djthumper wrote:Flying Monkey wrote:my original plan was to start hitting junk yards and such to try to find just a better geared G80. Want at least a 3.73. I think the 3.73 would be better on 33's then my 3.42 (non-G80). And if I go to 35's later with BL ill definatly need something higher then then 3.42.
If you are looking at re-gearing anyhow I would only want to do the front and rear once. I would just get an 8.6 rear end and start setting that up with 4.56 gears. They will give you plenty of torque with the 33's and if you decide to go to the 35's later will still provide you with plenty of torque take a look at this gear ratio guide to see what I am talking about. It isn't that our engines lack power, it actually gives us a slight advantage to make up a slight loss of torque. But we can have all of power in the world and the truck won't move without torque.
Diacom wrote:
Flying... was the one you found with the G80 an 8.0 or 8.6 rearend? That's a good price either way, but just hate to think you'd have to purchase another diff later when you want to upgrade.
fishsticks wrote:An auto locker is a device like a lunchbox or Detroit Locker, which locks when power is applied. A G80 is NOT an auto-locker. A G80 requires one wheel to slip/spin before it tries to do anything. This is bad for a number of reasons, and unlike any locker out there. GM doesn't even call it a locker. RPO codes list it as "Axle, positraction limited slip" and it's designed for street manners, not abuse. (Citation: http://www.trailvoy.com/docs/vinrpo/2002_VIN_RPO.pdf)
I don't like being a hater but I watched yet another G80 go in a full size on the last trip I was on. He was on a blue trail trying to get over a tree root. Not much wheelspin at all and his ratchet failed. We pulled it out and he ran open the rest of the trip.
Honestly guys, If all you're after is the G80....buy a much easier to find 8" rear end. The G80 WILL fail before the ring and pinion does. I can't think any failure I've seen/read about not being caused by a snapped ratchet, exploded spider gear or broken carrier case. Upgrading to an 8.6 G80 isn't addressing the actual weak point of the assembly.
If you have a G80 already, great. Use it until it dies. But it's a waste of money to go 8.6 with the G80 unless you are set on regearing lower than 4.10... and if you are regearing, you'll have he carrier out anyway, and can install a real locker.
Save up, do it once, do it right.
Flying Monkey wrote:Very good write up thank you.
fishsticks wrote:An auto locker is a device like a lunchbox or Detroit Locker, which locks when power is applied. A G80 is NOT an auto-locker. A G80 requires one wheel to slip/spin before it tries to do anything. This is bad for a number of reasons, and unlike any locker out there. GM doesn't even call it a locker. RPO codes list it as "Axle, positraction limited slip" and it's designed for street manners, not abuse. (Citation: http://www.trailvoy.com/docs/vinrpo/2002_VIN_RPO.pdf)
I don't like being a hater but I watched yet another G80 go in a full size on the last trip I was on. He was on a blue trail trying to get over a tree root. Not much wheelspin at all and his ratchet failed. We pulled it out and he ran open the rest of the trip.
Honestly guys, If all you're after is the G80....buy a much easier to find 8" rear end. The G80 WILL fail before the ring and pinion does. I can't think any failure I've seen/read about not being caused by a snapped ratchet, exploded spider gear or broken carrier case. Upgrading to an 8.6 G80 isn't addressing the actual weak point of the assembly.
If you have a G80 already, great. Use it until it dies. But it's a waste of money to go 8.6 with the G80 unless you are set on regearing lower than 4.10... and if you are regearing, you'll have he carrier out anyway, and can install a real locker.
Save up, do it once, do it right.
fishsticks wrote:An auto locker is a device like a lunchbox or Detroit Locker, which locks when power is applied. A G80 is NOT an auto-locker. A G80 requires one wheel to slip/spin before it tries to do anything. This is bad for a number of reasons, and unlike any locker out there. GM doesn't even call it a locker. RPO codes list it as "Axle, positraction limited slip" and it's designed for street manners, not abuse.
bartonmd wrote:The main counter-point that I've got to Donnie's "get an 8" if you want a G80" is that the 8.6" G80 is a stronger unit than the 8" G80...
