corvette setup help.

[vetteboy]

Need some help with the setup on my car. I think my 60’ time are way off. the car has the 427 400hp with a 4 speed pure stock 3300lbs. The last T&T the car ran 1.62 to 1.63 60’ @ 11.56 117MPH. The car has Santhuff front spring with cheap 90/10 shocks(new front shocks on order) and the rear has toms IRS. The rear spring is stiffer then a L88 spring and I have QA1 double adjustable shocks. The clutch pressure is set at 400 and I could go as low as 220(I'm work my way down on pressure). I run the tires about 10.5 psi. If I make the rear spring to stiffer I spin all the way through first gear.
Do you think the rear of the car is to stiff or to soft?
Too much clutch pressure?
Too soft on the tires?
Weight transfer to slow or fast, not enough?
When I go to T&T I only get about 4 runs so I’m looking for more advise of what to try next . Thanks in advance. Brett

[tj310]

Slow motion launch is sure cool ! The way the car jumps I say too much base . We run pretty much zero base and add in some centrifugal to get the car to launch. 1.60 60s with a stick aren't too bad for that ET but the mph indicates your leaving some on the table , my opinion.---Trevor

[Jeff Jewell]

2 things I see...

It looks like you need to adjust the rear toe-in a bit. When the rear squats, the rear tires toe-out, reducing the contact patch. Ideally, you want the tire straight up and down when the rear is under load. In the first video, the tires look like they are toe'd-out too far after the hit.

It also looks like you are basketballing the rear tires a bit too. I'd keep the softer springs in it and adjust the hit with rear shocks and clutch settings. That will help get rid of the basketball effect.

Hope this helps.

[Ben Kallies]

Brett,

I used to run an IRS in my C/S '71 Corvette, and the set up that worked best for me was a heavy rear spring (600 lbs/in), and lots of base pressure in the clutch. This helped the front end to come up high, which planted the rear suspension, and stopped it from bouncing. 60 ft times were in the 1.50-1.52 range with low 11 et's. Of course the high base pressure eventually left me with a broken inner axle. I'm not claiming to be an expert because there are a lot of things that I never got the chance to try, but in my experience, the more power I was able to put to the rear tires, the better it responded. Good luck, and have fun.

-Ben

[L79racer]

I think you can drop the base another turn. I have my 66 vert down to 280 lbs with 11.8 grams of weight on Tim Hyatts levers. What size slick is that? The 3300 lbs, is that with you in it. My 66 with an aluminum headed small block hard top only and no bumpers, full stock interior came in at 2805. Did you do anything to front end for bump steer? My front is almost on bump stops and the nose is almost fully extended all the way down the track.

[Bob Pagano]

"the nose is almost fully extended all the way down the track"

L-79, There in lays a problem, the reason your frontend is in the air is because air is pushing it up as you go down track. Get it to settle back down and you will pick up et and mph.

[L79racer]

Originally Posted by Bob Pagano

"the nose is almost fully extended all the way down the track"

L-79, There in lays a problem, the reason your frontend is in the air is because air is pushing it up as you go down track. Get it to settle back down and you will pick up et and mph.

Bob, I guess it needs some kind of chin spoiler. I believe that was a problem for the L-88's at Daytona. They were getting too light in the nose at high speed. Any recommendations to get it to settle down besides a spoiler or air dam? If I get it to settle it would solve or help my bump steer.

[Bob Pagano]

Its been many years since I ran mine, front end was done by Jack Arnew and there was a big difference after the car was done. Can not say a spoiler would help or not, could not use the in Stock or SS unless the car came with them. Some company makes a shock that locks down when you hit the switch, been a long time so cant remember that either....getting old sucks. bp

[Bobby Zlatkin]

But, it beats the alternative.
That's how you have to think of it.