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Locking Differential ( Yes I Did Do A Search)

jake1530

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jake1530 Enthusiast

jake1530

Posted
Posted

Gentlemen, I was wondering if somebody could take a minute and explain something to me please. I have a 2005 GMC Sierra Z71 and I remember it does have a locking differential and I was playing around in the snow today, and came up with a couple of questions. I like to stop on an incline then slowly step on the gas and watch the rear wheels spin till they both catch and drive up the hill. If they keep spinning I drop it in to 4 wheel drive. Childish I know but I like playing with my truck, and I’m not beating on the truck.

1st question. The wheel that moves the truck along during normal driving, does that vary from drivers side to passenger side, or is it always passenger side?

2nd question. I think it is the tire catching on the snow, but I hear a thumping noise when the second wheel starts to spin, is it the differential engaging making that noise?

PLEASE NOTE: I am not spinning the tires wildly or fast, just SLOWLY stepping on the gas enough to get the rear wheels moving. THANK YOU guys in advance, you’ve helped me plenty of time over the years!

pwall Senior Enthusiast

pwall

Posted
Posted

You'll feel the G80 lock......hence the noise you are hearing. That's normal.

I'm not sure on the first question. I'm thinking it's always one side, but I don't know. Good question.

Z45 Senior Enthusiast

Z45

Posted
Posted

Its a mechanical locking differential so there is bound to be some feel and some noise when it locks up. That said, I rarely hear mine but then again every truck I have ever owned going back many years has had one and to me its not a truck without it so I don't pay no never mind to any drive line noise. Heard them all over the years and know more noise is nothing to be concerned about. Matter of fact one dealer told me several years ago they did not like to order trucks for stock with lockers because customers would be coming back arguing something was wrong because they heard a noise.

 

 

 

music Senior Enthusiast

music

Posted
Posted

The differential is "open" until it locks. An open diff apples power to the path of least resistance (left, right or equal). If you drive a 2wd tractor, it has two brake pedals. If the left tire spins, you press the left brake, redirecting power to the right (now the side with the least resistance).

 

Edit: A good time to point out the "auto-lsd" system that Toyota uses. The Tundra has an open differential. They "simulate" a limited slip differential by using the ABS to apply brakes left/right just like the tractor example above. Nothing wrong with that, and many cars use the same technique. It's a lot less expensive too. It is not at all the same as a locking diff, however, as it can not "over-power" both wheels equally (i.e., equal slip) without applying the brakes and cutting power.

 

http://www.google.com/search?q=open+differential

sc4808 Enthusiast

sc4808

Posted
Posted

Question 1 It varies but is usually the passenger side because of the rotation direction of the engine but will be the driverside when turning left.

 

Question 2 Normal

gates59 Enthusiast

gates59

Posted
Posted

For question 1. It is always the pasenger tire that will spin except if you have a fwd. Then it is the drivers side. That is just because the way a differential is made. The easyer wheel will spin and that just happen to be the one.

clemsonblozz Enthusiast

clemsonblozz

Posted
Posted

the tire with the least traction spins first.. then when the centrifugal weights in the G80 sense a 100 or 200(cannot remember) difference between the two wheels, it locks up.. It does make a clunk, and it unlocks at 20 mph I think.

jake1530 Enthusiast

jake1530

Posted
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Posted

You guys are great, THANKS AGAIN for the education. Elcamino, thanks for the YouTube video, I was poking around and found a few making the EXACT same noise, found out its normal. Big worry off my mind. Thanks again.

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