How this idea? 20B + RX8 Transmission

[reddozen]

I'm with ted... Renesis trans is a bad idea. Not to mention the gear ratios are better in the jspec T2 trans anyway. If you're really insistent in "50/50 balance" then find someone local with a corner balancer and add weight to the ass end. That's what I would do rather than use a weak transmission. There are several threads on the RX8 club forums detailing all the weak parts and how / why they fail.

[RETed]

It's really a matter of physical limitations here...
With helical gear transmissions, stronger gears are a matter of making the gears wider.
You can get an idea of the strength of the transmission by looking at the length of the gear case itself.
Now, keep in mind that if you're looking at a 6-speed transmission, you're stuffing another set of gears for that extra gear over a 5-speed transmission.
So unless the RX-8 is using some different cut gears (dog cut gears) or exotic metals (highly doubtful), how does it's 6-speed transmission - which about the same length or slightly shorter than a 5-speed FC turbo / FD gear box - have stronger gears???

Rumor has it that the RX-8 6-speed transmission is a variant of the Miata 6-speed transmission.
Now, I can't confirm this, but it makes sense for Mazda to do this just to keep parts costs down...

So, go ahead and try and use that trans behind something putting down - at least - 300 easy pound / feet of torque at the flywheel and see how long it lasts...

Now, with that said and done...
Yes, if your shift technique is "delicate", you can minimize wear & tear of the transmission.
I do not doubt claims of extended mileage on these transmissions.
I do question why you would want to put it behind a 20B project?
Why not just stuff a non-turbo FC transmission behind a 20B if you're going to argue otherwise, since these transmissions are basically free for the taking?
There's "possible" and then there's "not recommended".


-Ted

[TitaniumTT]

Originally Posted by reddozen

I'm with ted... Renesis trans is a bad idea. Not to mention the gear ratios are better in the jspec T2 trans anyway. If you're really insistent in "50/50 balance" then find someone local with a corner balancer and add weight to the ass end. That's what I would do rather than use a weak transmission. There are several threads on the RX8 club forums detailing all the weak parts and how / why they fail.

No way man, the ratio's on the Jspec S5 TII trans are ABISMAL at best. The overdrive gear is the same to boot. I HATE the ratios in my trans, they suck.

Not to mention you never want to ADD weight to get a balance.

Originally Posted by RETed

It's really a matter of physical limitations here...
With helical gear transmissions, stronger gears are a matter of making the gears wider.
You can get an idea of the strength of the transmission by looking at the length of the gear case itself.
Now, keep in mind that if you're looking at a 6-speed transmission, you're stuffing another set of gears for that extra gear over a 5-speed transmission.

But the Aisin trans does NOT do this. Gears 1-5 are in the same case and the same length as the Type-R box. The 6th gear is in the extension housing.

Originally Posted by RETed

So unless the RX-8 is using some different cut gears (dog cut gears) or exotic metals (highly doubtful), how does it's 6-speed transmission - which about the same length or slightly shorter than a 5-speed FC turbo / FD gear box - have stronger gears???

See above for the explaination. I've owned or dissasembled or held in my hand gears for all the trans' listed in this thread and I can tell you that there is not a noticeable difference in the size of the gears between any of them.

Originally Posted by RETed

Rumor has it that the RX-8 6-speed transmission is a variant of the Miata 6-speed transmission.
Now, I can't confirm this, but it makes sense for Mazda to do this just to keep parts costs down..

.

It is, I can confirm it and Flyin Miata has used those trans' to some pretty serious HP levels.

Originally Posted by RETed

So, go ahead and try and use that trans behind something putting down - at least - 300 easy pound / feet of torque at the flywheel and see how long it lasts...

I plan on it, in about a month or so, except I'm making WAY more than that @ the flywheel. i'm putting down 323 to the rear wheels, and I'm NOT delicate. i have every bit of faith in the trans that was "blown" when I bought it for $200 delivered. Every single gear, sync, hub was reuseable. The bearings showed signs of wear, and of course I'm going to have the sync's replaced but I have no doubt that the trans will take the torque that I'm making.

Originally Posted by RETed

Now, with that said and done...
Yes, if your shift technique is "delicate", you can minimize wear & tear of the transmission.
I do not doubt claims of extended mileage on these transmissions.
I do question why you would want to put it behind a 20B project?
Why not just stuff a non-turbo FC transmission behind a 20B if you're going to argue otherwise, since these transmissions are basically free for the taking?
There's "possible" and then there's "not recommended".


-Ted

Ted, I understand where you're coming from, but honestly, how can you make such strong rec's based on internet research? Have you ever dissasembled an RX8 trans before? Compared it to FD/FC and miata gears? I have, and I built a trans that bolts in with some MUCH better ratio's than the craptastic mack truck shifting S5 TII box.