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HELP! DD's driveshaft about to bite the dust!

M

mbiker72

NAXJA Forum User
Location
Syracuse, NY
Ok, so installed a Rusty's budget boost on my 2000 DD. Everything went great with the exception of a small resonant hum (vibration) around 30mh and a strange vibration when i let off the gas. So i decided to do a T-case drop, also from Rusty's. When i was installing it, it was a PITA to get the x-member holes lined up with the frame rail (using that term loosely) holes, but i eventually got the bolts in. Now however, i have a massively loud speed-sensitive clunking whenever i am coasting or braking, and it seems it is getting worse every day! I need to get this resolved and I have almost no money (thank you Clarkson University tuition). Is this u-joints binding? is the slip-yoke bottom out on the output shaft? i dont know whats causing this, please advise. Thanks in advance.
BTW, yes, I am a noob at this. :compwork:
 
you should jack the rear up and put on stands, then put her in drive and crawl under neath and try to pin point the clunking. And then get someone to push the gas and brake etc.. and again try to pinpoint the clunking. Then post up your results. and how big the budget boost? With two inch or more on 99 and newer jeeps they say you will need a cv driveshaft/ SYE
 
mbiker72 said:
Ok, so installed a Rusty's budget boost on my 2000 DD. Everything went great with the exception of a small resonant hum (vibration) around 30mh and a strange vibration when i let off the gas. So i decided to do a T-case drop, also from Rusty's. When i was installing it, it was a PITA to get the x-member holes lined up with the frame rail (using that term loosely) holes, but i eventually got the bolts in. Now however, i have a massively loud speed-sensitive clunking whenever i am coasting or braking, and it seems it is getting worse every day! I need to get this resolved and I have almost no money (thank you Clarkson University tuition). Is this u-joints binding? is the slip-yoke bottom out on the output shaft? i dont know whats causing this, please advise. Thanks in advance.
BTW, yes, I am a noob at this. :compwork:
Click to expand...
change out your ujoints and shim the rear with 2 degree shims.
 
do you have an angle finder. If not they would have one @ Clarkson, find the angles on the drive shaft to t-case and to the pinion.... you could always try shimming the axle but no guarantees... Where about are you from? Clarkson isnt to far from me...
 
it only makes that noise when im coasting, when the drive shaft is loaded up, i.e. accelerating, even driving constant speed, and hard braking, it goes away, but the the second i let off the gas...thunk thunk thunk...it gets louder linearly with speed., its not intermittent, it makes that sound every single rotation of the drive line.
 
Hey I had something simular and I had changed out all my u joints but come to find that it was my rear end. Same symtoms, not saying:dunno: this is yours but maybe want to check before replacing anything. It was a D35 in mine I had ten teeth broke off the ring. Was my DD, so had to drive it untill when she locked up and jack up myu ujoints and straps.
 
im pretty durn sure that the rear end is ok, at least i hope, everything was butter smooth until the lift, which wasnt long ago and i dont do any serious off-roading with this truck. Does anyone reasonable locale have some shims and or the availability to help me with this? Im thinking replacing the u-joints is the best idea at the moment, they arent too expensive, anyone know how much shops charge to replace u-joints if i hand them the shaft and the joints?
 
check your front d/s and see if your exhaust is hitting it. if you dont remove the exhaust mounting plate that sits between the tranny and the tranny mount, doing the TC drop pushes the downpipe over into your driveshaft.
 
that thought had crossed my mind, i will take a look at that, but why would the sound change depending on whether i was accelerating or not in 2wd...
 
as the motor torques when you accel, the exhaust will move a bit...

even more so if your motor mounts or tranny mount are worn out.

i'm telling you this b/c i have a 2000XJ. I also tried a TC drop from rusty's and thats what happened to me.
 
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I hope it's not your rear end, but like I said just a thought, but yeah need to try to pin point the clunking and JNickel101 made sense on that, but need to find it for sure. And I brought my driveshaft and ujoint in to a shop and only charged me $15. So not to inexpensive to be able to have it done in like ten mins.
 
Look near the u-joints on the rear drive shaft and see how close the output shaft coming out of the transmission is to the driveshaft going down towards the rearend. There are two u-joints connected to the rear driveshaft, so check both of them. More than likely there is a little bit of driveshaft binding. A little trick I learned to see if the problem is the lift, is to put a big load in the rear so the Jeep squats down a little and the driveline angles are closer to stock. Once I did that the problem went away, so I then knew I needed some 3 degree shims for the axle. (Cheap fix). So, why don't you find some rather large ladies at your school and take them for a ride?? I actually used a bunch of bricks in the back setting over the rear axle to do the test.

Oh yes and don't forget... Never ever let anyone get under a vehicle that is on jacks and in gear! Holy crap... try to explain to the Cops why your friend has been ran over by a Jeep in the driveway and see how they take it.
 
Hey dude, did you do a shackle or an AAL in the rear?

With 2" of lift and a TC drop, he shouldnt have any problems with binding. yes, i know the 2000s are a little more prone to vibes, but this sounds a lot worse than driveline vibes...
 
4LowandGo said:
Look near the u-joints on the rear drive shaft and see how close the output shaft coming out of the transmission is to the driveshaft going down towards the rearend. There are two u-joints connected to the rear driveshaft, so check both of them. More than likely there is a little bit of driveshaft binding. A little trick I learned to see if the problem is the lift, is to put a big load in the rear so the Jeep squats down a little and the driveline angles are closer to stock. Once I did that the problem went away, so I then knew I needed some 3 degree shims for the axle. (Cheap fix). So, why don't you find some rather large ladies at your school and take them for a ride?? I actually used a bunch of bricks in the back setting over the rear axle to do the test.

Oh yes and don't forget... Never ever let anyone get under a vehicle that is on jacks and in gear! Holy crap... try to explain to the Cops why your friend has been ran over by a Jeep in the driveway and see how they take it.
Click to expand...

:twak: nEVER let your friend get under your jeep. It's your jeep, so you crawl under it. And yes a little common sense and safty is applied here. IF your to much of an idiot to know how to take percautions then do not attempt, Allow a professional to do your work. I just guess us Michiganders are little more hands on when it comes to our jeeps. Must be a Georgia thing. You know the farther South you go the dumber they get.
 
haha, im one of the ones who prefers multiple factors of safety when underneath, chocks, jack, jackstands, parking brake, put it in 4wd etc...Anyway, thanks for the tips, im going to see if i cant locate a place where the exhaust is contacting the driveshaft, i also think im going to drop the rear shaft, and drive it around in "front wheel drive" to see if that eliminates any issues.
 
NO!!! dont do that. you dont have an sye. you cant do that...well, you can, if you want to see your slip yoke come out and ATF spill out....(yet another advantage to doing an SYE)

you can drop your front shaft and drive around without it attached....
 
mbiker72 said:
haha, im one of the ones who prefers multiple factors of safety when underneath, chocks, jack, jackstands, parking brake, put it in 4wd etc...Anyway, thanks for the tips, im going to see if i cant locate a place where the exhaust is contacting the driveshaft, i also think im going to drop the rear shaft, and drive it around in "front wheel drive" to see if that eliminates any issues.
Click to expand...


Yeah that is what I did after the ujoints and stillhad the clunking then checked rear end.
But yeah I agree with dropping the driveshaft and see if that works. Yeah those newer jeeps are tricking when putting aftermarket shit on. Considering that you shouldn't have to use a tcAse drop, but hey you know.
 
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