Topic: drivetrain clunk noise at approx 50 mph

[jktoy]

I have a clunk noise that occurs every second with a quick secondary clunk a tenth of a second after the first clunk and it kicks in at around 60 mph (sounds similar to the wheels of a train going over train tracks type of clunk).  It occurs in 4th and 5th gears yet i don't think it's the transmission, I think it's more speed related and coming from the t-cases (dual cases stock gears).  Especially since i have a marlin rebuilt tranny in the rig with less than 10K miles.  I also used a stethascope and the clunk is more pronounced in the t cases than in the tranny, not sure which t case though.  The clunk occurs in 4wd or in 2wd at approx 60mph.  4x4 low or double low do not produce the noise.  My guess is that a bearing is bad within one of the cases yet would like to get input?  Reason I think it's a bearing and not a tooth to a gear is the frequency with which the noise occurs (1 clunk per second...too slow to be a gear noise... I would think).  I'm worried I'll tear down my cases and not be able to isolate the noise, so I'd like to do the most diagnostics possible first.  Any help would be greatly appreciated.  I know it's not the driveshafts too due to troubleshooting.


22RE 85, runner, manual tranny rebuilt by marlin with 10K miles, dual cases stock gears purchased from allpro approx 5 years ago (no previous issues with cases)

Also, if someone has the transfer case/tranny gear paths diagrams so I can better isolate the problem I would greatly appreciate it.

[Rocksurfer]

Sounds like a tooth, but chances are it's the R&P, believe or not the R&P has telepathy and can throw sounds to where ever it wants, ususally through the driveshafts which is an excellent amplifier.

[jktoy [OP]]

thanks for the input.  I'd be surprised to get the good of amplification through d shaft but I'll check it.  anyone ever heard of this problem and it being in the t case?

[Rocksurfer]

Last year in Moab a friend of mine went through and had the exact same sounds and thoughts you have, we were thinking it was something in the tcase until we removed the rear ds and the sound moved from the tcase area to a low growl from the 3rd. Pull the rear ds and put it in double low, as you are crawling along have someone crawl along next to the rear 3rd and see if it is from there, you may be surprised. That rear ds amplifies the sound and will make you think it is coming from the tcase.

[79coyotefrg]

yep i agree,  broke ring gear tooth,  easy,  drain the rear diff, you will have chuncks  if its a tooth broke

[BUBBA]

yep i agree,  broke ring gear tooth,  easy,  drain the rear diff, you will have chuncks  if its a tooth broke

x2