chris walrod

Indylaw,

The goal of these ratio changes is to shorten the gaps of the current US spec ratios. I never need 6th gear in my car. So we might as well install a ratio that can be used and even the shift splits. If we changed the final drive ratio, we would still have the gaps, but at a different RPM.

Have you noticed the gap or RPM drop from 2nd to 3rd gear? At least on my car its pretty big.

Chris

chris walrod

Indylaw,

BTW, I forgot to ask how you like your car? My 993 is my third 911 and I am still thrilled every time I get in the car to drive it

Chris

Greg Fishman

[quote]Originally posted by IndyLaw:
<strong>Pardon my ignorance, but isn't there a ring & pinion somewhere that could be changed? Kind of like changing a 3.73 chevy rear end for a 4.11 rear end instead? If so, it seems like that would be much cheaper.</strong><hr></blockquote>

You can change the R&P. But IMO all you do is make first gear useless, and the problem with the 993 gears stays the same just at a slower speed. The problem is the gap between the gears is too much, and even when shifting at redline there is too much lag in the next gear. Now changing your R&P and gears might be worthwhile also. {Edit): Didn't see Chris's response sorry for the duplicate.

Whirlwind

A ring & pinion change would bring all of the gears closer together. I'm making up redline numbers here for simplicity in math, but here goes:

If redline is: 1st) 40mph, 2nd) 70mph, 3rd) 100mph, then making a change comparable to switching a 3.73 R&P to a 4.11 (about 10%) would create the following new redline numbers:

1st) 36mph, 2nd) 63 mph, 3rd) 90mph.

Yes, the whole range has shifted down, but instead of a 30mph gap between gears, there is only a 27mph gap. I know this isn't as effective as a whole new gearbox, but for what it sounds like people are after, I'd think you could save $5,000.

I'm the admitted new guy here, so my "answer" here is really a more detailed question. Far be it for me to tell anyone anything about 993's on this forum.

Greg Fishman

Indy,
I don't discredit what you say but I think that even a 10% reduction is not enough. According to my manual when you shift at 6500 rpm from second to third the rpms fall to ~4100rpm. Ask Brian about it when you talk to him. Not sure what the labor is to swap the R&P is but I bet it is over 6 hours. I have seen him take that long to just set the black lash on the R&P just so. I think the R&P is about $1500 also.
I have the RS gears in my race car and the rpms fall about 1200rpm or so when making shifts and the car has no noticeable lag in acceleration.

JohnM

You can get an 8:32 R&P set for the 2WD models (from Porsche Motorsport if you like) but it is a straighter cut than OEM and (so I am told) pretty noisy as a result. I did look into shorter R&P sets for the C4 a while back, there do not seem to be any (in fact Powerhaus said they do not make any R&P sets for the C4 and to the best of their knowledge neither does anyone else).

Whirlwind

You're absoluteley right, Greg. You'll still have a 2400 rpm drop, it would just be 10% easier to get those revs back again.

I agree 100% with the problem. As a new 993 owner, I find myself about a mile down the highway before I realize that I'm still in 4th gear. Except for some noise reduction, there's not much need for even 5th gear at highway speeds.

I don't know what other people's habits are, but I find that if I want to "goose it" on the highway, I drop into 3rd gear. To avoid wear and tear, this requires a lot of rpm matching coming out of 6th.

Viken

[quote]Originally posted by Greg H.:
<strong>I thought the C4S came standard with an LSD</strong><hr></blockquote>

Yes, all G64 transmissions had LSD as standard.

Greg Fishman

[quote]Originally posted by IndyLaw:
<strong>
I don't know what other people's habits are, but I find that if I want to "goose it" on the highway, I drop into 3rd gear. To avoid wear and tear, this requires a lot of rpm matching coming out of 6th.</strong><hr></blockquote>

I was following my wife home from Putnam park one weekend and she was driving my street car. I noticed that when she needed to accelerate at speed the car was quicker than I thought it would be. I didn't hear any shifting so when we got home I asked her what gear she was in. She said "I don't know, all the way over and up". Turns out she was in 5th instead of 6th, the only other manual she had driven was my former E36 M3, so she had no clue the car had an extra gear. No harm done except a little lower MPG. Next time she drove it she said she like 5th better, LOL.