twokrx7

iTrader: (1)

Anyone found out if the Rx8 6-spd will retrofit into a third gen?

CrackHeadMel

iTrader: (2)

YAW power said when they were dyno'ing the renisis that it had the same bellhouing pattern as previous rotaries

Mld>7

The renisis is still a 13b!.. it even says it on the side of the engine. You should also know that the Rx-8 tranny isnt designed to hold as much power as the Fd's.. you may have problems in the future with reliablility.

Evil Aviator

So what is the torque rating of the RX-8 6-speed transmission?

astrochild7

iTrader: (3)

that would be sweet if you could a 6 spped is in my dreams

j9fd3s

iTrader: (3)

you guys are 6 speed happy, more is not always better

Rotortuner

Very true, it would be nice to have more gears so that you an take more advantage of tourqe amplification. However there is more floating rotating mass rotating inside the 6 speed. its likely they wont shift quite as fast as something like a 4 speed.

CJG

rotarygod

iTrader: (1)

Unless your powerband goes up to about 9500 rpm there isn't much point having the RX-8 gear ratios.

Evil Aviator

I like 6-speeds, but the RX-8 6-speed has a pretty bizarre gear ratio. There is only one overdrive gear, and it is the shortest "windout" gear on an "RX" vehicle since the 0.862 in 1976. This is the first car I have seen that needs to run the chassis dyno in 5th gear, lol. Also, what's the deal with the stump-pulling 1st gear ratio?

1) 3.760
2) 2.269
3) 1.645
4) 1.187
5) 1.000
6) 0.843

Who would want this in their RX-7? I think those ratios are too tight for anything useful, although I am welcome to input from those who have better insight on this issue.

Now the 4.444 rear end gear may be another story. Does anybody know if the RX-8 uses the long pinion design?

BLUE TII

iTrader: (9)

Is it true the Honda S2000, Mazda Miata and RX-8 6-speeds are all very similar units built by AISIN? I thought I read this in a magazine.

I don't believe the S2000 or Miata 6-speeds are known for their strength...

This sort of component sharing would not be that unusual for Japanese cars, BTW.

cewrx7r1

iTrader: (2)

You have to compare them with different differential gears to see the over all affect.

Gearing for the same ratio for top gear, you would have:

6 speed with a 3.5 diff-------5 speed with the 4.1 diff
(1) 13.13------------------------14.28
(2) 07.94------------------------08.26
(3) 05.76------------------------05.70
(4) 04.16------------------------04.10
(5) 03.50------------------------N/A
(6) 02.95--------------------(5) 02.95

The 6 speed with this setup would have a taller 1st and 2nd gears, with 3rd, and 4th almost equal. 5th being a new gear and 6th the same.

This could work as with about 350RWHP with stock 5 speed, 1st is almost useless for full acceleration, and 2nd gear still bearks loose a litte. The 6 speed would help here. Then you have the gear inbetween the old 4th and 5th.

I'd take it if you can get a 3.5 rear.

Barwick

NONSENSE!!!! You can always figure out how to use that new gear.

What about using the automatic differential with a 6-speed gearbox? Make use of those 3.91 gears in the automatic.

j9fd3s

iTrader: (3)

ive driven a few miata's with and without the 6 speed, and unless you drive on the auto-x track its just more work. 1st redlines at like walking speed and 6th is lower than the 5 speed's so it turns more rpm on the freeway, and then you have 4 other in between gears, where 3rd is good on the 5 speed box....

i dunno call me lazy but i'll take the 5speed

mike

twokrx7

iTrader: (1)

I'd settle for a 5-spd with decent synchros, tired of crunching 5th on the rebuilt trans ... was hoping the Rx-8 6-spd would have better designed synchros.

crispeed

Actually a lot of the 6-speeds are like that now. The 6-speed Getrag in the Supra is also the same. The 1st gear ratio is also very close to that of the Mazda's 6-speed and they share the same 5th gear ratio. On a NA car you would need more in-direct gears to help with acceleration.
Sometimes #'s on paper don't look all that good but in actuality they work out for the better.

rotarygod

iTrader: (1)

I drove the RX-8 a couple of times and the 'stump pulling' gear ratio doesn't seem that bad. The car will still do 80 mph in 2nd gear but that is at 10000 rpm vs 75 mph in my 2nd gen in 2nd gear at 8000 rpm. Remember that the total tire diameter is MUCH taller than the previous cars so some of that low gearing is made back up. Just so you all know, I can personally verify fuel cut at 10000 rpm in that car!

j9fd3s

iTrader: (3)

they used triple cone synchros on i think 2-5th

mike

joe-c

iTrader: (2)

i was wondering about this for awhile now

j9fd3s

iTrader: (3)

you dont know?!

t-von

iTrader: (8)

Here's some quick misc info of the Rx8 tranny.

