autobonrun

When I bought my 96 C4S in 2005, the PO already changed the stock gears on third through fifth to Guards Transmission gears then used the old fifth gear for the new sixth. Bill Verburg was kind enough to graph my setup in the attached link.

http://forums.pelicanparts.com/porsc...utobonrun.html

I understand 1st and 2nd are fixed on the shaft in the 96 model and is probably why he just did 3-6. I'm at the point where I may do an engine drop this spring to fix a chain housing leak that is only accessible with the engine out.

I'm considering biting the bullet and changing out the shaft with a new 1st and 2nd gear. This would bring the biggest benefit to the gear update as you can see from the big RPM drop on the graph in going from 1st to 2nd.

What am I looking at in terms of material cost and labor cost for this change? I haven't given any thought yet to what the proper ratios should be but I'd like to see if this is something I want to consider from a cost standpoint or just stick with what I have.

Also, if I do this update, I assume the new gears would no longer be fixed on the shaft?

Steve Weiner-Rennsport Systems

There are four ways to change 1st & 2nd gears and all require new mainshafts.

1) Use the RSR m/s which has a removable 1st & 2nd (may not be available)

2) Use the RS (G50-31) m/s with its tall 1st and removeable 2nd

3) Use a '95 m/s with its stock 1st gear and removeable 2nd

4) Use our custom Guard m/s with its 3.50 ratio and removeable 2nd (best for street performance)

For dedicated race cars that need a "full-active" transmission, the RSR m/s is desirable for the obvious reasons, however street & dual-purpose cars are better served with either the RS m/s or ours.

In all cases, 2nd can get moved closer to first to eliminate that giant RPM drop.

993KT

A little off topic, but if the timing chain gasket is leaking, a) it's not that major of an issue, and most people just live with it, b) does not require engine drop, if you remove a bunch of stuff in the back. It really depends on what else you want to fix or upgrade while you are there. I'm planning on the carrier re enforcement, AC delete, new cat, so I'll do the chain cover gasket while I'm there. I think you can pull the tran without dropping the engine also. Nice justification though, if that's what you are going for. Honey, I need to change the air filter, so I really should do the 3.8 kit at the same time I seem to remember the main shaft is about $2k. I'd be interested to see if you go through with that, as that's on my todo list also. Good luck!

autobonrun

Thanks for the responses. 993KT, I also have a small leak near the transmission/engine connection that's been there since the PO changed out the other gears. I plan to get that taken care of as well. Very small but I'll take advantage of the opportunity if I do the gear change.

Steve, I wish your shop was closer to me I'd just drop my car off with you. I like options 2 and 4 but it sounds like my best option will be #4 since most of my driving is on the street. What's a fair labor hour to do a engine drop and install the new main shaft and gears? Sounds like you sell the Guards main shaft and gear set and I assume the 3.5 is first. What ratio do you use for second?

Steve Weiner-Rennsport Systems

Call me next week,.......the answer is complex with many variables.

MarinS4

I have changed my POV a bit over the years regarding how/where work is done. Sending trans or motor cross country on a pallet is not a big deal. The inconvenience is minor compared to the cost/inconvenience of having to do it twice.

I plan to send my motor to Steve to correct for an oversight during the last local build.

KaiB

Call Steve, do what he suggest to you after he gleans a bit more information from you. Be frank and honest and he will be with you. These guys are the best in the business.

BTW... I really like the idea of a short-short 2 through 5 and a taller 6th. This gives you a really sporty box and a high 6th for cruising. I believe Stevie would disagree as he doesn't like the idea of the gap btw. 5th and 6th. I say, who cares, the 6th is used as an overdrive and the rest are there to enjoy.

Have the tranny dropped locally, crated and shipped to the boys.

You'll be a happy fellow.

autobonrun

Excellent input guys. I'm back from traveling and plan to call today.