hi guys, a little question concerning a posi rear end.

i've got a stock 2.75:1 9" rear end on my 69, and i wanted to upgrade it to a 3.89:1.
is it possible to change from a normal diff to a posi gear and what exactly does that involve?

i assume the entire planetary system needs to be changed apart from the ring and pinion gear, but any info about this would be more then welcome.

thx in advance

 

I haven't done that, so I am certainly no expert regarding changing the gears from what you have to a posi rear with new gears. However, If it were mine, I think I would look around for something like a 9" 31 spline Detroit locker in a junk yard. That, in my estimation, would be the easiest way to get what you want instead of tearing into your current rear and replacing everything. But, this may be the second time I have been wrong today. The first was getting out of bed and going to work.

 

There are a few companies that make aftermarket POSIs that are realtively easy to put in. Changing the gears is much harder. You would probably be better off finding a complete pumpkin to swap in with the gears you want.

The biggest thing is make sure you know how many splines you have on your axles before you start.

 

mmmmkay,

i see what you guys mean by trying to find an axle that's already posi from the git-go in a junk yard, but down here in belgium the only thing you find ford-wise in a junkyard are fiesta's, mondeo's and escorts, all front wheel drive 1600cc jobbies.

i know, i was born in the wrong country to have this hobby...

but, i saw that richmond gears makes posi kits for 9" fords, and if you say they're relatively easy to install i'll have a closer look at those...

btw soaring, i got a holiday today hehe[8D].

thx guys

 

Find a local tranny and rear guru to assemble for you. It is not for the first time do it yourselfer. You can buy all the parts in catalogues or even a completed pumpkin, but shipping that would be $$$. Even a junkyard dog may have problems requiring repair by said guru...

 

thx 69, that's indeed the way i'll go. i'm just gonna order the stuff from summit or mark williams, or maybe NPD, but i'll install it together with a friend who's got some more experience in rear ends...

thx for the info guys.