Jason Saini

****UPDATE - I HAVE THE CONFIRMED '09 RATIOS, AND THEY ARE DIFFERENT. 3RD is 1.536, and 6TH is .787... so, good news for cruising, bad news for 3-4 rev drop. They should have just changed 6th. I will updated these charts accordingly, but another time. Cocktails are calling!****

I figured I'd start a new thread because my gear chart got buried pages deep within the misinformation of the other thread.

The 'strengthened' transmission, is acutally the MX-5 transmission. I saw a new RX-8 version of it when I was in the Mazda Tech center in Irvine last month. This is 100% confirmed. Completely different transmission, with slightly different ratios than the current Aisin box.

Provided the ratios don't change from the MX-5 transmission, the following should be a very accurate gear chart showing the differences between an '04-'08 car and the '09 R3. I omitted 1st gear from this, but first is significantly shorter, so it will run out sooner.

I'll work to verify that the ratios aren't going to change. We hope to have a test-mule transmission here to play with in a month or so, and when we do I'll let everyone know how it holds up.


Car (1st 2nd 3rd 4th 5th 6th FD)
04-'08' RX-8 (3.760 - 2.269 - 1.645 - 1.187 - 1.000 - 0.843 - 4.440)
09' RX-8 R3 (3.815 - 2.260 - 1.640 - 1.177 - 1.000 - 0.832 - 4.770)

Revs @60, '04-'08 RX-8 - 2nd - 8391.9 / 3rd - 6084.1 / 4th - 4390.1 / 5th - 3698.5 / 6th - 3117.9
Revs @60, '09 RX-8 R3 - 2nd - 8807.4 / 3rd - 6391.2 / 4th -4586.9 / 5th - 3897.1 / 6th - 3242.4


Speed @Redline, '04-'08 RX-8 - 2nd - 63.6 / 3rd - 87.8 / 4th - 121.6 / 5th - 144.4 / 6th - 171.3
Speed @Redline, '09 RX-8 R3 - 2nd - 60.6 / 3rd - 83.6 / 4th - 116.4 / 5th - 137.0 / 6th - 164.7


Rev drop, '04-'07 RX-8 - 2nd to 3rd - 6746.7 / 3rd to 4th - 6715.0 / 4th to 5th - 7839.9 / 5th to 6th - 7845.0
Rev drop, '09 RX-8 R3 - 2nd to 3rd - 6885.3 / 3rd to 4th - 6809.6 / 4th to 5th - 8061.4 / 5th to 6th - 7894.2

terrypk1

so does this mean the car will accelerate significantly faster in 1 and 2 gears?

or might be slower ( due to the more shifitings you will have to do )

ZoomZoomH

iTrader: (1)

should give noticeable better acceleration at exit of a turn on a road course, where shifting points matter less than getting better entry/exit speeds.

hell, even in a 1/4 drag race i think the new gear ratio will get faster trap speed.

dmc27

the MX-5 transmission is considered a very good trans, correct? Or is just considered good when compared to the POS Aisin in the 8?

LionZoo

I still don't like the fact that the 2nd to 3rd and 3rd to 4th shifts have about the same rev drop. In my opinion a 4th that drops the revs to about 7200 would be ideal from a performance point of view.

The current Aisin unit is not a bad transmission from a shifting point of view, it's just fragile.

velociti

iTrader: (1)

i'm sorry. POS how? it's been praised almost universally? do you mean in terms of the widespread gear grinding or what? i love the transmission and it hasn't done me wrong, though 4th and occasionally 5th now are starting to grind under hard acceleration. *****.

