Pinion angle?

[Warthog]

I’m hopin someone can help me. Watch a bunch of videos of people basically rattling to hear themselves talk. I don’t need history lessons or how a car works. Just wanna know what size shim I need. The driveshaft is -17 degrees on the bottom however if I place the angle finder…my phone it says -18 degrees. Lol checked all over and that’s the readings I get. So figured I’d go with the -17 since I did see all the people in the videos measuring on the bottom…bout all I could get from em. The axle or pinion measures -6 degrees. Measured from rear diff cover bolts, the little metal shelves? On the pumpkin and the u joint. The pinion nose slopes up so didn’t figure that was a good spot. Anyway that leave’s -11 or -23 if I add them. Thought I was supposed to have a positive number to subtract but that’s the numbers I got. Does this seem high? With a 6 degree shim I’m still at -5? It’s a cherokee xj 87 with rubicon express 3.5 leafs. Not sure if I will need to do any shimming on my comanche or not but the cherokee is up on the building block first. Any help would be greatly appreciated!

[Htchevyii]

I use the free Tremec app to calculate it. The correct angle will depend on if you have a stock driveshaft or SYE.

[ghetdjc320]

Use whatever shim you need to get the following angles based on your specific driveshaft type. Whatever angle needed to get the proper geometry, I like to take the pinion down about 1-2* from that point to account for axle tube twist under load. 

[Pete M]

On 8/25/2023 at 3:59 PM, Warthog said:

I’m hopin someone can help me. Watch a bunch of videos of people basically rattling to hear themselves talk. I don’t need history lessons or how a car works. Just wanna know what size shim I need. The driveshaft is -17 degrees on the bottom however if I place the angle finder…my phone it says -18 degrees. Lol checked all over and that’s the readings I get. So figured I’d go with the -17 since I did see all the people in the videos measuring on the bottom…bout all I could get from em. The axle or pinion measures -6 degrees. Measured from rear diff cover bolts, the little metal shelves? On the pumpkin and the u joint. The pinion nose slopes up so didn’t figure that was a good spot. Anyway that leave’s -11 or -23 if I add them. Thought I was supposed to have a positive number to subtract but that’s the numbers I got. Does this seem high? With a 6 degree shim I’m still at -5? It’s a cherokee xj 87 with rubicon express 3.5 leafs. Not sure if I will need to do any shimming on my comanche or not but the cherokee is up on the building block first. Any help would be greatly appreciated!

 

 

where exactly are you measuring the angle?