Caltrac Setting

[Nightmist66]

I finally have the rear end housing and leaf springs hung under the car and about to set up my new third member. I am about to bolt up the Caltrac bars and would like to know what some of you stick racers would recommend for a starting point. I have the double adjustable Caltrac brackets(two holes). Clutch is a somewhat aggressive unit, 28×9 bias slicks, and double adjustable shocks. Which hole would you recommend starting with and what kind of baseline for preload on the bars? TIA

[jayb]

Not a stick racer (not for a while, anyway...), but on my cars I always use the bottom hole and put a half turn preload on the driver's side.  Seems to work good with the trans brake...

[475fetoploader]

I left at 5500 with a trans brake. It hit plenty hard. I used the bottom hole and preloaded the left side bar, between 1/4 and 3/4 of a turn. Seems like I settled at 1/2 a turn. I can’t see where a clutch would ask for something different.

[Nightmist66]

Thank you both. Is the pass. side set at the default "zero point"?

[cjshaker]

Yes, the passenger side bar should be at the point of just touching. Remember, that should be done with driver in the car, fully weighted and in a settled state on the suspension. If the car moves left or right on launch, put a bit more preload on the side of movement.

You probably remember that I was having a hell of a time getting my car to hook. It either bogged or spun with no recovery. Didn't matter if I was in the top hole or bottom. Tire pressure adjustment didn't make much difference either (in my limited amount of racing). I just had to slip the clutch, which was touchy at best. That was with a Ram HD unit, and I'd imagine yours won't be much different, or maybe even worse.

For what it's worth, what changed everything was when I went to the 3.08 1st gear in the Jerico, and 4.30 rear gears. That gave me a much better starting line ratio, and the car basically leaves on its own now. I don't just drop the clutch, but give it a semi-quick release, the front pops up and the car takes off with no drama. Your starting line ratio will probably require you to try and slip the clutch as best you can.

[mbrunson427]

The recommendation we got from Calvert for our Mustang was 2 turns on both sides for a starting point. Run it up until it top bar is just barely touching the top of the leaf spring, then screw it down 2 turns from there. For street driving we go to the "just touching" point and then back it off one turn. We have done that same procedure on The Mustang, Cougar and 64 Fairlane and never had to do anything different, although none of those cars have a crazy amount of power so they have always stuck just fine launching like that.

[Falcon67]

And here's another take -

Top hole, weight in the driver's seat.  Both bars just touching the spring plus 1/2 turn.  Shocks set on 8.  Haven't touched the settings in 15 years.  Car lifts the front tires with anything from the 300 HP motor to the 500 HP one. 

[Nightmist66]

Not a stick racer (not for a while, anyway...)

Need to get back in the game, Jay. 

[Nightmist66]

For what it's worth, what changed everything was when I went to the 3.08 1st gear in the Jerico, and 4.30 rear gears. That gave me a much better starting line ratio, and the car basically leaves on its own now. I don't just drop the clutch, but give it a semi-quick release, the front pops up and the car takes off with no drama. Your starting line ratio will probably require you to try and slip the clutch as best you can.

I do remember the launch issues, Doug. My SLR comes out to 13.09. What RPM are you leaving at now? I don't really like slipping the clutch on a launch, more like slipping off the clutch. Pedal.

[Nightmist66]

The recommendation we got from Calvert for our Mustang was 2 turns on both sides for a starting point. Run it up until it top bar is just barely touching the top of the leaf spring, then screw it down 2 turns from there.

This is kinda why I asked. I have heard some guys going between 1-2 full turns.

[cjshaker]

For what it's worth, what changed everything was when I went to the 3.08 1st gear in the Jerico, and 4.30 rear gears. That gave me a much better starting line ratio, and the car basically leaves on its own now. I don't just drop the clutch, but give it a semi-quick release, the front pops up and the car takes off with no drama. Your starting line ratio will probably require you to try and slip the clutch as best you can.

I do remember the launch issues, Doug. My SLR comes out to 13.09. What RPM are you leaving at now? I don't really like slipping the clutch on a launch, more like slipping off the clutch. Pedal.

I'm leaving at 5000, but that's with a 3.78 stroke and not much low end torque. Your engine will probably be different, and maybe leave best below that.

Chris didn't say how many adjustments are in his rear shocks, but the idea is that they will probably need to be tight. I have mine on about the tightest settings that they can be. Still, with no slipper clutch, it's barely hanging on. I think I need to slow my front end rise down a bit, so I'm getting double adjustable front shocks. With no slipper, the clutch still hits hard and I think is causing my front to top out too hard and fast, which still unloads the rear tires. To be honest, I think it would work better on the strip with a softer clutch. The Ram HD has been a great clutch, but it's a very fine line between just the right amount of slip, too much, or dead hook. I think that my SLR is just good enough to get me past that, as is. I still have work to do to get my 60' times down where they need to be though.

Point being, every car is different, so getting a starting point is good, but likely won't be where you end up. I'm sure you're aware of that though, as I'm sure you've done lots of reading on it. There is a good CalTrac thread pinned on YellowBullet which you've probably seen. Good advice to start you off, but it quickly shows that no single setting works for everyone. I have 1/2 turn in the right, 1 turn in the left (the car drifted left just a bit, and the 1/2 turn extra stopped that). 2 full turns to start off seems like a bit much, but if that's what CalTrac recommends? Maybe I should try that....

[Posi67]

Jay pretty much nailed it however as mentioned every car is going to like something a bit different. Seems to me I tried the 2 turns preload in the beginning and no idea where that advice came from but it wasn't good.

 

[mbrunson427]

Seems to me I tried the 2 turns preload in the beginning and no idea where that advice came from but it wasn't good.

I guess I should explain our setup so nobody gets crossed up here. All the cars we have cal tracs on so far are street cars, running normal street leaf springs, no calvert mono-leafs. Shocks are just ordinary street gas shocks. When I have called into Calvert, seems like I have always gotten a hold of either John or his son Brent. Just ordered a set of bars a few weeks ago for my uncle's F-150 and when I called Brent answered. But yes, it was John that recommended 2 full turns for our setup and it has always worked. The Cougar and the Mustang both have the Total Control chassis stiffening braces on them and they go straight as an arrow. Advice was given circa 2012, so maybe some different advice would be given today?

[John67427]

I use the bottom hole and have had them all over the place as far as pre load. Finally just have them touch spring and half turn of preload with me in the car. Shocks are very firm using Viking D/A. Bias ply 9x29’s Leave at 3750 with clutch setup. As everyone said each car has a different personality due to torque/ hp range, clutch setup, shocks, tire pressures, track etc. etc....

[Nightmist66]

Thank you everyone for chiming in. I have a good idea now. I believe I will start in the lower hole and go with half a turn on the driver side to start.

Dale, thanks for the chart. I thought my memory served me right that the upper hole was for a harder hit and the bottom was softer.

John, I can only hope my car leaves as nice as that with the wheels up. I dunno if this little mill is going to have the steam, LOL.