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Old 08-18-2023, 11:57 PM   #1
stubs
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72 c20 pinion angle

Does anybody have or could measure their pinion angle on their 1972 c20. I'm trying to get a reference so I can set mine up
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Old 08-19-2023, 09:18 AM   #2
HO455
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Re: 72 c20 pinion angle

It's not really that simple.
Is your truck a coil or leaf spring truck?
Two or four wheel drive?
Is it lowered?
Is it lifted?
Does it still have the factory drive train?
Two piece driveshaft?
How old are the engine and transmission mounts?
The pinion angle needs to be set up in relation to the transmission output yoke's angle (also known as the engine angle)

So if I told you my pinion angle was up 2.5 degrees it is unlikely that would mean much when it came to your truck.
Here is a current thread on the subject with links to further information to help understand the the physics involved.

http://67-72chevytrucks.com/vboard/s...d.php?t=846700
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Old 08-19-2023, 09:36 AM   #3
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Re: 72 c20 pinion angle

The answer you get most of the time is 3 degrees or less.

In a Truck this is sometimes not going to happen in the Real world.
Especially with bigger tires and lift kits or lowering kits.

Here is one link talking about it.
Link: https://www.motortrend.com/how-to/pinion-angle-change/

Here is a Calculator that member HO455 shared a couple of years ago.
link: https://spicerparts.com/calculators/...gle-calculator
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Old 08-19-2023, 10:27 AM   #4
stubs
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Re: 72 c20 pinion angle

I get the 3 degrees deal I'm just looking at stock coil C20
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Old 08-21-2023, 09:42 PM   #5
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Re: 72 c20 pinion angle

If you have a 2 piece driveshaft, basically if the front driveline is 3 down make the pinion 3 up. so that they are parallel. Problem is that the pinion moves up on acceleration so some say to make the rear 1-2 up at most. as far as the engine/trans goes, the front driveshaft should be within 1 1.5 degrees the same slope as the engine trans combo. Are you having vibration issues?
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Old 08-22-2023, 06:54 PM   #6
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Re: 72 c20 pinion angle

Quote:
Originally Posted by stubs View Post
I get the 3 degrees deal I'm just looking at stock coil C20
I just measured two of my trucks, they're both 3 degrees up and both 3/4 ton 2WD trucks. One is leaf sprung, the other is coil. One truck has a factory two piece drive shaft, the other has a factory one piece shaft, both trucks at factory suspension heights.This subject gets so blown out of proportion that the simple necessary facts get lost in the non-pertinent details, (BS)! HO-455 pretty well summed it up, we need more info! How many shafts? Automatic or stick? Motor and Trans on factory mounts and crossmembers? The bottom is, the crank centerline should be in the neighborhood of 3 degrees down. The pinion angle should match or closely match the same angle as the motor, only up not down. They should be looking at each other for the optimal set up... Two piece shafts are a little more detail oriented than one piece shafts. U-joints need to work in tandem, one counters the other. That goes out the window if that carrier bearing centerline is not inline with the crank centerline! Then the final two u-joints play in cancellation harmony...Why are you asking for pinion angles? Did you twist the trailing arm perches on the axle? I did that on Nasty Sally's 12-bolt when I put big block juice to the rusty factory mounts.
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Last edited by Ironangel; 08-22-2023 at 07:11 PM.
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