Tranny or Transfer Case??

[9dawgs]

Hi Guys, a couple of weeks ago I posted saying I was getting ready to replace the transmission in my '99 D1. Now I'm not so sure. The symptoms are a bit confusing so before I go and purchase a $950 rebuilt ZF I thought I'd run it by the experts here. Here is what has been happening.

Prior to the initial fault below the vehicle has had a bad vibration starting around 55-60mph. I had just bought a new flex coupling for the drive shaft from AB but didn't have time to install it before this. I had the tires balanced and rotated but the vibration persisted. The flex coupling was my next step.

Initial Fault:
1. While pulling away from a stop sign and in the middle of crossing over a 4 lane highway, the car stopped going forward accompanied by a loud grinding noise.

2. The grinding noise went away when placed in Neutral. It returned when place in Reverse or Drive.

Attempted Fault Diagnosis:
3. Towed it home. Checked transmission fluid and all is well but just a bit low. Replenished fluid to correct level and tested with same results as 2. above.

4. Moved T-case selector to Neutral and placed gear selector to Drive. No noise. Moved T-Case selector to Low and placed gear selector to Drive & Reverse, loud grinding.

5. Returned gear to Neutral, no grinding.

Here are my suspisions. It would seem to me that the gears in the transfer gearbox are not meshing properly to transfer the torque to the transmission. If that is so, would the T-case be at fault?

Has anyone ever experienced this fault? My factory manual does not say anything about a grinding noise in the transmission or transfer case in the "fault diagnosis" sections.

A quick reply would be great. Thanks!

[Disco Mike]

Start your truck, put it in drive, set the e-brake and while it is running crawl under and look to see if one of your drive shafts is turning.
Sound like you blew a diff or axle.
Mike

[9dawgs]

Originally Posted by Disco Mike

Start your truck, put it in drive, set the e-brake and while it is running crawl under and look to see if one of your drive shafts is turning. Sound like you blew a diff or axle. Mike

Ok, just did what you said. All I can say is "HOLY COW!" Sure enough just like you said. The front drive shaft is spinning close to the t-case. The grinding noise is coming from where it connects in the middle with the front section of the shaft.

With this information is all I need to do is to replace the front drive shaft?? Man, that would be soooo much easier than pulling the t-case or tranny. Please say YES!

Oh, by the way.... YOU ROCK!! Thanks man

[Disco Mike]

Slow down, I don't think it is the drive shaft that is the problem, is the drive shaft turning the front yoke on the front diff??
Mike

[9dawgs]

Nope, it looks like the sliding joint end (female splines) that comes forward from the t-case is wallowed out and spinning around the male end that attaches to backside of the front diff. The grinding noise is coming from where the male & female ends join together.

[9dawgs]

Here's the culprit... The end you see attached to the t-case is spinning, the male end you see sort of sagging in the socket there is not. With no movement of the front wheels, it's like the front shaft has been disconnected.