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-   -   Change Ford 9" - 28 spline to 31 spline (

fredbaker 09-27-2009 01:52 PM

Change Ford 9" - 28 spline to 31 spline
I apologize if this has been answered before but could not find it. Can a Ford 9" posi-trac carrier with 28 spline be changed to 31 spline ? If so, what is needed ? I have a chance to buy a 4.11 posi-loc with 28 splines and would like to upgrade to 31 splines. :confused:

SDLuck 09-27-2009 02:24 PM

Change the spider gears to the other splines,I believe thats all thats required,if you can fine the correct axles.

302 Z28 09-27-2009 03:03 PM

Why do you feel it is that important to have a 31 spline? Yes they are marginally stronger, but do you have the HP to take advantage of it?


enjenjo 09-27-2009 03:03 PM

There are some small bearing posi carriers out there. These can't be changed to 31 spline. There are also some big bearing carriers that are not bored large enough for 31 spline axles, but they can be bored out to fit.

35pontiaccoupe 09-27-2009 04:06 PM

I personally would avoid trying to make something work that wasn't designed that way. I have tried too many times only to buy the more expensive thing that I should have bought the first time.. Just wait for a 31 spline posi to come around and then you won't have to worry about a swap working or not. You shouldn't need a new ring and pinion Unless you're wanting to change the ratio anyways..

eloc431962 09-27-2009 04:12 PM

I agree with Vince on this, Leave it alone unless you have excessive amount of HP and are going to be on the track fairly regular, Other then that the 28 spline will do anything else just fine.JMO..Cole

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