Stock pinion angle.

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gnvair

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Sep 1, 2018
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I am looking for a solid number of what the stock pinion angle was on a 78-88 Chevrolet V8 powered A/G body. The numbers I am finding online are all over the place which tells me that either people are not measuring it correctly.
What I am looking for in reality is what the angle is on the engine and transmission
AND
what the angle should be on a stock rear axle.
Typically the angle should be the difference between the 2. I see some people just measuring the rear axle and calling that the pinion angle.
Just looking for good numbers.
 

ck80

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Feb 18, 2014
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What matters is that trans output shaft and pinion are equal but opposite, and, thus parallel planes for the drive - so trans output shaft is 4 degrees down, pinion angle is 4 degrees up, so on so forth.

With a 40 year old gbody you've got guys with mixtures of old and used rubber trans mounts, control arm bushings, poly and rubber combinations, aftermarket control arms and/or crossmembers, so on so forth.

So it's no surprise you get varied numbers, including guys with 'bone stock'parts having varied degrees of worn rubber gm bushing/mount parts.

You keep things parallel and within a reasonable range after having been corrected.

But as defined and commonly used, yes, the 'pinion angle' is that angle the pinion itself is clocked upwards from the flat plane, not the difference between the output shaft angle and the pinion angle.
 
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gnvair

Royal Smart Person
Sep 1, 2018
1,098
1,296
113
Southern New Jersey near Philly
What matters is that trans output shaft and pinion are equal but opposite, and, thus parallel planes for the drive - so trans output shaft is 4 degrees down, pinion angle is 4 degrees up, so on so forth.

With a 40 year old gbody you've got guys with mixtures of old and used rubber trans mounts, control arm bushings, poly and rubber combinations, aftermarket control arms and/or crossmembers, so on so forth.

So it's no surprise you get varied numbers, including guys with 'bone stock'parts having varied degrees of worn rubber gm bushing/mount parts.

You keep things parallel and within a reasonable range after having been corrected.

But as defined and commonly used, yes, the 'pinion angle' is that angle the pinion itself is clocked upwards from the flat plane, not the difference between the output shaft angle and the pinion angle.
My engine and transmission are -3 and I had the rear axle at 0 and it vibrated like crazy on the highway especially on deceleration. I currently have the rear at +3 and it still has a vibration.
Unfortunately, my measurements were not accurate with the original protractor I used when measuring prior to replacing the rear.....my issue is I was having a very difficult seeing the small graduations on the analog protractor (age is catching up to my eye site)
I have since bought a very accurate digital protractor but I am still without an accurate baseline for the rear axle.
 

565bbchevy

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Aug 8, 2011
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Michigan
I bought a pair of these years ago and they work great.
 

gnvair

Royal Smart Person
Sep 1, 2018
1,098
1,296
113
Southern New Jersey near Philly

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abbey castro

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I just did mine after replacing the 10 bolt for a Strange Eng S60 (Dana60) on my 87. Go to Spicerparts.com and use their calculator. They have an excellent writeup to determine your range of acceptable angles. If you are using the OEM upper and lower control arms you have no way to adjust the pinion angle. If you have upper adjustable (I have QA1 double adjustable) you can adjust the angle. I used the Klein tool. Best place to measure the transmission angle is at the damper, your trans output shaft is at the same angle as the engine damper (i.e. crank centerline) Operating angle at both ends of the driveshaft should be equal to within 1 degree of each other. I do not have any vibrations at all. GM Service Manual 1986 pg 4A-7 Front Universal 1 degree 18 minutes, rear universal + 0 Degree 57 Minutes
 
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