Am I doing this right? Pinion angle

[that guy]

Checking pinion angle. First pic is of angle finder on the driveshaft, I get a measurement of -1/2 degree.



2nd pic is of angle finder on the pinion coming out of the rear end, I get an angle of -1 and a half degrees.



Making my pinion angle -2, correct??? Pros and cons of more and less angle? Just trying to make my car hook better that's all.

What angle do these cars like? I have solid lowers and adjustable upper control arms.

Thanks for the help guys

 

[Roger]

-12 subtracted from -1 1/2 = -1 degree, however how much the car squats will affect the angle.

Hopefully Jack Cotton will chime in here, or give him a call - his customer service is the best.

 

[that guy]

Forgot to mention this is with the front wheels on the ground and the rear end jacked up, weight of the rear end resting on the jack.

 

[that guy]

So am I at least measuring it correctly?

 

[1chance]

Dont have any idea as to what this will help. Thinking it will reduce drivetrain stress? Maybe this is why my car will break the trans mount, and rear trans seal leaks sometimes?

 

[craggar]

To do it properly you need to have the car at ride height and race weight if that's what your going for. I usually just put the jack stands under the control arms on the front and the axle tubes on the diff. which has always worked on my ladder bar setups. A drive on hoist would be perfect for doing it.
Then measure the back of the tranny, d/s and diff. Figure out the difference between the three and that's your P/A.
I haven't got to mine yet on the GN but a 4 link likes 1-2 degrees and which is pretty much what our cars have.

The goal is to have no angle once the car is moving.

 

[turbo nasty]

Need to mimic real world conditions.

Car on a lift that supports all four tires

You in the drivers seat or someone real close to your weight

1/2- 3/4 tank of fuel

Measure the slope of the driveshaft vs. underneath the pinion ?(should be a flat spot to put the protractor) the difference is your pinion angle.


Street car no more than 2 degrees, the pinion should be down in relation to the prop shaft.

 

[cruzn57]

caution

excess pinion angle (down) can cause vibration on deaccelleration, just a word of caution, ( been there done that)

 

[that guy]

So do I subtract the angle of the driveshaft from the angle of the pinion of the rear end? Or do I calculate the difference between the two? This stuff just makes my head hurt. How do you determine the difference? Given what you see in the pics, is my pinion angle -2 or -1? Or do I need to do it again?

Funny how you read all over the internet it is real easy to find pinion angle but no where can you find an example clearly saying how it is done

Maybe I am reading into it to much, but man does this make me feel like I have the mathematical abilities of a 6 year old. Maybe I do???

Thanks to all who have responded, please clarify.

 

[MSDGN]

Here...check this out:

Pinion Angle - Wolfe Race Craft

...in talking to some suspension guys the best way to do it is on level ground with the suspension fully loaded but it can be done by jacking up the rear only as long as the suspension is supported either under the axle or pumpkin...the way you are doing it you are relating driveshaft angle to the pinion angle...has nothing to do with the angle of the car to the ground...

 

[MSDGN]

I can't see the reading on the pic for the pinion..is the arrow to the right or left of the 90 degree mark?...it should be to the right which would indicate that the pinion is pointing down...somewhere around 89 degrees...if it's on the left side at around 91.5 degrees then you're at +.5 degrees...not good...
do you have adjustable uppers?

 

[MSDGN]

My bad...you said the driveshaft was -.5...I'm confusing myself now...just need to know for the pinion what side of 90 degrees the arrow is on...then I can tell you what your pinion angle is...

 

[that guy]

My bad...you said the driveshaft was -.5...I'm confusing myself now...just need to know for the pinion what side of 90 degrees the arrow is on...then I can tell you what your pinion angle is...

To the right at 1.5 degrees. Pinion is definitely pointing down towards the ground.

 

[MSDGN]

You're at -2...that should be fine...

 

[Chuck Leeper]

Pinion angle is not a tuning "tool".
Setting the pinion angle helps free up HP, as the greater the angle, when under accel, the higher the HP required to turn the pinion...
The trik is to get the angle set static, so that suspension deflection, when under accel, the angle moves as close to zero as possible. = less HP loss.

 

[turbo nasty]

Pinion angle is not a tuning "tool".
Setting the pinion angle helps free up HP, as the greater the angle, when under accel, the higher the HP required to turn the pinion...
The trik is to get the angle set static, so that suspension deflection, when under accel, the angle moves as close to zero as possible. = less HP loss.

Spoken like a true prodigy... you have been doing this just a few years huh Chuck.... lol

 

[craggar]

Pinion angle is not a tuning "tool".
QUOTE]

Dave Morgan would disagree with you. In his Door Slammers book he says it is a tuning tool. I'm not saying you're wrong but it depends on who you talk to. I do know on my 69 Camaro I went from 2 degrees to 3 degrees and my 60' went from 1.3 to consistant 1.28's.

Maybe I freed up some hp or maybe I got more bite. I don't know which but it did change.

 

[Chuck Leeper]

Whatever..

Pinion angle is not a tuning "tool".
QUOTE]

Dave Morgan would disagree with you. In his Door Slammers book he says it is a tuning tool. I'm not saying you're wrong but it depends on who you talk to. I do know on my 69 Camaro I went from 2 degrees to 3 degrees and my 60' went from 1.3 to consistant 1.28's.

Maybe I freed up some hp or maybe I got more bite. I don't know which but it did change.

"floats your boat"...
Or better yet, whatever turns your crank!!
Could be that degree got the deflection set to release that extra HP??