While plowing on slippery surfaces, my 4x4 Only Spins Two Wheels
 

Over the last two years, I have had a tough time plowing with my 1999 4x4 GMC Sierra 1500. With any decent amount of snow, I keep getting it stuck. A few days ago, with the snow drifts, I had 3 to 4 feet of snow on my driveway. I got it stuck 4 times. I got about ½ of my 800 foot driveway done before I gave up and called somebody with a bigger truck.

I have about 400 pounds of bricks in the back of it.

Anyway, yesterday I jacked up all four tires and put jackstands under it. Only the passenger side tires were spinning. The drivers side would spin a little bit, but if a put a little pressure on them, they would not spin at all. So it looks like I have an open differential. It looks like it was designed that way.

If it was a limited slip differential, if the tires on the right do not have traction about 50% of the power goes to the other wheel.

With an open differential, if the tires on the right do not have traction, all of the power only goes to the wheels without traction.

That sucks for plowing.

I’m pretty sure I need a locker for the rear. I know I don’t need it for the front since that would make it tough to steer.

I see air lockers, electronic lockers and automatic lockers. Does any have any thoughts or recommendations on what to get for a locker?

There is a place in Torrington CT called JT's Auto & 4x4 and I was thinking about going there to get a recommendation.

It is not a daily driver and is used mostly for plowing.

maybe a worn out rear end David and needs rebuild?
I would defiantly get the front checked as well. the sky is the limit as far as lockers go but if it is just to plow then I would rebuild to stock .
I got a Detroit trutrac in my rear and it locks when it is needed and acts open in the turns. good thing about Trutrac is there is no clutches to wear out. only worm gears.

Thanks for the advice Dawg!

I'm pretty sure that right now, since it's the open differential type it's working like its supposed to.....which is crappy. I think that to get limited slip, the original buyer would have had to pay an extra $250 for that option.

I found a Detroit trutrac that might work on Amazon.com: http://a.co/deyBHZI

yes good move with the trutrac. read the reviews, that will tell ya a lot.
Have it professionally installed though. there are good place that will do it and set up your backlash and pinion.
Btw Summit has it for same price and would have a better warranty than the place you found it.
And Summit will give tech support if needed
https://www.summitracing.com/parts/dtl-913a481

OK, sounds good. Unless you know someone better, I will go talk to JT's Auto & 4x4 in Torrington.

On the Summit site, it lists that it has to have a:


Rear Axle Model: GM 8.5 in.
or
Rear Axle Model: GM 8.6 in.

This is the ring gear size right?

I checked all the codes in the glove box and the ring gear size is not listed.

I'll look at the number of rear end bolts tomorrow, but one website said if it's a 10 bolt it's a 8.5" ring gear 30 spline 6-lug axle. Does this sound right?

One of the codes in the glove box is GT4: " 8491 P RAX M AXLE REAR 3.73 RATIO".

Also, I don't think JT's 4x4 is going to work out. I sent him info and asked if he could install the TruTrac and all he asked is if I could send a picture of my tire tread. The tires are 1 year old Blizzak snow tires. Maybe he is a parts and tires retailer. I don't know.

You could try CT Axle in Ellington
http://ctaxleservice.com

I've heard they are decent and willing to spend time with folks discussing options....

Thanks for the recommendation!

It's a 10 bolt rear end, so I guess it has a 8.5" ring gear, 30 spline.

Call Summit for help David. they might figure it out for you or take it to Connecticut driveshaft in east Hartford.
8.5 and 8.6 is ring gear size David