New rear end

vortec4800 · September 1, 2003

I want to get a new rear diff for my truck, which one would be the quickest accelerating, and how much do they run?

MiSdIrEcTeD_1 · September 7, 2003

Id go with an OE 3.73 limited slip from GM.. Not sure on how much that would cost; maybe check it out on a GM website. I think that would be the most logical and easy swap.

vortec4800 · September 7, 2003

Anybody got a part number on that?

Also: any way you can tell what gear ratio you have from the VIN #?

PSWired · September 9, 2003

I'd have to disagree with Misdirected on this one. The OE limited -slip (option code G80) is actually a locking differential. This is not a problem, besides the clunking when it locks. The problem is that its design is very weak when higher than usual amounts of torque are run through it. What happens is the differential carrier actually ruptures and causes the entire unit to explode! When this happens it can also take out your tranny or transfer case, which is bad news. This can also happen on stock vehicles without mods if you get into a situation where you apply lots of torque to the diff and it locks. A better alternative would be Eaton's Posi differential. It is a limited slip unit that uses clutches to control wheelspin. It is not a true locker, so it's not the best suited to rock crawling or extreme off-roading, but it is an excellent street and light off road diff. So my vote is for the Eaton Posi and 3.73 gears.

bigdogs · September 9, 2003

I'm new to this forum as well as to the newer GM vehicles but was wondering where you heard the G80 is a weaker rear end? I have that option on my 2003 Duramax/Allison 2500HD which says it puts out 520+ ft/lbs of torque. I did have an Eaton posi years ago in the 10.5" 14 bolt corporate axles and that was a gov lock type that could act a little odd, although I have not had this new truck long enough to see how this unit works.

varmint2506 · September 12, 2003

I'd have to disagree with Misdirected on this one. The OE limited -slip (option code G80) is actually a locking differential. This is not a problem, besides the clunking when it locks. The problem is that its design is very weak when higher than usual amounts of torque are run through it. What happens is the differential carrier actually ruptures and causes the entire unit to explode! When this happens it can also take out your tranny or transfer case, which is bad news. This can also happen on stock vehicles without mods if you get into a situation where you apply lots of torque to the diff and it locks. A better alternative would be Eaton's Posi differential. It is a limited slip unit that uses clutches to control wheelspin. It is not a true locker, so it's not the best suited to rock crawling or extreme off-roading, but it is an excellent street and light off road diff. So my vote is for the Eaton Posi and 3.73 gears.

The G80 unit is a pretty good for the average use. Mine lasted 150 or so thousand miles before it exploded. If I'm not mistaken, the G80 is not a true locker. It has clutches also to take up the pressure while making a sharp turn while the unit is engaged.

1BADHD · September 12, 2003

The G80 has clutch paks in it. Therefore its a limited slip. It is not a locker. And for a 4.8's torque.......it is plenty strong.

But.....fow what it costs, just go get a Eaton unit that is not a factory unit. OEM is also Eaton. The aftermarket unit has more holding power in the clutch packs. And get a 4.10 rear gear. That will launch you off the line.

robsawatsky · September 13, 2003

Yes, the Eaton G80 uses clutches but they aren't meant to allow any slip when it is engaged (i.e. the axles halves are effectively locked). It uses the clutch to lock against the side gear. The electronic locker uses a ball ramp mechanism and locking pins instead of a clutch. I suspect this provides more solid locking and is less resistant to wearing out. Also, the electronic locker can obviously be activated by a switch to engage full-time in severe off-road conditions. Eaton refers to both as lockers, because that is what they do, unlike a limited slip differential, which has preloaded clutch packs that clamp based upon input torque not wheelspeed differential.

vortec4800 · September 13, 2003

How much would an Eaton 4.10 run me?

ddombos · December 17, 2003

I've had a tough time finding an 'aftermarket' G80. What vendors are you guys using? Most aftermarkets are the Easton Posi differentials. I'd prefer the locking, and I'm thinking of just going with the OEM in order to slip it past the dealer in the event of a warranty issue where the rear-diff would void my warranty on a front suspension item. I've had similar happen in the past.

I live in SW Michigan for those who know of shops who have parts and/or would do the install.

SportSide 5.3 · December 17, 2003

thunder racing has some gm 4.10's and 3.73

www.thunderracing.com

2ksleeper · December 18, 2003

I had a G80 & 3:42's in my truck and I got tired of doing peg leg right turns. The G80 Eaton is a limited slip/locking hybrid that locks when it detects slippage between the wheels & it will not engage above 25mph. I swapped to an Eaton limited slip posi-traction & 4:10 gears & love them. My truck turns about 2400rpm at 70mph with 28.9" dia tires. The Eaton LSD is a good street gear & is very easy to predict its engagement, making side drifts fun. The gears, differential, & rebuild kit cost me about $640 from reider racing & had them installed at my brothers shop for about $340. You will also need some sort of programmer(ie hypertech, predator, superchips) to adjust your speedometer after the swap.

December 18, 2003

I'll cast my vote for the 4.10 gears and the Eaton posi-traction. It doesn't get any better than this. The G80 is intended for towing under a controlled acceleration condition. Great for its intended purpose, but as mentioned above, it will blow up if you drop the hammer from a dead stop with a highly modified engine (such as a supercharger). The G80 does too good of a job under these conditions and can self destruct in the process. Just my 2 cents!

SportSide 5.3 · December 18, 2003

how much better would u say the eaton posi is over the limited slip diff. from the factory?

awdvkd · December 19, 2003

Limited slip- one wheel turns, usually the one that is slipping. G80- once one wheel is going 5 mph faster than the other its locks and both wheels turn. The ONLY thing bad about lockers are that it can cause the rear of the vehicle to come around, with limited slip the wheel that is not under power keep it driving straight, it just tracks. Lockers also cause tires to wear faster than limited slip, not much though. It only applies to the rear axle, the front is a whole different story. I have had three trucks with G80's in them and all have gone at least 130K. There always seems to be a group of people who are confused with the definition of abuse and performance. ANY Diff will explode if abused, I use my truck on a farm and they are tested daily under some pretty grueling conditions. I really like the G80 and feel it is very solid as long as you don't trash it.