Pinion angles and caster

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bellaire35

bellaire35

10 Year
Joined
Jul 20, 2014
Threads
115
Messages
503
Location
Costa Rica & Texas
hello all,

Before I start taking measurements and consider adding shims I wanted to post pics of my front and rear drive shaft and pinion angles. I figure many of you experts can look at the photos and give your suggestions. I understand I need to take measurements to be the correct shim degree.

Front:
Installed AAL and 1" extended shackles. The pinion looks to be turned up. Adding a shim with the fat part towards the front would rotate the axle and possible correct the caster?


Rear:
Installed AAL and 1.5" extended shackle. Once agin same scenario as the front it appears. Get measurementsfor shim degree and fat part installed facing rear axle to rotate the counter-clockwise?

image.webp


image.webp
 
Pick up a magnetic - base protractor (either analog or digital) and record the measurements. Then you can determine the shims needed to correct pinion angles. Caster angle on a stock front axle should be about 1 degree. Big tires and SOA should be about 3 degrees. Remember that front pinion angle and caster angle move together, changing one will change the other. Preference should go to caster. If the axle is OEM this should not be a problem.
 
The most accurate method is to remove the drive lines and measure off the companion flanges and parking brake drum.
 
Here's what I did, I hope this helps.

I removed the drive shaft and also picked up a magnetic angle finder and checked the drive line angles.

full


Pinion flange angle reading
full



E-brake angle reading
full


For my application I used 3 degree shims with perfect results (no vibration and no sounds)
The magnetic angle finder was purchased from Lowes for $10

For more data please click my build thread in my sig.
 
Not sure i used the app correctly but here are my findings:

Front
Angle 1 (18.1)
Angle 2 (09.6)
Driveline operating angle (08.5)

Rear
Angle 1 (01.2)
Angle 2 (03.6)
Driveline operating angle (02.4)
 
If I am guessing correctly, the front drive shaft needs shims to get the TC flange and pinion flange more parallel.
Clearly from looking at the front drive shaft, my axle needs to be rotated downward to create this angle.
Insert fat part of flange towards front of axle?

Could not get a full shot including the TC flange.




The rear seams to be ok, maybe a little degrees off.

image.webp
 
If you are using regular joints the flanges need to have roughly the same angle on them. A double cardin setup is much more forgiving and they can point at each other. The fat part of the shim will go towards the side you want to lower, its usually on the side that has the extended shackles in the back. In the front it will not be as cut and dry especially with a shackle reversal.
 
Please school me on geometry.

If I want to rotate the pinion flange to be more perpendicular with the TC flange I would need to rotate the axle counter clockwise? If this is the case, then the shim would need to be installed with the fat part towards the TC?

Am I looking at this wrong?? Maybe I am overthinking this or not thinking at all. If the shim was installed fat part towards the shackle then the axle would rotate clockwise thus causing the pinion flange to point further out of spec?

I do not have SOA

image.webp
 
Wow, you two are really taxing my 9th grade Spanish:confused:
 
Ahh, but if it's a SOA setup it's the opposite. Just thought I would throw that out to confuse the noobie's.
 
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