915 transmission output flange length Options

[Gary]

Anyone have a 915 tranny with the coarse splined flanges that they could measure? I need from the CV mating face to the end of the splines, not the diameter. I have a sportomatic flange that is supposedly longer, but would like to verify.

Thnx.

[PRS914-6]

3.877" Off a 1977 915

[Gary]

Cool thanks.

The 914 output flange length is 3.915" by my calipers, or about the same as the 915. The 915 sporto is 4.275".

Who cares? Well, if you replace the 914 half shaft, which measures 20 1/8" with a 1969-1973 911 half shaft, which measures 19 1/4", you have 7/8" or 0.875" length to make up. Swapping the 914 output flange with a 911 sporto makes up 4.275-3.915 or 0.36" of that difference, leaving about a half inch delta. This swap has been referenced a few times in the garage. I did it on one side two weeks ago and all is happy. Seems that the quarter inch per CV is OK. I'll let folks know in a few weeks when I've been running this setup longer. Cool thing is it's a complete bolt on affair, and the 911 half shaft is still available (got mine for $220 from GPR a few weeks back).

[PRS914-6]

I went a different route. I used the very large 108 mm flanges off a 69 911 and large CV's and got free floating axles from Sway-A-Way. It only cost a little more to do that way. I'll never have to worry about CV's or axles. (just the tranny)

[Mueller]

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Paul, did you get hollow axles by any chance??


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[Gary]

No hijack...

I'm curious too. Guessing he used the 33 spline 20 1/4 inch Sway-A-Way, part number 2020. Best price I saw was $200, special order through CB Performance. Still need CVs though, and with the complete half-shaft available for just north of $200, the sporto flange solution looked pretty good.

[PRS914-6]

Actually I have the 32420 race axles. (solid) I had an opportunity to buy them from a guy who never used them. They may be overkill even on the 3.6 but I'll never have to worry.....

[John]

I think you have it just about right on the trans output flanges. I use 911 coarse output flanges on mine as well.

I had a set of axles from an earlier 911 (1974-1984), but ended up only using the CV Joint boots. I used 914-6 axle shafts (I already had them) which utilize the same splines as 911 CV Joints (1974-1984). I turned the axle ends down on my lathe so the CV's would fit the shafts (basically made the spline area before the shoulder longer).

This worked out for me as all I had to do was buy new CV joints.

Good luck with the 911 axles. (We run some on the track car, but we have custom spacers for them as they used to max out at full droop).


just my $0.02

[Gary]

How can you tell when the CV's max out?