bad clunk in drivetrain, checked all obvious causes.....help

[wisekise]

4 days ago my sport started to get a "clunk" with a slight pause in acceleration. At first it would only do it rarely around 19-25k rpms under acceleration. stopped by the tranny shop and a tech drove it and said it was not the transmission, maybe the slip yoke or the rear diff. i took it to my office/shop and greased the yoke and checked the rear diff. almost no fluid in the rear diff! but at least no metal in there and the r+p look good. i have seen no evidence of a leak since i had the axle seals replaced in august. filled it up and drove it home, on the way it got alot worse, occurring every 3-4 seconds, but only on accel not during a coast. got on here and searched, searched, and searched some more. i drained the tc fluid with no obvious signs of destruction(metal shavings, burnt smell) then jacked it up in neutral and started turning the rear driveshaft. i had some play in the rotation, started the turn, and when i stopped there was some slop afterwards. i could not tell where the slop was coming from, the rear end or the tc. with no visible signs of damage, where do i go from here? button it up and take it to the mechanic?? oh, the tc is a bw4405 and the rear is an 8.8, 4.10s and an aussie locker.
any words of wisdom? i need to get it operational fast, since i luckily have a ride to work temporarily.
thanks

 

[wisekise]

bump for the morning crew

 

[wisekise]

btt
nobody with a similar experience?

 

[Vargas]

I'd drop the rear driveshaft and take a good look at the u-joints. Also, check pinion bearing for slop.

 

[wisekise]

what should i look for with the ujoints? i have never took one apart and looked it over. but i did check for play in them while i had the x jacked up in neutral and they seemed solid. i had thought about the pinion bearing, but if there was slop in it, i would think that it would chip a tooth on the ring or pinion at those speeds?? or could it just make a loud clank like i am hearing, and not do major damage?
i will check tomm, as i had to work late today. thanks

 

[storlied]

Sometimes it can be difficult to see any slop in the ujoint without removing the driveshaft and playing around with the joint. I knew it was my issue, but there was no evidence at all until I actually took it off, it didn't matter what I did.. or if I was in N or front DS removed.. nothing.. Take that thing outta there n check it out, it's only a matter of a few bolts.. they can be difficult so spray em down with some PB and get ready for some excersize.. maybe urs will be easy.. dunno.. good luck..

 

[Vargas]

What storlied said.

Much easier to feel bad roller bearing in a u-joint when the weight of the driveshaft is not hanging on it. Once the DS is out, you'll have an easier time feeling play in the pinion bearing.

 

[wisekise]

thanks guys, i'll get the pb blaster ready. i'll post up the findings tomm.

 

[storlied]

Warning!: Don't let it fall on you. That might hurt.

 

[tenikiwon]

What type of acceleration? Normal, or to to floor? Do you have a 2WD option, if not and you don't want to do the brown wire mod, just take off the front d-shaft and see if the problem continues. I stripped the splines out of my front d-shaft twice and never realized it.

Is it just one clunk, only from a dead stop? How loud? (slip yoke on the rear d-shaft can need grease and with make more of a quiet bump)

 

[danwaters]

When you have the driveshaft off grab a hold of the flange on the rear end and try and move it forcefully forward and backward. That will let you know if the pinion bearing is worn or the pinion nuts isn't slammed all the way down on the crush sleeve. Pull the cover and inspect the differential ie spider gears, missing bolt into the cross pin. You didnt lose any bolts off the back of the ring gear that secure the ring gear to the carrier did you?

 

[wisekise]

What type of acceleration? Normal, or to to floor? Do you have a 2WD option, if not and you don't want to do the brown wire mod, just take off the front d-shaft and see if the problem continues. I stripped the splines out of my front d-shaft twice and never realized it.

Is it just one clunk, only from a dead stop? How loud? (slip yoke on the rear d-shaft can need grease and with make more of a quiet bump)

normal accel, first around 19-25k rpms, then after adding 3qts of gear oil to the rear, the frequency increased to every 3 secs.??? but inside the pumpkin looked fine?? i have done the bwm because of the aussie locker in the rear.

