Time for a new gearbox.......

Gumba11 · 08-17-2005, 02:31 PM

Hey all,

I have a 1977 930 with a 4 spd gearbox and no gear mods.

I am curious. I have been thinking about putting a 5 spd gearbox in my car now for about 3 years. The 4 spd works great on the track but I think a 5 would be more rounded for street and track use. I am told it feels like an extra 100 HP when you make the change. If this is true then I want to do it.

I am curious what gearbox I should be looking for. Is there one that converts easier than the other? Do I HAVE to do the G50? Is there an affordable box to switch to?

Thanks for any advice here.

.................................................C

adomakin · adomakin's Garage

chris i think porsche made a 5 speed 930 box for one year. well rare though if thats true.....other than that im thinking it might be G50 time

Natchamp · 08-17-2005, 04:06 PM

man, right when we were finally going to get that 930 shifter going ;P

David · David's Garage

I've gone round and round on this one.

FWIW, here's my take from what I've read: The 915 will work and it appears to be an easy change but you better keep a back up because you'll trash them. The G50/01 /03 or whatever out of a NA car will work a little better but you'll need to machine some off some of the bell housing and input shaft, cut out your torsion bar tubes, and go coilover. You will probably trash the NA G50 eventually. The 89 930 G50/50 or later turbo G50/52 can handle the torque but you still need to do the mods like on the NA G50. I figure with the transmission, clutch, hydraulic setup, and other stuff I'd be looking at over $8K for a G50.

If you change the 930 R&P to a 8:39, the 4 speeds will be very similar to the first four gears in the G50/5X. You just wouldn't have the overdrive 5th and the better shifting transmission. Andial has the R&P for $1500, add another $1000 for someone to install and set it up.

The final choice and what I plan to do is change gears in the 930 box. The gears are about $800 each aftermarket but you should be able to change them yourself. I was going to change mine with my current project, but I've decided to get my engine running and tuned and then decide if I can live with any of my current 4 gears (like 1st) and save buying one gear.