Limited Slip Differentials

[SourTooth307]

I guess I'll start off by saying that my 84 is my first 4WD vehicle and as such one of the first times I've really cared about things like limited slip vs. a standard differential. This weekend I stayed at my parents house in a little town in the Appalachian Mountains in Northwest NJ and took my K/10 with me because of an impending snow storm. I parked it on the snow covered lawn so the driveway would be free to plow that night and sure enough we got a good 4-6 inches of snowfall.

When I went to leave the next day I tried to take off in 2WD (it was slghtly downhill so I thought I could do it easily) and ended up getting stuck. I tried 4H next and got no where, even went down to 4L with no luck. What I was seeing was my driver rear and passenger front wheels were spinning but not the others, a classic case of having standard diff's. I eventually rocked it out in 4H and was on my way, but I really felt the sting of the standard diff's on my truck. Kind of a shot to the "it can get out of anything!" ego......

The reason I bought my truck mainly was for winter weather and because I wanted to get into off-roading. After the struggle I had yesterday I wanted to learn more about how the axles in my truck work. 2WD I get, but can someone educate me on how the 4WD modes work? I'm fairly familiar with the anatomy of the drivetrain (engine, trans, transfer case, shafts, diffs, and axles) and I get that it's all mechanical and there's no computer system governing the power distribution, but I guess I'd like to know how the power is distributed in a few different 4WD scenarios. Like on dirt, snow, or mud. If I want to get into off-roading, am I going to need to upgrade to limited slip if I'm pretty much just looking to do trails (wet or dry), rough terrain, and maybe cross a river or two here and there? Not really interested in any rock crawling or mud bogging at this point.

Anyway, thanks in advance. Looking forward to learning all I can about this stuff.

[enaberif]

Truck axles are limited slip. This is why lockers exist for. You can put lockers in the front and rear of your axles so that both tires are spinning at the same time.

Tires also play a HUGE role in snow.

[rich weyand]

If you still have the RPO sticker in the glove box, you can see whether G60 is listed or not. My guess is not, or you should have had to spin both rears to get stuck.

[Slammed84]

If im correct a limited slip will transfer power to both axles if they are seeing the same amount of traction. I figured this out on my posi rear end trying to burn out one day. I was on a part of the road that was worn pretty smooth on the right side and it was only spinning the right tire. I thought my posi was screwed up and started to worry.
Further down the road I stopped on fresher pavement and lit both sides up just fine.
So I guess basically if one side is easier to spin then that side will spin?
I dunno, those things are kinda complicated.

[SourTooth307]

Originally Posted by enaberif

Truck axles are limited slip. This is why lockers exist for. You can put lockers in the front and rear of your axles so that both tires are spinning at the same time.

Tires also play a HUGE role in snow.

What exactly are "lockers?" I have 33" ProComp Mud Terrains and a 4" lift so I should've been ok there.

Originally Posted by rich weyand

If you still have the RPO sticker in the glove box, you can see whether G60 is listed or not. My guess is not, or you should have had to spin both rears to get stuck.

I prolly did spin both rears initially when I tried to pull out in 2WD.

[Keith Seymore]

Originally Posted by rich weyand

If you still have the RPO sticker in the glove box, you can see whether G60 is listed or not. My guess is not, or you should have had to spin both rears to get stuck.

G80 is the RPO for the posi/limited slip rear end.

K

[Keith Seymore]

Originally Posted by Slammed84

If im correct a limited slip will transfer power to both axles if they are seeing the same amount of traction. I figured this out on my posi rear end trying to burn out one day. I was on a part of the road that was worn pretty smooth on the right side and it was only spinning the right tire. I thought my posi was screwed up and started to worry.
Further down the road I stopped on fresher pavement and lit both sides up just fine.
So I guess basically if one side is easier to spin then that side will spin?
I dunno, those things are kinda complicated.

The issue is that the open differential will send the power to the path of least resistance; so if one tire is on ice all the power gets sent there while the tire with traction does nothing.

