I'm not really sure what the issue is. Noise? Perceived wear? Open loop gas mileage? A custom geared transmission will cost you more money than it's worth. Either swap rear ends, go Megasquirt to tune open loop (~4000rpm+) fueling, or get some ear plugs :v
Noise, not so much... Drivetrain Wear... Its a 1.6 I4 made to rev to 7k in a 2100lb vehicle... lol... Gas Mileage is a fairly large factor... Not for a money saver factor though... More for a fuel range factor on the long runs... I will probably be building myself a MegaSquirt in a few weeks so that I can start the high RPM open loop tuning...
What about a 3.636 ring and pinon gear set? :dunno:
I also autocross the car.. I think that the 3.636 rear would KILL what little power the 1.6 has... Even with a simple 5psi turbo kit I think it would still be dead on most of the autocross courses I run on (Small tight courses)..
Change your rear end. What year is your car? If you have a NA it is likely you have a 4.3 or 4.1 rear end. 90-93 will be a 4.3, 94-97 should be a 4.10:1. There is a 3.909 and a 3.636 that will do a good job at lengthening the gears. Both these gear sets came off 6 speed NB miatas. The 3.636 was not offered stateside. If you have a 90-93 you will need to swap to the larger 7" rear ends. The 94-05 miata read ends can accommodate the 7" gears. Expect to pay 500-800 on the rearend if it's a torsen, more for the 3.636 because they are rare and sought after.
Go on flyingmiatas website. They have a gear calculator. You can see how these different rear ends will effect your final speed and Rpms.
The only transmission gear options we have is the quaife gear set. Your looking at $3,000 not installed. If you had a 400hp miata, sure this would make sense.
This ain't a Honda. We don't have 10 different transmission gear sets that are interchangeable.
Well that's not really what I wanted to hear lol... I didn't know if an RX7 had similar gearsets or something like that...
I've got a 90, which means I have the 4.3..
I've got a spreadsheet i've been playing with this morning...
Switching to a 3.9 would buy me back like 300 rpms @ 70..
Then switching to a 195/55/15 instead of a 205/50/15 would buy me both less rolling drag resistance as well a little taller gearing...
hmmm... I wonder if that will get me what I need. Basically, I want to be able to cruise at a solid 80mph and still maintain high 20's to low 30's mpg range... Most of the rallies I do have checkpoints at less than every 300 miles, so I can typically schedule my stops accordingly... But I like to have that little bit of leadway wherever I can...
