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Discussion Starter #1
On my NA, I am not a fan of the gearing. I do a lot of long range highway driving on road rallies, at "above average" rates of speed... And would like my miata a little more down in the RPM's for gearing..

I'm not against cracking open the case and replacing gears, i'm just not sure what the options are like for miatas, like if there is a gearset from a similar trans that can be swapped in...

I like the 1-3 ratios, but i'm curious if there is something like a .95 for 4th, and like a .780 for 5th, then I can swap out for a 4.1 FD, which will put me around 3200 RPMS @ 70 (with a 205/50/15), and 5k RPMs @ 108 or so... Which i'm perfectly fine with...
 

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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
 

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brontosaurus
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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.
 

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Discussion Starter #5
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...
 

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Just dial in your fuel with MS then. Aside from pumping/friction losses you won't save much, if any fuel swapping rear ends compared to fixing the fuel. MS will have a steep learning curve though, so hopefully you're ready for that.
 

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Discussion Starter #7
Just dial in your fuel with MS then. Aside from pumping/friction losses you won't save much, if any fuel swapping rear ends compared to fixing the fuel. MS will have a steep learning curve though, so hopefully you're ready for that.
I've got experience with Hondata, Chrome, AEM EMS, EvoFlash, RomRaider, PowerFC, FCDataLogIt, DSMLink, and a little bit of Motec & LINK... MS shouldn't be too hard from what I see. It actually looks like one of the more simplified systems i've worked with compared to subaru ECUS....
 

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I've got experience with Hondata, Chrome, AEM EMS, EvoFlash, RomRaider, PowerFC, FCDataLogIt, DSMLink, and a little bit of Motec & LINK... MS shouldn't be too hard from what I see. It actually looks like one of the more simplified systems i've worked with compared to subaru ECUS....
Good man. Yeah, once you pick up the couple idiosyncrasies of MS you'll be just fine. Hopefully you're going DIYPNP or MS3? Make sure you use the sequential injection add-on if you do.
 

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Discussion Starter #9
Good man. Yeah, once you pick up the couple idiosyncrasies of MS you'll be just fine. Hopefully you're going DIYPNP or MS3? Make sure you use the sequential injection add-on if you do.
Honestly, that's what I DONT understand is what all the differences are... There are so many options I don't know what i need.. I've been chipping honda ecus for over a decade, made all kinds of custom circuitry for cars for lighting/ECU control/etc... But there is just SO MUCH information on MS I can't figure out what is what.

In the meantime I may also pickup an eManage Blue since I can get it for pretty much free, and I already have the tuning software (I used to tune eMb and eMu as well), and throw that in there and see what it can get me...

It also helps that I get dyno time for pretty much free lol.
 
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