ajb4507

I am building a 1989 mustang with a 460 big block. I have heard that a
stock 8.8 posi out of a GT will not stand up to the torque of the 460.
Is this true? Should i use a 9" instead, if so what 9" would fit into
a fox mustang?

big1

Both "Rear's" have real strength. What sort of driving do you intent? Will you be drag racing this car?
If the car is mainly for street use and your using an automatic transmission the 8.8 should do the job, but if you intent to drag race or your using a manual transmission (and want to "bang'm") I wouls suggest the 9in.
I don't know of any 9in. that's a direct bolt in, but having one narrowed and set up for the proper spring perch's would diffently be worth the expense.

__________________
When in doubt :DON'T
Valley Station, Kentucky
Dream EXPression Racing
http://fordexp.freehomepage.com/photo3.html

reel_story

I had a 460 in a 1979 mustang. I put an newer posi 8.8 rear end in the car and it hanlded it fine. The motor was not built to radical but still had huge torque for a mustang. In my opinion if you are going to use somewhat stock size tires and not drag race the 8.8 will do just fine. It won't matter if you have 1000hp up front if you only have stock tires that are spinning when you launch you will be putting the same torque on the rear-end as you did when you used that 200hp 302 to spin those tires with before.

The big downfall to my mustang with the bigblock was getting the front suspension set up right for street use. It is really heavy in the front and I had a hard time getting it to feel stable in corners even at normal speeds. That is a lot of weight up front in those cars. Good Luck!!

ajb4507

hey thanks for all the info, The engine is out of a 73 Thunderbird and i plan on running it on the street with a mild cam and a new intake and a set of heads off of a 68 Lincoln 460 with new Manley 1.76 exhaust and 2.19 intake valves. what did you do for the suspension up front?

reel_story

I had purchased a saleen suspension kit for mine thinking the lowering and stiffer than stock springs for corning would be enough to offset some of the extra weight but in my opinion it was not enough.

If I did it over again I would possibly look at the springs out of that '73 thunderbird and see how much different they are in length and stiffness compared to your stock mustang springs.

ajb4507

yea sounds like a good idea. Back to the 8.8 would a stock rear including the stock differential and axles be able to take the torque of a 460 (I'm hoping around 500 to 550 ) or should i upgrade to a 31 spline set?

reel_story

Again in my opinion the 8.8" will be fine unless you plan on drag racing and/or putting wide sticky tires on it.