With every project i start, i do extensive researh befoe it begins. I would just like to share the information i have learned so far on this build. With the prices of direct replacement rearend at close to $2500 without breaks, I am trying an alternative solution. Alot of people say that a DR rearend is the way to go, but hotrodders and chassis builders have been fabricating rearends for cars for many years. This is will be a guide on the build as it goes along and any problems i may encounter.

How to ID a ford 9in
The ford 9 in and 8 in are almost identical to the untrained eye. The easiest way to tell if it is truly a 9in is you will not be able to use a socket to remove the two bottom left nuts that hold the third member in the housing.


Information about the Ford 9in.
- there are 3 different types of OEM axles 28 tapered spline, 28 solid spline (newer style) and 31 spline. This is important bc the 28 tapered spline cant be narrowed if one wishes to narrow the rearend and reuse the axles.
- There are 2 types of third member cases. One is made of cast iron. (WAR stamped on the third member for ID purposes) The other Nodular Iron. (identifided by the N stamped on the third member) Nodular iron is the stronger of the two.
- There are three different flange types. small ford, big ford, and big ford new style. This is important if one is trying to go from a 28 to 31 splines axle. The 31 spline axle is thicker then the 28 spline thus requiring a larger diameter flange/bearing.
- The ford 9 in was produced from 1965-1986 and has been in every thing from the mustang to vans. Lengths vary from 67.25-57.25 in.
- The ford 9 in came from the factory with both an open and posi differenteal. Both can be identified by the code tag attached to the third member. Its on the bottom of the tag (Example 3L50 this is a 3.50:1 geared posi third member) if there is no L in between the numbers its and open differental.

Farther reading:
http://dfwmotorsport.com/Fairlane/9inchrearends.htm
http://www.kevinstang.com/Ninecase.htm

Here is the plan i bought a 28 solid spline third member and housing from my local junk yard. I chose a big ford new style flange bc i want to change to a 31 spline axle. Housing lenght comes in at just under 60 in. This is ok bc im going to have to buy new axles bc im narrowing the rearend to fit my rs and going to a differnt spline count. Im going to use the stock torque arms, LCA, and panhard bar set up. Car is going to be a street strip with a 385 and th400 it is going to raced in a stock suspension 10.5w drag radial class.
I will get the gear ratio and differental type tomorrow of the 9in i got from the junk yard bc im going to try to rebuild the third member.
Feel free to add any information.


Stay tuned for pics
$ spent so far
$100 for housing 3rd member and 1 useless 28 spline axle from local junk yard
$3 for sand blasting and painting. (I have my own sandblaster)
$350 price "quoted" for narrowing, welding brakets from 10 bolt and fabbing a torque arm mount from the local chassis fabrication and hotrod shop.

 

hey whatever happened to this thread i start measuring mine up tonight and was curious how yours went?

 

Since the Versailles, no cars have used the 9", only F150 pickups and e150 vans. You can't use the truck / van versions, the axle tubes are too thick and too heavy. I believe the station-wagon versions of the big cars are the same. The Versailles version seems appealing for the rear disc brakes, and for being occasionally find-able in the salvage yards, but they're more hassle than blessing. The desirable versions are too covered and too scarce. As such, invest in an aftermarket deal, or forget the 9" entirely. The 8.8 is stronger, far more readily available than the old 9", and far cheaper than a comparable 12-bolt.