WTB: 6 speed transmission

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Originally Posted by MoonieGT

What's the motivation behind this? Just currious. I thought I read that: 1) the ratios don't benefit fuel mileage, 2) on the track/auto-x you just end up shifting more -> slower, 3) the 5 speeds are stronger. Is any of that correct?

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Isn't the top gear ratio the same for the 5 and 6-spd? Just has 1 more gear.

Yes, on a road course, you will be faster with the 5-spd.

the 6-spd is stronger...survives 500whp+, whereas the 5-spd has a limited life over 300whp. The MYTH is that a 5-spd will break over 200whp+ (MT.net), which has been proven to be completely false over and over and over and over....but they still insist the 5-spd is too weak to run on a turbo car making any kind of power, but they sometimes throw "250whp" out there since 200whp is just soo ridiculously low. I have over 300whp, been that way for over a yr, and I don't have ANY ISSUES with my 5-spd. AND I BEAT THE CRAP OUT OF IT. The motor just finally gave up, but my built motor is already at Day Custom engine.

Rob is right, the cut on the teeth is different from American Iron, and the 3.63 is radically different from the 4.10 and 4.30 judging from my spare 3.63 in the garage which is next to my spare 6-speed, lol. Bo London built mine and it makes very little noise (good install) with a slight whine at 50mph.

The gearing with the 6-speed and 3.63 is sweet. This combo makes 1-5th gearing a touch "tighter" than a 5-speed/4.30, and then you have 6th gear so you get to cruise at 80mph at 3600rpm. I got 24mpg running 85mph with a 400lb tire trailer yesterday. If you can't find the 3.63 then go with the 3.90, I would appreciate gearing a touch tighter than what I have currently, but that highway gear is sweet. At 250whp, you'll use all of the 3.63 considering I was seeing 145mph on the front stretch of TWS on Friday.

Don't think the 6-speed is "strong" though. People are still wearing-out and blowing up 4th gear; I see 330*f gear oil temps with only 250whp so I am careful. I've had good reliability though with about 20 track days on my trans, but I baby it, slow clutch engagement, and lift over bumps at HHR.

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Originally Posted by ray_sir_6

The MYTH is that a 5-spd will break over 200whp+ (MT.net), which has been proven to be completely false over and over and over and over....

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list of people I know personally who've blown 5-speeds:
Andrew Kidd
Matt Andrews
Emilio Cervantes
Nick Cahill
People who've blown 4th gear at 330-350whp in a 6-speed
Bob Bundy
Andrew Kidd
Nick Cahill

We've been through this before and we'll have to agree to disagree on this deal.

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Originally Posted by ray_sir_6

Isn't the top gear ratio the same for the 5 and 6-spd? Just has 1 more gear.

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FM gearing calculator tells the truth.

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Originally Posted by ray_sir_6

Yes, on a road course, you will be faster with the 5-spd.

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Negative. My 6 w/3.63 drives like a 4-speed w/ double lows. 1st gear is for pulling it on and off the trailer, 2nd is for cruising the pit, 3rd is the lowest gear I ever use on the track. I only use 6th at TWS from "apron to apron".

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Originally Posted by mr brg

list of people I know personally who've blown 5-speeds:
Andrew Kidd
Matt Andrews
Emilio Cervantes
Nick Cahill
People who've blown 4th gear at 330-350whp in a 6-speed
Bob Bundy
Andrew Kidd
Nick Cahill

We've been through this before and we'll have to agree to disagree on this deal.

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Matt Andrews popped his at close to 400tq from a 2.0l stroker FM engine, so that hardly belongs on the list.

I can name 8 cars that have never popped their 5-spds, and they are ALL track cars. SM-Ts built by K.Verges at MSR-C. They are all making 270-280whp. KVs first car has been getting flogged at MSR-C almost every weekend for several yrs with zero failures...and he only runs a 1:18. :P

We had to replace 2 SM and ITA Miata Torsens at the 25hrs a few years ago, 2 out of the 3 cars broke them. No transmission failures.

I totally agree to disagree on this. I don't think either of us will lose any sleep over it.

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Originally Posted by mr brg

FM gearing calculator tells the truth.

