No first gear in 901

[Scott Clarke]

Hey-
My first post. Last weekend my previously perfectly fine 901 gearbox (in my '70E) sudennly refused to shift into first. I had just started the car, shifted into first, and let out the clutch. It imediately popped out of gear (this had neverhappened before). I put it back into first, it popped out again, and that was it. Thereafter the shift lever would not move beyond the neutral plane. I was able, with some effort, to get the lever to the right, and found that 2nd-5th were fine. I used 2nd to get back into the garage. I have subsequently disconnected the linkage, and have found that I can select everything but 1st by moving the coupler by hand. This gearbox has always shifted well and has been quiet. Any ideas?
Thanks,
Scott Clarke

1970 911E
1987 924S

[Rick Lee]

I have no experience with the 901, but I believe there is a chapter in Wayne's book on rebuilding 1st gear in the 901.

[john walker's workshop]

the pressed on syncro teeth are probably worn down so much that the operating sleeve can't hold them anymore. the teeth on the op sleeve usually match the condition of the teeth on the gearset. pretty normal on those trannys. it can be repaired by removing the engine and trans together and pulling off the trans nosecone to access 1st and reverse gears. the op sleeve, press on teeth, syncro, brake band and gasket are the parts needed. a special tool pulls off the teeth by way of a press, and the new one is pressed on.

[Scott Clarke]

John-
Thanks for your response. Replacement of the parts you list seems reasonable. Any idea why this would happen suddenly, and why it is not possible to shift into first? It feels like something is definitely preventing the slider from moving onto the first gear syncro hub. Also, what other parts should I consider replacing while it is apart?

[john walker's workshop]

if the teeth actually break off, like they do in the 915 trans, the syncro expands and prevents the op sleeve from passing over it. unusual in a 901 trans, but possible. not driving it until it's fixed would be the best thing. as with any trans, when it's out do a complete teardown and replace the normally worn parts. all syncros, brake bands, and op sleeves are the normal things you would replace. some hubs and bearings may be needed too, especially the mainshaft bearing in the intermediate plate.

[stealthn]

Scott,

I had a very simular experience, I just posted an update on. It turned out to be the clutch. Although John Walker is right it could be the syncro/dogteeth/etc.
Drain the tranny fluid and look for "broken parts" during the drain, volia gear problems.
Mine turned out to be a clutch close to going that needed adjustment.

Of course this is on a 79 SC.

Good luck, hope for the cheapest.