# Manual Transmission Upgrade? MF3/MZ0/MR5/MZ4



## dillonm24 (Nov 5, 2020)

Hey, just wondering how this went.


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## endarvr (5 mo ago)

So FYI, I did this. Swapped out the stock MF3 in my 2011 Eco to a 2014 MR5. *It works, though my car now illuminates the up-shift light even though I'm in 6th gear on the MR5 *(I may just get behind the dash and try to disable that light, since I need to replace my cruize control light anyway). A few notes:

2014 MR5 is larger, and seems heavier (this is likely in part due to larger outer case, and larger shaft bearings, though I swapped the open diff with an LSD, which contributed a few lbs as well). This is a consideration if you are trying to keep weight down. The same applies to the GMPP (upgraded OEM clutch/flywheel). So if you can deal with reduced longevity and the longer gearing, may be better to just stay with Eco parts. Guessing 20-30lbs more on the MR5+GMPP which I "upgraded" to (not to mention increased rotational inertia).
From what I can recall, there are only two sensors on the manual trans: reverse switch + input shaft(?) speed pickup. Given that my car now illuminates the up-shift light even though I'm in 6th gear on the MR5 (=5th gear on the MF3), it seems that the computer is inferring the selected gear based on input shaft speed and output shaft/wheel speed.


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