Well, technically, a Quaife gearset in a 5-speed case. Purchased from David de Regt (codingparadox) a few years ago to replace my FM-built assembly that
expired on the track. Lost
3rd gear on this box about a year later and it was rebuilt using brand-new parts from Quaife. Been flawless ever since, mostly because I no longer use my L.E. for HPDE days.
The gears are much stronger than stock (even the stock 6-speed) and the original transmission put up with years of autocross abuse and hard street driving with north of 300 lb-ft of torque. Due to the semi-straight-cut design, they are noisier than OEM, which is ultimately why I've pulled this tranny from service. I only use this car for pleasure now (I have my
MSM for track-day duty) and have decided to turn down the boost, install a 6-speed and enjoy a (comparatively) peaceful driving experience. Other than the noise, the gearbox is a sweetheart that shifts flawlessly (on a par with any good 5-speed) and the synchros are in great shape. Ratios are ideal for a turbo car and, with decent tires, you can remain fully hooked up in 2nd gear.
For those that are interested,
this is a decent thread that addresses Miata gearbox issues and the quest for a bulletproof solution. Also
this. Many others can be found with a judicious search.
To create this gearbox yourself, you'd need to buy the gear set from Quaife in England (figure about $2,600+), about
$800 in OEM/Mazdacomp parts for a proper rebuild, properly clearance the case, plus add the required labour. You can have mine for
$3,200, shipped anywhere in Canada or the Continental U.S. For obvious reasons, I don't recommend this as an option for a track rat. It should, however, last indefinitely in a high-po street car, or for medium-high power (i.e. not Bob Bundy levels of ludicrousness) autocross use.
