Difference between drive shaft flange to IRS vs SRA spacer

[May93]

I know this is an old thread but it’s exactly the same issue I'm dealing with currently. I have a 2001 Bullitt with the 3650 transmission and a 2004 rear IRS. The differential flange is also the 2004 setup. Original driveshaft was too long and now the aluminum driveshaft is too short. It will work but I don’t like the 2 inch gap. Has anyone made a 1 inch spacer yet for these things? I also noticed a different yoke being offered but didn’t see a part # listed. Any help is appreciated. Thanks!

 

[cool hand]

From all of the reading I've done you want 3/4" to 1-1/4" play with the yoke buried in the transmission. I have SRA in an 03 cobra that has roughly 1-3/4" play with the T56. I'm using the cobra flange and driveshaft to keep the bigger ujoints and getting a custom spacer made, I'm thinking 11/16".

I can post cobra flange and ujoint adaptor part #s next week.

 

[May93]

From all of the reading I've done you want 3/4" to 1-1/4" play with the yoke buried in the transmission. I have SRA in an 03 cobra that has roughly 1-3/4" play with the T56. I'm using the cobra flange and driveshaft to keep the bigger ujoints and getting a custom spacer made, I'm thinking 11/16".

I can post cobra flange and ujoint adaptor part #s next week.

I think your picking up some extra length with the T56 transmission. The aluminum driveshaft has the 04 IRS flange and the yoke I changed over to the factory 3650 spline. The original yoke on the aluminum driveshaft was shorter and made for the T56 transmission.

 

[May93]

I made a 1 inch spacer out of mild steel but damn is it heavy. I'm a little concerned the extra weight will add unwanted load on the pinion bearing. Thinking maybe a spacer made out of aluminum would be best.

 

[04Mach1Blurr]

Spacer out of aluminum would be better, but more expensive. you can run the steel one, I would just have it balanced at a shop (driveshaft and spacer). I just used a tr3650 aluminum driveshaft with my 3650 and 04 cobra diff. Just swapped out the pinion flange for the tr3650 one.

However I just snapped 3rd gear bad, so I think I'm going to just bite the bullet and buy a built t56 swap and swap the rear pinion flange back out for the cobra one (spare 03 IRS diff in the garage)

 

[cool hand]

Here is what I had made by a fellow terminator owner. I suspect he make more if there is demand. PM me if interested.

 

[May93]

Spacer out of aluminum would be better, but more expensive. you can run the steel one, I would just have it balanced at a shop (driveshaft and spacer). I just used a tr3650 aluminum driveshaft with my 3650 and 04 cobra diff. Just swapped out the pinion flange for the tr3650 one.

However I just snapped 3rd gear bad, so I think I'm going to just bite the bullet and buy a built t56 swap and swap the rear pinion flange back out for the cobra one (spare 03 IRS diff in the garage)

I made it myself on a CNC lathe and mill so the balancing should be no issue. The cost of aluminum wouldn't be much more then the mild steel other then the price for weight of material.