This came to me last night, I was upgrading all my bolts for my suspension to grade 8s and was checking my pinion angle. BMR and UMI say to take the TQ angle and minus the driveshaft angle. Wouldnt true pinion angle be right at the yoke? Iv always taken mine right off of the U-joint or yoke? Is that wrong or should I do this simple math?? To me seems like waist of a few seconds of my busy life..lol Im no expert just wondering....

 

Ive been told to always check it at pinion/yoke

 

When people here use the term pinion angle they are referring to the angle of the pinion in relation to the driveshaft, not the actual angle of the pinion itself.

 

I take mine off the tailshaft with a smart level. I then zero the level and then put on the bottom of rear housing.

 

I use the angle of the engine / transmission centerline and take the difference from the rear end / pinion. My transmission angles -3 degrees there for I set my pinion angle to a +1 degree angle. This gives me a difference of -2 degree pinion angle, all the other driveline / torque arm angle stuff is bs. You are setting the pinion angle and not the driveline angle.

This explains it in more detail, ehh well I guess this uses driveline angle

http://www.ssz28.com/tech/Pinionangle.html

 

car on the tires level pull the driveshaft, set the TA so the pinion to the angle you want.

 

pinion angle is the "degrees of working angle of the u-joint". it is the comparison of the centerline of the pinion in relation to the centerline of the driveshaft. driveline angle is the comparison of the front working angle to the rear working angle. the optimum setup is to have the front joint and the rear joint angles the same, which cancels out vibes. GM spec is 1.5 degrees for both. in the performance world it is common to slightly increase the rear angle to help chassis bite, but the farther you go the worse the vibes will be.

best method i have used is to place a small carpenters square on the pinion yoke with the yoke positioned 12-6/9-3 o'clock. the square then runs alongside the driveshaft where you can easily compare the readings of your meter. this is where you want to see 1.5 to 2.0 degrees difference with the pinion yoke at the lowest point(negative angle), somewhat representing a "v" shape if looking at the driveline from the side.

anyone who tells you to measure pinion angle compared to the horizon is clueless. what if you have just the rear of the car jacked up? that is why it is the comparison of the two angles with the rearend compress into the car at ride height.

 

Right or wrong, I always check the pinion angle with the rear of the car compressed a little, and the front jacked up so the tires are just touching the ground, so that the suspension is as close to the state that the car is going down the track. I have over the course of time figured out where the car compresses to during a run (I put an extra o-ring on the shocks, that after the burnout was set on the shock body, so that as the shocks compress it would push the oring up the shock shaft, sort of a shade-tree travel measurment) and compressed the rear to that level. It usually worked out to about 2 inches from the car's standard ride height stance. I cant' say that's good or bad either, just my personal experience.

With the car set like this I always aimed to keep the pinion and the driveshaft at the same angle, which also worked out so that the driveshaft was at the same angle as the drivetrain, everything was zero.

By doing this, the U joints are strait, which should put them in the least possible mechanical bind.

I can't say it's better then any other way, or right/wrong, just how I have been doing it since I've had adjustable suspension on the car. I can say I have tried changing it, as much as +/- 2.5 degrees, and not once ever saw any indication on the track that either helped, so I put it back.. to what I am calling zero (everything in line)


Again, this could be totally wrong, but after over 150 passes on the same driveshaft, and no measurable u-joint wear at all it can't be totally off/wrong.


fwiw, I also did the initial alignment of the front end, with the back of the car compressed the same way and the front jacked up at full extension. This is how I set the toe (at zero, and it never toes out thru the entire range of motion) This worked with the stock k member/a arms and whatnot pretty good, car tracked strait as could be and never felt darty on the brakes, etc.

Again.. not saying that's the right thing to do either, but it worked for me.

Madman probably can elaborate on this stuff alot more/better then I can. All the stuff I've done is little bits and parts of differnt people's ways of doing things, and I adapted the info to work for what I had to work with. Now, with a fully adjustable front end I have to do that over again, and have the ability to set the caster way back for stability and get the toe/camber right again too.... this will for sure take a good while longer, and still need someone with an alignment machine once I have it in a workable state.

 

Just so I can throw my 2 cents in:

We run pinion angle off the yoke of the rear end Only.

 

the yoke should be 2 degrees down relative to the driveshaft angle.

that way when the yoke shifts upward in its arc under accel, the yoke and the shaft will be straight.

 

Essentially, what you guys are doing pretty much end up about where I have mine set.. I've tried Brian's method of checking the pinion angle, and when I compared how he does it to how I had my car set, it ended up within a 1/4 degree of where I had the car already.


And being that I've tried -2 and +2 from what I call zero with literally no measurable difference, I was satisfied with my method, as well as madman's Just 2 different ways of getting there.

 

But where are you getting your 2 degrees from in relation.

 

I tried a variance of +&- from what I am calling zero, which is where the pinion angle is with the car in what I would call race stance, nose up back compressed an inch and a half or so.

The madman method, is pinion angle in relativity to level ground, by my understanding, which works pretty damn good (by the # of cars he's gotten to leave hard and run fast)

 

So you just put the guage on the pinion and when it says negative 2 stop there? My pinion points upward so that would be one hell of a driveline angle if I were to just do that. And I am sure you are losing e.t. that way.

 

Ask Madman if this is right.. but load the car, driver, etc, then put the ga on the level ground, make sure that's zero, then put it on the yoke, and check and see where it is..

Whatever you do just make sure it's consistantly done, and you'll find if there's any change.

I've never seen a big change, which is why I try to keep it all in line as much as possible to prevent a mechanical bind (drag by the driveline)

Old leafspring car, you absolutely need lots of pinion angle... but cars with rod ended suspension that doesn't deflect at all, the need for it from what I've found seems to be substantially less.

 

FWIW I used to set my pinion angle off the rear end only in relation to the ground and it ended up being crazy negative. I know it has worked for madman for a long time, but my car didn't like it. It caused a weird wheel hop type issue during my burn out. I set it to -2 in relation to the engine/tail shaft and the hop went away. I'm sure it was more than likely u-joint bind.

 

Alot of that has to do with how the car sits too, if you have the car sitting low and somewhat level you won't have the issue as much...

There's alot of variables with what works for each person, madman's method, the way I check my personal car, as well as plenty of other ways are all viable.

 

Like I said before these cars have the pinion facing upward to get a negative 2 Driveline angle. I can not imagine twinsting my adjuster till that thing was neg 2 pinion. If it works it works. Just crazy.

 

If you were having wheel hop issues during the burn out, that might have been fixed with some LCA relocation brackets. If your LCAs are running parallel to the ground or down hill toward the front of the car, then you'll have wheel hop.

 

Steve I know it's been a while since I was down there last but my car has all that stuff, you name it it's there. Not trying to start a fight but it was caused by the pinion angle. I'm not sure wheel hop is the correct way to describe it, but it wasn't smooth.