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Old 09-02-2014, 10:38 PM   #1
Join Date: Sep 2014
Posts: 8
Thumbs up trany or transfer case clunking!

hi I got a 1990 Jeep wrangler YJ with 6cy. engine an a ax15 trany-5spd. and a 231j transfer case and from day one the Jeep has been making a clunking noise off an on while in gear. It also will clunk when you go from reverse and then put it in 1st gear and let clutch out it will clunk(snap). I have replaced TC chain and input geat and put new gears in the rear end and all new Ujoints in both drive lines and it still is making the occasional clunk even going down the road in all the gears the noise comes and goes! Im stumped!! Help!!

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Old 09-03-2014, 10:23 AM   #2
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Join Date: Mar 2012
Location: Ridgway, Pa.
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1st thing that comes to mind for me is either a bad trans mount or the stabilizer bushing is shot. Could also be a worn out rubber in the motor mount as well. Allowing the drivetrain to "slap" when shifting or changing directions.

'87 YJ, 4.2L built and bored, 8.5" of lift, 8.8 rear, AX15/NP 231, Tom Woods drive shafts, Flat fenders, 12,000LB winch, Custom bumpers, Rattle can paint job. Never completed...
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Old 09-03-2014, 10:40 AM   #3
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Location: Raleigh, NC
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When it makes this noise while in gear, does it happen as you roll onto and off of the throttle, or does it happen while you are at a steady speed?

If it is at a steady speed, I am inclined to agree that it could be worn TC or Engine mounts, or possibly a suspension component. The TC and transmission don't tend to 'clunk' once they are under load.

Crawl under the jeep, with a helper in the cab, shift the jeep into neutral and run the TC through its gears while manually rotating the driveshafts clockwise and counter clockwise...hear your clunk?
Clutch down, transmission in 1st, TC in 2Hi, do the same procedure....hear the clunk?
You can also put the wheels in the air and check to see if your rear axle is the culprit, or have your helper load and unload the suspension while you are under it, listening for a clunk, could it be spring bushings?
Are your rear springs worn to the point that the slip yoke can push into the TC extension tower?
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Old 09-04-2014, 09:06 PM   #4
Join Date: Sep 2014
Posts: 8
new 4 inch rough country suspension lift was just installed(I know should of made sure jeep ran first! oh well) new springs and bushings in all in kit. we took the rear driveshaft right out of it and the front driveshaft also to eliminate forward and rearends. the Jeep still makes this awfull snapping/clunk noise when under load it seems? it sounds like a chain or something snapping/hitting the case but I put new chain in TC and new Input gear in the planetarys in the TC case becasue ther was some wear. the shop thats working on it says that its in trany(I guess?) they did find a broken trany mount earlier and reweled and fixed it from what i was told. they also inspected clutch and all components and the look like new they said.....this shop is decent and they arent tryn to buffalo me, I know them and ther work. what do you mean by a stabilizer bushing 0III0forlife?
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Old 09-04-2014, 09:09 PM   #5
Join Date: Sep 2014
Posts: 8
also it does make the snapping noise in every gear it seems when your rolling down the road but it does not do it constantly. seems to be when you step on it or let out of it it does it the most. the weird thing is it will snap once or twice and then thats it till you gas on it or let off it.
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Old 09-08-2014, 10:32 PM   #6
Join Date: Sep 2014
Posts: 1
What did you figure out? My 95 is doing the exact same chunk/clunk type noise, and it does not matter if I have it under a load or at a steady speed. Sometimes I can go for 5 miles and everything is perfect, and other times it chunks every 1/4 mile.
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Old 09-10-2014, 09:02 PM   #7
Join Date: Sep 2014
Posts: 8
nothing yet I found another used trany and in process of installing that right now... will let you know if that cures the issue.
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Old 09-18-2014, 09:50 PM   #8
Join Date: Sep 2014
Posts: 8
found another good used ax15 trany and swapped it and its fine now....guess we know were the clunking was coming from!!

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