Miata 1800 Transmission Pictures for RX7 Conversion
These are pictures of the 94 – 97? 1800cc Miata transmission needed for the RX7 conversion.
The important thing is that flat / machined area of the center plate – makes it easy to identify from the outside.
IT MUST BE MACHINED — if it is “cast” (like the RX7 center plate) then it is NOT an 1800 it is a 1600!!
The 1800’s have the needed wider gears and the double-cone 2nd gear synchronizer.
This is a closeup showing that flat/machined area of the 1800 Miata
This image shows the 1800 on the left versus the 1600 on the right
In the 1600 the 4th gear on the cluster gear does not line up fully with the gear on the input shaft — NO idea why Mazda did this!
This misalignment means the actual gear tooth engagement is really WAY less than it could be. Great picture of what we have seen when the 1600 Miata box was used.
The Miata 1800 4th gear to input shaft gear fully aligns — so WAY more tooth engagement than the 1600 and the actual gears are slightly wider.
This is the diagram with the dimensions needed when modifying the Miata input shaft to fit the RX7. This is in case you want to do the gear swap yourself and/or have a local machine shop modify the input shaft