What should be my correct pinion angle? I've lowered the car and i'll be putting on a spohn torque arm and relocation bracket next week. Just wondering where i should measure the angle from? The driveshaft? The yokes? Not sure and i don't wanna have any vibration or break anything.

 

Suspension specialist Dick Miller bases pinion angle settings on horsepower. Miller likes to see 2 degrees of negative pinion angle (relative to the driveshaft) on applications in the 400hp range, 3½ to 4½ degrees in the 500hp to 650hp range, and up to 7 degrees with 700 horses or more. Miller also acknowledges that the greater the pinion angle, the more horsepower the driveline will consume, but it’s a compromise that must be made. Miller notes that these angles are merely guidelines, and each individual combination should be fine-tuned.
Video example of methodology...
http://www.youtube.com/watch?v=UAQgLbhQ0uk

 

I'll have to watch the video when i get home can't go to youtube at work. but negative pinion angle in relation to the drive shaft means the angle of the pinion yoke is 2° more than the drive shaft?

 

yes. The idea being, that under acceleration, the pinion and the driveshaft will (optimally) form a straight line.

 

Pinion angle will depend on HP, but it will also depend on what sort of bushing you have in the front support. A rubber or poly bushing will deflect, allowing the torque arm/pinion to move upward. A rod end will not deflect. Steve Spohn set mine at -1.8*. That's with the rod ends, and transmitting 800HP and 800 lb-ft.

 

one point eight? Dang..that's getting the definition specific. Wow... I have the poly mount now but I'm moving the anchor point to the crossmember instead of the stock tranny tailshaft. As always, thanks for the great info Injuneer.

 

800hp holy sheit muslim. I'm not even close to that haven't i dynoed yet but i'm hoping for 350. I'm checking out the video now. Oh i have the poly mount btw. I just bought the spohn set up cross member with drive shaft loop. SKU 402 from thier website.

 

That video is perfect. Thanks guys. I picked up a magnetic angle finder today just waiting on the parts now.

 

I wonder what you'll find your current angle to be. Let us know how easy/difficult it is.

 

He made it look easy with the $250 digital protractor. I've found that you can get similar accuracy with a $40 Sears digital level. Much easier than playing with the little gravity protractor.

 

Will do guys. Should be begining of next week. If the torque doesn't show up before tue i won't put it on until after the 21st cause i'm on leave. FL bound! Home sweet home.

 

Ok so i put on the torque arm and crossmember. The drive shaft angle was 2.5° and the angle at the base of the torque arm at the diff was 5° and i adjusted it to 2.5°. Now that the new torque arm is connected directly to the body theres a bit more noticable vibration. Also the rear end is howling a lot louder or the fact that it's attached to the body is making it more noticable. Does the pinion angle make a difference in rear end noise?

 

I'd bet the increased noticability is due to the attachment to the body. Is this a Sphon?

 

Yes it is a spohn, why do you ask?

 

Am i measuring the difference between the shaft and pinion and trying to get a 2° difference? For example if the shaft is 2° the pinion should be at 4°? It's just considerable louder rear end whine than before and i don't wanna break anything. Plan on pulling the cover and inspecting the gears and wear pattern monday and taking a pic or two.