Cal Trac springs

Looking to see if anyone has a vidio from under car launching on these springs? Basically where to set pinion angle (Duster Dana 4.88 gear and 9x30 Hosier radials auto)

I set mine at 3 degrees down when I ran CalTracs.
Gus

Are you just using the CalTrac springs, or do you have the full CalTrac suspension? When you use the Calvert suspension setup with the lower bars you don't need much pinion angle since the rear end doesn't rotate much. If you use their springs without the bars then you would nee a bunch more pinion angle.

I run mine 1 deg down from parallel to the trans, work great

I'm at 4° down. Nickel width air gap at rest. Bars in bottom hole. Upper shock mount moved to framerail to get them as vertical as possible.

Has been 1.36 60 ft. on a 275 drag radial.

https://youtu.be/rYA-Ipb1GWE?si=iFTO6vt4d1qXuCq0

Yes whole Cal setup, been thinking of moving top of shocks over close to frame to get more vertical. Car will be 340 F/Stock auto, moly cage 3115 pounds

Nice

Whole setup, “doesn't rotate much” what I wanted to hear.
Amazing how ‘off’ the suspension is, to get rear square to car I had to move axel spring perch back on pin 1/8” (right side was more forward)

Pics

5 degrees down, car gets a LOT of axle rotation, it's why we have the wheelie bars set so high (the bars are for safety not tuning). This is something I have seen on many mopars using that type of wheelie bar, the big mistake is they are set too low and it unloads the tyre at the hit.
The car has been 1.29, (1.34 on the back wheels) 60ft @ 4000lb + with a 29.5 x 10.5 radial slick. Watch the vid below 1/4 time and you will see what a typical launch is like and how the rear reacts. (F/F to 40 sec in to miss the staging stuff )

https://www.youtube.com/watch?v=8iUhVr2rxm0

Mine is 3° down relative to the trans. Calvert recommends 2-3° if I'm not mistaken.

Calvert recommends 2 to 3 degrees of pinion angle with the bars parallel to the ground and a small gap. Need to put weight in the driver seat when making your adjustments.

As you can tell from the responses there seems to be a pretty wide range of what will work. Mine have been on so long I don't remember what the pinion angle was set at.

If you want to know for sure what might be best for your car give Calvert a call, their customer service is top notch.

Cool to see you are building a F/SA car! Keep us posted on your progress and let us know when you get it on the track.

The reason I run mine only 1deg down from trans is it works great SO FAR at launch, BUT if I go down more on the pinion I get a driveline vibration at a light cruise 70mph & up,, Street car problems LOL , I have OD trans & a 4.10 gear with a short driveshaft its very sensitive to the angles, smooth as glass the way I have it now that I have a Mark Williams driveshaft

From Calvert's faq

What pinion angle works best?
We suggest a pinion angle to be between 2-4 degrees negative, measuring off the transmission yoke and pinion yoke.

What I always did. We had horses back in the day and wife bought 50 pound bags of feed, I put 5 bags in the driver seat then adjust the weight and 4 link bars. I did a lot of freebies back then all the buddies cars, rears, suspensions, motors and trans, but just a hobby

Thanks, if I don’t get it done soon time will pass me by, old folks home calling me every month. lol
Bad part I’m getting rotator surgery next week then 4 months later the other shoulder, to much lifting and falling!