901 5th Gear Swap

[hausey187]

I have an early 902/1 transmission that I'd like to swap the 5th gear in. I already have the gear set but am wondering how difficult a job it is. I've searched a bunch online and feel like I missed some topic somewhere on how to do it but mostly just find people debating the best gear choice. If anyone can point me in the right direction, I'd appreciate it!

[Bob Ashlock]

I think people are hesitant to give advice on this because it's going to depend a lot on your skill level and ability to study various illustrations and instructions. The Porsche 912 "Orange Book" does give a pretty good breakdown and that's what I've always used. If you've never cracked a 901 tranny open before, I recommend some good study time up front. You CAN do it, but take it slow, be well organized and methodical. You will need a few special tools, such as the syncro dog-tooth removal tool, Part #: PEL-SIR-P225 and there is a type of plastic "holder" Part #: TOL-721-T76 that is useful for keeping everything organized while working on the 'shiskabob' of gears, sliders, etc. These are offered for sale by Pelican or can be borrowed from other members. You will probably have to "make" a few tools and an old clutch disk is handy for locking the mainshaft in place. The other tricky thing is assessing the wear and whether to replace or reuse certain parts... what to replace and what to put back in service. There can be subtle differences in the synchro bands and sharpness of the dog-teeth on the gears and sliders. I have gone through this half a dozen times and improved each time. My current transmission "Frankentrans" is populated with some re-used parts from a few other trannies and works perfect. The worst part is the stinky smell of the tranny oil that will permeate your workshop for weeks!

[hausey187]

Thanks for responding, that's the info I needed. I'm an aircraft mechanic and work on vintage Vw's so I'm capable of the task but wasn't sure how much was involved. Since I'm trying to get the car on the road for the summer and I know I'll find other things that need replaced I think I'll pick up an Orange Book and pull it apart over the winter. Thanks Again!

[WFBowen]

As Bob Ashlock accurately stated giving advice on transaxle work can be either needed information for a skilled mechanic or an instruction manual for disappointment to a less competent individual. The former results in a successful gear set change, the latter in a box full of 901 gearbox parts.
Either way, an excellent source of 901 gearbox info can be obtained from Dr. Evil who has conducted numerous Porsche trans workshops and sells his dvd’s online. He’s here on Pelican user ID mike95125 . https://forums.pelicanparts.com/members/8624.html . I don’t know him but have heard great things about his 901 rebuilding skills.

[hausey187]

Thanks for the reply, totally agree! I'm going to collect information and break into it this winter. That way I can take the time and refresh anything that needs it.