1969 Torino

[Ron Sutton]

Rob,

I tell most everyone, "we can go no faster through the corner than the front end has grip" ... and since we have 285's on the front of a big car ... we need to optimize them to their fullest potential, within the limitations you have put on the car yourself: no fender mods, 2" of front wheel lip, etc.

Here are the keys:

1. Your KPI/Caster Split should favor the caster by 0.5 to 0.75 degrees. Your C6 spindles have 9.15 degrees of KPI. Which would mean you want 9.65 to 10 degrees of static caster. That "seems like" a lot of caster, but just what the doctor ordered. GM runs this spindle at 7.7-8.3 degrees of caster in the stock Z51 & all the fast Corvette track guys run 10.0-10.5 degrees of caster.

2. You will want the A-arms installed to achieve "anti-dive." That means the LCA angles down in front & the UCA angles up in front. This will compliment the suspension set-up I'm going to recommend. And it will provide you with dynamic "caster gain" as the suspension compresses. You need about 0.5 degrees of caster gain. If you end up with more ... which would be good ... you need to reduce your static caster by the amount above 0.5 degrees.

3. How much camber gain you can end up with will also affect your roll center. Since your priorities are road course track days, Silver State high speed runs & Optima type "all around" performance events, you'll want a slightly higher front RC than you would for AutoX. I'd say 4" at ride height & 1.25"-1.5" in dive. That is easy to get by increasing the UCA angle (taller spindle or ball joint) ... which will also increase camber gain.

4. If you end up with 2.0 degrees of camber gain, I'd suggest a "starting point" of .75 degrees of static camber, for a total of 2.75 degrees of camber in dive (suspension compressed). If you end up with less camber gain ... add more static camber ... and keep the 2.75 degrees total. Other tuners may tell you need way more camber, but they're not used to working with a KPI/Caster Split favoring the caster.

5. Run .060" total toe-out. Yes ... out. Then play with the Ackerman & bump steer ... so you end up with .140"-.150" toe out ... in dive ... with the wheels turned 20 degrees.

6. You need to transfer a high amount of weight off the rear tires & onto the front tires for optimum cornering.

7. You need to achieve & maintain a low roll angle to optimize the front tire contact patches.

8. Therefore the optimum suspension set-up for your ride would be a high travel front end ... to achieve high pitch change & low roll angle ... also known as soft spring big bar.

I'll hop back on here tomorrow & outline the suspension set-up to achieve this ... along with tuning tools to balance the car at the track.