Transfer case...

[Jgreemo]

Hi all, I just returned from a trip up to Mammoth and after driving around in heavy snow for a week, I am convinced my 4 wheel drive is not working correctly. I did notice some driveline binding in tight turns but for the most part, the front wheels weren't doing much with very little power being sent forward. I recently installed a set of Mile Marker hubs and I have the original limited slip rear end. The Sub is used mostly for the snow and occasional trip through mud down in Mexico, but beyond that just mostly highway. I know the system was working last winter, but not so sure now.

I know there are some rock crawlers on this page, so I am curious as to where a problem might be. I assume I have the NP 208 TC and it seemed low range was still working with 4 hi not doing much. Are other units available for a mid 80's Sub? How about rebuilds and if a kit is available, is it something I could do myself?

As a newbie to 4 wheel drive, any help would be appreciated. Is there a safe way to test the transfer case and limited slip diff?

Thanks in advance.
Jon

[dieselcrawler]

It's just a matter of checking to see if both the transfer case and the hubs (you just put on new ones?) are locking in correctly. It's easy to test this, you don't even have to jack up the truck. A driveway, and maybe some cardboard to lay on, or not caring to get dirty. Start by checking the front drive shaft, make sure it turns freely. Now lock in both hubs, and go back and turn the driveshaft, it should maybe turn a little, but once the hubs lock in, it should stop. There should be a little lose motion, perhaps 1/4 of a turn in the drive shaft. Now unlock one hub at a time, and turn the drive shaft. If you have an open diff in the front, one side, the unlocked side, should spin as you turn the drive shaft. Try each side, maybe a few times just to make sure the hubs work free. Once you're sure the front end locks in and out well, unlock both hubs, the pull the transfer case shifter into 4wd. Try to spin the drive shaft. It sould again, maybe turn a little, but then lock up. Lock and unlock it a few times, to make sure.
If you're getting some hopping or binding when turning, or if the steering wheel wants to fight you in pulses, you should check the front axle universal joints at the steering knuckles. I have greaseable ones in all my trucks, and make sure to grease them every oil change, along with all steering joints. If you're are so far gone as to be freezing up when you turn, it's time for new ones, and then a steady diet of grease.

Sorry this got so long, but I hope this helps...

Greg

[Jgreemo]

Thanks DieselCrawler for the quick reply. I'll check out the TC as soon as the rain stops. I just installed the hubs about a month ago and this was their first use. I was getting some mild hopping pulling in/out of parking spaces, so i'll check and grease the knuckles.

Is there a way to check a limited slip rear diff? I know the NP 208 has only a marginal reputation but I don't know what GM installed in the rear diff. I also heard that after a 100k miles or so, all limited slips become open diffs due to wear. As I don't do a lot of heavy offroading, it would be nice to get the 4x4 back in a cost effective fashion for tractions sake.

I appreciate the help.
Jon

[dieselcrawler]

Yours should be the corp 14 bolt semi-floter rearend. The only way I know of to check a posi- or limited slip unit is to put the truck on a spot, the side of the road perhaps, where one rear tire has good traction (on dry pavement) and the other is in grass, ice/snow, or other slick surface... put that built 6.5 turbo to use, and mash it... hope you don't hear loud banging and snaping! *grin*... the idea is to get one tire to spin, or see if the one with traction gets you moving... some types will alow some tire spin untill the tire reaches a higher rpm, others are the clutch type, and have some friction all the time. Keep in mind, this is the West Virginia backwoods approch to testing this, use at your own risk, other terms apply, etc etc.

Good luck, perhaps some one who knows more about these things will post...

Greg