Negative. My 6 w/3.63 drives like a 4-speed w/ double lows. 1st gear is for pulling it on and off the trailer, 2nd is for cruising the pit, 3rd is the lowest gear I ever use on the track. I only use 6th at TWS from "apron to apron".

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I guess I should amend my last statement:

...with a stock rear end.

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Originally Posted by ray_sir_6

Matt Andrews popped his at close to 400tq from a 2.0l stroker FM engine, so that hardly belongs on the list.

I can name 8 cars that have never popped their 5-spds, and they are ALL track cars. SM-Ts built by K.Verges at MSR-C. They are all making 270-280whp. KVs first car has been getting flogged at MSR-C almost every weekend for several yrs with zero failures...and he only runs a 1:18. :P

We had to replace 2 SM and ITA Miata Torsens at the 25hrs a few years ago, 2 out of the 3 cars broke them. No transmission failures.

I totally agree to disagree on this. I don't think either of us will lose any sleep over it.

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Matt popped that trans before the huge motor went in.

I thought Keith said he was running 1:21 and 1:22 all day in his SM-T? He was running 1:15 in the Blowtus at NASA TT; there is no way in hell that SM-T is 3 seconds behind the 400whp+, 1500lb, crazy aero, 255 Hoosier'd Blowtus, unless it's attached to the bumper with a chain. If it is and Keith wants to sign in and correct me, I'll eat my hat (but not the Robispec hat).

Also, there is no way in hell he's making 280whp from a 2560 on a log manifold. I've seen 1.8's with 2560's take enough spark angle to detonate from 12-18psi and they aren't going to put down more than 260 at the most on a Dynojet, and at that level you know as well as I do that after a few laps it will detonate and die. At 15psi you get extreme diminishing returns on that turbo and I've never seen more than 240whp come from one at that level.

Not sure if my 5sp was "blown" or not, but I know I had enough of the balky 2-3 and 4-3 shifts blowing my TT times. Enough was enough and if I'm going to swap, may as well go with the 6sp and the 3.63 rear. The 5s/4.10 was only good for 130 at TWS and that cost me for sure. Just a tad over 200hp.

It could have been opened up and repaired, but then the rest was still 115k miles, and I showed it zero mechanical empathy over several hard sessions (lession learned, 1 motor + 1 trans). Now I'll go for the trifecta and see if I can toast a 3.63 diff.

It will be interesting to compare data between the two setups next time I hit tracks that I have current data on. I'm also thinking that this setup and the 13" wheels may work pretty good. The car handles much better, but runs out of steam on top pretty fast with those wheels and the 4:10.If I recall, redline in 5th just past the s/f at TWS around 122mph.

Agree with the possibility of 4x4 shops perhaps not being the best choice with import pumpkins, and the choice of installer won't come lightly. I'd prefer to do it once.

Searching and searching the interwebz, the 6sp and 3.63 seems to be the preferred setup for the hardcore track junkies and I really see no reason to experiment from it. But it seems the 6sp grenade too, so we'll see. If I can pick up 1 second I'll be happy, as the driver has 1 or 2 more left in there somewhere..

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Originally Posted by mr brg

Matt popped that trans before the huge motor went in.

I thought Keith said he was running 1:21 and 1:22 all day in his SM-T? He was running 1:15 in the Blowtus at NASA TT; there is no way in hell that SM-T is 3 seconds behind the 400whp+, 1500lb, crazy aero, 255 Hoosier'd Blowtus, unless it's attached to the bumper with a chain. If it is and Keith wants to sign in and correct me, I'll eat my hat (but not the Robispec hat).

Also, there is no way in hell he's making 280whp from a 2560 on a log manifold. I've seen 1.8's with 2560's take enough spark angle to detonate from 12-18psi and they aren't going to put down more than 260 at the most on a Dynojet, and at that level you know as well as I do that after a few laps it will detonate and die. At 15psi you get extreme diminishing returns on that turbo and I've never seen more than 240whp come from one at that level.

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Yes, all day...on shaved RA-1s maybe. On slicks he runs 1:18s. I used to hang out with the guy who built and dyno'd KVs cars (Chris) and he had them making as much as 300whp, but dropped them to 270-280whp cause they actually ran faster laps.

