65' Mustang 8" to 9" swap questions
 

Hi there, I'm relatively new to the forums, but have been looking at them for a year or two. Anyways, I have a question that some may help me with.

I am going to a custom built 9" with 4.11's. I have every down that I need to do, minus one fact that is bugging me.

I am confused on the u-joints. Can I use the stock sized 8" joints for now? I believe I have the 1310 U-Joint in there currently, but have heard that the 1330 U-Joints is stronger?

To switch u-joints do I have to change the driveshaft or anything else?

Any help is appreciated.

Thanks

The pinion on the 9" rear uses 1330 joints, your trans probably has 1310. If you want to keep your driveline you can replace the u joint at the diff with a 1310-1330 cross over joint, you can get them from a driveline shop.

not always. my ford racing pumpkin uses 1310 on the yoke.
to determine to seee what u-joint you'll need you'll just have to measure the size of the new yoke in pumpkin. That is the distance betweeen the two tabs the joint sits in and the diameter of the cup that fits in there.
unfortunately the 1310 comes in 2 sizes.
1-1/8" cup dia and 1-1/16" cup dia. but both are about 3.25" long over the axis

i converted a 6banger rear to a 9" and by the time I had it all together i learned a lot about u-joints and sizes. in any case the 1330 will be stronger, but you can only mount it if the driveshaft and yoke are sized for it.
so measure the yoke in the 3rd memeber for what u-joint should go in there. if it's a new one the manufacturer can tell ya. if it's 1310 size the u-joint you had will usually fit. if you want to upgrade to 1330, you might have to change driveshaft (and yoke)

I'll have to check the center section when it arrives next week. I just had the driveshaft built last year when I put the t-5 in the car, so it is still basically new.

The yoke on the carrier is supposed to be a new Ford Racing part, so I'll just ahve to wait and measure.

Thanks for the help.

You won't have to change the driveshaft, that's what crossover u joints are for, they're one size one way and a different size the other way.

65-66 8" and 9" used the same U joints.