Sounds like this should be in the Suspension section, but I want to start up some discusion focusing on fabrication of front spindles for FWD drag racing.

A lot of chassis builders talk about running at least a little scrub radius, so the driver will have some "feel". I know the NoRad project is designed with a LOT of backspacing in the front wheels. How much is 'a little' when it comes to a FWD drag car?

What kind of KPI range are the Pro-FWD cars currently running? 5-7degrees, or more?

Ready, set, discuss....

 

Nate,

Our old yellow ZX2 had ~ 7deg. KPI and ~8deg. Caster. I know it's not ProFwd., but it did have fabricated spindles. This was also a strut type setup, not a-arm like the current trend in ProFwd. The Zx2 recieved a touch more caster when it was front-halved, it now sits ~11deg. I liked the additional caster, as it should help the car straighten itself out. Our car did have a touch of torque steer, but it always went straight, even with a mild cross wind.

Brian

 

Interesting that you bring this up, as I spent some time yesterday deciding how i'm going to do the suspension on Sindicates car. The lower control arms are fabbed, but the strut has yet to be mounted. I'll have pics very soon. Anyways, on Rado's car, there is 0 scrub. The center of the tire is directly on the steering center and we have about 8 degrees of caster in it. We went this route to eliminate torque steer and make it possible to steer the damn thing with those big *** tires! lol. I'm setting up sindicates are at 9 degrees of caster and pretty close to 0 scrub. Forgive my terminology if it's not correct, i'm still learning this suspension stuff, there's alot more to it than most people think!

 

KPI is more commonly referred to as SAI (steering axis inclination) its a little more of a current term

 

tfnaaf: Yeah, I'm just used to saying king pin, because of the air-cooled's I used to work on. I haven't built anything with actual 'king pins' in years!

Tony: looking forward more updates on Sindicate and Egam's setups. When I get my camera working again, I'll get pics of one project that I'm working on, full-tube Mini Cooper (old one) with Porsche powertrain and suspension. (79.9" wheelbase + 50" rocker width = not much space to build and 'ideal' chassis) hehehe

Brian: got any pics of the spindles or suspension from the Ford?

The setup I'm working on looks like it will end up with the ball joints very close to the rotor, with less than 1" scrub and 7degrees SAI.
With the lack of space, we're looking at rockers and inboard shocks.