limited slip diff type?

[972sparky]

anyone know what the name of this type of limit slip diff is? I'd like to look into rebuild kits, like clutches and stuff. but never seen one like this?

any idea who makes it for gm?

Had one of these in a 2008 Avalanche, only had an axle seal go out due to the brakes overheating with a stuck piston otherwise no problems for 150K miles. Here is a rebuild writeup. https://offroadtb.com/rear-axle-g80-differential-rebuild/

 

[intheburbs]

The G80 is not "weak" and does not "break easily."

If you do stupid stuff - burnouts, donuts, etc - yes, it's more likely to break. If you drive with some modicum of maturity, it will outlast you. I have 3 G80 trucks with over 650,000 total miles and have had zero G80 issues.

 

[Fless]

It's very different, the AWD transfer case is like having a 3rd center section to prevent wheel hop.

When in Auto the front axle and driveshaft are engaged and turning but the computer is waiting to decide how much power to transfer from the back to the front.

This seems to be somewhat correct, although at what point does the front diff actuator couple the front propshaft (and transfer case) to the diff? It wouldn't be needed if they're already coupled. They are separate until the front diff actuator is commanded on.

At least that's the way mine is on my NP246 AUTO system -- I can tell when the front engages, maybe 1/2 second or so after sensing rear wheel slip. The T/C always keeps the front propshaft spinning at an appropriate speed so the engagement can be quick, but it's not coupled to the diff until the actuator, well, actuates it.

Obviously your newer systems might operate differently, but if there's a front diff actuator, I don't see how. Enlighten me, please.

Running in AUTO theoretically won't cause any additional wear on the diff, unless it's engaged by the computer. Clear as mud?

 

[BlaineBug]

It's very different, the AWD transfer case is like having a 3rd center section to prevent wheel hop.

When in Auto the front axle and driveshaft are engaged and turning but the computer is waiting to decide how much power to transfer from the back to the front.

My wife has a Nissan Rogue, all wheel drive. There's a button to "lock" it temporarily. So I would assume that it's somehow clutch based as well as it has both functionalities but is extremely dumbed down in operation for the user.

 

[BlaineBug]

This seems to be somewhat correct, although at what point does the front diff actuator couple the front propshaft (and transfer case) to the diff? It wouldn't be needed if they're already coupled. They are separate until the front diff actuator is commanded on.

At least that's the way mine is on my NP246 AUTO system -- I can tell when the front engages, maybe 1/2 second or so after sensing rear wheel slip. The T/C always keeps the front propshaft spinning at an appropriate speed so the engagement can be quick, but it's not coupled to the diff until the actuator, well, actuates it.

Obviously your newer systems might operate differently, but if there's a front diff actuator, I don't see how. Enlighten me, please.

Running in AUTO theoretically won't cause any additional wear on the diff, unless it's engaged by the computer. Clear as mud?

Our trucks do not have vacuum or electronic actuated hubs like some trucks have. They are always locked full time with the front differential. The transfer case is what is uncoupling the front differential from the drivetrain alone.

I can tell my Auto transfer case runs like having AWD in the sense that it gives power to both front and rear differentials full-time but allows for slippage between the front and rear so that there isn't binding on dry pavement.

 

[Caddylack]

The G80 is not "weak" and does not "break easily."

If you do stupid stuff - burnouts, donuts, etc - yes, it's more likely to break. If you drive with some modicum of maturity, it will outlast you. I have 3 G80 trucks with over 650,000 total miles and have had zero G80 issues.

Everything lasts when you baby it. It's the stupid stuff that I care about.

My dad put 400k miles on a 4L60E, but that doesn't mean anything for me.

 

[swathdiver]

This seems to be somewhat correct, although at what point does the front diff actuator couple the front propshaft (and transfer case) to the diff? It wouldn't be needed if they're already coupled. They are separate until the front diff actuator is commanded on.

