Also worth noting that if the front drive shaft (or u-joint) breaks, it is common for the shaft to spin and strike the transfer case, or transmission, causing a large hole and destroying the unit. check and grease the drive shafts (and u-joints) !!

 

Is the Check Engine Light on?

Can you check the motor mounts and transmission mount? Your looking for split rubber.

There is a white plastic collar in the transfer case shifter assembly and if it breaks/cracks it can cause the shifter to jump out of it's detent within the transfer case and basically bounce it into neutral. Honestly it's very easy for this to happen because of the age of the vehicle. Requires a look by removing the console and two plates on the hump to get at.

Here's my thinking. It's not the transmission causing a decel problem but something either physical or engine control that is causing the driveline to bounce and the transfer case shifter is your signal to get to the bottom of it.

 

interesting video - so one should only use diff lock temporarily. I'll have to check that out as I will be driving the disco now and my daughter will get my car. LOL

 

thanks for the help guys - looks like I have some leads to go on here. Mounts / Collar

 

Keep us informed, keeps you from spending big bucks.

 

Diff lock should only be used when the wheels can slip as in off road, non paved roads, or in snow or ice. You should not be using it when driving down the highway!!

 

Okay I've been driving it for a day now and it just happened to me where I was slowing down from 55 miles an hour and I felt a little bump and sure enough that **** had clicked up into neutral so I'm thinking maybe it's the motor mounts and I'm wondering how do I check those?

 

Bottle jack, try to raise the motor off it's mounts, not too high, just enough to see if the rubber has separated from the metal mount, same with tranny. If one is busted it will tip the motor to one side easily. Use a board or get the ram under something solid on the motor. Is the Check Engine Light on? Like I said earlier you might be having a sensor issue when decelerating which would cause the motor to stumble enough to jiggle the shifter out of it's detent. Been there, done that and my stick would pop into neutral, ended up being a bad spark plug wire. Also I replaced the plastic shifter bushing (made my own) and that held the stick firmly.

 

Old school method is to have someone watch the motor(hood open) and hold the brake hard, rev the motor with it in drive. You will see the motor raise on one side if the mount is broken, then try in reverse to check the other side. Just be careful the helper doesn't stand in front of the truck when doing this, and hold the brake pedal tightly so the truck doesn't move.

 

Well after driving it for a while and hearing some scraping noises every once in a while (kind of like brake pads that get too low and the little metal scraper hitting the disc) I decided to climb underneath and this is what I found:


I'm surprised I didn't end up stranded with this thing in the shape it was. I decided to just do the one. There were no needles left in either side of the one pair of arms on the u-joint.

Gotta hand it to jimvw57 for calling it right off the bat. Replaced the $12 rear u-joint on the rear driveshaft and it drives like new again. No more popping out of gear, no more screaching, no more clunk when shifting into R, no more vibration at 40 mph. Wasn't too bad of a job either. Thanks guys!