CUCV 4x4 question

[LanceRobson]

During the Rausch Creek trip my M1008 got "high centered" on a rock at the rear differential. It had both rear tires off the ground and both front tires firmly on the ground.

The transfer was in "4 low" with the front hubs locked.

The front wheels would not turn to pull it off. The rears just spun in the air and there was no apparent motion or noise from the transfer case forward.

Is this normal, or do I need to start looking for a problem?

Thanks for any insights.

Lance

 

[mangus580]

Front wheels were not even attempting to spin?

If thats the case, you have a problem someplace.... Usual spot is a bad front hub... or one not 'really' locked.

 

[pevrs114]

Make sure hubs are locked, then check the transfer case shifting linkage, ane make sure it's actually locking the t-case into gear. Sometimes under bind/load, t-cases can pop out of gear. If you were getting movement at the rear axle, then the t-case is definitely in SOME gear. See if you can replicate the problem at home, and see if the front driveshaft is spinning at all (have a buddy watch it while you apply go-juice). I'd start by eliminating out the easy/cheap fixes first (hubs, linkages, etc) before digging into harder/more expensive work.

Also, go to Pirate 4x4 and there should be an article in the tech section on clearancing a 14bolt axle for better off-road ability.

 

[CUCVFAN]

Start looking. On a M1008, if it ain't in low, it's in neutral, so i would lean toward hubs or t-case problem.

 

[LanceRobson]

The rear tires were driving just fine in low. Is it possible for the rears to be in gear and the fronts to be out of gear?

I'm just not seeing how it could be, but I'm sure not a transfer case expert. The front hubs were definitely turned all the way into the locked position.

 

[tsmall07]

Did you look to see if the front drive shaft was turning?

 

[86M10086.2L]

Deff check the front driveshaft. I just got rid of a truck that the front driveshaft was so worn out that you didn't even hear it spin but it was turning and not driving the front axle in the least bit. To check it put it in a vice and use a big pipe wrench and try to spin it hard. I had another 88 blazer that did the same thing, and by hand it felt great. Splines locked, good to go, or so I thought. put it it 4hi and all you heard was grinding. Other than that I would suspect one of the hubs might be broken. The factory GM hubs, although reliable are no the most robust and can break with out trying to hard. From what I hear, if you have tranfercase problems you usually know about it not too much of a mystery. Although it's possible the shift forks could be worn and its not engauging properly. BUt you can usually identify that with excessive grinding whenever you try to shift the tranfercase in and out of 4 wheel drive or they tend to pop out of gear as well.

 

[OLDCHEV4X4]

My vote is towards a hub problem. They get water and mud and crap in them. And then they wouln't engage.
Did you see my hub's Lance? I wrap duct tape around them to keep the crap out. And replace the inner seal every year.

 

[hobie237]

Re: RE: CUCV 4x4 question

... if it ain't in low, it's in neutral,....

Wait... what?

 

[mangus580]

Re: RE: CUCV 4x4 question

... if it ain't in low, it's in neutral,....

Wait... what?

If its in low, it MUST be in 4x4, with the way this t-case is designed.

if its not in low.... it would be in N (ie. if it kicked out of low) as its the next one in line.

 

[hobie237]

RE: Re: RE: CUCV 4x4 question

Ah, OK, thanks for the explanation. I was just confused since I've used it in both 4H and 4L and both are most decidedly not neutral.

I would like to test mine sometime, just to make sure everything is working properly. I understand that since the front is an open, if either hub is unlocked, it will send power to that side and thus there will be no forward motion. So, is there any good way to test it besides jacking the rear wheels off the ground and seeing if it can pull forward?

 

[LanceRobson]

RE: Re: RE: CUCV 4x4 question

Well, I checked for front shaft rotation and it's turning.

I left it in 4H and jacked up the front tires, one at a time, and with them in the locked position, the tires both turned.

I popped the locking hubs off and both were dirty and pretty dry of grease. I didn't have any more time so I left the truck in the shop and will get back to it in a day or two.

Does anyone have the Chevy PN for the O ring seal?

The local Chevy dealer's parts guys gave me the "trout look" and went into the service bay to ask the older mechanics if they remembered anything about "oldish 4x4 hubs, ya know, like '85s?"

Thanks

Lance

 

[hobie237]

If you can pull the old o-rings out, NAPA, CarQuest or a similar "real" auto parts store can usually match them up to something off the shelf.

 

[OLDCHEV4X4]

The local Chevy dealer's parts guys gave me the "trout look" and went into the service bay to ask the older mechanics if they remembered anything about "oldish 4x4 hubs, ya know, like '85s?"

LOL The "Trout Look".....And 85 aint old!
Lance, didn't we have a conversation around the campfire about being old? Ohh....You might have been sleeping in your chair..

 

[LanceRobson]

Shhhh....My sons already think I'm old enough to fart dust.