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I quickly did this info sheet on pinion angle, mainly as it applies to the front and for those with aftermarket double cardan drive shafts. It is pretty basic, but may be helpful to some.

There really isn't a pinion angle that will work for everyone, lift height, tire size, gear ratio, etc, will have an effect on what is the correct pinion angle for your set up. So the best way to get the pinion angle right is with a little experimentation. Start low and increase it until the point you feel vibration then go back to the previous setting. This will give you the best compromise between pinion angle and caster.

Before setting pinion angle you should make sure that the track is correct and the axles are in the right position.

There are various methods and special tools available to measure pinion angle, but with a quality angle finder and a little bit of patience you can measure it pretty accurately. I use a Sears Digital Torpedo Level and although short surfaces are a little finicky to measure, it works very well.

If you have any significant vibration from a drive shaft you will shorten the life of the drive shaft u-joints and centering ball, as well as risk damage to the t-case and/or diff.

http://www.trailduty.com/temp/pinion_angle.pdf
 
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Thanks Phil.

I know why I’ve been eating drive shafts. The idiots who set my Jeep up after I lifted it set the pinion angle on the front at 10 degrees :shaking:
 

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Discussion Starter #4
The idiots who set my Jeep up after I lifted it set the pinion angle on the front at 10 degrees :shaking:
That will definitely do it. You need to drop that by about 4-5°.

FWIW Here's my current front control arm lengths, center to center:

Upper: 19-1/2"
Lower: 22-15/16"

This gives me a pinion angle of 5°. Caster is a little low and the steering feels a little light, but I'm used to it now and it drives fine.
 

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Hi, I can't get the link to work. Is there any way to attach the pdf to this thread?

Thanks
 

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Hi, I can't get the link to work. Is there any way to attach the pdf to this thread?

Thanks
Same here. Link doesn't work
 

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Does anyone have a working link to a page showing how to measure pinion angle accurately?
 

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Ok so I placed my magnetic angle finder on the circular part next to the diff cover on my front D30 and got exactly 90. So, according to this thread, I subtract that number from 90 and so my pinion angle is 0. Now, where exactly does this put my caster? My thinking is that this would mean it is at 6 degree due to there always be a 6 degree relationship btw pinion and caster correct? Is this a suitable number for an aftermarket double carden shaft or do I need to shorten my front lower control arms?

I am getting a gear swap/tatton front shaft installed this weekend and I want to make sure if I have to make any adjustments beforehand. Thanks
 

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Bump. Is this accurate?
 
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