727 big and small inside the same?

[RobBob]

Are the internals the same for a big block 727 transmission and a small block 727 transmission? I have an early 1966 Big block 727 that I want to upgrade, but parts are getting harder to find. There are lots of small 727's for sale. Can all the internals be swapped from the small to the large casing?

 

[gtx6970]

yes

 

[Ghostrider 67]

Yes. Some will have different set ups like 4 pinion planetary's, 5 disc clutches and various numbers of springs etc...depending on application.

 

[R413]

Yes, almost. In the same Year BB and SB are mostly the same with small variances for 2bbl or 4 bbl carbs. When trying to mix differs year parts there are many changes.
*62-70 takes different seals for forward (front) clutch pack than does the 71 and up.
*70 and older has a different forward (front) clutch drum and stator support than 71 and up
*66 and older input shaft and stator support is smaller diameter And the slime count is different for torque converter than 67 and up and it takes different sealing rings.
*the piston for the second gear band changed around 71
*the stator support changed around 71
*the vent in the front pump changed around 71
*the rooster comb is different where it actuates the NSS in 1969
*the center thrust washer went to a 3 tab unit around 1977. Rear clutch has relief cuts for the 3 tabs.
*the spline angle on the output shaft that hold the planetaries changed around 77.

These is more I can’t think of right now.

 

[493 Mike]

Yes, almost. In the same Year BB and SB are mostly the same with small variances for 2bbl or 4 bbl carbs. When trying to mix differs year parts there are many changes.
*62-70 takes different seals for forward (front) clutch pack than does the 71 and up. Newer style seals retrofit.
*70 and older has a different forward (front) clutch drum and stator support than 71 and up
*66 and older input shaft and stator support is smaller diameter And the slime count is different for torque converter than 67 and up and it takes different sealing rings.
*the piston for the second gear band changed around 71
*the stator support changed around 71
*the vent in the front pump changed around 71
*the rooster comb is different where it actuates the NSS in 1969
*the center thrust washer went to a 3 tab unit around 1977. Rear clutch has relief cuts for the 3 tabs.
*the spline angle on the output shaft that hold the planetaries changed around 77.

These is more I can’t think of right now.

Mike

 

[66Satellite47]

Post #4 is pretty complete. There are numerous front servo/band lever ratios, depending on the application. The wide bushing front drum/stator support and servo piston change did start in '71 along with the front pump vent. There are BOTH 3 or 4 disc front drums and you want a 4 disc drum. Number of springs in the front clutch also vary depending on application, should coordinate with servo lever ratio. The planetaries vary too in both BB & SB versions. I got numerous SB cores, several SB 727's from vans, they had the 4 disc front drum and usually the front 4 pinion planetary. A police package SB from later '70's or early '80's probably has all the HP internals. 3 pinion planets use 3 tab thrust washers, 4 pinion use 4 tab. Valve bodies and governors also vary with the application that vary the shift timing.

 

[RobBob]

So what would be the upgrades to convert my big block non-lock to a lock-up?

 

[R413]

And the 3 pinion planetaries are more than adequate. Had several guys racing mid 10’s with slicks on B-bodies 3500lbs and no problems.

Not worth spending the time/money for the 4 pinion units. If you have them use them they work fine.

 

[66Satellite47]

When I started collecting 727's there were enough complete HP 727's around, $25 - 75 each. Of course my used Hemi trans had both sets 4 pinion, picked up a few more sets from some wedge 727's. The 360 van 727's and the police package had the 4 pinion front I believe.
I have my ideas of what parts to use for different applications, other folks have theirs.

 

[oldkimmer]

U can use a 67-70 tranny and just change the input shaft and keep all the original parts with that tranny. Of course u will need to change the converter. Or go with 71 to 77 and use the wide bushing drum and pump as well as the input shaft. U will have to check and adjust the end play also. Kim

 

[Hemirunner]

And the 3 pinion planetaries are more than adequate. Had several guys racing mid 10’s with slicks on B-bodies 3500lbs and no problems.

Not worth spending the time/money for the 4 pinion units. If you have them use them they work fine.

I destroyed one of those long ago at 650hp and 4200lbs. I’m running the billet steel 5 pinion.

 

[oldkimmer]

Heavier cars are harder on parts. Kim

 

[Hemirunner]

Heavier cars are harder on parts. Kim

Definitely