v-vib-bra-at-tion-n

[woody9]

ARGH!!!!
did 14 FF swap on rear and can't seem to pin down a driveline vibration! Flange location from old axle to this one was the same, so no length issues on the shaft.
Have rebalanced/rotated wheels/tires, all new brakes back there and 1 new drum, had shaft balanced today.... and it's still there. Not too noticable until 55+ or so, but I think it's there at the lower speeds as well.
Axle flange does have 1 of the 'ears' that locate the u-joint a bit worn, but I set it to the other side when installing the u_joint caps. He (at balance shop) said a GM part nr 26020811, and a price of $160. (O U C H !!!!!!!)
Heavy 3/4 ton - 1 ton flange?
Before I raid my piggy bank and last remaining beer money, has anyone else experienced this fun? did the flange help? Is there something else obvious I'm overlooking?

 

[Espen88k5]

Do you have an other set of wheels you can try? It's alitle work but it will rule that out.

If the only thing you did before this started was the 14 bolt. I would say your on the tright track. If axle flange's wollowed (sp!) out a litle, that would get you shaking.

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[woody9]

Yep. Before I changed the front to 8 bolt I swaped 'em around with the other 2 in the set I bought. Plus, rebalanced and rotated 'em again! No difference.

 

[Espen88k5]

If you wait to long before changing the crosses(U-joint's) out it will start to wear the axle flangs out , and then you have a more expensive part to change to get it to stop them wearing each other out.

Dont know to much about this, but I know I have an issue with my crosses that I'l have to do soon.

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[woody9]

the 'crosses' (if you mean U-Joints?) are new in the rear (the adapter/large-small one) & good shape up front.
that's what bugs me about it...? the pieces seem to check out, except that 'ear' that (to me) seems inconsequential as the u-joint caps are held in place the those cape plates and shouldn't slide when the drive shaft is turning.

 

[nd_4_mud]

You said that you bought one new drum. Well from my experience aren't the drums balanced to. May be that one drum is not balanced or a weight fell off. Just a guess here.

Knowledge is the key to the universe, and I hold that key when i am sleeping.

 

[woody9]

10 -> 14FF Pinion ANgle?

wondering if there's any significant pinion angle change that i need to deal with on this?
Assuming (and i know what that means!).. both GM standard axles, that shimming to correct/adjust wouldn't be necessary? Shaft didn't need adjustment, just used the adapter U-Joint?
Anyone?