ZF6 Bucking, Locking, Binding ... Need help / adevice

[xory72]

Hello all,

I am new here and this my second post thus far. I bought a 2000 F350 7.3, ZF6 (manual) 4x4 with 225K mile a few weeks ago. I drove it home some 300 miles and have been driving it every other day and all seemed fine.

Last night I was doing some cosmetic work and when I was finished I backed the truck up to park it for the night but while in reverse it was like the drive train locked up. I pushed in the clutch when it happened and it did not release ... the truck just rocked back and forth. There was a god awful sound. I released the clutch again and it moves a few feet and locked up again I pushed in the clutch and it rocked back and forth again. I proceeded forward, drove around the block and all was fine in 1st, 2nd, 3rd and 4th and returned to my driveway, went to back in and it binded (locked up) again. If I moved real slow the bind would not happen. So I parked it for the night.

This morning I started the truck and let it warm up. As I went to leave I made it about 1/2 a mile and I heard the bind noise while in 2nd (sounded like gears not lining up so I pushed in the clutch and while still rolling I felt the truck tugging while making ugly noises (even while in neutral) and it eventually stopped. I put it in reverse, moved a few feet and the same binding noise as previous night happened pushed in the clutch and the truck rocked back and fourth like the night before. I turned around slowly and limped back home in second going real slow making all sorts of noises, parked the truck and decided to post for help.

So ... here are details;

1. happened in reverse first
2. when moving in reverse, gets loud clunky & has resistance, even real slow
3. engage clutch when it happens and truck stops and rocks back and forth like something is locked
4. at first move forward and had no issues (till this am)
5. now when moving forward I get binding / resistance then starts to make noises (sounds horrible), truck tugs etc
6. then engage clutch it still rolls but but truck wants to lock up and when just about stopped, it locks up and rocks (even in forward)
7. put back in reverse and locks up

NOTE: my front drive shaft has been removed to eliminate anything from the from front axle or 4 wheel drive part of it. Hubs are NOT locked and only rear shaft is connected. Transfer case is in 2w

IMO this leads me to the rear diff?
Am I on the right track?
Has anyone experienced this?
Any advice, suggestions, ideas?
Should I open the rear diff to take a look?
Is this a transmission issue?

I was not sure if I should have posted this in the drive train section or not. Sorry if I got it wrong. If I should move it, please let me know.

I look forward to all your help / advise. I am mechanically inclined and have done all my car work for years, but this is my first diesel and truck so this is all new waters to me.

Thanks

[xory72]

just an update ....

I opened up my diff and found the problem. Both front and rear pinion bearings are shot. So bad that the pinion was wobbling and not lining up with the ring rear and casing the teeth no to line up and therefor locking up.

So ... looking like a complete ring gear, pinion, bearings etc for me. I cannot find what rear end I have (no tag or information on the door). I do have a 12 bolt diff thought. I just do not know if it'a a 10.5 or 10.25 and what gearing I have.

As soon as take it apart I'll figure that out.

Also, sorry ... this should have been posted in the Drive Train section, but I thought it originally was a transmission issue.

[1ofakind79]

All superdutys have a 10.50 sterling if your truck is single wheel or a Dana 80 if its a dually.