KV is "modest" when he talks about his SM-Ts, cause he doesn't want anyone to really know. Just watch his vid against the C5 Z06 (w/ mods) on youtube and tell me if he is only making 225whp like he claims? If you want a comparison video of what a REAL 226whp Miata runs like when compared to a similar power-to-weight car, you can watch my vid against the 500whp Evo. Compare what happens on the straights, and it's pretty obvious he's close to 300whp.





Hint - KV pulls the Vette, I get pulled (badly) by the Evo

Guess how many 5-spd KV has gone thru? How many of his other 7 SM-Ts have broken a 5-spd? Zero. He is still using the same tranny as in that video from 06.

I ran all weekend with shit like a 500whp STI, 700whp GTR, C6Z's on Hoosiers at both TWS and HHR and pulled the Vettes on the front-stretch at TWS due to exit speed and the GTR beat me up in the corners at HHR thanks to the 335 Hoosiers; he did not pull me through the kinks or on the corners where I could carry momentum and he's an HHR member...and I made 250-ish whp on ATS' dynojet. I'd like to know how the hell he's making 280+whp on a stock motor, not blowing it up, and doing it on a 2560 with a log manifold without water injection, and I know he's not running more than 25* of spark angle especially on the stock coil with 9:1 compression.
http://www.altaperformance.com/share...1_1_comp_e.jpg
The compressor map doesn't post far enough "right" to support that kid of flow on that turbo and he's not running 17psi through it. If he were somehow making that kind of power he'd bend the rods. Put a 2871 on it and run 16psi through it with 15* of spark and it might happen, but that motor won't take it and his turbo is tiny.

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Originally Posted by ray_sir_6

Isn't the top gear ratio the same for the 5 and 6-spd? Just has 1 more gear.

Yes, on a road course, you will be faster with the 5-spd.

the 6-spd is stronger...survives 500whp+, whereas the 5-spd has a limited life over 300whp. The MYTH is that a 5-spd will break over 200whp+ (MT.net), which has been proven to be completely false over and over and over and over....but they still insist the 5-spd is too weak to run on a turbo car making any kind of power, but they sometimes throw "250whp" out there since 200whp is just soo ridiculously low. I have over 300whp, been that way for over a yr, and I don't have ANY ISSUES with my 5-spd. AND I BEAT THE CRAP OUT OF IT. The motor just finally gave up, but my built motor is already at Day Custom engine.

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Sorry to interrupt the pissing contest, but could you please define "BEAT THE CRAP OUT OF IT" for me? Track, Drag, AX, Street, all of the above?I'm curious about the statement of a 300hp, beating the crap out of a 5sp, in a '91 and it's holding up. What rear end are you running?

For me, the vids are not worth much. Apples to oranges kinda thing with different drivers/tires/etc.. I'm more interested in lap times. I can't find anything from Mighty Mouse other than this one apparent hpde session. And it looks like you are babying it alot because of traffic (I would shoot myself if I was in that group). So wheres the hard driving? How many track hours this past year at 300hp? What times are you getting at msr-c (or elsewhere)?

How many races/sessions are the SM-T cars putting in a year? You say "we" swapped Torsens. Are you driving one of the SM-T/SM/ITA's in the enduros? How many races/sessions per year on the FI 5sp getting?

Also, why would you say on a road course a 5sp will be faster? I would think that most tracks only involve 3 gears. 2-3-4 in a 5sp and 3-4-5 in a 6sp, so the amount of shifting should be equal. Have you tracked both? Impressions?

Again, not interested in pissing matches or drama, just trying to get facts regarding the issue of what is the best setup for miatas that are tracked hard. The majority of the web says 6sp is better for FI reliability and you say otherwise. Help me out here?

Damn, back to hijacking..

Thread drifting is a sport on this forum.

Wow! As the OPer I had no idea what I was about to start. All great information as far as I'm concerned.

My car was dynoed at 215 whp/187wtq when Gary had it 2-3 owners ago. So I'm guessing it's still making somewhere near that power. My 5 spd was supposedly rebuilt a few months before I bought the car. I got right at 10 track days (if you count the 2.5 laps I drove last Thursday) on it before it grenaded. About half at MSR 3.1 and half at ECR. Granted, part if not most, of the strain on the trans was probably driver error. I still consider myself a track noob.

Anyway, keep the info coming in. I don't want to waste money buying the wrong thing.