LionZoo

The MX-5 guys like their 5 speed better than their 6 speed. I say we take the S2000 unit and call it a day!

zoom44

well the previous generation miata's transmission was deemed good enough that the 6speed version was dropped into the RX-8. i dont know anyone whos ever called it a pos. as stated it can be fragile but its a very good tranny

77mjd

I don't like the fact that the revs in 6th @ 60 actually went up. That will be even worse for gas mileage.

dmc27

Lionzoo - that's what I was wondering. the 5 speed mx-5 trans seems to be well liked by owners, but I honestly know nothing about the 6 mt.

sounds like you answered your own question.

but like lionzoo said - it's fragile. somewhat lost in the engine replacement madness is the fact that there have been some tranny replacements as well.

dmc27

ok, so I guess I know plenty about the 6mt, then - thanks zoom.

thought the 5 speed mx-5 was not Aisin.

Mazmart

iTrader: (12)

The Aisin in the 99 to 05 MX5 is considered indestructable whereas the 06 Mazda NC Miata 6 speed has been less than stellar. I hope that they are considerably improved if the 09 RX8 6 speed turns out to be family to that box.

The Aisin in the RX8 is not a bad box but it isn't forgiving to errors in operation, especially grinding of gears, improper clutch engagement etc.

Paul.

LionZoo

I have to agree with what rotarygod previously speculated in another thread that the current tranny's woes stem mostly from rpm issues. Miatas seem to have no issue with transmission reliability and keep in mind the Mazdaspeed Miata has more peak torque than our cars.

Mazda made one change between the MSM tranny and the RX-8 tranny: they changed the 4th gear ratio from a 1.26 to a 1.19 for the RX-8. Why? The original 1.26 ratio would help with the 4th gear complaints...

dmc27

Ahhh. Thanks Paul. Obviously I wasn't paying enough attention over the last year & a half, as I knew the 5 speed was held in high regard.

No issues with mine (except the smell of redline fluid all the damn time) - so I will rescind my POS comment. Somewhat. Fragile isn't exactly a term one likes to hear regularly associated with the trans. Maybe POS goes too far . . . or maybe the smell is just making me bitter.

RoXanneBlack8

will the new trans bolt right up?

will the new ring and pinion bolt right up?

has thisbeen discussed already? prolly

Jason Saini

I rebuild all the gearboxes for our race team, and I've personally rebuilt dozens of each of the boxes in question. I have some insight into each version.

1. Venerable Miata (and 1st gen RX7) 5-speed. This box is nearly bullet proof, even in forced induction applications. Has been upgraded throughout the years, including helical reverse and dual-cone 2nd gear synchro in '94. Curiously, in '99, the retaining rings that keep the gears from 'overthrowing' were removed from the shift rods. PPF mounts from the passenger side.

2. MX-5 (2006+) 5-speed. This is a new version of the same venerable 5-speed box - exactly the same internals, and intermediate case, with a new bellhousing and tail shaft. This trans adds dual-cone synchros for 3rd and 1st, I think... it's been a while since I've been in one. This is the box that's so highly regarded by MX-5'ers, but it caused us nothing but problems when we tried to race them in the MX-5 Cup. The cases were twisting, and 3rd or 4th would regularly shear off. There was heavy evidence of the case twist. I don't think any of this would be a problem in a street application. PPF mounts from the driver's side.

3. Aisin 6-speed for '99-'05 Miata/Miata Turbo. Generally regarded as bulletproof, not raced as widespread as the RX-8 - but raced enough to know it's a good box. As noted above, has a better 4th gear ratio than in the RX-8. PPF mounts from the passenger side.

4. Aisin 6-speed for '04-'08 RX-8. Generally good reputation for street use, but very fragile for racing use. Big problems with 3rd/4th being overthrown and losing their shift-keys detent *****. Very poor metal quality for both steel and aluminum parts. Quick wear on shift hub slider teeth and matching gear teeth - causing grinding. Doesn't last very long in race use. We've made some upgraded parts that make them last better (one recently finished the NASA 25hr race,) but still a compromised design. At best, our fixes only extend the inevitable demise. PPF mounts on the driver's side.

