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89JEEPYJ 02-04-2011 02:05 PM

Vibration at 60mph, wierd things happen at that speed
hello i ahve a 89 yj. and i get a vibration at 60mph+. i jacked up the rear of the truck and put it in gear and get it up to 60mph. when this happens and i look under the truck. For some stange reason the frnt driveshaft begins to spin witch i believe is causseing my vibration. any idea on this??

amx4080 02-05-2011 07:42 AM

Look at the u-joints first. If they are worn, it can cause vibration. Simple to drop the rear driveshaft and replace the u-joints (remember to mark the position on the shaft and transfercase output to make reinstalling easy).

As to the front driveshaft spinning, you don't say if it's a slow rotation or actually under power. If it's a slow rotation, it's just caused by the vibration of everything else. If the front driveshaft is engaging, you have other problems.

89JEEPYJ 02-05-2011 03:26 PM

well it appears to be spinning relatively fast, when the rear tires are off the ground there is 0 vibration. I was kinda nervous to grab a driveshaft spinning when i wasnt sure of its speed

89JEEPYJ 02-13-2011 01:09 PM

shims have been this size for over a year and recently i dont know what changed but it appears the shims are too big, causing the driveshaft angle to be too steep for my set up. The driveshaft sits parallel to the ground. Heres some pics without the driveshaft. would you say the shims need to be removed?

89JEEPYJ 02-13-2011 01:10 PM

i removed the shaft to change the universals. and when i was removing i realized that the universal on the rear end is hitting the bolts that holds the straps witch hold the universal

Garyk 02-13-2011 01:23 PM

Way too much of an angle..

89JEEPYJ 02-13-2011 01:26 PM

thats what i was thinking. So should i just take out the shims. Those are the shims that came with the leaf springs(built in) and it used to be fine. But i dont know what recently happened where it got wurse

RednekYJ 02-13-2011 01:31 PM

remember what i said about an angle locator?:facepalm:

89JEEPYJ 02-13-2011 01:34 PM

my only prob is It wasnt like that when i did the springs. Is it possible that the center housing spun itself upwards and the axles stayed in the same spot or something like that. Im like 90% it wasnt like that be4 i want rock crawling

89JEEPYJ 02-13-2011 01:37 PM

like if you look at this picture a few months ago you can see that the casing is at a 90degree angle to the ground

89JEEPYJ 02-13-2011 01:54 PM

i just looked at it and the center house most deff spun on the outter shafts how did this happen and how do i fix it??

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