Petevb

But I still badly want a shorter 2nd...

BGB Motorsports

Agreed. I sort of like the auto blipper.

I had a customer with a GT4 coming next month ask me if I could source a 2.7L 981 gearbox with the shorter 1-2 and upgrade it with Matt's shorter 3-4-5-6 ratios along with a lightweight flywheel and a bunch of other upgrades! The shorter ratio box on this project has has me all giddy and I am starting on working on trying to get the mapping in the ECU adjusted for the new math...

How long has there been an option for selecting multiple quotes??!?!?? I had no idea!

vantage

The auto-blipper of forum software.

GTgears

I know. I'm just having some fun. Being able to shift down to 1st doesn't fix that 2nd is too tall and that the 1-2 gap is too big.

Too lazy to multiquote...

I don't think the non-S 3rd gear will be short enough mated to just alternative 4-6. That's leaving too much on the table. Better to do 3-4-5 and leave 6 stock if it's about the last $1000.

BGB Motorsports

Agreed! My brain was either moving slower or faster than my fingers. The only rationale for the 2.7L box would be for those that absolutely, without a doubt, need something more than your 4 gears. I intended to use all of your gears and dump them into a fresh 2.7L box on top of the existing shorter 1-2.

rickdm

If you want to limit second gear to 60mph all you need is a rev limiter.....6500 ought to do it ;-)

GrantG

Actually that won't do it. 2nd is so tall that even 6,000 rpm gets you over 60 mph

ceebee

GT gears
It would be helpful if you could do a compare of the max speed in each gear as from the factory
and max speed in each gear with the most common lower geared ring and pinion.

Petevb

As has been mentioned before, there is no lower ring and pinion currently available for this car. Thus it's not possible to answer your question.

ceebee

Surely Matt can do the calculations for one or more of the likely possibilities and give some
numbers for comparison.

Petevb

Matt has said elsewhere that there are both technical and business hurdles, and he won't be making a ring and pinion for the GT4. Perhaps someone else will, but I have yet to hear of it. I would prefer a R&P option, but this discussion is on a new 2nd gear, which seems the next best thing.

If you want to speculate, simply multiply all speeds in gears by a fixed percentage of your choosing...

Mike J

Wait, maybe I do not understand - the problem is the gaps between the gears, not the final drive. Sure, we can reduce the final drive so top of 2nd is more reasonable, but that would mean a stump puller version of 1st, which is not great for starts. The gap would still be too big - or am I missing something?

Petevb

It actually looks pretty reasonable- Porsche themselves did a shorter R&P between the 997.2 GT3 and GT3 RS. 1st is very tall now, 48 mph, so dropping it to 42 and 2nd to 68 would work pretty well.

It is true that rev drops are important, but to some extent you do get tighter rev drops, because with a R&P you'll be doing the tighter rev drop 4-5 shift at close to the same speed you'd have previously been covering the wider 3-4 gap.

GTgears

Pete's right, this is going off topic. This thread is about optimum speed for 2nd gear.







As you were. I'm not actually one of those territorial people who feels he owns a thread and that it has to go down a single narrow path of discussion. I like when a thread get a life of its own and develops multiple topics because it is just that interesting.

DeerHunter

I agree wholeheartedly. Now, any theories as to why Canadian GT4s have been held up in port for almost five weeks now?