Engine/Transmission (1994 - 1998) Vibration problem

[dwitner]

Just did the 5th gear fix and put the truck back together. Replaced all the U joints in the rear drive shaft while I was in there (clutch too). Now the truck has a noticible vibration at 20-25 mph and 60-65 mph. At 60 the truck now makes a new funny humming noise. There is no new vibration in the shifter and it feels like it is coming from the rear of the truck. Is the drive shaft out of balance. Clutch feels good and the transmission shifts like it should. Any help would be appreciated.

 

[Willie G]

It sounds like the u-joints. Sometimes they can sound like a B-29 engine. Are the balance weights still on the drive shaft? Did you install it in the same relative position? You can disconect the strap bolts on the rear end and rotate the shaft 180 degrees and reinstall it.

 

[dwitner]

I chalked the lenght of the driveline so it went back together the same way, I have not looked for the weights so I will do that then I'll knock it loose and put it back in 180. Thanks for the help.

 

[SBrandon]

Have a similar ordeal, my problem is the pinion bearings which also lead to my ring and pinion going out. Ive been chasing the vibration for two years when finally my pinion seal started to leak, very agrivating but If i was to bet Id check it.

 

[Extreme1]

When you replaced the u-joints, did they flex real nice like they should? When driving the bearings in, if you go a little too far it can bottom out and cause what you are describing. After I get the retaining ring installed I usually drive the bearings out tight against them. Then I check to make sure there isn't too much play in the new joint which can be fixed by driving it back towards center again. I've never had this happen on another vehical so maybe yours won't get too loose.



One dignosic step would be to remove the rear shaft and run the front shaft up to speed to see if it still does it. That would narrow it down a little.

 

[dwitner]

I ran the truck with it up on a jack and it appears that the vibration is coming from the rear shaft. I'll try driving the bearings back out but I think they are out against the clips. The rear pinion seal is leaking a little but it has been doint that before the u joint change, dont think the problem is there. Thanks for the help.