 

[wisekise]

When you have the driveshaft off grab a hold of the flange on the rear end and try and move it forcefully forward and backward. That will let you know if the pinion bearing is worn or the pinion nuts isn't slammed all the way down on the crush sleeve. Pull the cover and inspect the differential ie spider gears, missing bolt into the cross pin. You didnt lose any bolts off the back of the ring gear that secure the ring gear to the carrier did you?

pumpkin was clean, thats what is so damn confusing didnt get to the rear driveshaft tonight, i will tomm.

 

[wisekise]

progress, or lack thereof .
got a late start cause of work, rtv'd the rear diff cover and while letting it cure i started on the front driveshaft and on the last t-30 torx bolt the cheap ass torx set i bought snapped off in the bolt head. i couldnt get the damn tip out of the bolt head so off to the parts store for tools. even with a punch, chisel, pick, drill, and a bfh, that sob is still there. i ended up just bending the cap to get the ujoint and driveshaft out. the two caps just fell off, i am guessing that shouldn't happen but i also dont think that would create the violent of a clank. i could be wrong though. i checked the front pinion yoke, in all directions, it was tight. i turned the yoke and it felt like there was some slop in the r+p but the x was not jacked up so i could only get 1/4"-1/2" of turn. then i said F it, it was way past dark, i was getting rained on, and had not ate yet. back at it tomm.

 

[danwaters]

progress, or lack thereof .
got a late start cause of work, rtv'd the rear diff cover and while letting it cure i started on the front driveshaft and on the last t-30 torx bolt the cheap ass torx set i bought snapped off in the bolt head. i couldnt get the damn tip out of the bolt head so off to the parts store for tools. even with a punch, chisel, pick, drill, and a bfh, that sob is still there. i ended up just bending the cap to get the ujoint and driveshaft out. the two caps just fell off, i am guessing that shouldn't happen but i also dont think that would create the violent of a clank. i could be wrong though. i checked the front pinion yoke, in all directions, it was tight. i turned the yoke and it felt like there was some slop in the r+p but the x was not jacked up so i could only get 1/4"-1/2" of turn. then i said F it, it was way past dark, i was getting rained on, and had not ate yet. back at it tomm.

1/4 - 1/2 inch of slop seems like alot. Especially if the wheels were on the ground. That means your pinion gears is moving alot before it contacts the next teeth on the ring gear.

 

[Vargas]

When you turn the pinion yoke by hand, can you detect any fore/aft movement in the yoke?

 

[wisekise]

When you turn the pinion yoke by hand, can you detect any fore/aft movement in the yoke?

Yes, a little...if I am understanding your question. When I turn the yoke it moves 1/4-1/2" in between teeth and then I feel the slop, kind of like there is binding there somewhere. That would explain the noise and clunk if the r+p gears are jacked up. It never fails...I am so close tmy sas I am pissed off I have to drop $$$ on the effin d35. I might just rip it out and run cut off cv stubs for a little while.

This is the 2nd time a problem up front has had me chasing ghosts in the rear of the x just because it "sounded" like that was where it was coming from.

 

[Vargas]

I understand there is play when you turn it. When you are rocking it back and forth, can you detect any movement toward or away from the motor?

 

[wisekise]

vargas- no play in the pinion yoke to and from the motor
progress....:frustrate
at least this ordeal let me know of some kind of leak in the rear axle, cant find where but it was empty when i dropped the cover, and it took a whole gallon of fluid to fill and still wasn't to the fill hole on the rockcrusher cover. this will be addressed when the front is dealt with.
drove it today with no front driveshaft.....definitely a problem with the front r+p. the clunk turned into a clank and could be felt solely in the front of the x. now i just have to decide to either fix it or rip it out and run 2wd for a while then ramp up the plans for an sas. but with no other vehicle for a dd, and an upcoming trip to the obx where 4x4 is necessary, it seems i am in a proverbial pickle.

 

[tenikiwon]

Personally I'd just go for the SAS. You have the rear locker for the OBX, air down as far as you need to and just be smart. (ideally you aren't going along)

Good luck.