Bill Verburg

The above graphs were done incorporating the tires specified by the factory
RSR 285/645 x18
GT2 305/670 x18
and rev limits
RSR 7400
GT2 6700

Bill Verburg

For Pete, I added a g97/63 , 2009 Cup, rev 8400, rear tires 27/68 x18

trophy

Great data Bill.....

I am currently looking at rations for my car, with the engine build going on and subsequent increase in Rev limit (7500 to 7800) i am wondering where I will end up on ratio's. I actually like the look of the Gt3 Cup ratios, are you able to do these with a 7500 rpm with a 25.5 or so tire?

Always love your posts Bill, your analysis for transmissions is thorough and thought provoking.

Bill Verburg

Sure, but 25.5" is an awful tall tire, 275/35 x18?

callipygian 911

Bill,

I've spent some time studying your very helpful charts, and I realized that the sizes of remaining Quaife gears on discount are not particularly useful.

So, looking at your many charts (on this thread and others) and the choices Guards offers, I came up with the following scheme below. Since this car is mostly a street machine, I want to keep my stock 1st gear as well as the stock 6th for "overdrive" on long trips, although I realize I'll have to get the revs pretty high in 5th to enter 6th at around 2500 rpm. Kind of a mismatch, but one I'm willing to put up with.

My question is, which would be a better ratio for 3rd gear? From my best reckoning, it looks like 1.579 would fit in better with this scheme. Would 1.550 be better than 1.579?

1st - 3.818 stock
2nd - 2.176
3rd - 1.579 (or 1.550)
4th - 1.250
5th - 1.031
6th - 0.775 stock

trophy

No looking at 305 or 315 30/ 18's they are 25.3 to 25.5

os993

Since this topic comes up fairly often, I always include my re-gearing ratio, which I did approx 10yrs ago, with RS LWF. This combo, IMHO, has been GREAT! Perfect for daily use and my local tracks (Thunderhill, Buttonwillow, Laguna). I am VERY glad I also replaced 6th - I use this gear almost daily (anything above 65mph and you can use it).

Oh, also replaced with steel synchros all around and used Guard gears.

2nd - 2.25
3rd - 1.65
4th - 1.286
5th - 1.040
6th - 0.821

Goal was to go a bit more aggressive than Euro ratio. I also re-build the factory LSD with new discs. Job was done at Jerry Woods, FYI...

Bill Verburg

Just a guess but I'd say you won't be happy

2009 997 Cup gears, 305/30 x18, 7400rpm

callipygian 911

I picked these out with the exact same goal. I'd say my selections are a little more aggressive (closer) even than the ones you have installed, ignoring 6th of course. Also, Guard Trans no longer offers 1.650 for the 993 gears, but it does still offer all of the other ratios you have, besides 3rd is the one I'm puzzling over.

Still, with the ratios I'm asking about, I'm curious which of the two choices for 3rd gear would be a better fit with the overall 1 -5 scheme. I realize they're pretty darn close, but I was wondering what the regear experts think.

As an aside to explain my desire to retain the stock 6th gear: I live in San Diego as you can see from my avatar info, where almost everyone drives 75 - 85 mph on the freeways. I commute about 20 miles to work and I spend almost all of that commute in 6th gear @ 2500 - 3500 rpms. Never had a ticket in the past 10 years of living here either (knock on wood).

trophy

Wow, amazing what difference a 1000rpm and a shorter tire will make.

Still looks like your transmission is the best one.

Bill Verburg

Here is OS993 and I added a friends, MJB. Mike tracks the car a lot and likes his gearing very much

To me OS's looks low but I haven't driven the car so maybe it works for him

Petevb

Nice. However the faster shifts of the sequential probably let them stack the ratios a bit closer. My car covers 77 to 95 awfully quickly- using those ratios looks like a lot of shifting through that range...

callipygian 911

Thanks, Bill. Every datapoint helps.

What would really help is one of your amazing graphs, as I feel like they describe what's happening with a gearset in a very complete way. In lieu of that, I carefully traced over several of your graphs and estimated in some cases what vectors my ratios should work out to. Not sure how to do this in excel.

Here's a photo of my crude handiwork:


According to this collection of my best estimates, as I thought, 1.579 seems to fit in with my 1st - 5th scheme better than 1.550 in the way of a prospective 3rd gear. Again, 1st and 6th are stock and the rest are Guard gears.

*the dotted line is the red line at 6800 rpm, 7000 rpm is the dot above it

Analog Theory

Bill,

Maybe you could add my build and comment (currently 100% street use) from stock 1st.

2.176 2nd
1.6 3rd
1.286 4th
1.063 5th
0.821 6tg (Euro factory)

77'3.6vram

Use the factory G50/32 or SW's recomendations for your gears. You can't go wrong.I am extremely pleased with my setup. I use my clone for 90% street & 10% offroad/dirt frozen lake rally style driving.