heavy_chevy29

i have a stock suspension 3rd gen camaro. its all adjustable aftermarket stuff. it has a 434 sbc on alky around high 600-low 700 hp. car has been a best of 9.85 @ 136 with a 60 of 1.41. the best 60 to date is 1.37. i think i can get this car into the mid/lower 1.3Xs 60. im trying to check/set my pinion angle. for some odd reason ive always had a tuff time with setting/understanding how to set the pinion angle correctly. i have the car sitting on blocks so its at ride height and i can get under it to adjust things. if i put the angle finder on the front of the head its at 0*. so i know the engine is at 0*. should the pinion be pointing up or down at this point. with the drive shaft out my pinion is pointing up about 1 to 1.5*. does this sound right. if anyone has an idiot proof way to set the pinion angle please let me know. like i said this is one of those things i just never seem to be able to under stand.

AlkyIROC

Pinion angle should be at the same angle as the engine/transmission centerline through the crankshaft etc.

The engine/transmission crank centerline and the transmission yoke should be pointing at the diff yoke. With tall tires on the rear, the diff yoke will normally be higher than the transmission yoke if the vehicle ride height is kept the same. The diff yoke/pinion should still be at the same angle as the engine/tranny.

If the engine balancer is higher than the trans yoke then the diff pinion will be higher in the front than at the rear. If the balancer and trans yoke are are level to the ground then the diff pinion should be level to the ground. If the front of the engine is lower than the trans yoke then the diff pinion will be down compared to the back of the pinion.

To offset for diff rotation under load, you can angle the pinion down a couple of degrees from the engine/tranny centerline so in your case since the engine is showing 0°, you can adjust the pinion down at the front a couple of degrees. The goal is to have the pinion rotate back to zero when the diff rotates under load.

Pinion angle has no relation to the driveshaft or the ground unless the angles are extreme such as in a very lifted 4x4. People always use the driveshaft as a reference normally because it's generally at the same angle to the crank centerline but only in a stock suspension and tire car. You can remove the driveshaft and still set the pinion angle properly.

Proper pinion angle does nothing for performance. It just makes the u-joints happy so they'll last longer.

Shagwell

^ IMO relating the pinion angle to the transmission angle is ment for commuter cars such as grandma's station wagon where the only thing you're doing is making sure it doesn't have any vibration.

Unless your engine/trans is at some really odd angle/height, I simply set pinion as the relationship of the diff to the driveshaft. For instance, if the ds runs 2* down towards the back & the diff is straight forward, then you have -2* pinion angle. In a big tire'd car like mine the driveshaft often runs straight back or even slightly up-hill, thus the rear has to point down enough to get your desired angled.

From racecars to the street cars, that has always worked well for me. Both my cars go consistent 1.1x or better 60fts, the street car I'm tuning on right now is a "full weight" '02 mustang that goes 1.4x's on 275 radials with a clutch.

heavy_chevy29

what about lower control arm angle. i have them set so at ride height they are parallel to the ground. is that ok or should they angle down to the rear?

AlkyIROC

Those are tuning aids. Each car and track is different. You adjust to best suit the conditions.

articwhiteZ

iTrader: (56)

there are a few books out that will give you a better insight to setting it up.
HP books.. still needs to work more info into the one they have out.

right off the top of my head.. with a auto trans ya want no more then 6 deg.
this could be neg 2 for the drive shaft..and neg 4 for the rear end. ya just want it to add up to no more then 6 deg total. when sitting unloaded. under load things line up better. and runs smoother (parts). and.. yes ya can go faster!

below is from just one Book on race car suspensions. and is repeated in a few other books.
the net is a good place to get some info. but always check out the info with the top name Guys who work on nothing but Race cars for a Living

pinion angle affects the efficiency of power transmission from the driveshaft to the rear end. the pinion angel is spread between the pinion centerline
and the driveshaft centerline. for maximum performance. its ideal to have a slight down angle.(min .2degrees) under full power.

Obviously, the pinion angle changes as power is applied. and the axle housing begins to twist as the pinion tries to drive the ring gear.
rear axle wind-up can take some of the initial energy or "Hit" away from the launch. As a general rule
a leaf spring rear suspension should have between 5 - 7 deg of static pinion angle (pinion down) and a factory four link should be set at 4-6 deg.

keep in mind that these angles are for Competition. if you primarily drive your car on the street. you shouldn't have more then 5 deg angle max.

the u joint are designed to run at this angle. which allows the cups to rotate. and live a long happy life....

I my self run my car with a Ladder Bar set up and run a total of 6 deg (pinion down) a combination of rear pinion and drive shaft. adding up to the 6 deg...the car will tell you what the track is like on a Launch. and you can adjust with your foot/pedal.. or start tweeking..I use my foot/pedal.
as soon as you get 2 or 3 books on race car/street car set up..the light will come on!

1bad406

iTrader: (1)

Thats exactly how I set mine up. Drive shaft angle in relation to the diff angle. I was told to run around -2 -1 with all heim joint components because they will flex less bringing you close to 0 under acceleration.