Ask Gary how many and how long a 5-speed lasts in his red car. I chose a 6-speed because I wanted to make it home from the track, the ratios are awesome with the 3.63 and my car is faster because of it...significantly faster.

I have broken one 5 speed in my SM Turbo car and have raced it and tracked it extensively, including winning the NASA 2008 4 hour enduro overall and first in class in the 6 hour enduro the next year. That said, renters have broken 2 of them.

I think the loose nut behind the wheel affects transmission longevity to a significant extent.

Track, drag racing, and street. 4.1 torsen rear.

The gears are more spaced out in a 5-spd.
http://www.flyinmiata.com/tech/gearing.php

It also has a higher top gear. If you go with a 3.63 rear then it will space out the gears to make a 6-spd better.

I was on the pit crew for a 25hr of Thunderhill Miata team a few years ago. KVerges was also on that team.

All of KVs cars run the same 4.1 rear end, plus stock 5-spd. The comparison is to better estimate whp levels, since KV isn't gonna give out his real numbers. You'll see his "225whp SM-T" pulls a 380+ C5 Vette, while my dyno'd 226whp 5-spd Miata gets drug by a 500whp Evo. The Evo weighs over 3800lbs with driver, my car weighed 2350lbs with driver. This clearly shows that KV is sand-banging on his whp rating. I wouldn't be surprised if he was meaning 225tq.

And KVerges has shared his experiences. thanks

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Originally Posted by kverges

I have broken one 5 speed in my SM Turbo car and have raced it and tracked it extensively, including winning the NASA 2008 4 hour enduro overall and first in class in the 6 hour enduro the next year. That said, renters have broken 2 of them.

I think the loose nut behind the wheel affects transmission longevity to a significant extent.

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I don't doubt that my hamfisting helped mine to it's grave. Thanks for the input.

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Originally Posted by ray_sir_6

Track, drag racing, and street. 4.1 torsen rear.

The gears are more spaced out in a 5-spd.
http://www.flyinmiata.com/tech/gearing.php

It also has a higher top gear. If you go with a 3.63 rear then it will space out the gears to make a 6-spd better.

I was on the pit crew for a 25hr of Thunderhill Miata team a few years ago. KVerges was also on that team.

All of KVs cars run the same 4.1 rear end, plus stock 5-spd. The comparison is to better estimate whp levels, since KV isn't gonna give out his real numbers. You'll see his "225whp SM-T" pulls a 380+ C5 Vette, while my dyno'd 226whp 5-spd Miata gets drug by a 500whp Evo. The Evo weighs over 3800lbs with driver, my car weighed 2350lbs with driver. This clearly shows that KV is sand-banging on his whp rating. I wouldn't be surprised if he was meaning 225tq.

And KVerges has shared his experiences. thanks

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Thanks for the re-cap.

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Originally Posted by ray_sir_6

Isn't the top gear ratio the same for the 5 and 6-spd? Just has 1 more gear.

Yes, on a road course, you will be faster with the 5-spd.

the 6-spd is stronger...survives 500whp+, whereas the 5-spd has a limited life over 300whp. The MYTH is that a 5-spd will break over 200whp+ (MT.net), which has been proven to be completely false over and over and over and over....but they still insist the 5-spd is too weak to run on a turbo car making any kind of power, but they sometimes throw "250whp" out there since 200whp is just soo ridiculously low. I have over 300whp, been that way for over a yr, and I don't have ANY ISSUES with my 5-spd. AND I BEAT THE CRAP OUT OF IT. The motor just finally gave up, but my built motor is already at Day Custom engine.

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I guess you don't beat yours up as bad as me, I've cratered 3 5 Speeds in the last two years or less, and I normally stay around 5 PSI or around 215 WHP.



and MR. BRG you know that I've had my trans replaced at least once for sure. I'm very sad that you forgot me on your list :(

At 215whp? WOW. I have been running 1.2-1.3 BAR (17-18 psi) on mine for over a yr now, and not even a whine from my 5-spd. The motor died, and I am sure the Greddy turbo is gonna end up dying in the near future as well (gonna run 1.6 BAR {23-24psi} on the built motor with it). I'm gonna see just how much I can get out of the TD04H-15G before I upgrade. Has anyone made 320whp on a Greddy (no porting, no modding of any kind).