A Riddle: Jeep Can't Back Up

Out wheelin' President's weekend. First day went smooth, ran great. 2nd day I encountered this:

I tried to back up and the jeep stopped. So I pulled away in forward and tried reversing again...it stopped. Every time I tried reversing, it would go 5-10 ft back and stop. EVERY TIME I TRIED.

Here are the symptoms:
- hubs locked, t-case in 4wd; backs up a few feet and stops
- hubs locked, t-case in 2wd; backs up a few feet and stops
- hubs unlocked, t-case in 4wd; backs up a few feet and stops
- hubs unlocked, t-case in 2wd; backs up just fine

Symptoms point to front axle or t-case. From what i could tell and see, it seemed like the front axle, I would reverse slowly and see the front tires stop dead on.

Who wants to take a guess at what the problem is? :?
And yes, I do have an answer for you all, but I will let you all get some best guesses in.

 

Weird. It backs up then the front wheels lock up? It's probably something really stupid like a linkage or a shifter or something.

 

Have any of your kid(s) bicycles or scooters turned up missing recently?

 

there something stuck up into the front drive setup?

 

Automatic brake adjusters going crazy?

 

T-case shift linkage lost a pin and one shift rail not moving?

 

When you say stop do you mean stall, ie kills the engine? Or do you just stop moving and the engine keeps running?

 

good question, i was assuming that it just stopped dead in its tracks, being in gear this would likely stall the engine.

however, if it somehow keeps running......... well thats jsut a whole new can of worms isnt it.

 

My guess...

...something is wrong with the locker on one of the front wheels.

 

good question. jeep STOPS dead in it's tracks. yes, it would kill the engine, as when the front end stops, it stops the transfer case, and stops the rear axle. i suppose in 4low i could rev it up and force it anyways, but i was looking to to fix problem rather than demolish my drivetrain.

some good guesses, but yet to hit the nail on the head.
it is not any type of linkage problem.
it is not a locker problem.
it is not a shifter problem.
it is not a bike/razor scooter/child wedged in the driveline.
it is not a problem with the front wheels.
it is not a problem with the brakes.

...keep guessing!

 

Something with the front pinion maybe? In reverse it moves into the case and jams it up?

 

Ehhhm...Let's see...Hub problem?

 

nope, not a hub problem.
i'll give you a HINT: it IS in the pumpkin.
not driveshaft, brakes, hubs, t-case... it is in the pumpkin. i really can't believe that none of you have guessed broken ring/pinion yet. not saying that's it, but that was my first thought when i was pretty sure it was in the front axle.

post some more guesses, i'll post a pic/answer either before i leave work or when i get home.

 

You can usually hear a broken R&P regardless of direction. Maybe a shim? Hell I have no clue haha, but it's almost always something small and overlooked.

 

Looks like you know what the problem is ...

Maybe the pinion is loose enough that it travels into the ring gear and binds, if the rotation (reverse) pushes it that way?

 

Rollpin came out of the cross-shaft and it backed out and bound up?

 

Is the pin that goes through the spider gears contacting the pinion gear and locking the front differential up?

 

did you leave a shop rag or wrench in there when working on it. from past experiance this is not a good thing to do

 

what a great answer, but no.


yes, i have known what the problem is. i wanted to see if anyone could possibly guess the problem...


and the winner is........

great job. actuall the roll pin BROKE in half, allowing that cross-shaft to come out far enough to touch the ring gear and stop. going forward the gears just slid it back in, reversing it would bind up in the gears.
i did however one-up this and broke that cross-shaft in half. WTF?! sure didn't expect that. all in all, $30 for parts from dealership and the cost of oil and i'm back in action.

any ideas on what would cause that rollpin to break? ist shouldn't have much of any force on it at all...maybe the shaft brock and then pushed into it and broke the pin?

 

Really? that's strange that it would let you back up in with the hubs unlocked, and the t-case in 2wd...I wonder why that is, I would never have guessed that it was the rollpin