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jackshaft diagnosis

Posted: Mon Dec 10, 2007 6:09 pm
by rogerramjet
Hi All

I have a vibration problem in my 1991 suzuki sierra. The vibration is there in two wheel drive, four wheel drive and in front wheel drive (with tail shaft removed). Vibration continues with clutch in and gear in neutral.

That means problem is in gearbox output shaft, jackshaft or transfer case. Is that correct? Most likely would be jackshaft?

Jackshaft looks fine and so do UV joints, although when I turn jackshaft by hand the transfer case moves side to side slightly and there seems to be a slight hard spot each revolution of the jackshaft. Does this isolate problem to jackshaft or could there be something wrong in transfer case or gearbox?

Thanks in advance

Roger

Posted: Mon Dec 10, 2007 6:31 pm
by alien
check you dont have mud in your rims first =) i fell for that once.. hahaha

Posted: Tue Dec 11, 2007 1:10 pm
by ScrawnC
Remove jackshaft completely and check for free movement of uj's through full range of movement. You may have a seized uj. If not jackshaft check other two as well.

Posted: Tue Dec 11, 2007 2:38 pm
by v840
Also check your tcase mounts.

Posted: Wed Dec 12, 2007 1:44 am
by Bajan Tim
had this exact problem recently.....
it turned out that one of the unis was ceased on one axis....
only realised it when i decided to check it a second time an took it out completely, replaced both with some greasable ones

Posted: Fri Dec 14, 2007 6:37 pm
by rogerramjet
Well it was exactly like Bajan Tim, one axis on a uni is ceased.

What is the best way to fix? Complete new jackshaft or get someone to rebuild unis? I would imagine the jackshaft would have to come from suzuki which would be expensive would it? Although I don't know if its worth fixing an old shaft and whether theres additional costs like rebalancing and alignment issues?

Posted: Fri Dec 14, 2007 9:36 pm
by Bajan Tim
I had my unis replaced with some greasable ones

Posted: Sat Dec 15, 2007 12:06 am
by zookimal
Just pull the jackshaft out and put a new uni in the transfer end. If that's all the problem is it's a cheap fix.

Posted: Sat Dec 15, 2007 9:05 am
by v840
Replace both unis on the jackshaft, it saves having to pull it out when it happens to the other one. They've both done the same amount of revolutions so its probably nearing its used by date anyway.

Posted: Sat Dec 15, 2007 2:42 pm
by rogerramjet
cheers fellas

Does anyone know if there will be a problem if I put the bolts the other way round when I re-fit the shaft? It is better that way because you can access the nuts with a socket (or an impact socket as they were really hard to get off).

Posted: Sat Dec 15, 2007 5:47 pm
by NIK
Either way should be fine but I can only get mine in one way so thats the way they are staying 2 12mm spanners to do up.
Nik