PM.