Reflections on Changes with Time and Aging After Major Maintenance of the Jimny Sierra (JB43W Transmission & Clutch Replacement)

A customer who owns a Jimny Sierra reported noise coming from a specific gear (especially 4th gear), so I first drained the oil to assess the internal condition, and found a large amount of metal powder attached to the drain bolt’s magnet.

2015 model ABA-JB43W M13A 5MT PT4WD Mileage: 196,000km

It’s almost certain that a bearing in the 4th gear inside the transmission case is damaged. Along with replacing the clutch with a new one, we’ll replace it with a transmission obtained from a relatively reliable rebuilder.

The engine and transmission form one large integrated unit. This unit is secured to the frame with three rubber mounts (left and right of the engine, and behind the transmission), floating on seismic rubber. So when the transmission is detached, the center of gravity changes, causing the engine to tilt forward and distorting the mount rubbers.

If no precautions are taken, the moment the transmission is separated from the engine, the engine tilts forward, the axes between it and the transmission become misaligned, and the transmission case interferes with the center tunnel. This can lead to a deadlock situation where you can’t move forward or backward.

To prevent this, we support the front of the engine from below with another telescopic support rod, but since the Jimny has lateral rods and relay rods lying underneath the engine, we need to set it carefully through these gaps.

After removing various parts such as the propeller shaft and center muffler, it’s finally time to detach the transmission.

Looking up at the Jimny’s transmission mounting position from below the lift, it’s positioned quite high and fits tightly into the center tunnel. Especially with this vehicle being lifted about 3 inches, the leading arms that run parallel to the frame on the front left and right hang down, making it extremely cramped when inserting the transmission jack (equipment to support the heavy transmission), leaving almost no space for the mechanic.

It started to seem faster to just do it manually rather than fussing with various aids (I remembered doing this last time too, haha), so I removed the transmission from the tight space (the photo shows installing the new clutch after removing the transmission).

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Then, I manually install the rebuilt transmission in the same way.

Despite the daytime temperature being only 5-6°C, this series of tasks is power-intensive, making me sweat profusely even in short sleeves. While performing these physically demanding tasks that require the same strength as when I was younger, I suddenly consider my age. Yes, I’m approaching the retirement age of my grandfather’s generation of company employees.

When retirement age was 55, I was in elementary school, and my perspective on adults might have been different from now, but I remember that people who had reached 60 (five years after retirement) were unmistakably elderly in every way, and I felt no incongruity at all with 55 being the age to retire from active service.

However, my current physical abilities, despite making some adjustments after frequent scintillating scotoma last year, are quite different from the elderly image I had as an elementary school student (of course, I’m careful about various things and make efforts because of work like this). It makes me wonder if the Earth’s rotation and revolution have simply become faster compared to the past, making it seem like time passes quickly while aging slows down. I seriously question whether advances in medicine and changes in social environment can prevent aging to this extent.

This sense of incongruity seems to apply generally to others as well, and the talk of a “100-year life” somehow doesn’t quite convince me.

This is an illustration called “A Man’s Life/A Woman’s Life” that Osamu Tezuka drew in “Wild Maria” in 1970 (Showa 45), the year I was born. Don’t you think it’s an interesting illustration?