[billetman]

Hey everyone,

I have a 99 Z71 and recently when I put the truck into drive, I hear a really sound clunking sound. I checked the U-joints and they are good, I also checked my thrid member, and it was worn out. I put a new yukon locker in it, but the clunking still exists. Anyone have any ideas of what this could be? Maybe the emergency brake being worn out?? I'm at a loss for ideas of what it could be. Any help would be greatly appreciated.

Thanks alot.

Billetman

 

[murdog94]

Did you check the play in the rear diff when you installed the locker? because 99% of the time with these trucks the Ring and pinion are warn and have slack in them that the tranny takes out when put into drive.

 

[Blacksheep1]

My 89 has done it for years lol...

 

[billetman]

murdog94, yeah I checked the play in it and it seemed fine to me doesn't mean it couldn't be the problem. Could it maybe be the transfer case yoke having slack in it??????

 

[stephan]

In addition to U joints which you have already checked, I've had a couple problems with clunks like you describe when dropping it into gear. Like Murdog said it could be too much backlash in the ring & pinion. Lay beside the truck, not under it, while a helper puts it in gear. Do you see the driveshaft rotate 1/8 turn or more? Also does it make the clunk worse when you put it in drive or reverse. Some are almost negligible in drive, but the clunk is unbelievable in reverse.
Another bad clunk I've found is caused by loose trans or transfer case mount bolts & the torque of the engine causes them to clunk when dropping it into gear.

 

[TJbear]

Mine clunks very obnoxiously when placing it in reverse. More like a loud CLANK. The sound seems to be coming from the Tcase. Interestingly when it is placed in 4wd, the clank/clunk almost goes away.

 

[billetman]

I haven't checked the problem out anymore, but I will check the transfer case mount bolts next time its on the lift, thanks stepan.

Also, thanks to everyone for your help. I hope to solve the problem soon.

 

[BowTieFan1]

I have the same problem on my `04 Silverado. A neighbor who lives across the street from me, who is a mechanic, looked at it and told me it is the chain in the transfer case. He told me if there are no problems using it in 4 wheel, then don`t worry about it yet. His cost to fix it though, is about $3000. I did`nt even bother to ask what a dealer or certified shop would charge. Heck, I could buy a whole new transfer case for less.

 

[billetman]

bowtiefan1, yeah my dad and I thought maybe it was the chain in the transfer case getting loose, but we werent sure. Thanks for the input!!

Billetman

 

[billetman]

Hey everyone, just wanted to say that we found the problem this weekend, the chain in the transfer case had some play in it. Thanks to everyone for your feedback.

Billetman