MSM 6 Speed worth rebuilding?
 

Over the weekend I let a friend co-drive my 05 MSM at an autocross. On his last run he told me he missed the 2-3 shift that was necessary before the finish line, and I didn't think much of it as I've missed that same shift multiple times over the years. While driving home from the event I noticed that 3rd was grinding EVERY time I was shifting 2-3. I texted my friend and asked how badly did he miss that shift, and his response was "pretty bad". :facepalm:

This car will very soon be getting a built BP4W with TonyMontana and Ryan_G's old TSE EFR setup, and my plan for that was to keep it around ~300whp to hopefully save my 6 speed. My dilemma now is do I even bother with trying to replace a synchro or find a new MSM trans or regular Miata 6 speed? Or do I buy once cry once and just swap a BMW trans? My car has 146k miles on the original drivetrain at the moment. My friend who co-drove my car is a mechanic and has offered to do the work of replacing the synchro if I buy the parts. He has rebuilt one T5 trans before with success.

Today I decided to drain and refill the Ford honey and see if that made a difference.

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Shavings present on drain plug magnet
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One visible sliver of synchro brass that I could see
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Fluid itself was pretty dark and swirly

This fluid had about 3 years and 20k miles on it (Yes I know I should've replaced this sooner). Does this look like a normal amount of metal shavings or glitter to you all? I refilled with new Ford fluid and the 3rd gear grind is still there on every 2-3 shift, so I'm thinking something is definitely fucked.

I did also remove the Miata Roadster short shifter and inspected all bushings and turret bolts, they are all good.

I have tried my best to search this interwebs this afternoon to see if anyone has successfully documented a 6 speed trans rebuild and came up with nothing.

What are your thoughts MT.net? Anyone got an MSM 6 speed for sale? :likecat:


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Here's a shot of what she currently looks like, as it has been many years since I've posted a pic here.

Also, current pictures of cats!
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Bambino in his Santa costume.
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Jemima doing what she does best.
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Big size difference!
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Chillin on the couch.

it might be worth a shot to try the Ford motocraft fluid if you are looking for an easy way out, threw some in mine and cleaned up some of the shifts. Maybe source another 6 speed in the meantime. Otherwise, I am not sure about a rebuild -- anything is possible with enough money ha

Rebuilding a MSM maybe difficult depending on the level of damage. Some of the MSM specific components are no long available through Mazda. It has been a few years since I went through the parts list, but IIRC the syncros are the same between the non-MSMs and MSM 6spds. The difference was in the gear part numbers and some of the shaft bearings.

I may not have explained it well in my first post. The trans had the Motorcraft fluid in it already, and I just drained and refilled it with fresh Motorcraft fluid and the grind is still there after the fluid change.

The trans feels normal and fine on all other gears, it’s just the 2-3 up shift. No whining noises while cruising or under any throttle. As far as the different parts go, that seems to be the same info I have come across while searching all the forums.