mooreperformance

iTrader: (3)

Alright guys I think I found a new alternative for a stronger rear. The 8.5" rear that came in 70-76 chevelle,GTO,F-85,Le Mans, 70-76 Camaro, 70-75 Nova, 77-81 Z-28/trans ams, are said to be just as strong as the 12 bolt. http://chevyhiperformance.com/techarticles/48518/
Since it came in so many vehicles the housings are available for really cheap. My local salvage yard is selling one for $150! Since all of these vehicles do not come with a torque arm bracket we run into the same problems with the Ford 8.8". Luckily I have a local shop that is reputable with welding cast iron. I would just cut the axle tubes from my 10 bolt and weld them on to this housing, and same with the ta bracket.
So Here's the plan. Housing $150, bearings $67.50, Moser custom 30 spline axles $315, Moser spool $190, summit aluminum cover $140, Gear install kit $90, 4.10 gears Richmond $172. Total comes to $1,124.50. Then I need to add $200 for gear and spool install, and welding labor for axle tubes and torque arm mount. So I'm thinking it's gonna run $1400 -$1500 for a stout and efficient rear end. What are some opinions?

ls2 bait

iTrader: (11)

alot of money and not knowing if its going to work...........but someone has to be the first so go for it. if it works u may have urself a loyal following.

mooreperformance

iTrader: (3)

Well that's the thing, I don't think any one has done it before so it would be unique. But I am a broke college student so I may just put 4.10 in the stocker and just be easy on the launch. I'm just kind of hoping billingsley or maybe driveline solutions would look into this and tell me what they think.

MeentSS02

iTrader: (11)

As long as someone reputable took interest in this project (like Billingsley, etc), it would be worthwhile. The F-body really does need a more budget-minded solution to combat the shortcomings of the 10-bolt.

If a big name doesn't come on board, however, I could see this turning into another 8.8" fiasco. And that is something that would NOT be tolerated again.

mooreperformance

iTrader: (3)

The 8.5" should as light as the 8.8" and as efficient if not more, still as strong as the 12 bolt and it would be keeping it gm. With custom axles made exciter rings should be able to be pressed on so abs could still be retained also. If some one would be interested in making this work, please post, or pm. I wouldn't mind being the first f-bod in the nation to do this.

TRex

iTrader: (3)

You will need a jig to assure the axle flanges, tubes, and TA mount are aligned properly, no small feat.

Also, you might want to look at the differential availability. One of the reasons to go 8.8 is the readily available selection of differentials. 8.8's have stock posi's available with 31 spline diffs, don't know about the 8.75 ten bolts.

Third, I don't see any advantage over an 8.8, which requires basically the same amount of fabrication work and is a proven strong drivetrain for strip use.

mooreperformance

iTrader: (3)

The advantage is keeping it all gm, and is as more available (at least locally). There are plenty availabilty of parts for the 8.5" just look in a summit catalog, that's where I got most of the price quotes. The main reason why I brought this up is because no one has done this before and I personally wouldn't mind another gm alternative to upgrading the drive train.

MeentSS02

iTrader: (11)

"Keeping it all GM" is not that great of a reason...the Ford 9" design is one of the best out there. When you start modding these cars to the point that it needs a new rear end, keeping it GM should probably be the last thing on your mind.

ls2 bait

iTrader: (11)

ive been thinking of the ten bolt like that in the gn's. its a 8.5 unit and obviously can take some serious abuse. before u go saying of they are autos, ya and a lot of them have trans brakes.

Sandmann120

iTrader: (1)

The 8.5s are known for being very stout. THey have been used in everything from second-gen F-bodies, SS Impalas, half-ton trucks, and the list goes on. The availabilty is great, and there are lot's of hop-up parts out there as well.

I may have to talk to my local chassis guy about setting one of these up. I'll keep you guys posted.

SPANKY LS1

iTrader: (24)

In my opinion, the whole reason to upgrade rearends is for piece of mind, yet I'd always worry about a hodge-podge welded up, pieced together rearend like an 8.5 or 8.8. Do a 9", do it once, do it right. As far as the "8.8s are strong, plenty of 8 second Mustangs running them", and "8.5s are stout, plenty of fast GNs running them" guys, I'm not doubing the strength of the rearend internally, I'm doubting the structural integrity of the welded up, pieced together housing. Ever wonder why the 8.8 didn't take off when people started retrofiting them a few years ago? Because the housings were failing repeatedly. For that kind of money ($1400-$1500) you could do a STOUT 9" for that same money, that has been proven time and time again in our cars. Just my .02

Shawn

MeentSS02

iTrader: (11)

Yeah...simply welding **** together and calling it a stout rear end simply because of an 8.5" measurement ain't gonna cut it. Quality control would be a MAJOR concern if these were to be mass produced. The 8.8s were failing quite a bit due to some questionable welding/design. I wish people wouldn't think this is some trivial matter...

mooreperformance

iTrader: (3)

I realize the risks of chopping up and fabbing one up are, that's why I am not doing it myself but am hoping that the people fabbing the 12 bolts and 9" for us will take this idea into consideration. btw the ford 9" may be the strongest but a bit overkill for many of us. Plus it's very heavy and has the most drive train loss, otherwise I would have a 9" already.

TRex

iTrader: (3)

The 9" is a welded steel housing, so the welding doesn't need post weld heat treatment and can be mig welded easily. Nodular Iron needs post weld heat treatment and is best welded using stick welding (which is less efficient).

The 12 bolt housings being fabbed by Strange and Moser are specific castings, so they are easier to mass produce.

BTW, you might want to look at the relationship of the 8.5 tube id to the 7.5 tube od. That is what makes the 8.8 so attractive, the 7.5 tube fits in the 8.8 tube with very little clearance, making the welding process easier.

A fabbed 8.5 would not be any cheaper than an aftermarket 12 bolt or 9". The fab work is labor intensive, and unless someone made a pumpkin casting with the torque arm mount cast in it will not be as cheap as an aftermarket cast 12 bolt.

The cheapest way to get an aftermarket rear is to get the housing from the shops and then fill it with stock or used internals. The only reason to do the 8.8 or 8.75 would be for lighter weight and greater efficiency, and they are not going to be a lick cheaper.

mooreperformance

iTrader: (3)

Have the issues with the t/a mount been resolved with 8.8"?

MeentSS02

iTrader: (11)

I think with enough welding they were, but the whole 8.8" thing kinda fell through...

ls2 bait

iTrader: (11)

according to the guy who builds them he is on his 5th design with the now and he had resolved the welding issues. apparently hes welding them a diff way and using more bracing. hes also sliding the axle tubes into the 8.8 chunck instead of butting them togather.

Wnts2Go10O

iTrader: (12)

8.5's are ALSO in the GN, GNX, and Regal T-types. theres are a few out there runnin 10's-9's with these rears..

SPANKY LS1

iTrader: (24)

Yeah, with cast mounting points, not with welded, rigged, jimmied mounts. The internals and overall strength of the rearend isn't the issue, its the housing, mainly the T/A mount.

91Z28

Another cheap source of 8.5" would be the 90's B bodies, not too old yet and plenty cheap and very available.