What to do with my 915

[ChuckleBeast]

Originally Posted by riparian

Glad to hear it. It is too easy to procrastinate. “So what if I have to bring it to a full stop to get it in first…”

Did you have the gearbox done locally or ship it? Curious if you can recommend a shop.

Brought it to Exotech in Plaistow, NH, $2400 to replace synchros, dog teeth, bands for first gear and sleeves. Bearings were in good shape. Mark the owner was awesome to work with and I highly recommend.

[riparian]

Thanks for the information.

Originally Posted by ChuckleBeast

Brought it to Exotech in Plaistow, NH, $2400 to replace synchros, dog teeth, bands for first gear and sleeves. Bearings were in good shape. Mark the owner was awesome to work with and I highly recommend.

[Schulisco]

If it were mine, I also would start with the lowest hanging fruits, as written already:

Shift linkage, shift coupler, proper adjustment. And last but not least - make sure, that the right transmission oil is filled in the 915! Even if no one want to hear it as I repeat it prayer wheel like...I don't want to know how much gearboxes has been overhauled due to shift problems without assuring the right transmission oil. It's the most imprtant thing I check before I tear the gearbox oout of the car for overhaul.
The 915 urgently needs an old fashioned mineral only transmission with a numoerous drag torque to speed up the the synchros for smooth shifting. If you use a modern low viscosity transmimssion oil, the synchros cannot do their job and you get a bunch of shifting problems. On my 915 it shifted pretty well when being cold. But the longer I drove and the more the gearbox and the (modern) oil warmed up, the more I struggled to find the gears...the workshop was intended to make a good job and filled a modern low viscosity trsansmission oil in it.
So changed the oil to the oil Porsche recommended in the workshop manuals, mineral SAE90 GL5 (very important, GL4 is NOT appropriate!!) only, and now it shifts a bit uncomfortable when its cold, but when it warmed up, it's quite nice now! Of course all linkage and the coupler have been overhauled and adjusted as well. The brand of the oil is not that important, check out the specs of it. The focus must be on the 40°C & 100°C viscosity: Cold (40°C) around 150-180mm/s², warm (100°C) not less than 15mm/s². See more e.g. here: https://forums.pelicanparts.com/porsche-911-technical-forum/1108783-gear-oil-recomendation-new-zealand-2.html

This is far more cheaper and quicker. If the gearbox still won't shift properly afterwards - ok, then you're sure, that you have to overhaul it because every other opportunity has been checked before.



Thomas