What are our options?
When am I making too much power for the 8" to handle?
What are the correct widths for the different years of classic Mustangs?
What is the best 9" for my application?
What about this 8.8 rear end that the latemodel guys are having such good results with?

These are some of the questions we hope to answer with this FAQ.

My first thought is that if you don't want to replace your entire 8" rear axle housing, but are making some serious power, Currie has recently come out with this product: Currie Alumin8

 

For those with a small-block and a C4, your rear gear is almost always a 2.80

The easiest / least expensive way to get a better ratio is to find a V8 Maverick or Mustang II 8" chunk in a junqueyard....3.55s are mucho common and will run ~$100-125. There were lots of 3.40s also. The chunks swap out in about 45 mins, quicker if you've had a lot of practice

The downside is that most of the MAV/MII chunks are open. There are some Maverick/Mustang II Limited-Slip Differentials (LSD) chunks out there, but aren't easy to find. However, for a street car an open chunk works fine, and its about the cheapest/easiest way to go.... B)
________
California medical marijuana

 

Here are answers to alot of the questions. I've had this site bookmarked for sometime.

http://www.kevinstang.com/Ninecase.htm

There are links on the bottom of this article that show widths of different applications as well.

 

Some more "rearend links"...

How to tell an 8" from a 9"

The following are all "geared" :bang: (pun intended ) toward the Versailles rear, but there's good info on rebuilding ANY rearend in them...
http://home.earthlink.net/~hetclub/disc/brakes.htm
http://home.comcast.net/~bossbill302/rearaxle/
http://www.stuart.iit.edu/students/2112/re...restoration.htm
http://www.mustangsplus.com/tech/versaill/index.htm
http://www.smcrinc.org/disc_brake_tech_article.htm
http://www.ultrastang.com/Ultrainfo.asp?Page_ID=4
http://www.geocities.com/cping3/vers...rtnumbers.html

 

 

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Care to expound on that smilie?

 

can I run an 8.8? would be nice to swap in an axle that already had disc brakes

 

Well don't just beat around the bush.......

You CAN but it's a little too wide for the 65/66 body PLUS you'll have to weld on some leaf spring mounts.

 

My machanic just happen to have a 9" with 3.55 laying around his shop..I am gunna switch my 8" out..
What difference will i feel as far at power or torque.. Any? :notnice:

 

Depends on what gears you have in there now.

 

I got the bottoum of the barrel low stock rear 8"

 

and the gear ratio would be?........

They had more than one.

 

3:00.1

 

3.00:1 oops i think thats it thats what the vin says

 

Then YES you will notice a considerable difference in low end grunt and decreased fuel mileage.

 

OK so is that a bad thing, will i get more torque to the rear wheels, i am very green to this

 

You will not get more there because you aren't changing your engine or transmission but it will create the feeling of more because you have lowered your final drive ratio.

Cloney is better at explaining the technical aspect than me, I bet.

 

do you happen to know the difference in WMS? 57 1/4"?

 

"95 and newer had 31 spline & disk brakes. This is a great axle to use and you can find it very easily, plus the disc brakes are a nice mod in and of themselves. '96 and newer have 4.10 gearing available"

59 3/4" WMS on the 8.8

then I can run my Magnum 500's

but then I could fit newer Bullit wheels

 

Be aware that the 9" weighs more than the 8", so if you don't make that much power (say less than 300), don't drag race and only need a common ratio (3.25, 3.40, 3.50, 3.55, 3.80 or 4.11), consider sticking with an 8" if you already have one.
Try to find a stronger C7 or later casting third member with the extra ribbing if you currently have a 66 or earlier casting 8". Also, some of the rebuilt "posi" rears (not trac-locs) that are retrofits are more durable with steel clutches instead of the fiber ones. And, if you can find a 4-pinion spider instead of the stock 2-pinion it will be stonger as well.
Daniel