915 Gear Compatibility

[surfdwn]

I finally tore down the tranny on my '86 today and was not pleased with what I found. The dog teeth on 1st gear are definitely shot (not a big deal), but there is significant wear on the first gear on the input shaft, with small pieces of corners missing, etc. Fifth also has substantial wear.

My questions is: I have a '73 915 complete tranny that was working fine. I realize the cases are different and the gear ratios are different, but....

Can the gear cluster from the '73 be used in the '86 case? If not, what are the differences? It would be a lot easier (and cheaper) to go this route.

Thanks for the help.

David Nolen

[Dave at Pelican Parts]

You might have more luck posting in the 911 forum, as many more of their cars came with 915 gearboxes than ours.

I think 915 gears are interchangeable across the years with no problems. I think. But ask the 911 guys, they should know better. The ratios are likely different, so you may wind up with a gearbox with mis-matched gear ratios.

--DD

[red-beard]

No. The later years are asymetric gearing as opposed to the early years. You can convert one to the other.

The 1973 and 1974 915's are highly sought after for the 7:31 pinion ratio, which makes the cars very peppy off the line.

If you move to the 1973 Tranny, you will have to use a mechanical speedo.

Dogteeth, sliders and synchros are repalceable. Gears should not be chipped. If you are seeing real gear wear, something serious went wrong. Find a different tranny instead of wasting time trying to fix one with bad hard parts. There are plenty of good ones for a lot less than replacing hard parts.