Transmission Conversion

Converting a C56 transmission from a 20V for use in a RWD MR2:

I wanted to use the c56 transmission that came with the silvertop, as I did not have a c50 or c52 to work with due to the fact that my car was an automatic.

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So let the conversion begin! I purchased a full new seal set and got to work. You need to drill out a hole for the new oil seal so that you can swap the selector shaft around. drilling this hole took a lot of time and I needed my makita high-power dremel for most of the work. Finally though, the oil seal went in nice and smooth. Be careful, it is easy to remove too much material, I did this and needed to patch up a hole with some JB-weld. Also, while drilling this hole, try and prevent bits from entering the transmission, this is almost impossible, so after the conversion I put in some cheap tranny oil, ran the car for a few km, then drained and put in new oil. The number of shavings that came out with the oil change was impressive.

You need a selector shaft and end-plate from a c50/c52, so I purchased some from a local enthusiast. I also put in new oil seals for the drive-shafts. Finally, I put in a magnetic drain plug just for the hell of it. Also, I made the tranny nice and shiny by cleaning it with a wire brush.

I tried ordering a new slave cylinder, but despite having the right part number from exedy, the slave didn’t fit, it was the wrong shape. So I ended up using the old slave and rebuilding it using a Toyota kit, about the same price, fits perfect.

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The last thing is you need to swap out the speedo gear. The c56 has an electronic speedo gear whereas the c52 uses a mechanical one (cable). The MK1 MR2 makes use of the mechanical type, so unless you swap it out, your speedo gauge will not work (or you can install an electronic speedo and use the new sensor).

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