Jonte

I took over a project recently where the previous owner has taken the engine out while leaving the 915 gear in the car.

The splines look to be ok but the shaft end going into the needle bearing is rusty.

Any thoughts on how to fix this? I would like to avoid having to tear down the gear if I can...

Mark Salvetti

That would be the main shaft. I think you can clean that up. It just needs to be smooth to engage with the pilot bearing, and the splines need to be clean so the clutch slides on them and doesn't get hung up.

The rust is a bit heavy, so not sure if you should soak the end in a water/vinegar solution, or go at it with steel wool and emory cloth first. Probably a wire brush or work carefully with a wire wheel on the splines. You can remove the guide tube for better access (you'll want a replacement o-ring to reinstall).

I'll be curious to see what other folks suggest.

Mark

GTgears

Remove the guide tube, clean things up, and replace the seal.

Was the gearbox stored full or empty? You probably want to pull the cover plate on the bottom and look inside with a flashlight. Might be rusty gears inside of it. Do this first before wasting time on the splines.

TerryShugart

3M makes rotary brushes that are fiber and can be chucked into a drill. They come in different colors depending on the grit required. They will knock the rust off without scratching the spline or leaving behind metal pieces like you can get from a steel wire brush.
Terry
75 911S

Jonte

I believe the gear is full, but will definitely check that. Thanks!

Jonte

Thanks for all the supportive replies!

my concern is that the rust is so bad that the outer surface is a bit distorted.

I was was thinking if I need to patch it up with something once all the rust is gone?

r911

people have dealt with worse:

r911

mask it all off with blue tape and then use a fine abrasive emory cloth very lightly, followed by a polish or cutting compound like for body work on a fiber wheel or a cloth

clean well and expect you may need to replace things earlier than usual

- address usual failure or wear items now: e.g. TO bearing and clutch fork

put some decent gear oil meeting the spec. in and run it 200 miles then change it - do that until you don't see anything bad, then fill with Swepco

Jonte

I'll give it a try! Thanks all!