Hey Guys, with the season winding down I thought I post some videos from my last time out (Oct 23) at Cecil. I'm struggling with the launch and looking for thoughts.
Combo is 68 Cuda, weights 3225 with,
motor dyno'd at 870hp 750tq with what turned out to be a bad valve job so, it's probably a little higher then that.
Trans 727 w/ 5800 stall converter
rear is a dana 60 w/ 4.88 gears - 13.5 x 32 stiff wall hoosiers (104" rollout)
shocks d/a all 4 corners
My thought is I have too much rear and have to take some gear out before I can really tune it

Pass 1 was shot from the hit
Pass 2 60' 1.37 - 1/8 = 5.95 @ 117.5 1/4 = 9.30 @ 146
Pass 3 60' 1.37 - 1/8 = 5.96 @ 117 1/4 = 9.31 @ 145.5

Pass1 - front shocks too loose 7 on comp


Pass2 - front shocks too tight 10 on comp


Pass3 - front shocks set at 9 (little better)


any help welcome
Thanks

I would send them to Calvert, they will be glad to help.

No expert here, slowed vids down to see and I would try a little preload into the left bar to stop it going left.... loosen rear shock extension till it hooks and stays hooked is what they say but I would try and stiffen them up 1 at a time as its hurting that yre or go up on pressure......and try 8 on fronts, not easy,..........we found as much as 16psi best on our 3800lb RR with 720ftlbs on the hit with a Hoosier 10x29 small tyre with c/tracs/monos. Also 880hp/3225lbs you'd be running 8.90's@149-150, and turning near 8k rpm@the stripe w/'88's/32's. And as you say perhaps somewhat less aggressive on the hit.

How much PSI in rear tires ?
It's bouncing the rear so i would go tighter on the rear shocks and prob slow the front down a bit also .

the first pass was 8 1/2lbs

second and third 7 1/2lbs

I think it's bouncing also

Looking at pass #3, My car used to jump off the ground in the rear too. I sent my Afco's in for re valving to be able to slow the extension on the hit. It made a huge difference, and controlled the separation much better.

interesting.., I'm running afco's also. I think they may be set a bit fast now and I was thinking of slowing them down.
They're set at -20 from full tight

Spinning the tires at the hit is not the best way to going faster.
You know where you need to work on, the hit
I would start at the front and work back to the rear suspension to cure it not staying hooked

The first pass , shows the car can work with what you have . Just need to control the front

What shocks are in the front ?
What leaf springs in the rear ?
What’s the weight front and rear?
How much front travel?

Looks like your rear worked well on the first pass , but the front was too loose or the front is too light . A lot of front travel with a good front shock will give you a lot of control . Also 10-20lbs up front can make a big
Difference . Or just moving some from back to front

I believe we have similar power but mine is about 100lbs heavier. With 55% on the nose and a 113" wheelbase. Do you have standard or BG valving in the rears? My car is 36" ladder bar. My bet is with the Cal tracks your rear adjustment will need to be tighter than mine. Even with Afco BG valving mine runs -14C/-14R in the rears. With shorter wheelbase your fronts will probably need to be tighter as well. My fronts have been tightened once and run -0CC/-0R. You are making decent mph. For comparison heres one of my slips

Thanks Cab

The car weight ratio is almost dead 50 / 50.
the front shocks are d/a Vikings; rear d/a afcos from competition suspension.
I'm not sure how much travel the front of the car has. I'll have to measure it.

Thanks for the time slip Doug. That does help for comparison. I'm thinking that a 4:10 gear will probably add a little more wheel speed yet.

I may get a chance to get out to Capitol this weekend coming. I'm also adding some because she was too lean the last time out at 65% deg 65% hum.

First vid is good for the rear shocks , but need control of the front . A shock that separates slow and has a lot
Of travel can keep it hooked up .
Measure the front travel see what you have . If
You have to take the bump stops out altogether

Someone was on the brakes there lol.

Thanks Guys. This gives me a few ideas. I'd like to get out one more time but, I'm not sure the weather is going to stay warm enough. I think I may knock the combo down to a 4.30 ring and pinion over the winter and add an anti roll bar.

Thanks for the vids! Not that I'm one to take advice from but I'm in the camp with run#1 tire pressure and tighter extension front and rear. Again nice car!

Thanks