A727 Torqueflite questions (for gurus only lol)

[Lefty71]

Just a point of curiousity, since i know they are'nt a high failure item anyway, but;

Has anyone ever stacked up rear planetaries from a 70's 727 to compare with the newer four or six pinion planataries from a later model, like a 46-7RHE or an 48RHE??? Are there physical size, width differences??

TIA, Lefty71

 

[oldkimmer]

U need a 76 or later tranny to be able to use newer planetaries because the splines are cut on a different angle and the shaft is a little bigger. The older planetaries will not slide on the newer shafts. Then newer planetaries will slide on to the older shafts but will be loose. I haven’t tried the 5 or 6 planetaries. I have heard they will work but that’s it, I never tried it. I have t had any problems with the 3 or 4 either. Kim

 

[Lefty71]

U need a 76 or later tranny to be able to use newer planetaries

I'm working on a '78. Keeping in mind that spline angles have changed...... the question in my head is; if the rear planetary ring gear stays with the correct output shaft, then can only the planetary itself be changed ( since it only needs to match up to the rear drum)?? Or can those parts not mix-n-match?? Not talking about the front planetary here at all.
TIA, Lefty71

 

[oldkimmer]

A 4 pinion planet will interchange. Not sure on the 6 as I think the rear drum is bigger to accommodate the more pinions. Kim

 

[fishy68]

I'm working on a '78. Keeping in mind that spline angles have changed...... the question in my head is; if the rear planetary ring gear stays with the correct output shaft, then can only the planetary itself be changed ( since it only needs to match up to the rear drum)?? Or can those parts not mix-n-match?? Not talking about the front planetary here at all.
TIA, Lefty71

The spline angle on the output shaft that's different for different years engages into the front planetary, not the rear. The rear planetary is driven by the ring gear and where that ring gear slips on the output shaft, I believe, is the same on all years

 

[oldkimmer]

Yes, that’s why I said a 4 will work but I believe a 6 needs a bigger rear drum. They are found in diesels. Then I don’t think they will fit into a 727 case. I never tried it myself as I’ve only used 3 and 4 pinions. Kim

 

[Dana]

Call John Cope. He could tell you in half the time it took to type. If you do , let us know please. 219-374-0100