The limited slip provides a resistance to the easy side to divert some of the power to go to the side with traction. You can imagine if you had two brake pedals and put the brakes on the ice tire how it would work (and how it does work on a farm tractor). A limited slip is normally accomplished through the use of clutch plates in the carrier.

A true locker ties the two axles together temporarily, typically with gears or with a pawl arrangement, so there is no differential action.

K

[Bigstevex4]

Limited slip like said transfers some power to the other axle. If it has clutches they may need replaced. If youve ever driven some thing with a locker Youll kinow it the inside wheel drives around corners instead out side plus with a manual trans gear lag is brutel. I took the one out of my blazer rear and put it in front. with hubs its pretty managable.

[rich weyand]

Originally Posted by Keith Seymore

G80 is the RPO for the posi/limited slip rear end.

Oops. Right you are. My bad.

[SourTooth307]

Originally Posted by Bigstevex4

Limited slip like said transfers some power to the other axle. If it has clutches they may need replaced. If youve ever driven some thing with a locker Youll kinow it the inside wheel drives around corners instead out side plus with a manual trans gear lag is brutel. I took the one out of my blazer rear and put it in front. with hubs its pretty managable.

I'm not sure honestly, I think I'm gonna have to check the RPO codes and post it.....

[csdineley]

GM locking differential - how it works: http://youtu.be/MCxqUJCZGNU

Eaton Mechanical Locking Differential: http://youtu.be/ftyJvIO0DZ8

[naphtali5725]

anyone have a Eaton trutrac posi? wondered what they are like for a daily driver...

[wilkin250r]

I don't want to insult your intelligence, but if you're not familiar with terms like "lockers" then you may need to start at the very beginning. I would suggest a web search, and not because I don't feel like posting it (I actually love explaining things like this), but because there are people out there that have done a MUCH better job than I could, with computer animations and the whole works. A simple search term like "How a differential works" will not only produce various results for standard (or "open") differentials, but also delve into various types of limited-slip differentials, and even differences between 4-Wheel-Drive and All-Wheel-Drive (yes, there is a difference).

Once you're armed with knowledge on pinion gears, ring gears, spider gears, limited-slips and lockers, we can start answering questions on the subtle differences between clutch-type and helical-gear type limited slips, and differences between electronic and detroit lockers, and the fine details that aren't covered in the tutorials.

[77K10Silverado]

My 77 K10 came with a locking diff in the rear from the factory. Used it in 6" snow last night and could hardly spin the tires! They sometimes refer it to a "Gov Bomb" because the have a history of exploding! lol I think that mostly happens when someone is very rough on their truck and possibly have it lifted with larger tires. If you drive sensible it works great in snow/sand/mud.

[greg64]

My 77 is 2WD, but I have an Eaton limited slip in the rear-end, AND proper winter tires that are studded. I'm pretty much unstoppable in snow. The diff helped 50% and the tires helped the other 50%. I was actually thinking about converting my already franken-truck to 4WD, but my traction is so good now that
"why bother?".

Oh, and I live in the mountains and we get lots of snow here.

[motornut]

I too have the G80,in a 79C Jimmy.
the day I looked at it,and drove it up an icy lane it made a difference.
since then, on sand and mud it's helped.
I can see keeping the pedal down after it locks,can break things.
I let off the gas a touch when i know it's spinning/locking up
And then you will hear the horror stories here....but anything (almost 40 yrs old lol)can break when you abuse it,or don't maintain it

[naphtali5725]

Originally Posted by greg64

My 77 is 2WD, but I have an Eaton limited slip in the rear-end, AND proper winter tires that are studded. I'm pretty much unstoppable in snow. The diff helped 50% and the tires helped the other 50%. I was actually thinking about converting my already franken-truck to 4WD, but my traction is so good now that
"why bother?".

Oh, and I live in the mountains and we get lots of snow here.

i live in the mountains as well. the reason i got the trutrac posi, hope it does as well...

how far are you from kamloops, bc?

