Necred

Hey guys,
I have recently bought (Jan 06) this truck (93/4wd/auto/99k) and i now am noticing a "clunking" sound whenever i put it in reverse, its definitely coming from the rear of the truck, what do yall think it is? its not as noticeable putting in drive, just rev....

92DIESEL

Most likely the cross pin in the diff. From what I understand if its a open differential then not hard to fix, if posi

Good luck,
Michael

90firstgen

Might be a wild goose chase but check the rear u-joint. Mine made a noise like that when it needed replaced.

Necred

thanky,
I hope u joint, maybe it'll be allright until i get "roun to it", if it cant destroy anything else (not a daily driver) i can live with it a while longer..

edwinsmith

Well, depending on how worn it is, if the u-joint lets go the drive shaft can flop around a lot and bang stuff up and maybe even bend the shaft. Best to fix it now.

Edwin

wannadiesel

As was said, check the u-joints first. If they are tight, it's the cross pin in the diff if it's an open rear. If it's a power-lock the clutches are gone, and it'll be a little more difficult and expensive. You can see pics of that ugliness in my photo gallery. Somebody posted pics of a cross pin worn more than halfway through, but I forget who. Reider Racing has the parts for either diff, you should have 32 spline axles. http://www.reiderracing.com/spidergear_kits.htm

mhuppertz

Chock the tires, put the t-case in neutral, get under the truck and twist the drive shaft hard each way. Pay close attention to the yoke going into the diff. It could be a combination of wear in the diff and a bad u-joint.

Necred

thanx, i will test it this weekend....at 100k, i would be surprised if its diff., if the original owner has been honest about its usage & mileage.

nailhead

A buddy of mine lost the front rear-shaft U-joint on his M715 this weekend. It trashed the end of the shaft, kinked it, and may have messed up the hydraulic plumbing for the hoist. What it didn't do is the Worst Case Scenario: catch on a pavement defect (crack, pothole, etc) and flip the truck end-over-end. This is why I pay particular attention to the maintenance and condition of this one U-joint, FWIW.
- Chris

mhuppertz

Is your Truck an extended cab, or regular? If it's extended you will have a two piece driveline with a carrier bearing. More joints to check!

Underpsi

My truck is regular cab and it has a 2 piece drive shaft. maybe cuz its 2wd?

mhuppertz

Oh, yes you are right. Sorry, I have 4x4 myopia!