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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 85BURBAN on July 28, 2009, 12:11:28 pm

Title: driveshaft question
Post by: 85BURBAN on July 28, 2009, 12:11:28 pm
recently had to replace the rear driveshaft in my 85 jimmy do to the original one breaking,after i installed it i noticed the driveshaft from the transfer case to the rearend is not straight it appears that the truck was lifted it looks like maybe 2 inch springs and 2 inch blocks i know im gonna have to shim the rear axle because the angle looks really off and i think thats what caused the driveshaft to break but am i an idiot or should that driveshaft be straight any input would be appreciated
Title: Re: driveshaft question
Post by: Captkaos on July 28, 2009, 12:18:22 pm
You lost me...  The actual driveshaft looks bent?
Put it on something flat and roll it, you will know if it is bent enough to be visual.

Where did the old one break?
Title: Re: driveshaft question
Post by: 85BURBAN on July 28, 2009, 12:35:08 pm
if you look at the driveshaft coming of the rearend up to the transfer itlooks like its a few inches to the right where it meets the transfer case and the original broke at the rearend
Title: Re: driveshaft question
Post by: Captkaos on July 28, 2009, 01:26:04 pm
As in Side to side viewed from the rear?  This is how it is supposed to be.
Title: Re: driveshaft question
Post by: 85BURBAN on July 28, 2009, 01:31:28 pm
thanks capt i thought so but i just wanted to be sure,have you heard of other people with jimmys and 4 inch lifts needing shims
Title: Re: driveshaft question
Post by: VileZambonie on July 28, 2009, 04:52:57 pm
Shims are used to change the pinion angle. If the rear axle is twisted or the transfercase is not mounted correctly it will appear to be crooked. Get a tape measure and start taking some measurements.
Title: Re: driveshaft question
Post by: 85BURBAN on July 28, 2009, 08:14:50 pm
im a little confused vile are you saying the driveshaft should be straight?
Title: Re: driveshaft question
Post by: VileZambonie on July 28, 2009, 08:45:46 pm
In a straight line as viewed from the top or bottom? yes

In a straight line as viewed from the side? no
Title: Re: driveshaft question
Post by: 85BURBAN on July 28, 2009, 09:35:46 pm
as viewed from the top meaning standing above the driveshaft and looking down at it or laying under the truck and looking up at the driveshaft ,then ive got some work to do because like i said earlier the output of the transfer is notin line with the rearend yoke
Title: Re: driveshaft question
Post by: VileZambonie on July 29, 2009, 05:10:07 am
How's your crossmember and transfercase mounts? If it's the straigh crossmember those are prone to rotting and cracking.
Title: Re: driveshaft question
Post by: Captkaos on July 29, 2009, 05:04:28 pm
the transmission and the rearend are offset from each other so the driveshaft isn't parallel to the framerails or to the ground.  This is by design to keep the U-joints from binding.
Title: Re: driveshaft question
Post by: 85BURBAN on July 29, 2009, 07:58:08 pm
after much staring and making coworkers stare it looks visually from the rearend if your under the truck with the gas tank right behind your neck looking up it looks a little crooked but according to the tape the output of the transfer case it centered in between the frame rail measured coming off the tranfercase at 90 degrees
Title: Re: driveshaft question
Post by: 85BURBAN on July 29, 2009, 09:32:56 pm
i think the slight vibration has to do with the pinion angle ill be out there tomorrow morning with my sons protracter trying to figure out what angle shims