901 Transmission Assessment

[helidoc]

Just took apart my '68 911 901 transmission to inspect and rebuild as necessary. The question I have is how to assess the gears and synchrod. I have seen some internet posting on the "points" bing sharp but don't know how much. I will post some pictures as would appreciate some feedback as to whether mine should be replaced or are acceptable. I don't know how the trans worked beforehand as the car has been sitting for 35+ years. Thanks in advance.

[Discseven]

Your dogs and syncros on gears shown look good to me. Syncros... slightly worn. With gearbox open, I'd replace syncros by default.

Here's comparison of new and beat up dogs, and new and near useless syncro.





Can drive these worn parts but shifting's in grandma-mode... no offense to grandma.

.

[yelcab1]

The shiny synchros are worn, you can replace them or flip them around to the new side. Dog teeth (synchro hubs) all all good.

[spuggy]

I keep hearing you can flip the synchos. I was given the option when my '86 915 was being rebuilt. Seemed like a good idea.

Flipped synchro on 1st lasted ~1000 miles for me. I'd say do it once, do it right...

[john walker's workshop]

The shift sleeves can't be evaluated unless you inspect the inside surface that rubs on the syncro ring. Pointed teeth and inside surface wear are the things to look for. Pic of a normal inner surface and a worn one. The little triangle area behind the point. The smaller triangle is the normal one. The pic flip flops between my imac and ipad. Weird.