tonytaylor

My C2 has broken it`s gearbox ( transmission) so I now have a choice of 3rd or neutral. It`s not a complete suprise to me ( I believe I may have moaned about poorshifts here), and it happened on track.
My problem is what to do now; I am considering a number of options ( in approximate order of cost):

1) Replace tranny with a used 964 G50 5-speed unit - the cheapest option but I`m probably buying a high milage item that I`ll destroy in short time at the track and be back to square one.

2) Replace with 993 6-speed used unit - not much more expensive than option 1 but likely to be lower milage and have better ( closer) ratios for track use but still have the weaker brass synchros in 3rd and above ( and is rumoured to be weaker than the 5-speed unit)

3) rebuild the box repairing the damage and using steel synchros.

4) rebuild the box using steel synchros and change the gear ratio`s to be more track orientated. On track the G-50 is, to me a 3 speed unit -2nd for chicanes/hairpins, 3rd everywhere else and 4th to stop you riding the rev-limiter in 3rd. I use my car on the road so with the RS clutch I don`t think I want to raise 1st, but 5th I could live without. I could drop 3rd,4th,and 5th ratios to give me 4 useable gears. Unfortunatly this would render the car unsaleable to anyone else, but its value isn`t that high anyway.

5) Fit a 993 RS box which has good track ratios, steel synchros, and an LSD and wouldn`t harm resale. Unfortunatly this option is £2.5k more expensive than option 4.

The box gets pulled on the 28th july and I would like it to be ready for the 13th August so I need to make my mind up soon. I would appreciate any advice!

Cupcar

I installed a 993 RS G50/32 Supercup 6-speed in my car. It has close ratios, (3.154,2.000,1.522,1.241,1.031,0.829) steel syncros on all gears, all ratios interchangable, motorsport LSD and reinforced shifter internals.

I would not hesitate to install one of these gearboxes, it is a direct bolt in for the 964. It also has a revised shifter detent system and dual cone syncros on 1 & 2, so it is much better shifting than my G50/10 5 speed.

.Also I put in the 993 RS shift rod with the updated universal that eliminates slop and would recommend this as well.

P.S. Tony did the 993 M/C ever fit?

tonytaylor

Cupcar,

Thanks for the reply - I am leaning towards the 993RS tranny, its just the extra £2.5K thats making me think!

Re: the 993 MC - I did post on the RS brakes topic but it seems to have been lost in the forum change over.
The 993 MC was a direct bolt on but we had to use the 993 servo as the return spring on the 964 MC was on the MC itself but on the 993 it was integral in the servo - which was also a direct bolt on. ( obviously they managed to fabricate an adapter from the 10mm 993 MC to the 6mm 964 brake pipes). All is now fitted to the car with no problems associated with the change.

Cupcar

Tony-

Thanks for the master cylinder update, did it make the pedal harder as well?

If we ever have a FAQ for the 964 your experience should be part of the brake upgrade section. Wonder how the connector was made, could it have been an off the shelf metric adaptor?

tonytaylor

Cupcar,

The pedal is much firmer. Braking is much improved since stopping power is now related to hard I push on the pedal rather than how far my foot is in the "treacle" - its much more linear. It allowed me to brake later and harder without locking up as the point at which the brakes start to lock is easier to judge.
There also seems to be a partial return of ABS but I`ll know better when it rains.
The adaptor was I believe 2 off the shelf items. Work was done by 9M and I`m sure they could provide the same for anyone else.

joey bagadonuts

Yes, close-ratio gears sound like fun! There's nothing cooler than hearing someone work their way through the gearbox on those long straights. Like you said, Tony, the stock 5th gear is useless at the track.

Is there much difference in price between rebuilding your tranny with 993RS ratios and buying the 993RS gearbox?

tonytaylor

The 964 G-50 is a 5 speed and the 993RS is a 6 speed ( you knew that!) so if I drop the ratio of 3rd/4th/5th to, say 993RS ratio, this would be cheaper by about £2000-£2500 than the 993RS box that may be for sale ( 993RS trannys aren`t common used). The advantage of the 993RS box is that it would still have the 6th gear for motorways etc, plus it has an LSD which would add another £1000 to the rebuild 964 price, plus its "new"

RSAErick

Not at Spokane Raceway Park, with the longest straight in North America. Yee Haw!

RSAErick

I rode in an RS America with steel syncros and the ring and pinion changed on its G50. All I can say is WOW! The difference was truly remarkable with respect to acceleration out of corners. That's what I'm going to do when I save up enough money.

Good luck with whatever you choose to do.
Erick

joey bagadonuts

That's very kind, Tony!

Yeah, Erick, I guess there are a couple straights at Road America (WI) which beg for 5th, as well. It's just that 4th is so long that you can only upshift as you approach the corner. Can you say major "pucker factor"?

Most of the local PCA drivers think the long straights there are boring, but I think a busy gearbox might change that. And at the short courses, a quicker 3rd gear would definitely catch everyone by surprise. Boy, now I'm thinking about the swap.

Christer

RSAErick

Exactly! In third gear, the difference is immeasurable. The example for me came in a third gear corner that starts up a relatively steep hill at about the apex. It's a lug up the hill in my car, but the RS America I rode in powered up there like you couldn't believe! Right in the power band, baby!

tonytaylor

Cupcar,

What are your max in gear speeds in 3rd/4th/5th with the 993RS box ( I est 98/122/148 mph)

5th gear on a circuit must be something else! Here in the UK there`s an airfield with a 2 mile straght ( Bruntingthorpe ) where 996tt`s have been speed trapped over 190mph.

JW Hubbers

Nor on the good old Nürburgring
I need 5th three times every lap

Cheers,

JW

Cupcar

Tony-

V (MPH)@6800 RPM G50/32 6 speed

1=46
2=72
3=94
4=116
5=139
6=173