5. '06+ MX-5 (and '09+ RX-8) 6-speed. Single case, or toploader design (much stiffer structure than the mult-part case on the other designs.) Very large gears, much bigger than the other gearboxes. Dual cone synchros on all but 5th, 6th and Reverse. The weakest link on this gearbox is the 3/4 shift fork. It's weak metal, and breaks quite easily. We have made a billet replacement for racing use, and I hope that the new RX-8 box has an upgraded part. We've passed on everything we learn to Mazda, they are acutely aware of this issue. There is an adjustment for 3/4th shift throw, and this being mal-adjusted is the cause of most complaints from street users - the dealers can't do anything about it, because it's not in the shop manual... we've worked with Mazda, and it should be added. There are also three plastic bushings that break when the trans gets to racing temperatures. Finally, the 3/4 shift hub is prone to cracking under racing use. The gears are very durable, and the teeth on the hubs/gears stay sharp even after two seasons of racing. MOST of this gearbox is bulletproof, and Mazda is aware of the weak links... I'm sure they have integrated some of these fixes into the RX-8 version of the gearbox, knowing the weight/hp increase that it will need to hold. I can only assume that they delayed putting it into the RX-8 until they learned as much as possible about it. I would confidently say this is the best gearbox of the bunch. PPF is mounted on the driver's side of the case.

Sharp readers will note that on both the 5-speed and the Aisin box, in the Miata application the gearbox is trouble-free, and the RX-8 and MX-5 applications of those same boxes, they don't hold up as well. REALLY sharp readers will notice that the PPF mounts on opposite sides in each case... making me believe that's too much of a coincidence. I think the side it's mounted on makes all the difference in how the tranny will last.

Overall, I'd be happy they went to this box... it should be much better than the current one, especially for street and autox/occasional track use.

As soon as we get one here to play with (hopefully very soon,) I'll let you guys know if the improvements made it in there, and how it holds up for us on the track.

secret8gent

hey I made a thread on this!
https://www.rx8club.com/series-i-tech-garage-22/4th-gear-ratio-132539/

I'm looking forward to when the details are confirmed.

delhi

I thought the 8's tranny is fantastic. Smooth and sure. In contrast the MX5's 6-cog is terrible. No way as good as its 5spd brother.

Jason Saini

Read my breakdown above - this is my experience with racing a building these boxes, not the opinions you heard over on miata.net. Take the time to read my breakdown above, and learn about each trans. The biggest complaints you hear about MX-5 6-speeds is due to an adjustment procedure missing from the shop manual...

See here:
http://forum.miata.net/vb/showthread.php?t=237737

LionZoo

Very interesting info Jason. It's odd that most people have problems on the 3-4 shift, but my gearbox is crunchy when cold on the 1-2 and 2-3 shifts unless I take care to shift very slowly. I really wish there was some way to put in a S2000 gearbox.

erx8s

Jason

Great info thanks , can i pick your gearbox brain and ask your candid opinion on the new clucthless Dual fully automated systems like the Audi / VW Dsg and the newly soon to be released Evo X TC SST .

Do you see this style box ever going in to a rotary engined car ? Possibly the new 16 X , If Mazda ever get around to actually making it .

Cheers
Michael

CERAMICSEAL

Jason,

thanks for a lot of great info. The early Miata went through even more synchro changes than you mentioned. It gained dual cones in 94 and again in 96 to my memory.

Quote: Sharp readers will note that on both the 5-speed and the Aisin box, in the Miata application the gearbox is trouble-free, and the RX-8 and MX-5 applications of those same boxes, they don't hold up as well. REALLY sharp readers will notice that the PPF mounts on opposite sides in each case... making me believe that's too much of a coincidence. I think the side it's mounted on makes all the difference in how the tranny will last.

The PPF is of course positioned in relation to exhaust position, are you saying that torsional forces are at work differently depending on the side the PPF is placed on?

Here's a controversal statement: Rotaries are harder on gearboxes than piston engines of equal power and even similar power curves.

Seal.

grantg

One other data point is that the Porsche 911 (997) uses Aisin gearboxes now (except in the GT models and Turbo)

Razz1

Can we move this to the tech section? It will be hard to find in the future.

Plus some readers may miss this.

zoom44

oh its a moving off to tech we go