Few questions about my 9"

[Dragonacc]

Ok, so my project 70 Mach 1 should be putting out around 450-475 hp, and I'm going to run it through a TKO 600 (Yes, it's pretty much overkill). What I'm not real sure about is the rear end. The rear is original to the car, standard ratio 9" inch, no posi or anything. I've pretty much decided to go with a 3.75 or up ratio and a DPI Black Gold differential, but my question is, what about the rest of the rear end? Will the stock axles handle the power or do I need to upgrade them? I don't really know much about rear ends, but I know the differential comes in 28 or 31 spline...what does that mean? And which should I use with the power I'll be putting down and the stock axles if they'll handle it?

Ok, not sure if any of that made a whole lot of sense but thanks for any help you can offer anyway.

Adam

 

[Ronstang]

If you are buying a new differential then considering your power levels a step up to 31 spline axles would be a logical step in my book. The 31 spline axles are larger in diameter than 28 spline and thus harder to break. There are also 35 and 40 spline axles but they are overkill.

 

[SadbutTrue]

If you are replacing the third member, might as well get some axles with it. Theres a chance your stock unit, with a rebuild, could work. But like I said... if you're going to replace it, might as well go with some 31 spliners...

 

[Dragonacc]

So anyone know a reputable place down south, in Georgia if possible, that I could send the rear off to? Also, how much am I going to be looking at spending? The differential is $650, no idea how much the gears will be or anything else for that matter..

 

[HistoricMustang]

The 28 spline will work fine unless you do the 1/4 mile events. I have used a 28 spline for almost 10 years road racing without the first problem (one rebuild of clutches).

HistoricMustang
www.historicmustang.com

 

[Dragonacc]

Well, that's part of the reason I'm going with the DPI black gold, there aren't any clutches to rebuild. But either way, I will be hitting the strip, but not too often, and probably won't be doing anything with slicks. Probably won't be launching over 2500 RPM or anything either. I'm really only looking to run somewhere in the 12s so will the 28 splines hold up?

 

[steel1212]

I know historic is budget minded, a good thing in my book, but to me if your wanting to upgrade a stock 9 with a 650$ diff why not pony up another 250$ I think and get some 31 splined axels and rebuild all the guts why your at it? Then sell your 9 inch chunck and find another 31 spline chunk out of truck or something as a spare

 

[HistoricMustang]

Dragonacc, how far are you from Augusta? I had mine rebuilt at "Augusta Transmision Clinic" - they do good work.

HistoricMustang
www.historicmustang.com