Custom gear set & tranny problem...

[hobieboy]

I'm considering rebuilding my 930 tranny because I'm having problem getting out of 3rd - have to use fair amount of force. Other than that, it only occassionally grinds when I shift into 2nd/3rd/reverse.

I am guessing it might be sleeve/shift fork issue? Anyone with experience like this?

So - I'm thinking that while I'm there, I want to shorten 3rd & 4th gear. I don't need a 186mph car, but I can use much closer ratio on track.

Anyone can suggest where to look for custom gear set? I don't think our host sells them.

[David]

I would recommend replacing the ring and pinion with 8:39 gears so you keep good gear spacing. This puts the four gears close to the first four gears in the G50/50 '89 930 5-speed transmission with a top speed of about 166mph at 6800rpm in fourth.

[hobieboy]

David,

That was my 1st thought as well, but it does not address one of the fundamental issue: RPM drop between gears (2nd to 3rd is just over 2000 & about 1800 from 3rd to 4th @ around 6200 shift points).

The drop seems to be the biggest problem as it drops me out of power range.

I rode in a student's car once who had a "935 gear set" according to him. And boy, the car is in max power band all the time.

Having said that, would love to hear from anyone who had gone with R&P or gear change though.

thanks

[David]

I'm planning the R&P change during my engine overhaul, but completion is still a few months away so I can't give any first hand advice. You might try the turbo911 site, there's some good info there.

I checked the rpm drop of the G50/50 from 2-3 at 6800 rpm is 1975 and 3-4 is 1620 while the 930 tranny 2-3 at 6800 is 2150 and 3-4 is 2040. These are significant drops, but I can't justify the cost of a 5 speed or new 930 gearsets over the $1500 R&P. Besides on the 6800 rpm 2-3 and 3-4 upshifts at 4650 rpm and 4760 rpm should be well within the 930 powerband.