Help Please - front 4 wheel drive will not work.

Hi guys,

I was out the other day for a round of hard driving and found myself having too much fun. I ended up jumping the jeep onto an empty dirt pad at the top of a mountain. This jeep will climb anything let me add!

Anyway as I was driving about 30 mph the back end swung around and I began to lose control. I counter steered and luckily I was able to pull it back together and not end up rolling it. Shortly after that I lost my clutch pedal as I drove it into the driveway. I was not sure what happened until today when I began working on it as to why I had lost control, well it turns out that the front wheels lost power and the back broke lose while I was driving down the road.

I pulled the rear driveline off and thethe jeep goes nowhere... I then observed the front driveline from up top through the transfer case boot and I see it spinning. I got under the jeep (to the side) while it is running and in gear and it does nothing but spin. I pulled the front differential cover off expecting to find all kinds of broken gears ect but didnt find anything. The gears do rotate except for the ones on both sides of the pumpkin leading to the tires. They do not spn at all.

I tried all the gears and nothing but spinning from the drive shaft. I dont know if this helps any at all either but I remember that when I first got the jeep I could not unlock the hubs if it was in 4 wheel drive. now I can unlock the hubs in 4 wheel or at anytime for that matter.

I did adjust the clutch bar and took the jeep for a drive today, that is how I knew the front was not working as I had almost gotten stuck in a sand wash. I'm wondering if the clutch has anything to do with it? if it is out of adjustment will it not engage the 4 wheel drive? I know it disengages somewhat because the gears would grind if I was not stopped to put them in to low.

Anyway any suggestions would be greatly appreciated.

Thanks,
Aaron

 

Did you find anything in the bottom of the diff? Sounds like spider and side gears are stripped but you should find chunks in the bottom of the differential housing after draining oil and removing the cover. Dana 25’s are notorious for exploding spider and side gears, particularly if you’re giving it any air time. At least that’s how I went through my first set.

 

i didnt really find anything inside that i found to be excessviive or broken. you can see metal flake in the gear oil but considering the year i didnt think it was that bad. there is no chunks aneverything looks in place. maybe the side gears did strip all the way? Also just got off the phone with somebody that said his bet is its a broken hub. I'm thinking he"s probably right since I just checked them and had to tap the passenger side with a hammer to get it to move.

i will get a new hub friday and see what happens. hopefully its that simple :/

 

Lock your hubs and with the front jacked up and the transfer in neutral. Spin the wheel and see if the drive shaft spins. If it don't then you are broken in the pumpkin.

 

If the side gears are not moving but ring and pinion are, it would imply that the spiders are more or less completely gone but that is usually more than obvious with a lot of debris in the case???????? Will be interesting what you find.

 

if there is a broken hub and they will not engage will that make a difference with this test?

 

Well a broken hub would account for losing 4WD but when you described the problem you mentioned the side gears and axle shafts weren't moving with the differential carrier, or at least thats how I interpreted it. A broken hub wouldn't account for that, spider and side gears are on opposite ends of the axle shaft.

A modification of Coach Walt's test. With hubs locked in and transfer case in 2WD jack one side of the front axle until the tire is off the ground. Spin the lifted tire, does the front drive shaft spin with it? If so then that hub is fine, plus it proves you spider and side gears are also fine. If it doesn't that hub may be your culprit but before tearing into it do the same test for the other side, one tire in the air with one on the ground then spin the one in the air and look to see the drive shaft spin with it.

 

ok i tried it and the front driveline does not rotate ar all. I tried to upload a video of what i described in the beginningb ut I guess u can't here or I don't know how.

I guess despite not finding chunks inside that it could just be they stripped out over time? So the test basically says it could be the hubs / gears if I'm correct. Your saying gears,right? If so are these easy to change? p.s u guys are great! i really appreciate the help!

 

sounds like maby the pin that holds the spider gears in place sheerd clean off. they would still be held in place by the axles but spin around in the carrier and not transfering power

 

is the slip yoke stripped ?, one end of the driveline turns but not the other end the slip yoke. or if you broke a ujoint on one of the axles then you will lose front end also.

 

u joints are all good. like i said earlier i had the jeep on, in gear and could watch the shaft spin and the gears inside move. side gears do nothing. could be the pin u mentioned. i really wish i knew more about these and the inner workings...

 

Yup then probably the spiders or pin. its a good time to think lockers if your gonna be replacein those especially if your wheelin heavy.

 

Ok I been looking around on the internet and found some spider gears at shop jeep parts.com since I have no idea what all this entails can you guys tell me if this is all I'm gonna need besides some more gear oil? It says spider gear kit for Dana 25&27, has 4 gears and the pin, not bad since its about 78.00

I'm also going to pick up new hubs since I have one that is questionable. I'll change those out first and then move on into the gears if the hubs don't fix the problem.

 

PROBLEM FOUND- I took the hub off of the passenger side as I was suspecious of that hub and the whole thing fell off in my hand. The 10 spline axel broke just outside the hole it comes out into the hub.

That explains why I didn't find anything inside. Anyways- is this something that can be replaced relativly easy? Or is this a complete rebuild of the differential?

 

A broken axle still does not explain why the side gears weren't turning. Granted you won't have power to the wheels but the side gears and inner axles should still turn.

 

Can you replace just the stub shaft or do you have to change out the entire shaft all together? Just wondering because I’m not even sure how the u-joints are retained.

 

I believe it is the inner axle that is broken, which is why the gears did not engage? I will start with the obvious and go from there, I guess. I pulled both hubs, the driver side looks in order, and nothing broken like the other side, so I really believe its just the passenger side that is damaged. Everything else in the differential looked fine. I will probable not get to pulling it apart until Monday or Tuesday but anyone offering advise and tips is greatly appreciated.

When I get into replacing this axle I plan on taking lots of pictures and creating a walk-through on how to go about this. It will help me out in the future when I break another