The input shaft size is the same as the 2nd and 3rd gen Rx7's, meaning it will fit the turbo II and Fd clutch disc. The clutch design is the older push type. They shift like butter once fully broken in. Speedometer is electrical like the Fd's. Bellhousing will match any older rotary.

diabolical1

iTrader: (3)

great info, t-von. thanks.

Xantium

I've had my rx8 for 17k miles and am on my third tranny.
Essentially the syncros wore out really fast the first time. Then they rebuilt it and it blew up randomly. The rx8 has one of the worst trannies out there.. its kind of why I'm selling the rx8 actually.

t-von

iTrader: (8)

Those are some very powerful words you got there. I'm sorry to tell you that your individual experience doesn't really speak negatively for the Rx8 tranny. The fact of the matter is that the mechanic that did your repair just did a poor job. Period! The tranny is very well engineered. I actually work for mazda and have never heard of any reoccurring problems with the tranny's however, any transmission is extremely difficult to work on when untrained. Background!

A couple months ago we had an 8 come into the shop that wouldn't engage 2nd gear. The child owner of the vehicle had been power shifting from 1st to 2nd which is abuse and voids warranty. He was fortunate as we convinced the warranty department to warranty the repair. Due to the situation, Mazda wasn't going to provide a reman but instead authorized internal repair. The very experienced mechanic had yet to work on an rx8 tranny. We ordered all the parts and began work. The tranny went back into the car and on the road for a test drive.

Everything seemed fine until he tried to engage 6th gear. No dice! Confused we drove back to the shop and he pulled and completely disassemble again. He found that he had inadvertently reversed the 2nd gear clutch hub sleeve by accident. With this problem rectified, we were back on the road for yet another test drive now to find that 2nd gear was now grinding into place. The mechanic was now getting frustrated.

Apart again it came. This time it was the syncro to the 2nd gear. He accidentally over pressed the gear into place crushing the new syncro. After receiving the new parts, we are now on another test drive. With gears 1-6 working great there was a sigh of relief. I told him to check reverse. Color metaphors began spewing out the mechanics mouth as reverse was now grinding. This time the reverse clutch hub sleeve was backwards.

I know this sounds redundant but the sleeves are really hard to tell the proper direction. Anyways, back on the road hoping that was the final straw. NOPE! Now 2nd gear was popping out and the shifter was tight. I suggested to him that maybe the shift linkage was bent from all the tear downs and reassembly. I personally felt this was why the 2nd kept popping out. I tested the linkage and sure enough, it was binding. With new parts on order, the mechanic decided to go to mazda training on the tranny. Buy this time he was and expert with the tranny and knew even more about it than the instructor. LOL!

When he got back from class he reassemble the tranny and now everything was perfect. The tranny now shifts even better than new. I told him that there was a bright side. He really got to learn something he was in fear of for many years. Now it's something he can easily do if he ever gets another one in the shop. I personally was fortunate and over came some fears at his expense and learned a ton.


The moral of this story is even trained professionals have limitations and fears. Transmissions repairs in general are extremely difficult to work on ( especially if you don't understand and can't visualize how they work mechanically ) and are better suited for specialized transmission shops because that's all they do. It's all about knowledge and repetition. Unfortunately, the Rx8 tranny is made so well that a huge percentage of Mazda mechanics have never and may never actually get the chance to internally worked on one in the real world. Training classes only educate you, but doesn't guarentee your going to retain all that knowledge in the future.


Xantium my advise to you is to find a mazda shop that is truely capable of fixing your problem.

j9fd3s

iTrader: (3)

its not electric like the FD, the rx8 uses the abs wheel sensors, so there is no speedo gear/drive/sensor in the rx8 trans.

j9fd3s

iTrader: (3)

yes these are difficult to assemble! did you watch or help em? the way the book has you do it you end up assembling both shafts, lifting them up in alignment, and while you're installing em in the case, you need to sneak in the reverse idler.

next time it would be easier with a jig, holding 60lbs of shafts/gears isnt any fun, and it cant be how they do it at the factory....

also we've just been replacing the whole assembly, by the time you add up the internal parts ($$$ and they dont have em!) and the labor, its cheaper and quicker to to the whole thing. i know thats not what tech line says, but they are incorrect on this one.