Classic Mustang Rear End Questions...What's best for a 350-450hp application???

[edgars23]

Hey guys, I am new to the forum here and am hoping that I can find some answers. I own a 1968 Mustang with a 289 (actually 306 cubic inches now) that has been warmed up pretty nicely. I am not sure how much HP i am making...but i estimate a rough 350 hp's. The reason why I estimate that is that I ran against my friend's 01 Mustang Cobra (423 HP modded) and was able to keep up with him. Regardless, I may one day in the future step up to a Paxton Supercharger and try to hit the 450 hp range. If i do that...the stock 8" rear axle which I have now will not hold up. So here is my question:

What is the best way for me to go around and build a rear end for my car? Should i stick with the 8" and build it up with a Currie Alumin8, auburn diff and 3.90's? Upgrade to a 9" and build it up in a similar fashion? or do something wild and go with an 8.8" rear end? Which do you guys think would work best, why, and in the same breath how difficult would a swap with a 9" or 8.8" be? Any help is appreciated with this topic.

[danny]

welcome to the forum, have you checked with currie enterprises?

[69maverick]

The 8" will hold up! but you will want to put a posi unit in it or a spool . Now heres the thing,It will cost you more to build the 8" than it will for a 9" The 9" parts are a whole lot easier to find and the costs are lower. If the cost is not an issue then go with the Currie or a Strange If you are going to be doing some high RPM launches you will want the better rear. A Mustang 9" should be pretty easy to find.

[edgars23]

Hey guys, thanks for the replies. I did check with currie enterprises and they said that 350hp is the max a 8" live axle with their alumin8 diff cover and a auburn posi would be able to hold. I have also been keeping an eye out for 9" on ebay, somoe good deals out there. I do plan on taking it to the track a few times out of the year, other than that, just weekend cruises around L.A. and the coast. Any recommendations on a 9" build up? Also, to your knowledge, has anyone ever done a 8.8" install on a classic? I know the 8.8's are just as storng and in some cases more versitle than a 9".
-Edgar

[Racerock]

Like your thinking. On the right track.

Do you have Posi now? If so, you might just live with what you have until you take the plunge and put a blower on, or it breaks.

On the 8.8, there was a recent article (now where is that thing). Can't remember if it had a source that mods the axle, etc. But, you are right that the 8.8, is becoming a good standard, as it is pretty strong, and can be built up. The other benefit is that the power loss through it is much lower than the 9". I'd have to look at the width specs, but in my mind, it seems with a little bit of cutting and welding, and you'd be good to go, and get a rear disc setup while you are at it.

[danny]

didn't the baby lincolns use the 8.8 with disc setup?

[KA9MOT]

Originally Posted by danny

didn't the baby lincolns use the 8.8 with disc setup?

9 inch with discs and a very popular swap item. Also, what I would do if I had a nice Mustang to put it in. I wonder if I can get one to fit my B2?

I had forgotten about this set-up.

[KA9MOT]

Originally Posted by Racerock

Like your thinking. On the right track.

Do you have Posi now? If so, you might just live with what you have until you take the plunge and put a blower on, or it breaks.

On the 8.8, there was a recent article (now where is that thing). Can't remember if it had a source that mods the axle, etc. But, you are right that the 8.8, is becoming a good standard, as it is pretty strong, and can be built up. The other benefit is that the power loss through it is much lower than the 9". I'd have to look at the width specs, but in my mind, it seems with a little bit of cutting and welding, and you'd be good to go, and get a rear disc setup while you are at it.

Posi is GM's brand name for their early limited slip differential.

Posi is also mistakenly used for lockers, limited slip (other brands) and spools. I've even seen welded spiders (Lincoln lockers) called Posi.

While we know Ford never had a POSI, what we don't know is if this diff is open, has a limited slip (Trak Lock for Fords) or is locked by any of the various methods.

Otherwise good info Racerock.

[danny]

my brother uses lincoln lockers all the time-he goes through a lot of parts-he is a ford guy

[KA9MOT]

Originally Posted by danny

my brother uses lincoln lockers all the time-he goes through a lot of parts-he is a ford guy

Lincoln lockers break lots of parts regardless of brand......

[danny]

Originally Posted by Beefy's Bronco

Lincoln lockers break lots of parts regardless of brand......

you're telling me, he won't listen though. he seems to think that this is cheaper than the real deal

[KA9MOT]

Originally Posted by danny

you're telling me, he won't listen though. he seems to think that this is cheaper than the real deal

Wait until he breaks something very expensive, like his transfer case. We know that is rare but it does happen.

[danny]

Originally Posted by Beefy's Bronco

Wait until he breaks something very expensive, like his transfer case. We know that is rare but it does happen.

he doesn't lincoln the 4x4 he does the job right there, it's his mustang he lincolns

[Daniel Wood]

I would tell Currie what kind of hp I had or going to have, what transmission I was going to use, and what I was going to be doing with the car. And let them build you a 9 inch that will take the punishment you plan on giving it. And I would go with the disk brake setup also.

Just depends on how much money you're able to spend.

Do you have any pictures?

[edgars23]

thatnks for all the input. I will research the 8.8 swap some more, but for now, it looks like a 9" upgrade is what is needed. I am running a T-5 conversion and plan on going with 3.90's (or 3.89's, whatever will fit the chosen rearend) and I've heard some good things about the auburn limited slip. I really want to build it myself, so that I may learn and gain experience, which would mean that currie is out of the question. my budget is tight, especially because I am getting married in June, so I gotta do what I can afford. Thanks for all the interest in this thread and I will post the few pics that I have about my 68 when I get a chance.
-Edgar