RealityGT

^Holy crap you have a lot to say... no work?

mark kibort

I like the topic and i can always find time for 2 -3 paragraphs to help (is that a lot?) .... I type 100wpm, but with 50% accuracy!

Jimmy-D

^Please continue to participate. Your knowledge is appreciated

ShakeNBake

Anyone know approximately what a limited slip + 3rd + 4th + install run? I'm pricing it out but need some reference points.

sdillon

I confess I'm a bit lost by all of this. I understand that gearing does not change how much power an engine makes, but it does change how much rear wheel torque is available, doesn't it? So it seems to me that if you drive a track at 80 mph and that is middle of third gear in the rpm range, there would be benefit to having a slightly lower 3rd gear that, at the same 80mph, results in a slightly higher RPM. With that, it seems that you would have more acceleration out of an 80 mph corner with the lower 3rd gear because you're starting your exit higher up in the rev range where the motor is making more power. Is this correct?

Perhaps your broad point in all this is "it all comes out in the wash and is highly track dependent so don't worry about it". Otherwise, it seems like your arguments could be taken to an extreme where we only had one gear - sixth.

I'm sincerely not trying to be snarky, just trying to understand this better. Thanks.

jphughan

You understand it exactly correctly.

ShakeNBake

The only downside of lower gearing (assuming it's not limiting your top speed) is that you might have to shift more often or at a inopportune time on a particular track.

For example, at TWS going into turn 5 (old 997), I was bouncing off my rev limiter for about 80 feet because it was a wash to shift to 4th and then back to 3rd. If I was running the OEM 19" wheels with 5% longer gearing over the 18" wheels I typically used, it would address that opportunity and remove about 2 tenths a lap. PDK would have fixed this....

At COTA, in the GT4 - you have to be in 4th to get through T18 without running out of revs, but you don't want to be shifting while going through 16-18 laterally loaded. I find that 4th is too tall to accelerate to take advantage of the grip that appears as you enter 18, so my exit speeds out of 18 are limited to my entry speeds into 16...when I get a ton of understeer and lose the line. If 4th was little lower, I think I'd find some time there, not to mention being able to carry 4th through 19 as well.

I think you could optimize gearing for a particular track to reduce inopportune shifts and to maximize the area under the time-HP curve (maximizing energy produced/consumed).

trebien

There are some rumors of an ~18% reduced ring-and-pinion that I might consider waiting for...

GTgears

There's been a formal public announcement of an alternative mainshaft with 1st and 2nd gear you might want to consider...

Alan C.

Where can we find the announcement? I've looked without luck. Thanks.

GTgears

My saying so here isn't formal enough?

It's in the perfect world thread.

drwuss

More information please!

jphughan

I've been trying various things through the carousel dealing with this exact issue myself. Keeping in mind I'm on the OEM 20s and RE-71Rs, I found that if I stay in 3rd all the way through, I need to brake for T19 juuust before I run out of revs, and I get more acceleration from before the T18 apex to track-out, without it being so much torque that throttle management becomes tricky through there. That said, recently I've been shifting to 4th anyway just before the T16 apex (before the car sees max lateral load through there) mostly out of mechanical sympathy since by my eyeballing the digital speedo at T18 track-out it only seems to be costing me about 2-3 MPH there.

jphughan

Here you go:

jmartpr

How is that project coming along? Any ETA or specs/options?