2004 MSM Six Speed Transmission and Clutch

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2004 MSM

Six Speed Transmission

and Clutch Replacement

Recently I bought some MSM shocks and springs at a very reasonable price from a fellow named Bruce. During our conversation I found we both had a passion for our Miatas. A few months later, Bruce sent me a note he was having trouble with the shifter on the six speed in his MSM.

He wanted to swap the transmission and clutch at the same time. After a long discussion about the problems he was experiencing, I offered to assist him if he wanted to visit and swap the transmission in my shop.

I really like helping people like Bruce who demonstrate their willingness to dig in and work on a project too. In the meantime, I made a new friend and learned a lot by working with Bruce on the MSM.

Bruce brought a replacement transmission from a salvaged MSM, a Flyin' Miata stage one clutch and the miscellaneous items that would be needed. However, the input shaft seal he got was for a five speed instead of the six speed. Most box auto parts stores only sell the seal for the five speed. Beware of that if you have a six speed. I always get that seal from the dealer.

Long story short, we removed the old transmission without much issue. It only took a couple of hours to get it out. The lift and my Frankenstein transmission jack made the job much easier.

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Once the transmission was out, Bruce wanted to look at the shifter so he removed the shifter housing. Apparently, it cannot be removed with the transmission in the car. He had a suspicion there was a loose bolt on the shifter. Well, IT WAS LOOSE!

That explained the shifting problems he was having. Not being able to shift to reverse, not shifting between certain gears especially when over 4000 rpm, and the side to side sloppiness of the shifter at rest. I have two six speeds and have not had any troubles like this (yet).

A test with another bolt confirmed the threads in the shaft were not damaged. What luck, especially after seeing the condition of the bolt.

We went ahead and installed the replacement transmission and the new clutch. As always, we also installed a new rear main seal and Redline MT-90 oil.

The install went very well until we got to the starter. The middle starter bolt was acting cross-threaded no matter what we tried. It took about and hour of trying until finally, we ran a tap into that hole from the backside to clean the threads and the bolt went in perfectly.

Bruce called once he got home to report that the transmission and clutch were working fine. When he gets the new bolt he will have a spare six speed for the future. I hope he never needs it.

I love it when a plan comes together!