Rear-End Options?

[rebelgtp]

I'm definitely interested in what you do with that chevelle rear-end, rebel, and how much you end up spending.

Here is a link to where I talked to Shotgun about this setup viewtopic.php?f=14&t=14947 . He has been running this setup with the same rear in his black Cutty that is in his sig. The basic run down is get the rear that is 60 inches wide (or less) not the wider one so be careful with that. You will need to run a back space of about an inch more than normal on the rear (no worries for me I'll put 17x9 soft 8's on the rear). The ears on the pumpkin are at the wrong angle for a g body so you need a kit with spherical ends to allow movement of the rear with no binding. On the 12 bolt the spring perches are placed in front of the axle instead of the top, more than likely you will need to relocate those to have proper alignment of the springs. I bought my rear axle for $150 complete, build up of it will cost me less then building up the 7.5 that still would not be as strong as the 12.

 

[beermonkey9417]

well if you can find a good 8.5 housing for a g body on craigslist then order from strangeengineering.com for the innards.

 

[Chillin014]

Thanks for the info everyone. Now I am not really sure what to do...I was hoping there was a more defined path to take. Where is the weak link in the stock rear-ends? I usually fix things after they break but...this peg-leg, high gear ratio is driving me nuts.

 

[rebelgtp]

Thanks for the info everyone. Now I am not really sure what to do...I was hoping there was a more defined path to take. Where is the weak link in the stock rear-ends? I usually fix things after they break but...this peg-leg, high gear ratio is driving me nuts.

Think I mentioned it earlier but it might be buried in one of my posts. The weak spot in your 7.5 is the axles themselves. You can swap out the guts with a better gear ratio, find a good used F body posi from a 28 spline axle setup, get moser 28 spline axles meant for the GNX and you will have a much stronger rear. You still won't be up there with a good 9" or 12 bolt but maybe on par with an 8.5. Possibly could do the build up for for under $1k but if you need to buy an aftermarket posi then you are looking at over that mark.

 

[rebelgtp]

Oh if you are leaning to the 12 bolt UMI is having a sale right now of 15% off including the kit for putting the 12 bolt in a G body.

http://www.umiperformance.com/catalog/i ... ucts_id=77

 

[Bernhard]

The week spot in the 7.5 diff is also the ring gear it is just to small. G body cars are heavy 3500 to 3750 lb. And if you run slicks or street drag tires, and the car hooks. You will start to brake parts and you will be out any money you spent on the 7.5 diff. All g body owners have this cost if they drag race there cars or beat on them. Bernhard

 

[Doober]

If you're driving it on the street, it should be fine with a set of good 28-spline axles and a support cover... and unless you take it easy on it (no power/heavy shifts) that T5 is likely on borrowed time. If you plan on racing and making more power down the road, I'd upgrade both to heavier units.

 

[79loserbluebu]

The week spot in the 7.5 diff is also the ring gear it is just to small. G body cars are heavy 3500 to 3750 lb. And if you run slicks or street drag tires, and the car hooks. You will start to brake parts and you will be out any money you spent on the 7.5 diff. All g body owners have this cost if they drag race there cars or beat on them. Bernhard

The ring gear can easily be replaced though. I bought an 8.5" I found on CL or a forum in WI from an 87' 442 with 3.73 no posi for I think $350. It was a good good find however and didn't even expect it. But you can easily upgrade a 7.5" to handle it's own as long as you don't get silly with it.

My buddy at school has an 86" MCSS with a 383 stroker, TH400, and the stock 7.5" rear with an aftermarket differential and it's held up so far. He may have replaced the axles, but last I checked it was only $150 for both not including studs, so it couldn't hurt to replace them while you are down there as well as the seals and bears.

Zexel (now referred to as "Torsen") units found in 4th gen (98-02) Camaros are really nice as well. They came in 2 series and 3 series carriers and some with 3.73 stock. I've seen vehicles running in the 10's on the 10 bolt with that differential.

If you do decide to use the 10 bolt against all odds, make sure you fully weld the axle tubes to the differential housing. From the factory they were spot welded in two places, and it gets very weak the more and more stress you put on it.

 

[Chillin014]

Well regardless of whether I get a different axle or try to upgrade the current one, I need to change the gear ratio. Aftermarket differentials are almost 500, then I have to get ring/pinion, axles, etc etc. That just doesnt sound like a wise investment for me. I think I'm going to try to find one of the larger chevy rear-ends. :?

and just as I said that I found this ad.
http://houston.craigslist.org/pts/1607816327.html

Except I wouldnt want 4.11 gears and I'm not sure what other gear options are available for that differential. Is there any reason I couldnt use 28 spline axles if thats what my differential required?

 

[Doober]

You could use 26-spline, they're just not as strong as 28. If that posi unit is a gov-lock unit, pass, they're no good for performance applications. The other thing is you can get brand new axles for less than $25 more, regardless if they're 26- or 28-spline. Since you don't want 4.10 the only thing I'd look at from that ad is the posi, and I'd even pass on that unless it was rebuilt with really good parts... because...
http://cgi.ebay.com/ebaymotors/CHEVY-GM ... ccessories

In the time it took me to write this post I just found you a set of new 28-spline axles & 'new' 7.5" 28-spline posi for roughly the same price. Add an aftermarket support cover (they start around $150 I think) and you'll have pretty much everything you need to strengthen a 7.5" (granted you still need gears).

Good luck whatever you do 😉