[AllBlkdOut07]

About 5-6 months ago my truck developed this intermittent issue when shifting into reverse. After shifting the truck into reverse and applying the gas a loud bang sound comes from what feels like the rear end of the truck. It's so violent that it feels like something definitely broke. Then it would happen after being in gear but abruptly trying to drive in reverse, the same thing happens. It feels like something is slamming.

At first I thought maybe it was the trans, but I brought the truck to the stealership and they checked everything and couldn't find any issues. Today backing out of my driveway the truck slammed again but never went into gear and I heard a whining/churning sound. Turned the truck off, waited a few minutes, tried again and it was ok.

I'm thinking this might have something to do with the Tru-Trac. Anyone ever experience this, or heard of this being an issue? I may take the truck back to the place that installed the Tru-Trac and my 4.88 gears. In the two years since the install I've put on 10,000 miles and only started experiencing this issue around 500-1,000 miles ago.

 

[AllBlkdOut07]

bump.

No ideas?

 

[BlkSlvrdo129]

Can't really see how it could be the truetrac, and what I mean by that is the internal operation of the truetrac.

Do you have a diff cover with a drain plug? Something else I would try is to put it on jack stands and get under it while someone puts it in reverse and see if you can pinpoint the source of the noise.

The whining noise when you had it in gear sort of worries me more and is why I wondered if you had a pan with a plug, cause you could drain a little fluid and check for debris.

 

[01jackedZ]

The tru-trac doesnt lock in reverse, is it possible that is trying to lock or getting stuck, trying to unlock itself for reverse?

Edit: sorry for the complete lack of technical information, I dont fully understand how the diff's work to be honest

 

[Manbearpig]

They work on a worm gear brah

 

[brianZ71]

Slip yoke clunk

 

[HankScorpio]

Slip yoke clunk

Yes grease slip yoke

 

[AllBlkdOut07]

I've had other friends recommend this, but would it create a loud noise, It really does sound like I backed into a brick wall when it happens, and I feel something shift/move underneath me. Not sure if there is any damage, cause I waited and tried again 2 min later and it was fine.

 

[brianZ71]

It really can. The slip yoke needs to move in an out. When it's dry it'll stay in the same place as long as possible while your springs wrap, and then boom it'll break loose. Think of it like breaking a bolt loose.

 

[AllBlkdOut07]

Damn, ok, well I'll have to check that out then, thanks.

 

[HuckZ71]

I have the slip yoke issue, tho mine isn't bad. It's more of a very mild clunk (in reverse or forward from a stop) so I don't see how it could bang like that.

Is the sound more like a bang or almost a clang sound? My trans clangs when you put it in reverse almost like you hit a bell with a wrench and you can feel the truck shutter when it does it. Doesn't affect anything, been doing it for 2 years now it's just annoying

 

[AllBlkdOut07]

It's a VERY LOUD bang/jolt, and I'm not exaggerating.

 

[HuckZ71]

I gotcha, it definitely sounds like either the trutrac or the trans. Hopefully its just the trutrac but the way the truck shifts, it makes me wonder about the trans too. I would pull the rear diff cover and turn the wheels to feel if anything is binding

 

[AllBlkdOut07]

Forward driving I have ZERO issues, it's just reverse, and ONLY happens after acceleration, and NOT during the act of shifting into reverse. Just wanted to make that clear.

 

[HuckZ71]

Ahhh I understand now. Almost sounds like the trutrac is engaged when you first put it in reverse and then it's binding and disengaging afterward that initial loading

 

[AllBlkdOut07]

Exactly.

 

[HuckZ71]

I would try greasing the slip yoke first cuz that's simple. If that's not it, I would try this next

Can't really see how it could be the truetrac, and what I mean by that is the internal operation of the truetrac.

Do you have a diff cover with a drain plug? Something else I would try is to put it on jack stands and get under it while someone puts it in reverse and see if you can pinpoint the source of the noise.

The whining noise when you had it in gear sort of worries me more and is why I wondered if you had a pan with a plug, cause you could drain a little fluid and check for debris.

If you're still not sure but have a gut feeling it could be the rear or the diff, it would put it up on all 4 stands, take the diff cover totally off and have a friend slowly turn the wheels while you look with a flashlight. If it's suddenly not doing it, you may need to get the friend to idle the truck in drive with the brakes dragging to try and engage the diff, then go to reverse. Just remember, you now have very minimal lube on the gears so you don't wanna burn up the gears

 

[Hogg]

I would try greasing the slip yoke first cuz that's simple. If that's not it, I would try this next



If you're still not sure but have a gut feeling it could be the rear or the diff, it would put it up on all 4 stands, take the diff cover totally off and have a friend slowly turn the wheels while you look with a flashlight. If it's suddenly not doing it, you may need to get the friend to idle the truck in drive with the brakes dragging to try and engage the diff, then go to reverse. Just remember, you now have very minimal lube on the gears so you don't wanna burn up the gears

This is what I would try, just use the service brake to apply resistance to the drivetrain. I owuldnt worry about burning up the gears, unless you ran the rearend up to high speed for an extended amount of time.

peace
Hog

 

[AllBlkdOut07]

Thanks for the suggestions, I'll let you know the outcome/findings.

 

[jack3]

Yes grease slip yoke

my local mechanic uses rubber balls ( gum ball machine- size that gives a tight fit ) and grease! works for 1000's of miles