At least that's the way mine is on my NP246 AUTO system -- I can tell when the front engages, maybe 1/2 second or so after sensing rear wheel slip. The T/C always keeps the front propshaft spinning at an appropriate speed so the engagement can be quick, but it's not coupled to the diff until the actuator, well, actuates it.

Obviously your newer systems might operate differently, but if there's a front diff actuator, I don't see how. Enlighten me, please.

Running in AUTO theoretically won't cause any additional wear on the diff, unless it's engaged by the computer. Clear as mud?

I've not been very good at articulating how it functions, mostly because I wasn't entirely correct until made so recently on another forum!

Operation in Auto is best explained here:

Gears Magazine - Magna's MP 3010 Transfer Case

The Magna Powertrain model 3010 (MP 3010) transfer case (figure 1) has been the heart of GM’s four-wheel drive truck line since it was introduced in 2011 to replace the New Venture Gear transfer case system. The MP 3010 transfer case is an electronically controlled, one-speed automatic, active...

gearsmagazine.com

The MP3010 is the single speed version of the MP3023/MP3024 and for our discussion works the same.

 

[intheburbs]

Everything lasts when you baby it. It's the stupid stuff that I care about.

My dad put 400k miles on a 4L60E, but that doesn't mean anything for me.

Thanks for the laugh. I've been called a lot of things, but I've never been accused of babying my trucks. They're tools (and toys). My 2001 has been so heavily abused it's wearing rear axle number 4. Not failures of the G80, but from towing heavy. And, BTW, it has the original 4L65 and 325k miles on it.

And I do much worse to the 2500. That's the main reason I bought it. If it's not towing my 8600-lb trailer, it's towing my 4000-lb cargo trailer. And when not towing, it's cruising at 90-100, with brief stints to 110-115.

 

[j91z28d1]

Thanks for the laugh. I've been called a lot of things, but I've never been accused of babying my trucks. They're tools (and toys). My 2001 has been so heavily abused it's wearing rear axle number 4. Not failures of the G80, but from towing heavy. And, BTW, it has the original 4L65 and 325k miles on it.

And I do much worse to the 2500. That's the main reason I bought it. If it's not towing my 8600-lb trailer, it's towing my 4000-lb cargo trailer. And when not towing, it's cruising at 90-100, with brief stints to 110-115.

to be fair none of that uses the locking part of the diff. that's mostly ******* bearings and keeping the fluid cool under load. an open diff would be fine in all that. the rear end itself isn't what makes is considered weak, it's the locking mechanism. if it gets used, it seems is much more likely to break than the standard type of limited slip even gm uses in cars.

 

[VR4Play]

This seems to be somewhat correct, although at what point does the front diff actuator couple the front propshaft (and transfer case) to the diff? It wouldn't be needed if they're already coupled. They are separate until the front diff actuator is commanded on.

At least that's the way mine is on my NP246 AUTO system -- I can tell when the front engages, maybe 1/2 second or so after sensing rear wheel slip. The T/C always keeps the front propshaft spinning at an appropriate speed so the engagement can be quick, but it's not coupled to the diff until the actuator, well, actuates it.

Obviously your newer systems might operate differently, but if there's a front diff actuator, I don't see how. Enlighten me, please.

Running in AUTO theoretically won't cause any additional wear on the diff, unless it's engaged by the computer. Clear as mud?

NP246 auto system works by engaging the front diff actuator full time and applying the clutches in the TC to engage the front axle. There is always a bit of drag on the clutches as they don't disengage completely. Even in 2wd the front driveshaft spins. When the front diff is locked the clutches slip when turning which is what causes the wear. The newer trucks unlock the clutches all the way allowing the front driveshaft to free wheel. The older trucks do not. I don't remember the year break but my 2002 always slight pressure on the clutches and it is difficult to spin the front driveshaft by hand when parked and in 2wd which is why there is a sticker under the hood saying not to run on a 2wd dyno.