So your very first post on mt.net ... is a request for a vendor to re-post information for you in a thread? Because you are "too lazy." So it's not worth your time to enter "site:miataturbo.net g-force gearset" into google, even though doing so would have taken you less time than typing your post.

Deerhunter was exceptionally polite in his response to this behavior. Perhaps if you went and made an intro post (in the intro post section), and then bothered to search at all before posting another question, the community at large will not conclude you are a total tool.

 

Absolutely too late.

Ban.

 

Data point.

Put in a stock 5 speed thought it might get me through the next two autocross events.

It Didn’t.

 

How long did it last Bob?

 

lasted two drives to work and back running old Hoosier H20's as street tires in the dry. Then lasted about 22 autocross runs between me and a co-driver running 275 Hoosier A6 on 11" wheels. Stripped second gear going across the finish line on a fun run. Did Nab overall top time and top Pax for the day yet again though. I also got the transmission for free basically.

Gear ratio was shitty for autocross though I swapped out the OS-giken that I normally run with a 3.636. for a Torsen with a 3.909 but it's still too tall of second gear with a stock 5 speed especially for what seemed to be the tightest course I've run all year. Wasn’t a high HP favored course where you could actually put an abundance of power to good use except the shoot to the finish.

 

great amount of information... love it...

 

i have the option of running gear dependent boost. For instance one boost mapfor1-4th gear(rpm/tps/temp dependent), and another full boost map, for 5th, another for 6th, etc..
is the 5th gear in the 6 speed box a direct drive (connecting the input/output shaft with no gears) like the 4th gear ratio in a 5 speed?
Has anyone broken the 5th "gear" and at what powerlevel. i am at 400whp now but i want to be able to run a higher boost level in 5th gear (dont really need it in 6th as i will just about top out in 5th gear with a boost increase on my local tracks when using a 3.636 diff.

to simplify.. will the 6 speed handle a higher boost level in 5th gear than in 4th?

 

5th is the 1:1 gear in a 6 speed. Can't help with the other questions though.

 

I've known race teams to cryo-treat all sorts of engine and transmission bits to strengthen them. If I was going to build a transmission that may be on the threshold of being too weak, it might be an option.

In SoCal the dominant transmissions are all for the high horsepower off-road trucks that push 1,000hp and more. The formula is pretty simple--get a bigger, heavier, more expensive transmission. The low end side of a Mendeola or Fortin trans is $5k, while the transmission Jean Louis Schlesser uses for Dakar is $25k.

 

Data point

There were a raft of FRS's at last weekends Superlap Battle. Some of those cars well over 400whp. No broken trans AFAIK. I'll do some more digging to find out if they were all on stock trans and exactly what power levels. The cars were running between 255-295 Hankook Ventus TDs mostly. They are between a Toyo RR and Hoosier R7 in grip.

 

I'm salivating.

It would be so great if there was a drop in or nearly drop in gearset for our boxes.

 

PAR have been an option for some time, but I assume you want to pay a bit less, and preferably as a complete internal assembly making the job DIY.

 

FWIW the stock FRS has the same exact gear ratios, input and output splines as the Nissan S15 240 SR20DET also in an AZ6 box. Same center section housing as a Miata.

 

We got an FRS/BRZ trans in last week to see what we can do to strengthen it. It'll probably come apart in the next week or so. Any questions about it while I can put my hands on it? I have an NB 6spd in the garage so I can make some external comparisons if anyone would like (not gonna pull it apart).

Poking around online I found the service manual here: http://www.ft86club.com/files/BRZtrans.pdf Looks like gears 1-3 are triple synchro'd...pretty nice.

I also ran across a build thread for a BRZ making 440whp/340wtq on the stock trans. Accelerated Performance BRZ-400 - Visconti Tuning - Scion FR-S Forum | Subaru BRZ Forum | Toyota 86 GT 86 Forum | AS1 Forum - FT86CLUB Not really any higher than the NB 6spd has put up with from what I've read here, but it will feel a lot better with the triple synchros.

 

Thanks for the link.

Centerline between main and countershaft on both trans. They are very close together in the Miata AZ-6 which makes it difficult to fit bigger gears in there.

 

Yep, and will do. I'll only be able to get an approx centerline dimension on the Miata 6spd as I have no plans to open it up. Do you have one apart with which direct comparisons can be made?

 

Someone else can get the Miata dimensions if necessary. The FRZ one is hard for us to get our hands on.

 

PM bbundy? I think he has about half the 6 speeds in the US sitting in pieces in his garage.

 

Depending on how it's designed internally, would it be possible to have a different centerline distance with the same external dimension?
I.e. are the external dimensions the same Miata/BRZ (those would be easy to measure/inspect)?

Only a little would make a difference of course, but if the castings are identical it would be surprising if there is room to move the secondary shaft, but not impossible of course.
No way to measure though the plugs?

 

At least with the 5 speed you can measure the shaft distance inside the bell housing because you can see where the bearing would be in the casting. I wouldnt be surprised if you could do the same on the 6 speed box.