Mooneggs wrote:I have just been informed that the 626/mx-6 tranny is identical to the mx-3 except for the final gear
No, not at all. The final drive is the gearing that multiplies your torque, leverage. The Mx-3/Probe and Mx-6/626 tranny's gears themselves are all the same, the final drive actually changes the (final drive) ratio of all the rears. (There is word that the 626 tranny uses a longer 5th gear over the Mx-6 tranny, but I have yet to find information confirming that)
In front-wheel drive, it's a weird concept to understand what final drive is because FWD cars use all-in-one 'transaxle' system, but if you break it down using a rear-wheel drive system of a transmission + drive shaft + rear differential, it's easier to understand.
In explaining this, imagine an Mx-3 and a Mx-6, but say they're rear-wheel drive. They would both actually have the exact same transmission, so all the gears from 1 through 5 (and reverse) would all be the same.
1st: 3.31
2nd: 1.83
3rd: 1.31
4th: 1.03
5th: 0.80
From that point on, this is where it differs. The final drive would be determined in the rear differential in the rear axle. If you ever hear anyone with a RWD car talking about them changing the gearing on the rear end, this is it. This basically changes the the length of all the gears without touching the transmission itself. On a RWD car, a final drive of 4.38:1 would mean that the drive shaft actually turns 4.38 times for every 1 turn of the axles/wheels. For 4.11:1, well, I'm sure you can figure that out. By having a larger number for the final drive, you bring the gears closer together (shorter), so theoretically improving acceleration, but having a lower top speed. If you have a smaller number for the final drive, the gears become longer, sacrificing acceleration for top speed.
Here's a basic break down for a FWD drive system
In red those would be your actual gears, 1st through 5th and reverse.
In green is where your final drive is determined; the small pinion gear and the ring gear around the differential. When it comes to the final drive in FWD cars, for the Mx-3/Probe, the pinion gear turns 4.38 times to make the differential turn once. In the Mx-6/626, it takes less turns, 4.11 turns of the pinion gear to make the differential turn once. A RWD car uses pinion gear & differential ring gear system as well, it just sits external to the tranny, in the rear differential, but function is basically identical FWD or RWD.
Now, in reference to the pinion gear and differential and how it determines the difference between the 4.38 and 4.11 trannys, it affects your LSD options. One of the options is to use the LSD from a MazdaSpeed Protege, but it's ring gear is matched for a 4.11:1 ratio pinion gear, so you'd have use an mx-6/626 tranny with 4:11:1 gears, swap the pinion gear from a 4:11:1 tranny into your Mx-3 tranny (if that's possible), or use the ring gear from the stock Mx-3 (4.38:1) differential and put it on the MSP LSD. There's also the Quaife LSD, it's pricey no doubt, but you need to use the ring year form what ever tranny your using.
As for which one, hard to say. I'm giving the 4.11 gearset a try. I've heard mix opinions on which one to use, I know a ZE Mx-6 driver who used the 4:38 tranny cause he said it was quicker, as well, I know a ZE Probe drivers who's car is apparently quicker with a 4.11 tranny, both guys are low 14 cars with street tires. Alot of people complain that the 4.38 gears are too short. Even though Probes uses the 4.38:1 tranny, they actually put larger tires on it compared to the Mx-6 to get the acceleration they advertised. So it's really hard to say. Reason why I want to try the 4.11, cause I do think they're a bit too short, I think that with slightly longer gears, 1st gear would be more useful, probably a better hole-shot if your dragging, you'd stick in the power band longer too with each gear, also that means less shifting as well as less use of the longer 4th gear (4th in 4.38 is still much longer than 3rd in 4.11). Actually, if I remember right, the Probe driver I talked to says he doesn't usually use 4th when he drags (Mooneggs confirms this). As well, I may miss the quickness of 5th gear. Despite that it revs farily high on the highway, it sits right in the sweetspot for power. However, it almost means with the higher gears that 4th is longer too, so I can downshift to it as a higher speed, and and hold that gear longer.
I hope this clears up all questions about the trannies
If anything, it may give you mroe questions, but hopefully you'll have more information to help you out.