fishsticks wrote:
- It still expects all torque to be held by two tiny spider gears when locked.
fishsticks wrote:The argument about whether the G80 is a real locker has been beat to death on the internet, so it's not worth rehashing here. I'll submit this for thought: There is no mechanical means of fully locking the axles together in the G80. The clutches, especially when worn in, tend to slip slightly even under full cam engagement, so the wheels do not turn at the same speed. Therefore they are not locked together.
snowmirage wrote:Now I really havent taking this thing offroad much. Once on a back road in the forest the first week I had it, slid off the trail and sank into some mud had to get a passerby to yank me out. Other than that I had it in the snow for one Upstate NY winter the year I got it. But I never recall hearing, feeling or otherwise anything that would have lead me to beleive I had anything but an open diff in the back.
Now granted a sticker is just a sticker. Maybe someone replaced the glove box lid for some reason before I bought it at 67,000 miles... who knows I guess the only way to know for sure is to go crack open the pumpkin.
JamesDowning wrote:Technically the spider gears are rendered useless when the clutches activate. The torque is transmitted through the carrier housing to the clutch plates, and then directly to the side gears. The clutch compression force is transmitted from the left side to the right via item 11, again rendering the slider gears useless.
Would you then, by extension, consider any rear locker that operates using clutches not to be a locker? The Auburn Ected uses clutches in the exact same manner as the G80.
fishsticks wrote:bartonmd wrote:The main counter-point that I've got to Donnie's "get an 8" if you want a G80" is that the 8.6" G80 is a stronger unit than the 8" G80...
Can we sure that it's appreciably stronger? Has anyone bothered to look at them side by side?
The design issues with the G80 still exist in the 8.6" variety:
- Since all the internals are slightly larger, I doubt the carrier walls are any thicker.
- It still expects all torque to be held by two tiny spider gears when locked.
- It still requires a ratchet/cam gear with ridiculously tiny teeth to hold pressure on the clutch plates.
- It still requires wheelspin to engage, which shock loads the entire system every time it locks up.
Going 8.6 gets your a bigger R&P, larger bearing journals and stronger axles. But what good is that if the G80 is still the first/most likely point of failure?
The argument about whether the G80 is a real locker has been beat to death on the internet, so it's not worth rehashing here. I'll submit this for thought: There is no mechanical means of fully locking the axles together in the G80. The clutches, especially when worn in, tend to slip slightly even under full cam engagement, so the wheels do not turn at the same speed. Therefore they are not locked together.
There is really no way for that to happen... It either completely locks up, or the flyweight rod (or something else) breaks... If it's not 100% locked up, the cam keeps rotating, because the flyweight is still spinning, which causes the cam to ramp up even more... If the cam is 100% locked and the axles are still spinning different speeds (clutches worn out), something's going to give...
Only one side gets clutched to the carrier, so I think the spider gears do transfer load from the side gear that's locked to the carrier to the other one that's not... If you've broken spider gears, you weren't engaging it softly enough for your setup, and the conditions.
fishsticks wrote:Nope it's not a Detroit. No one ever insinuated it was. Sure they live in thousands of full size trucks, 99.5% of which never leave pavement (and therefore hardly ever engage the G80). Most of these guys (I'm assuming) are serious enough about upgrades to actually get out there and use them. As frequency of use increases, so does the failure rate.
The first/most likely point of failure in the 8" or 8.6" is going to be the G80. So it makes no sense to upgrade to the 8.6" G80 for strength only... As I see nothing showing there is a significant difference in strength between the 8" and 8.6" G80s. That was my original point. Bill did it because his 8" exploded on him and he needed a replacement right then. I get that.
Some of these guys are talking about replacing a functioning differential. If the get a G80 and want/have to upgrade later, they then HAVE to do a full carrier replacement and resetup gears. That's a lot of money that they may not realize they're getting into.
Not to mention that 8" rears are a dime a dozen and 8.6's seem to be getting harder to find.
Perhaps you've found the cause of the majority of ratchet failures out there.
I broke mine "bumping up" a rock on the rear. Sometimes you just need plain old inertia to get you over something. What does the G80 user do in that situation? Not climb the obstacle? That's no fun.