TF 727 Push-button Output Hub Converting to U-Joints

[Torqueflite]

The issue I'm having is the 1964 push-button 727's fixed output flange yoke, which I picture below. I'm converting to a slip-yoke drive shaft that will require a flange yoke to bolt to the output flange. The bolt circle is 3.25", and the inside of the lip around the perimeter that creates a well where the factory ball-and-trunnion flange sat is 3.94" diameter. Since these transmissions never came with a slip-yoke driveshaft, I'm stuck piecing something togeter. I've looked through both Spicer, Neapco, and Moog catalogs and find only one option with close to 3.25" bolt circle and just over 4" outside circle that can be sanded down.

Spicer 2-2-1769
-1310 series
-3.20" bolt circle
-4.016" outside circle
The issue is that this flange appears to have been discontinued a while ago since I cannot find it anywhere online new or used, and I called different suppliers without luck.

I prefer to run a 1350 u-joint, but there is only one with a 3.25" bolt circle that is both way too big in outside circle and also discountinued and out of stock everywhere I checked:

Spicer 3-2-189
-1350 series
-3.25" bolt circle
-4.5" outside circle

With the 4.5" outside circle I'd have to mill off the lip around the 727's flange and rely on the bolts to keep the flange yoke centered/captured, which I think is a bad idea since it could walk around under high torque situations. I might be able to save some of the lip that doesn't interfere on the narrow sides to help lock in the flange, but I doubt there will be much lip left. There isn't a pilot on the 727 flange.

How have others with 450 torque + engines running earlier fixed output flange 727s with a u-joint driveshaft dealt with the output flange to driveshaft front flange configuration? The easiest way and the only way to capture the front driveshaft yoke flange with the 727's flange, but the part appears unobtainable unless I luck out and one pops up on ebay.

I appreciate the feedback.

 

[Professor Fate]

So, what's wrong with simply turning down the 3-2-189's outside diameter to 3.94? Then you have it correctly centered in the output flange, you have the correct 3.25 bolt circle, and you have your preferred 1350 u-joints. Done deal.
I would NOT mill the lip off the drive flange and rely on the studs to center your driveshaft, unless you enjoy "mystery vibrations".
Early Valiant Barracuda Club - ball and trunion U-joint conversion

 

[Torqueflite]

So, what's wrong with simply turning down the 3-2-189's outside diameter to 3.94? Then you have it correctly centered in the output flange, you have the correct 3.25 bolt circle, and you have your preferred 1350 u-joints. Done deal.
I would NOT mill the lip off the drive flange and rely on the studs to center your driveshaft, unless you enjoy "mystery vibrations".
Early Valiant Barracuda Club - ball and trunion U-joint conversion

Unfortunately, last year I saw the link you posted, but it has two issues in that it either has incorrect information or is for a smaller output flange. The yoke flange 2-2-349 that article lists has a bolt circle of 2.875" and an outside circle of 3.625, both far off the 727 output flanges I have of 3.25" and 3.94". It wouldn't bolt to the output flange, and if it did it would be able to walk around on the flange.

As for turning down the 3-2-189 from 4.5" to 3.94", the towers would be undercut by approx. 1/4" at the base, which may or may not be a structural problem. The machining would introduce a sharp 90° stress riser where the towers meet the base that could be a weak point. I guess I wouldn't know until it popped.

 

[Inertia]

Keep in mind we ran those transmissions/couplers behind Max Wedges .

 

[446acuda]

The issue I'm having is the 1964 push-button 727's fixed output flange yoke, which I picture below. I'm converting to a slip-yoke drive shaft that will require a flange yoke to bolt to the output flange. The bolt circle is 3.25", and the inside of the lip around the perimeter that creates a well where the factory ball-and-trunnion flange sat is 3.94" diameter. Since these transmissions never came with a slip-yoke driveshaft, I'm stuck piecing something togeter. I've looked through both Spicer, Neapco, and Moog catalogs and find only one option with close to 3.25" bolt circle and just over 4" outside circle that can be sanded down.

Spicer 2-2-1769
-1310 series
-3.20" bolt circle
-4.016" outside circle
The issue is that this flange appears to have been discontinued a while ago since I cannot find it anywhere online new or used, and I called different suppliers without luck.

I prefer to run a 1350 u-joint, but there is only one with a 3.25" bolt circle that is both way too big in outside circle and also discountinued and out of stock everywhere I checked:

Spicer 3-2-189
-1350 series
-3.25" bolt circle
-4.5" outside circle

With the 4.5" outside circle I'd have to mill off the lip around the 727's flange and rely on the bolts to keep the flange yoke centered/captured, which I think is a bad idea since it could walk around under high torque situations. I might be able to save some of the lip that doesn't interfere on the narrow sides to help lock in the flange, but I doubt there will be much lip left. There isn't a pilot on the 727 flange.

How have others with 450 torque + engines running earlier fixed output flange 727s with a u-joint driveshaft dealt with the output flange to driveshaft front flange configuration? The easiest way and the only way to capture the front driveshaft yoke flange with the 727's flange, but the part appears unobtainable unless I luck out and one pops up on ebay.

I appreciate the feedback.

View attachment 1716057698

I'm not too familiar with 727s with flanges but don't some of the later bolt-on yokes like used in trucks and motorhomes shorty 727 have the same spline? If so, those might be easier to work with for what you are doing.

 

[Torqueflite]

I'm not too familiar with 727s with flanges but don't some of the later bolt-on yokes like used in trucks and motorhomes shorty 727 have the same spline? If so, those might be easier to work with for what you are doing.

Thanks. I already looked into the RV flange, but unfortunately the splines are much finer than the 1963 - (some) 1965. I didn't go further in seeing if the shaft OD and the flange OD where it rides on the seal are the same OD, but they look larger. It would have been a slick swap if everything was the same.