Jackshaft Uni Joints

[Nev]

Need to put a new uni joint on the transfer end of the jackshaft/intermediate shaft running from gearbox to transfer. Is this uni the same as all other uni's on the sierra? Repco only had one uni for the sierra on their system but I want to make sure it'll fit before I buy it. They wouldn't give me a part number.

Just off hand, when removing this shaft from the gearbox, do I simply loosen the four bolts from the underside, rear of the gearbox on the gearbox mount near the shaft and it will slide out? Do I have to remove the gearbox mount to take it out?

Many thanks, John.

[want33s]

Yep, they are all the same on my 89.. RUJ 1783. not sure about pre 86. the earlier transfers and diffs run smaller flanges, maybe smaller uni's too. ???
As for gearbox removal procedure.. I haven't had to remove mine yet ????

[nicbeer]

remove shaft is remove 4x bolts from transfer end then slide out of box.

[MART]

You must be able to get it out so the gearbox can come out without removing transfer. As you said just undo the four bolts and slip it out but I would drain the oil out of the gearbox or face the front down hill as the oil will run out,stinks like shit,never had to change a uni here,very strange,your bolts might have been loose,anyway while its out I would replace rear oil seal in gearbox because if the tailshaft was vibrating,it could have flogged the seal and when you go wheeling the oil might come out. I have a genuine manual and as usual they assume everybody is a trucken mechanic and it does not have a removal section,only a section on uni replacement,if you want i can post it up,cheers paul.

[Nev]

Thanks guys. Had a closer look at the shaft and there is quite a lot of play on the gearbox output shaft. Because of this I really cant work out whether the unis are actually worn or whether its just spline movement? I assume that there should not be play on the gearbox output and it looks like it is going to be more serious than a simple uni change. Is it likely that the spline is very worn or would it be a bearing race that has collapsed allowing this substantial movement?

[want33s]

I replaced the rear uni in my jackshaft this morning. I thought I had serious play in the splines but it was the tin dust cover on the yoke was loose. Couple of taps with a chisel to lock it tight. Jackshaft comes out easily (passengers side of transfer). 35 mins to remove, tighten dust cover, replace uni & re-install.