MadMax

I have an XF with 5.0 undergoing a bit of renovation. Took it for a run , and noticed vibration in the driveline on cruising and deceleration.

Combo is 5.0, T5, standard XF tailshaft, 9 " rear. Ive heard vibration is common. I don't like it - anyone shed some light????

PURSUTE

sounds like uni's to me.

check them for wear first. if they are ok you may have a problem with alignment.

i have an identical drivetrain in a HQ (i havn't driven it yet). i was told i may have problems due to the location of the 9"s yoke (off to one side).

ebxr8240

Yep uni's ?? check that they are central or in the middle of the carrier,maybe mismatch in the parts,bent drive shaft?

Balancing is important and not that expensive compared to damage that can be done..

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LTDHO

yeah, i agree, it'll have to be a part miss match. are ya still runnung the same rear uni you had with the borgy?

when i put a niner into my xe i had to change it

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MadMax

Front and rear unis are new standard XF, so they would be the same as on the borg warner. So Im thinking in light of what you are saying that it is a miss-match. What do I have to do with the rear uni to make it match to the 9 inch? Who did you see to fix it?

gregaust

If you have used an xf uni you have the wrong one in the rear.There is only a small difference in the diameter of the uni cap
that goes into the diff yoke .The xf uni caps will be slightly smaller.This will be enough to cause the vibe..Your best bet would be to go to a driveshaft place rather than mucking about with spare parts salesmen that dont have a clue what you're talking about..
A good driveshaft place can usually fit your correct uni's and balance it so you know it is then perfect..all for a reasonable price.
Something else to watch since you have had the diff conversion done is to have a quick look at the pinion angle.This can also cause a vibe that can be hard to trace.
Looking from the side of the car the front of the diff should sit horizontal to pointing slightly down..