80 4x4 Mystery Clunk in drive train SOLVED AXEL WRAP due to lift blocks

[69800]

The previous owner put in a new engine (22r) and a new clutch and pressure plate. The tranny is original l-43. When I let out the clutch to quickly I get a clunk but it does not feel like the transmission is hitting the floor or anything like that. It feels like a really bad u joint.. He said it was alway there and he thought it was the tranny mount. When I lay under the truck and watch while someone lets the clutch out quickly I can see no movement of the transmission. The u joints are all tight.  If I drive down the road and let up on the throttle ...then back down quickly... it clunks. It feels like a lot of slop somewhere. My tranny guy does not see how it could be in the tranny or t-case. He thinks mabey in the clutch assembly somewhere. We are getting ready to put in and L52 and I want to have every thing I need before hand. I hate to spend 100 bucks on a tranny mount if it is not needed.  

Any one got any ideas on where this slop could be hiding.

Thanks is advance again
Mark

[79coyotefrg]

dude, ive told you the L43 and L52 transfer case mounts are the exact same.

this sounds to me like you have a broken motor mount, popping the clutch loads the drivetrain enough that the engine raises off the broke mount then smacks back down causing your "clunk"

[69800]

 I forgot to tell you the motor mounts are brand new. the transmission mount is the only old mount

[79coyotefrg]

i'd still check the motor mounts,  even if they are brand new

look at the LARGE center bolt in the tcase mount, if its "herniated" below the upper part of the cross member then you need a new one BUT, that mount wouldnt cause the "clunk" you described

http://www.marlincrawler.com/transfer-case/parts-upgrade/crossmember-mount-oem

[69800]

My driveline has some play when I lay under the truck I can rotate it back and forth a fair amount.. If you were to put a mark on the rear end the play would be 3/8 to1/2 inch

[79coyotefrg]

   HOLY CRAP  Hopefully  its just backlash,   you need to pull the 3rd member

[81ToYbOtZ]

Mine used to do the EXACT same thing. If I shifted hard, or at high rpms, it would clunk just like you are saying, kinda feel it in your seat and feet at the same time. It ended up being the pinion bearing went out, and allowed the pinion shaft to slide back and forth, and have a crap load of slop in it. I just tightened the loose nut for about 200 miles till I got paid, fixed it for a while, but then it finally went out bad in town. It would lock up if I came to a stop. It was horrible, possibly deadly if it happened on the freeway. When I finally put a new third in, it all went away. So I say definetly pull your third out and check it.

[69800]

can the pinion bearing be replace or do you have to put in a new 3rd?
mark

You had no rear end noise prior to failure?

[pumkin toy]

can the pinion bearing be replace or do you have to put in a new 3rd?
mark

You had no rear end noise prior to failure?

you have to pull the third and disassemble it to replace the pinion bearings

[Yoat Goat]

Mine used to do the EXACT same thing. If I shifted hard, or at high rpms, it would clunk just like you are saying, kinda feel it in your seat and feet at the same time. It ended up being the pinion bearing went out, and allowed the pinion shaft to slide back and forth, and have a crap load of slop in it. I just tightened the loose nut for about 200 miles till I got paid, fixed it for a while, but then it finally went out bad in town. It would lock up if I came to a stop. It was horrible, possibly deadly if it happened on the freeway. When I finally put a new third in, it all went away. So I say definetly pull your third out and check it.

Does it feel like when you shift hard it unloads hard? Mine is doing that... but no play at the flange... Wtf?

[81ToYbOtZ]

can the pinion bearing be replace or do you have to put in a new 3rd?
mark

You had no rear end noise prior to failure?

Oh yeh, I had a bunch of rear end noise, mostly on the coast side of the gears. My driveline didnt have any slop at the yoke with the tires on the ground, but when I pulled it out, it had a bunch.

[69800]

mine had no noise but when you rotate the driveshaft back and forth its really sloppy
mak

[motoracer]

mine got about 1/2 play and its only got 100 miles on it brand new

[69800]

Thats strange. do you feel any slop when you get on and off the gas??

mark

[69800]

The loose driveline slop was ring and pinion out of tolerence. 20 thousands.. Rebuild third member with old ring and pinion which were in great shape but put in a bearing kit and slop is gone. Mystery clunk is still there and is Axel Wrap...due to lift blocks.... New 5 speed is GREAT