[Keith Seymore]

Originally Posted by wilkin250r

I don't want to insult your intelligence, but if you're not familiar with terms like "lockers" then you may need to start at the very beginning. I would suggest a web search, and not because I don't feel like posting it (I actually love explaining things like this), but because there are people out there that have done a MUCH better job than I could, with computer animations and the whole works. A simple search term like "How a differential works" will not only produce various results for standard (or "open") differentials, but also delve into various types of limited-slip differentials, and even differences between 4-Wheel-Drive and All-Wheel-Drive (yes, there is a difference).

Once you're armed with knowledge on pinion gears, ring gears, spider gears, limited-slips and lockers, we can start answering questions on the subtle differences between clutch-type and helical-gear type limited slips, and differences between electronic and detroit lockers, and the fine details that aren't covered in the tutorials.

Back when he was about 8 my son made a differential out of Legos.

He did that so he could explain to his grandfather how it works.

K

[greg64]

Originally Posted by naphtali5725

i live in the mountains as well. the reason i got the trutrac posi, hope it does as well...

how far are you from kamloops, bc?

I'm about 8 hours driving east of Kamloops.

[SkinnyG]

I'm intrigued with a Trutrac for myself - curious how it goes in an icy Canadian winter.

Kelowna, here.

[naphtali5725]

Originally Posted by SkinnyG

I'm intrigued with a Trutrac for myself - curious how it goes in an icy Canadian winter.

Kelowna, here.

i've wanted to move to Kamloops for a long while now, maybe one day...
i hope the truetrac is going to be good on the street, i'll need the traction

[Jeepwm69]

Truetracs are great. Little squirrely on ice, but not too bad, and they don't wear out like all the clutch driven LSD's.

[SkinnyG]

For ice, which would be better? Clutch, or Torsen?

[reporter000001]

you mean a open differential,not a limited slip.

Originally Posted by enaberif

Truck axles are limited slip. This is why lockers exist for. You can put lockers in the front and rear of your axles so that both tires are spinning at the same time.

Tires also play a HUGE role in snow.

this has all the info u will need.
http://www.offroaders.com/tech/limit...ferentials.htm


but a limited slip basically "senses" when the primary wheel spins, aka the right rear, and then locks the diff and spins both. until traction is regained, then at low speeds unlocks.

a spool or locker is lockes all the time and is EXTREAMLY dangerous in wet or snowy conditions. until you are used too it, you will be doing unexpected donuts alllllll the time.

a "red neck" solution to this is to weld the spider gears up. this almost ALWAYS results in a broken axle shaft, but its cheap... 50 bucks from the junkyard for an axle to play with


also, when installing a limited slip or spool, expecially a spool, youwill HAVE to replace the axleshafts and bearings. so your looking at 500 bare min. more close too 800 for a nice reliable install. include paint and seals and prob brakes while ur there, brake fluid a line, the cost keeps rising.

front lockers, i have no idea, but same concept.

TRICK and TIP, next time your stuck in the snow, or wanting to lay down 2 sexy black lines instead of 1 peg leg, get the primary spinning, and power jack the brake, tapping it with left foot while still on gas, rosking left and right with the steering... this will cause the spider gears to go into some sort of a "limbo" and lock the diff. ive done this in a 10bolt and a 12 bolt.....
heared this from an old dodge circle trck guy back in 2006, been doing it ever sense hen to be able to drift the rear end and keep up with these little zipper head cars...

good luck, the read end tollerance are more important than crank tollerances hahaha well, u know what i mean, its hard and no fun. be prepaied to dump a lot of checks and time into this project.
id just buy a plow haha.

[GRADYS Performance]

Anyone have experience with both a clutch type posi and a tru trac to compare how they work. I am going to put one or the other in my S10 and wonder which would be best on slippery boat ramps. I am not interested in leaving 2 stripes on the street. Just don't want to spin 1 wheel while pulling the boat out of the water.