901 synchro hub for first gear

[neilca]

Here is a tough question I have been noodling for a week, still cannot figure out,


Why is the synchro hub on the first gear of a 901 box different from the other hubs? They all use the same synchronizer. Can you use 2-5 hub on the first gear?

Thanks,

neilca

[Joe Ricard]

No, 1st gear only has one brake band. Obviously it works only in the forward / upshift direction.

It might work if you swapped in a hub. Let us know as I got a box of hubs .

[neilca]

I decided to go ahead and try replacing my first gear synchro hub with one from a "N" gear set I had left over. Everything went fine. I used a bearing puller and a press to remove the old hub and then used the press to put the new hub on, no problem. I used the two spring internals and reassembled the box. shifts fine.

I am guessing Porsche used the unique synchro hub on first to make it easier to engage the gear from a stop. The other gears get engaged at speed. My car is a race car so I am not too concerned hoe easy first is to engage, I will only use it in the pits.

I have not driven it yet, I will follow up with how well it engages while stopped.

neil