Pinion Angle with Cal Tracs

[malex]

Wondering what you guys are running for pinion angle with Cal Tracs. What works best?
Also wondering what method you use to determine pinion angle. It seems that some calculate by using trans, driveshaft and pinion angles, others use trans and pinion angle.

 

[bm02tj]

I would start with 1 deg down as they will cut down on axle wind
Using angle of drive train to get pinion angle

 

[66Satellite47]

Did Cal Trac have a recommendation?

 

[malex]

Did Cal Trac have a recommendation?

---
Cal Trac recommends 2 to 4 degrees negative pinion angle.
On my 64 I have 1 degree of transmission downward centreline angle and 2.5 degrees of pinion angle which totals 3.5 degrees. Should be good enough to take care of any axle wrap that there might be.

That led me to the next question of what amount of axle wrap is there with cal tracs, if any.

 

[Mike Gaines]

If the angle is "wrong", car will vibrate a LOT. You will know it.

 

[HEMI-ITIS]

3* is good,with more HP 5* is better.I have the complete Cal spit mono system with Viking shocks.

 

[gtxracer]

---
Cal Trac recommends 2 to 4 degrees negative pinion angle.
On my 64 I have 1 degree of transmission downward centreline angle and 2.5 degrees of pinion angle which totals 3.5 degrees. Should be good enough to take care of any axle wrap that there might be.

That led me to the next question of what amount of axle wrap is there with cal tracs, if any.

Malex, I have 2 degrees in my GTX, for what it's worth.
Bob

 

[6PKRTSE]

Calvert told me 5-7 degrees at more power level on the spray. So I went with 6-7 on my angle finder. All mocked up & welded in now.

 

[malex]

3* is good,with more HP 5* is better.I have the complete Cal spit mono system with Viking shocks.

---
I also have the split mono leafs, cal tracs and dble acting QA1's.

Trying to get an idea of how much, if any degree change on launch I jacked the diff up at the front of the centre section 1" to where the tires were just barely touching. I took another reading of the pinion angle. I also checked the car frame degrees, which didn't change at that amount of rise. The pinion angle had changed by 1.5 degrees. This was with the Cal Tracs set at zero pre load. There is a little change in pinion angle but not a lot with the cal tracs. A hard launch will likely make more of a change but how much I wonder.

 

[malex]

Calvert told me 5-7 degrees at more power level on the spray. So I went with 6-7 on my angle finder. All mocked up & welded in now.

View attachment 604831

---
I guess the more power it gets the more pinion angle change there is. Good to know, thanks!

 

[malex]

If the angle is "wrong", car will vibrate a LOT. You will know it.

---
I didn't notice anything last year Mike so that's a good sign. Over the winter I switched to an engine plate that lowered my engine about a half inch, so if anything I reduced the pinion angle a touch.

 

[dvw]

Cal tracks separate the housing from the body due to the short instant center. The more the body rises, the greater need to look at what pinion angle is required to straighten the drive line out under power. Let the rear axle hang and take a reading. It may surprise you.
Doug

 

[malex]

Cal tracks separate the housing from the body due to the short instant center. The more the body rises, the greater need to look at what pinion angle is required to straighten the drive line out under power. Let the rear axle hang and take a reading. It may surprise you.
Doug

---
Early on I used to get rise at the rear until I stiffened up the shock rebound so I never thought to check that. But you can bet that I'll be checking that now. Glad you mentioned this Doug!

 

[dvw]

Shocks limit suspension travel speed. This doesn't necessarily limit travel distance.
Doug

 

[malex]

Shocks limit suspension travel speed. This doesn't necessarily limit travel distance.
Doug

---
It slows down getting to your max pinion angle.

 

[malex]

Cal tracks separate the housing from the body due to the short instant center. The more the body rises, the greater need to look at what pinion angle is required to straighten the drive line out under power. Let the rear axle hang and take a reading. It may surprise you.
Doug

---
So here's what I know after lots of measurements. On my car. Calvert Split Monos, Cal Tracs, Dana and QA1 dble shocks:

Front of Dana behind yoke raised until tires start to unload: 1.5 change. 2.0 degrees Neg PA
At stock ride height, which is 21" distance from wheel lip to ground: 3.5 degrees Neg PA
Car raised 1 inch, 22" distance from wheel lip to ground: 2.5 degrees Neg PA
Car raised 2 inches, 23" distance from wheel lip to ground: 2.0 degrees Neg PA
Car raised 3 inches, 24" distance from wheel lip to ground: 1.0 degree Neg PA
Car raised 4 inches, 25" distance from wheel lip to ground: .5 degree Neg PA
* At 4 inch of raise the rear tires had lost almost all contact with the ground.

This exercise sure told me a lot about pinion angle change. From watching vids it looks like I'm getting about 2" of raise at max on my car. That tells me my car should be running about 2 degrees neg pinion angle during a pass. While there was pinion angle change it wasn't too surprising. Has anyone checked their cars to see what there PA is doing? I'd imagine it should be similar with the same components.

 

[cdr]

---
So here's what I know after lots of measurements. On my car. Calvert Split Monos, Cal Tracs, Dana and QA1 dble shocks:

Front of Dana behind yoke raised until tires start to unload: 1.5 change. 2.0 degrees Neg PA
At stock ride height, which is 21" distance from wheel lip to ground: 3.5 degrees Neg PA
Car raised 1 inch, 22" distance from wheel lip to ground: 2.5 degrees Neg PA
Car raised 2 inches, 23" distance from wheel lip to ground: 2.0 degrees Neg PA
Car raised 3 inches, 24" distance from wheel lip to ground: 1.0 degree Neg PA
Car raised 4 inches, 25" distance from wheel lip to ground: .5 degree Neg PA
* At 4 inch of raise the rear tires had lost almost all contact with the ground.

This exercise sure told me a lot about pinion angle change. From watching vids it looks like I'm getting about 2" of raise at max on my car. That tells me my car should be running about 2 degrees neg pinion angle during a pass. While there was pinion angle change it wasn't too surprising. Has anyone checked their cars to see what there PA is doing? I'd imagine it should be similar with the same components.

dont forget the front end raises under acceleration also. that would change what you are getting when just raising the rear

 

[bm02tj]

It is only the angle change from centre line of pinion and centre line of the transmission
not the ground or the car

 

[malex]

It is only the angle change from centre line of pinion and centre line of the transmission
not the ground or the car

---
Good point.
Going to do the rise again and check for transmission centreline change. Should be close aleady though, where I was jacking the front was lifting also.

 

[LemonWedge]

I run 3* down angle, measured by transmission output shaft and pinion yoke. Baseline setting of two flats of preload in the bars has always worked well for me.