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-   -   LB7: Clunk when backing up (not the slip yoke...) (https://www.dieselplace.com/forum/76-speciality-forums/125-drivetrain-2001-2010/980992-clunk-when-backing-up-not-slip-yoke.html)

db131994 12-30-2019 12:35 PM

Clunk when backing up (not the slip yoke...)
 
Truck is an '02 Crew Cab with Allison and 300k on the clock. This issue has been going on for 7+ years... Here's the explanation:

When I stop and go into reverse truck will roll about a foot or two and then you get a slip. Almost like a chain jumping a tooth. I usually only notice it when you back up a slight grade. Don't typically notice it on flat ground.

The transmission was recently rebuilt and that didn't change anything. I replaced the rear pinion seal, and the rear diff seamed nice and tight... I'm guessing it's the transfer case at this point, but would like to get some more input before I throw that at it... It does seem to clunk into gear harder than any other truck I've been in.

My previous approach was when it finally broke, I would know what it was... Now, we are pulling a Toy Hauler a long way from home, so that approach might not be as "practical" as it was before. Especially in the wife's opinion!

I did pull the drive shaft and lube the slip yoke splines, but that didn't do anything. Plus, this only happens when I go into reverse.

Appreciate any thoughts. The only other thing I could think of is the rear axle rolling in the U bolts, but I'm thinking more that it's the T-Case... I was going to try and mark the rear axle and U bolts to see if I can see any movement.

Thanks,

OkDually 12-30-2019 12:47 PM

Universal Joints checked out ok?

db131994 12-31-2019 11:11 AM

Yup, I replaced them this summer. Nothing changed.


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