Driveline Vibes with SYE, pinion angle set...

WebDog said:

pics of driveline and pinion?

I had this same issue and it was the output bearing in transfercase.

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kastein said:

With a CV shaft you want 1-3 degrees (depending on who you ask and how stiff your rear leafs are) between the pinion and the driveshaft, not 4... that's probably at least part of the problem.

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jk_surgeonfish said:

Yes, I agree should be between 1-3. I just find it odd that a small lift would require 6* shim.

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kastein said:

Have you verified your lift amount? Mine started out as 3.5" using HD OME leafs listed for 2" lift, it's settled in somewhat now that I've carted some heavy stuff around for a while. Measure from the bottom edges of your rear fender flares to the centers of the wheels, subtract 17", that's how much lift you actually got. Same trick works for the front except use 17.5" instead.

Springs breaking in / settling is a great reason (in my mind) to not do an SYE or shim your axle till a few months after the lift, that way you don't have to fix it again as soon as it breaks in.

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jk_surgeonfish said:

Ok... pulling my hair out here. I did a tailshaft conversion on my 99 Cherokee and put on a 3103-27CV yoke on the rear tailshaft. Then measured and had a new rear CV Drive shaft built for the correct length.

I know that after doing this conversion my rear pinion angle would be off and would require a shim under the leaf pack.

Prior to the shim I measured a DS angle of 12* and Pinion angle of 6*. So based off that I figured a 4* shim would get me where I need to be. I put the 4* shim in place and drove it. Silky smooth all the way till I get up near 65mph and then it sounds like a freight train.

I remeasured this morning and found my rear DS is 14* and rear pinion is 10* (which confirms that my first pinion measurement of 6* was right, 6*+ 4* shim = 10*). At this point I am like WTH? I either measured it wrong the first time or something. I was measuring using a socket with my angle finder on the bearing cap for both DS angle and Pinion Angle.

Here are the current angles with a 4* Shim in place: Transmission: 4*, Rear Drive Shaft: 14* (measured in middle of DS this time), Rear Pinion: 10*.

I'm guessing that I need to pull the 4* shim and put a 6* shim right?

This seems like a lot for only have a 2.5 inch lift in front and 2 in the rear? Any advice is appreciated.

NOTE: No vibes with rear DS removed, so it is not the front ds, not the tires or some bearing.

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RCP Phx said:

You definately measured wrong as your driveshaft angle would decrease as you rotate the pinion up!

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