Driveshaft vibration

So ive been battling with this for a while now. Changed shims once or twice, my angles seem pretty good but still getting a vibe 70+. 4.10 axles, PORC SYE Tom Woods Shaft. Re measured angle yesterday. This is what I came up with.
5 degrees at Tcase
16 degrees at pinion
15 degrees on Shaft.
I think I still need to drop the pinion by 2ish degrees? Do they make 2 degree shims? It would be nice if I could just slide one underneath the 6 degree shim without having to take the pack apart again just to see if it helps.

2000bluexj said:

Do they make 2 degree shims? It would be nice if I could just slide one underneath the 6 degree shim without having to take the pack apart again just to see if it helps.

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Yes, they do make 2 degree shims but no, you cannot safely stack shims, they need to be one piece to keep them from being spit out. They also make 8 degree shims.
Make sure to get steel and not cast aluminum shims. Big aluminum shims can break up and fall apart, not a lot of fum when you are 50 miles from the nearest paved road.

It sounds like the rear axle is at about the right angle, 1-2 degrees low is suggested, when using an SYE.
How about the front shaft's pinion angle? It can cause vibs as effectively as the rear shaft.
The front shaft should be pointed straight at the the pinion yoke with no more than 1 degree of difference, any more can induce terrible vibs.
The FSM call for less than 1 degree of difference.
Vibs become even a bigger problem if you have regeared. Spinning the shafts faster causes vibs to occur at lower vehicle speeds. After installing 4.56 gears, my XJ's front end felt like it was going to fall apart until the front pinion angle was corrected.

Happens without the front driveshaft installed. I will measure that to I suppose. I only run the front shaft when im wheeling and during the winter.

Last time I tried a TW shaft he couldn't balance it to save his life... and he had 3 times to do so.

I suppose I could swap shafts and see what happens. Or I could get the driveshaft balanced.

I'm not sure I understand your measurements correctly.

All your measurements are using the same frame of reference, correct? i.e. ground, frame, etc.

So is the driveshaft 15º down, and the pinion 16º up? Sounds to me like you need to drop your pinion DOWN 2º and use some 4º shims to make that happen.

Also, if that still doesn't work, get a magnetic dial indicator and check run-out on the shaft.

He said 16 on the shaft and 15 on the pinion so that is 1, where it should be.

Tony_SS said:

He said 16 on the shaft and 15 on the pinion so that is 1, where it should be.

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Read it again.

MoparManiac said:

I'm not sure I understand your measurements correctly.

All your measurements are using the same frame of reference, correct? i.e. ground, frame, etc.

So is the driveshaft 15º down, and the pinion 16º up? Sounds to me like you need to drop your pinion DOWN 2º and use some 4º shims to make that happen.

Also, if that still doesn't work, get a magnetic dial indicator and check run-out on the shaft.

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Collin is correct. That is what I meant to say. PLayed around with it today and it seems like a new pinion yoke is in order. Tons of slop where the u joint sits. I think I have a spare somewhere I need to find, otherwise I will pony up for a new Ubolt style one. And I do have some 4 degree shims on hand as well.

MoparManiac said:

Read it again.

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Well crap.. my bad... there's the problem. He's +1.

Talyn said:

Last time I tried a TW shaft he couldn't balance it to save his life... and he had 3 times to do so.

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I absolutely DIG Tom Woods work on driveshafts....

That being said I Have noticed his balances leave something to be desired, and the lower gears you run the more important this becomes. I have 4.56's on 33's and at highway speeds the shafts are Ripping! A little off balance makes quite a commotion.

It's worth checking them again.