Weird 4x4 binding problem 96 K1500

JD1987 · October 17, 2016

Hi, thanks for taking the time to check out a new members post. I just picked a new to me 96 K1500, its a cool truck, old county rig i think, with a spot and nice winch mount. Seller said a new motor 5 or 6 years ago. Not sure if thats true but it soubds and pulls great. Has 31 in tires, and may or may not have a lift.

Now to my issue: it had a shattered front passenger wheel bearing and busted CV when I got it, but those were quick fixes for the price. In 2wd (floor shifter) it cruises awesome at 70, but I put it in 4wd hi while I was cruising some logging roads (dirt/mud/gravel) the other night and it was almost undriveable. Like it kept trying to buck me over the side, or like I had a flat tire. This is at about 10-25 mph. This morning I tried it again, and it really felt like it was taking way too much power to move the truck, and I could see how much the tires were tearing up the gravel just driving along in a straight line.

Any thoughts on this? It isn't just dragging a wheel, theyre all turning, and not even really skipping, it feels almost like the front and the back are fighting each other. Could I have messed up anything on the axle replacement? The new one looked a little different, but seemed to be the same dimensions as near I could tell, and the parts store said it'd work...

sdeeter19555 · October 17, 2016

Same size tires front and rear?

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JD1987 · October 17, 2016

Yeah, front and rear are the same size. They're definitely not the stock tires, but theres no weird wear pattern on them either, like I'd expect if one was pointing the wrong way.

C/K Man · October 17, 2016

Sounds like a front differential problem.

BoatRDavid · October 17, 2016

Is it possible that the diff ratios are different -- front to rear?

sdeeter19555 · October 17, 2016

That was going to be my next question!

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JD1987 · October 17, 2016

Interesting, it wouldn't surprise me if someone had done something strange like an incomplete swap. Is there any way to tell what's inside without opening up the diffs?

Semikrazy · October 18, 2016

Jack it up and turn the rear driveshaft one full turn and watch how much the rear tires rotate. Then do the same for the front driveshaft and see if it's the same.

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sdeeter19555 · October 18, 2016

I wonder if that's why you had a bad cv? My bet is either the front or rear diff went bad and they swapped with another unit...what you describe is classic mismatch front/rear ratios. I'll be curious to see what you find.

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JD1987 · October 18, 2016

Right on thanks for the input. I went by one of those flashing signs that read your speed today, and it showed I'm going 3 to 5 miles an hour slower than what it says on the sign, though that may just be the tires. I'll have to get it up in the air this weekend, and keep an eye out for some Craigslist parts.

C/K Man · October 18, 2016

Someone could have changed the rear axle at some point too. In any event, a ratio miss-match between front and rear axles would likely eventually result in front differential failure.

arcasey · October 19, 2016

Could possibly be a transfer case issue as well with some of the internal parts binding when in 4WD. I just had some issue with mine and it was causing the truck to "buck" in 2WD and 4WD so I replaced the transfer case and the "bucking" stopped. Now I have a grinding noise that I need to find .

JD1987 · October 22, 2016

So I jacked up the passenger side today and it looks like spinning the rear wheel one full rotation pushes the front wheel about 10-15% further. With a little more than half a rotation of the wheel for every full rotation of the drive shaft.

Still have to figure out the math to find out what that means though... Not my strong suit

sdeeter19555 · October 22, 2016

If you want to definitively rule out gear ratios, pull the covers and read the ratios off the ring gear. Good excuse to change the gear oil too!

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barry G · October 23, 2016

So I jacked up the passenger side today and it looks like spinning the rear wheel one full rotation pushes the front wheel about 10-15% further. With a little more than half a rotation of the wheel for every full rotation of the drive shaft.

Still have to figure out the math to find out what that means though... Not my strong suit

wow, that is way off.

that is like 3.42 to a 3.73..

bizarre.

would love to know the outcome.

also, my speedo is slow too, these are the first electronic, don't sweat it. Does the speedo flicker to 5mph while idling up in park or neutral? that is not unusual either.

I love the 96-98... hope you get it going for a good deal.