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mrvwcastner
mrvwcastner Reader
5/23/17 8:15 a.m.

What's an MX5 Mazda Speed transmission and rear end good for HP wise? 300HP shouldn't be an issue I think. Would need 3.6 ring and pinon. I've got an Exocet that's due a complete swap this winter. 02 built FM2 turbo VVT motor that's broken a couple of 6 speeds in the car it's in currently. My thought was detune it and since my car is currently at 1431lbs I should be ok. I love the idea of leaving it at the 320 HP current tune if possible instead.

Parts list for BMW swap includes....???

Transmission Rear differential Adapter plate Clutch and flywheel Custom length drive shaft?? Custom axles??

Am I missing anything else?

Keith Tanner
Keith Tanner MegaDork
5/23/17 10:10 a.m.

The limits are not black and white. Rear end is good for 400 if you don't wheel hop it. Trans becomes a liability at around 250 (5-speed) or 300 (6-speed) but not a guaranteed immediate failure. I don't think weight is a significant factor, as most of the trans failures I've seen have been in higher gears where the Exocet is as much drag as it is weight.

KMiata
KMiata New Reader
5/23/17 10:14 a.m.
mrvwcastner wrote: Parts list for BMW swap includes....??? Transmission Rear differential Adapter plate Clutch and flywheel Custom length drive shaft?? Custom axles?? Am I missing anything else?

Few other components are needed. Upgraded clutch MC and clutch line, rear trans mount, reverse light jumper, speedo adapter, custom shifter setup, and some misc OEM BMW parts.

Knurled
Knurled MegaDork
5/23/17 12:56 p.m.
NickD wrote:
KyAllroad wrote: In reply to APEowner: I suspect that's a problem with the rubber Miata motor mounts more than the shifter. You load it up in second and try to shift to third but when you untorque the driveline that 2-3 shift becomes a 2-5 because everything rotated counterclockwise a few degrees. The shifter worked perfectly but the target moves while you are shifting.
I've done a few 2-5 powershifts in my day. It's always funny.

Not as funny as a 4-3 upshift.

klodkrawler05
klodkrawler05 Reader
5/23/17 3:09 p.m.

Ah yes the ole BMW money shift.

That however is rendered pretty much moot by the "race" style shifter that most serious BMW track enthusiasts upgrade to. The difference is astounding, you'd swear it wasn't the same transmission.

K-Miata was smart to integrate that as part of their package.

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