I just thought I'd put these here. I have looked through the service manuals for the 1st and 2nd gen and can't confirmed these numbers via official Mazda literature but they're the best I can find. Issues with these Mazda's seem so rare I'm not sure many people will ever need this.
It seemed a waste not to collate and share what I found - even though I'm not sure what someone would want to know from it. I was looking to guestimate if the gen 1 and gen 2 1.8MZR engined 6's have the same gearbox by comparing ratios as well as ebay sellers photo's. My comparisons continue but the diff is very different, which doesn't mean its not compatible. 1st 2nd and 3rd are the same which makes them shorter, but 4th and 5th have been tweaked to bring the final drive of them back on track and keep the revs down at motorway speed!
I'm not sure why they would go to the trouble of altering the final drive
I would also like to consider fitting a 6 speed from a 2.0 MZR as the lower 1st to 5th ratio's better suit my entirely city based drive to work. My work will begin by comparing part numbers and photo to see if they use the same mounts/clutch/driveshafts/control cables etc.
1st gen 1.8MZR (June 2002 - June 2005, and facelift up to mid 2008)
Gear ratios :1 (& overall)
1st 3.666 (16.09)
2nd 2.059 (9.03)
3rd 1.392 (6.11)
4th 0.97 (4.26)
5th 0.755 (3.31)
Rev 3.166
Diff 4.388
2nd gen 1.8MZR (mid 2008 - mid 2010)
1st 3.666 (15.05)
2nd 2.059 (8.45)
3rd 1.392 (5.71)
4th 1.03 (4.23)
5th 0.795 (3.26)
Rev. 3.166 (13.00)
Diff is 4.105
2nd gen 2.0 MZR 6 speed (mid 2008 - mid 2010)
1st 3.45 (15.14)
2nd 2.06 (9.04)
3rd 1.31 (5.75)
4th 0.97 (4.26)
5th 0.8 (3.51)
6th 0.68 (2.98)