8.5" ZR2 rear end, what replacement posi carrier?

I've made a choice for rear ends... I'm getting an 8.5" with drum brakes out of a 95 Sonoma Highrider, which is I believe the G80 carrier. We all know that's junk, so what should I run? I have to check what the stock gears are still, but I'd like to go 3.73 again. That's what is in the rear end that was in my 91 (red truck)

I've heard the word torsen and zexel or something like that thrown around, about to do some shopping on Summit but thought i'd start this first. I'll be using the truck for drifting and/or autocross and/or road racing. More so long open tracks opposed to tight autocross courses. Slipping cannot happen though.

Donor truck, sorry about the ass. haha




I'll obviously have to get the rear end narrowed roughly 4" total, that's the difference in ZR2 and 2wd IIRC. Should I stick with the stock axle flange or is there another route I should go to simplify rear disks? I'd love to go the 13" flynbye route up front, but rears are completely open since I can use basically any axle flange style, correct?

e-brake is not a concern, i'll be using a hydraulic e-brake.

4x4 is 4" wider & ZR2 is 6" wider than 2wd truck rears. Just FYI. If you plan on running vette wheels, like the C4 ZR1 11" wide ones I run, you could leave the rear alone & the ZR2 may stick out 1/2"-1".  I honestly can't remember if a Torsen/Zexel carrier is offered in 8.5"... maybe.

You planning on chopping a top? Need extra parts & pieces, huh?

I'm not sure how much narrowing an axle runs, or swapping to disc brakes, so just a point to consider-

2wd trucks were available with the 8.5" axle. IF you buy one from a blazer, then you get the discs for free.

car-part.com at least has an option to search for it now, although I see a few auto tranny's listed in the results, which makes me suspicious

http://car-part.com/cgi-bin/search.cgi?userSearch=int&userPID=1000&userLocation=All+States&userIMS=&userInterchange=%3EF%40B&userSide=&userDate=2000&userDate2=2000&dbModel=15.4.6.6&userModel=Chevy%20Blazer%2C%20S10%2FS15&dbPart=435.1&userPart=Axle%20Assy%20Rear%20(w.%20Housing)&sessionID=600000000000000000104981272&userPreference=price&userIntSelect=93837&userUID=0&userBroker=&iKey=&userPage=4

The 8.5 rears for the S trucks were necked down at the end of the axle tubes to run the 7.5/7.625 flanges. Typical 10 bolt flange. Run the blazer rear discs or do the LS1 camaro upgrade.. or I've got KORE3 C5 DIH adapters for the 10 bolt flange. You'd just need to remake or buy another flange adapter (since I ended up welding one of the two shut).. If you're interested PM me. Cost me about $550+ back a few years ago, never used it.. I'd sell the kit for $250 shipped & it comes w/ corvette parking brake shoes & I'll throw in some braided brake lines. Just add your C5/C6 rotors, abutment brackets (C5/C6 specific) & calipers (C5/C6 used the same).

as someone mentioned, with th right offsets, the zr2 rear end width can be good for you without shortening.
that was my original plan, already had the zr2 rear end before i parted out. i believe my math added up to being with the c5z06 wheels and zr2 axle I'd have to pull the bedsides a touch, but within reasonable range. perhaps some cutting and a nice aftermarket flare would be enough as well, although that is expensiver than just pulling a bedside.

More so long open tracks opposed to tight autocross courses. Slipping cannot happen though.

what do you mean by slipping cant happen? for drifting i believe a lot of guys love spools. for track duty i'm a big fan of the salisbury type diff, ran a salisbury in all of my racecars, and the rx7 has one too. i do not know the options for a 8.5, but not a big fan of lockers or torsens on a track.

Just throwing this out there:

Have you considered the Ford 8.8? Exploders had them with 31 spline axles, clutch-type posi and disc brakes. 3.73 ratio was pretty common, too. They're ~5" wider, with an offset diff, though. Cut the tube, slide in a short-side axleshaft and it ends up 2" wider than a stock 2WD S-series axle.

I have considered the 8.8, but with a different bolt pattern and offset carrier, i'd rather go 8.5 or ford 9". I'll be running my 17x8 +0's for now, then buying 18x9.5's or 9.5/8 stagger when I have the money.

I looked on summit and the only "posi-traction" carriers were Yukon and Auburn units. Here's a link to the search results. Most would require the bearing swap to run an 8.6 carrier in the 8.5 housing
http://www.summitracing.com/search/year/1995/make/gmc/model/sonoma/department/drivetrain/section/differential-rear-end-components/part-type/differential-carriers/axle-model/gm-8-5-in

GM 12bolt is also another option, my buddy with a 71 c10 is looking to buy a rolling chassis to swap his truck over to, so I could buy the rear end from it since he has a built one in his truck now.

I've been relatively happy with the F-body Torsen in my 7.5" but I'm not running big power.  A lot of the mustang and F-body guys that track their cars run the T2-R and it seems to have a good reputation.  They only make a T-2 version for the 8.6 though

http://s300909324.e-shop.info/shop/article_975420-0840F/GM-8.6%22-30T-T-2.html?sessid=VAuOeAMpoZpQKlQjdW4OQ8awDQsi9M8c2i6CHkXO7H5DbvVMU7CRUo5Dk1JIigru&shop_param=cid%3D1%26aid%3D975420-0840F%26 

I've seen a few guys try to run spools or welded diffs at auto-X and they're garbage.  You just can't get the car to turn unless you break the rear loose.

yea i can imagine how horrible it would be to autox or even open track a spooled truck.

I've had my eye on the Detroit Truetrac from Eaton due to some recommendations from close friends.  Just another option haha.

for the hell of it-

Two door convertible Blazer would look pretty cool....

I've had my eye on the Detroit Truetrac from Eaton due to some recommendations from close friends.  Just another option haha.

truetrac is a torsen system, which is a great option in the reliability department. no clutches to wear out.
I find them inferior to salisburys because torsens are displacement based torque transfer, and hence have a slower reaction time than a torque based setup like the salisburys.

Got it.  I haven't really done any research on lockers other than reading what is brought up in random threads and experiences close friends have had.  I'll probably go with the Truetrac myslef since I like the idea of no clutches even if it is a bit slower.