Im seriously thinking about getting a STS turbo kit after i beef up my trans in my Z71. Right now im running 35x12.50x16's and im going to be running 36x14.50x16's after these wear out. I've got 4.56 gears and a eaton posi in the rear with 4.56's up front on the stock open diff.

My question is after i beef the transmission am i going to have to worry about snapping rear end axels or possible CV joints in 2wd or 4wd? I don't do any offroading and im trying to get this thing down into some 14 sec 1/4 mile times. I don't wanna have to worry about punching it on the street and breaking an axle at a stoplight or on a roll. Already from a idle stop it barks the tires a little and from a brake stall of about 2000 it will turn em over for about 7-8 feet, so i dont know if it will break loose enough to keep me from hurting anything or not.

I've got about 102 lbs on each corner with the 35's and the 36's are probably gonna be about 130 lbs on each corner. I figured the additional rotational weight would add up to some of you higher hp guys running slicks. So how are your axel's faring up so far? BTW its a Ext. Cab Sport Side 1500. Don't know what the stock weight is, but the lift probably added about 300-400 lbs with all my accessories.

 

Bigkid blew up his stock g80 rear end. I currently have an Eaton posi, and I dont think anyone here has blown it up.

 

Isn't big kid running spray though? Sorry, i forgot to mention i kinda wanted replies from N/A, turbo, and s/c trucks. Spray puts extra strain on drivetrain because it all comes in at once vs. gradual from other p/a's. Im open to suggestions though, its good news to hear the only guy thats busted a G80 is someone on nitrous. Im going to try and keep myself from going over about a 360 rwhp mark to try and save the drivetrain. Im just wondering on any input if its gonna hold up with my tires.

 

A little background on the G80...
The G80 is engaged by an internal mechanism that spreads force against the two ends from the inside out to engage the clutches. The housing has huge openings in the casting leaving very little material connecting the right and left halves. The mechanism works in such a way that it stops applying force only when the RPM between right and left is equalized. If slippage continues more force is applied. Since you have 4.56 gears, a great deal more torque is available to carry out this lock-up procedure. Since you have larger tires a lot more traction and leverage on the axles is present than a stock setup with stock tires. The G80 also won't work above something like 30mph because a centrifugal weight prevents it. It's not a performance piece.
The weak housing of the G80 combined with the 10-bolts lack of suitable rigidity will ultimately result in carrier failure. With the gears and tires you have a stock G80 would be taking strain with even a stock engine.

Your concerns are valid. Luckily you already have an Eaton Posi. That's good for a lot more power but does not make the 10-bolt indestructable. The housing flexes. A telltale sign of that is the cover bolts walking themselves out causing leaks that quickly draw attention. That's a sign of things to come. If the housing distorts enough under load the contact of the pinion and ring gear is compromised enough to shear teeth.
You've no doubt seen Parish's truck run tens with a 10-bolt. How is this possible? It's simple - stock tires to minimize traction, running in 4x4 to distribute torque, and a posi out back. Put slicks on a truck like that, switch to 2WD and it absolutely 100% will blow up the rear end.

I did this with 6psi, 2900RPM stall, 10" wide tires, and stock 3.73 gears:

 

That's B-E-A-UTIFUL man! Wow, was that with slicks? I always wondered about the stock 30spline axles. 30 splines is hard to break, but come on, some of you guys beat the **** out of them.

I've always known c-clips to be a weak point in stock GM rears. I know most sanctioning bodies won't allow slicks without c-clip eliminators. I don't know how some of you guys get away with it?

 

Looks like you planted a grenade in your diff.....thats gotta suck. So i guess it looks like i need to just be looking for a rolled/parts only HD 6.0 4x4 truck. Swap out transmission, transfer case, rear end and hell might as well swap the engine while im at it. Are there any front axel upgrades i need to do? Cause if im going to be doing this much beefing up, i want to be able to pull a friggin pine tree up in 4 low, or better yet...leave some nice blackies off all 4 tires.

I hate like hell to have to do it seeing how i just unloaded about 1400 bucks on gears and a posi unit for the rear. But i guess it gives me a good reason to go to 5.13's, hopefully Yukon or Richmond make em for that rear. How much would a G80 with eaton posi and 4.56's go for in real good condition? Only about 8K miles on posi and gear.

Is the 6.0 HD rear the same as the Duramax rear ends and the 2500's, or is it different? I'd like to find something that still has the 6 lug pattern so i wont loose my wheels. Times like these almost make me wish i had bought a HD 4x4 to start with. I would just trade my truck in but i doubt the dealer would give me what i got in it, plus i still owe about 17k on it. Then i would have the joy of 5 more years of payments on a outrageously priced HD that would be equally equipped of my Z71. And theres no way in hell i would go through the suspension and body lift again

 

As I understand it,
a 2500 with a 6.0 gets a 9.5" 14-bolt semi-floater (these have c-clips)
a 2500HD with a 6.0 gets a 10.5" full-float 14-bolt. (no c-clips)
a 2500HD with a Duramax or 8.1 gets a truly massive 11.5" full floater.

Unfortunately, All 2500 trucks are 8-lug.

9.5" swap in old-body style trucks are popular with rear drums because the 9.5" used to be made in 6-lug versions and even 5-lug in the case of the 454SS truck. With the new truck you have disc brakes and ABS sensors to contend with. All 10.5 and 11.5 are 8-lug unless you have a rear end place custom build you a semi-float 10.5" 14-bolt by cutting the ends off and welding on new ends similar to those for a Ford 9". This is how I get away with running a 10.5" semi-float 5-lug 14-bolt in my truck.

 

For some reason i get this slightlest feeling this is going to be an expensive journey. What spline axels are the 10.5 full floaters? I might be able to get Moser Engineering to make me a set of custom billet axels with a 6 lug pattern.

 

Full-floating axles differ from semi-float in that they do not carry any weight of the vehicle - they only transfer torque. The wheels bolt to hubs that have their own bearings. The axle attaches to the hub and can be removed with the truck still sitting on the wheels. Converting a 10.5 from full-float to semi-float eliminates the hubs.

10.5" converted rears use 30-spline axles, but they are nothing like 8.5" 30-spline axles.

 

Yeah, 35-36's are too big for a 10bolt... at least if you plan on any off-roading. I think 33's are the max recommended. The weak point (offroad) seems to be the axles.