Bad Thump in Drivetrain "Not The Driveshaft"

[DrGonzo]

Yeah I need to pick up a dial gauge and check it out. I pulled up a youtube video to better help explain it as I couldn't follow his write-up on the other site and the manual made no sense either. After seeing the video it is all clear now. The original dif I replaced thinking it would fix the thump is still in my shed. So I'm going to check it first since it's already out and easier to work with. Once I get it into spec I'll just swap out the dif's.

[Jimvr4]

Link to youtube video?

[DrGonzo]

It's and old video and they are adjusting a Ford 9" but the concept is the same:

[Streamln1]

Could be a worn CV joint, best way to tell is to get the car up in the air and start moving stuff around, use something to hold the driveshaft from spinning and then try turning the wheels one by one and you can find where the slop is coming from.

[DrGonzo]

So I finally got around to checking the backlash on the dif and it was perfect at .004.

So I have eliminated everything in the back end now. It must be coming from the front drive train. Either the Transfer case, Trans or half shafts... Blah this problem is driving me nuts!!!

[DocWalt]

I assume the diff carrier bushings are good. If they are, my original post still stands

[DrGonzo]

Yeah all of the bushings are nice and stiff. Drive shaft carrier bearings were poly filled so they are also solid. I know it's not the output shaft as it was checked already. Going to start with the transfer case and work my way back through the front drive train.

[Nihil]

Drive shaft carrier bearings were poly filled so they are also solid.

Just curious about this, did you do the old school window urethane fill, or actually "re-build" them so to speak and fill with poly?

Going to start with the transfer case and work my way back through the front drive train.

I'm hopefully gonna get to all of this drivetrain maintenance this summer, and I don't think there's any decent write-ups around with pics or vids n tips...any chance you'd do anything like this? Just figured I'd ask

[DrGonzo]

I used a polyurethane sealant almost like the window urethane. I bought a couple different tubes and did some tests beads to figure out which would work better. I found a construction grade poly that was tough but still plyable. I don't remember the name though.

I'll see what I can do. I've not messed with the transfer case beyond resealing it so it will be a learning experience for me also. I will most likely be sending the trans off to get rebuilt as I don't have the tools here to do a proper rebuilt and honestly I really don't want to mess with rebuilding the trans.

[green-lantern]

This could still be the driveshaft, just filling the mounts won't eliminate the problem, just the slap.

My issue was the clutch. The rivets got loose causing the slack.

Your output shaft and spool were good right? Have you jacked the front up and tried to move the wheel back and forth? You could try it with one wheel up at a time then both up at the same time.

Edit: Oh but BTW my drivetrain got a lot tighter after I got the aluminum driveshaft. So it did help take up some of the slack. Actually it feels real tight now.

That' what she said