4x4 Troubles

Hi, I am new be gentle. Just purchased a 97 Z-71 5.7, auto, Np1, Push Button 4 WD. This truck has 4" body lift. 315x75rx15. When put into 4hi or 4 lo ,you here it lock in as normal, problem being after rolling only a few feet rear wheels begin to bind. Acts as though you have different size tires on, but all tires match and are almost new. Checked under carrige and there was red fluid around axle and rear of transfer case. Not a lot. After futher investgation found transfer case to be low, only about an inch deep in case. Going by dealer in morning to get fluid as I understand it takes a special fluid for this case.
Question, Could this low fluid cause this ? Have I got trans case problems ? If so is a rebuild cheaper than say junk yard replacement ? And finally, How much time to remove transfer case .
Maybe I have anouther problem altogether, not sure. Any help !!! Thanks

4wd is great when it works huh? i dont kno much about it but i would say that if it was low on fluid it wouldnt make it bind up like u r saying however fill it and try it see what it does if you did need a transfer case then one from the junk yard would probably be your best bet unless you have the time and kno how to rebuild it yourself... i think it sounds like the guy who had it before you could have changed the gears in the rear end and the front and rear gear ratios are fighting against each other... prob not the problem but its a possibilty

Welcome to your first post on AF
Like chevyman says.
Check that gear ratio.
9 times out of 10 Someone has throwed the wrong one in on you.
Let us know how it goes.
MT

Thanks, I believe you guys are right. Ratios must be off. I have called the dealer with vin# It is suppose to be 342 gears. Marking on rear tube indicates 342 gears. I guess my only option is to pull inspection plate and count teeth. Is it correct to divide pinion by ring gear to get ratio ? Thanks Steve !!! 75 90 syn Gear oil ? Thanks

10-4 on that chevyman caught that one.
I show SAE 80-90 API-GL-5 But 75-90 syn gear oil will work ok.
I think it is divide the ring gear teeth by the pinion teeth.
Also the gear ratio and no of teeth is usually stamped on the ring gear.
Let us know how it goes
MT.

There may be an easier way of checking the ratio.

A 3.42 is a 41:12 ratio (actually 3.4166666...)
A 3.73 is a 41:11 ratio (actually 3.7272727...)

41 turns of the driveshaft will give either 11 turns or 12 turns of the axle.

Jack up one wheel and turn the driveshaft 41 turns. With an open differential the wheel in the air will turn either 22 or 24 times. I'm not sure how it would work with a locker or limited slip, you may have to jack up both wheels and hope they turn together.

James

If you could put the truck on jackstands so the tires are off the ground. Place a mark on the tires with chalk at the same spot and have someone start the truck and put in in 4WD and hold the brake enough so they spin really slowly you would probably be able to tell if they are spinning at different speeds usuing the chalk mark as a reference

Well, finally got some answers today. I have a 342 front and a 456 rear. PO had changed rear after putting on larger tires. was going to change front but traded it off. Said he ran out of money !! So I guess I am looking at regearing front to 456. Anyone have any experence in changing front ring and pinion ? How much time for a job like this ? Cost ? Thanks Steve

456 gear ratio is way to low for normal driving and gas mileage.
You best bet would be to change the rear back like it was.
MT

This may have nothing to do with your problem but we just brought our Silverado in for 4x4 problem. It is my husband's truck but I have been working on getting the ext. warranty company to cover; therefore, I have been doing a LOT of investigating. It was diagnosed as transfer case. There was no fluid in and they saw no leaks. They said we didn't keep up with our maintenance. (bulls..t!Ext. warranty was not going to cover. Finally when the dealer went to replace the transfer case, the mechanic tested the old one for leaks by filling with fluid. There was a pinhole leak in the casing. Supposedly after talking with several people, this is a known but not admitted problem that GM has with the transfer case. The mechanic told us to keep an eye on it because it will probably happen again down the road. Other independent mechanic suggested not rebuilding it. (He was the one that told us to look for pinhole leak). Just thought I'd relay the message.