boulderbobo

Yeah, I know what to do...can't seem to pull the trigger.


Bob-

NP993

You guys really think that a taller 1st gear is worth $5,000?

I mean, you must really hate money, more than the average 993 owner...

matt777

The box I'm looking at is, from (memory), 3.818 (std /20 1st), 2.4, 1.717, 1.407, 1.13, 0.921. Its 2nd that gets changed not 1st. How much is it worth? That is a tough one. I'll certainly let everyone know what my thoughts are in the spring. I'll add a LWF too so it might bias my review somewhat. I have only heard good things so I'm hopeful. I'd like to swap out 6 to the /21 0.821 ratio but I may wait and see.

Blaine S

I would drive a 993 with the stock 5th in 6th position before I finalized the build. I had it that way for about three months and had to change it back to stock 6th. Again, I've had both configurations and IMHO the stock 6th is better left where it is. IF this is for a track car which is going to run somewhere with really long straights, maybe you need a better 6th gear. But what the hell would you be doing on public roads where you need that shift at 130+ MPH?


Ring & Pinion 9 to 31 3.444444444 MPH

1st gear 11 to 42 3.818181818 38.520
2nd gear 21 to 43 2.047619048 71.827
3rd gear 19 to 30 1.578947368 93.147
4th gear 21 to 27 1.285714286 114.391
5th gear 24 to 26 1.083333333 135.761
6th gear 40 to 31 0.775 189.773

matt777

The gearbox is already done (I'm buying a used regeared unit) so I have the choice of leaving the stock 5th as 6th or just doing the swap before I bolt the transmission back in. That said, winter hasn't arrived here yet so I can just do some cruising with my stock /20 gearing and see if I could live without the high OD 6th for long distance cruising.

Blaine S

Changing out the gear in the 6th position is supposedly the easiest to do and in my case didn't require a fully tranny drop.

Do you have a stock 6th gear?

However it ends up, you will *love* the shorter gears in the 993. I don't mean to dwell to much the 5th/6th thing - the new box will rock! Enjoy.

Matt Lane

I find this interesting. If (when) my transmission needs work, I plan to move 5th to 6th and get new 2-5 gears better spaced.

I could totally live without sixth in its current ratio. Cruising on the highway at 75 or so is fine in 5th. By the time you need 6, you're paying tickets. On our track, I barely need 5th, let alone 6th.

I guess in depends on how fast you drive on the highway, and how comfortable you are running slightly higher RPM. Offhand, how high are you running in US-spec 6th at 75MPH? 3,000?

M

matt777

Good point. Changing it out in the future could be done without a major effort. Yes, I have high expectations for a nice improvement!


I only use 6th when cruising at 80mph which is doable on certain highways around here. 80mph is around 3000rpm. I think the shorter /21 6th would be a better choice for me. Getting a gear set might be difficult. I haven't tried to source it yet.

boulderbobo

I was actually thinking about a shorter 2, 3, 4, 5 and move existing 5 to 6. And I think it is more like 8K.

mongrelcat

75MPH in 5th is ~3,250RPM, in 6th it's ~2,800RPM.

matt777

After a long drive I think the /21 Euro 6th would be the best choice (0.821 vs 0.775).
We'll see.

Bill Verburg

Time to drag out this comparison again

matt777

Thanks Bill. I have referred to that graph more than a few times lately.

mongrelcat

Man, that Zonker must be great fun.

GTgears

My only addition to this thread is that if it's not a racecar I personally think the 2.375 or 2.400 2nd gear ratios that are being discussed are too short. Stick with something like the 2.25 in the Zonker or a 2.176.

Same goes for third. 1.789 is a really really short third gear. It's a tiny little gear with huge overhang on the dogteeth. It's a motorsports gear with a short lifespan. Again, go with the 1.684 in the Zonker or even a 1.650 or 1.632.

Also, as has been mentioned, the LSD is totally optional. They don't seem to get much love around here, but for a car like this a TBD (torque biasing differential) is actually a very good option to consider. When barnstorming and canyon carving it lets you get on the power sooner and put more to the ground coming out of the corners. The usual argument that the LSD gives you lock up under braking doesn't apply as much on the street. On the track when you're bringing it down from 120mph to make a corner at 60 it matters. On a drive through the woods braking from 65 to 35 for that next hairpin it's not as relevant.