Sequential Shifting Is The Best Thing About My Motorcycle Powered Car

Illustration for article titled Sequential Shifting Is The Best Thing About My Motorcycle Powered Car

There are a lot of great things about driving a 12,000 RPM Honda that is over half a century old and has no roof or interior. It is visceral; you are connected to the drivetrain and the road in a way that is basically impossible in anything other than a go-kart. It does come with some drawbacks, like the fact that it is INCREDIBLY LOUD inside, and usually quite dirty. The advantages, however, outweigh the drawbacks in both quantity and quality.

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The shifter, for instance. My shift lever is connected to the transmission through two pushrods and a bellcrank. Inside the transmission, the shifter activates the gear change by rotating a drum that slides gears around, engaging and disengaging dogs. Push forward to shift down, and pull back to shift up. No H-pattern, no sloppy cable, and no electronic controls. The only thing between my hand and the gears is some metal and a few short steps of mechanical engineering, the only real kind of engineering.

Sequential motorcycle transmission
Sequential motorcycle transmission
Image: Andrew Walch (Flickr)
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I also have my clutch on the shift handle. The motorcycle transmission has a motorcycle slave cylinder, so it is easy to just use a motorcycle master cylinder to activate it. I like this part as well; it’s just like riding a motorcycle and I’ve always had better clutch control with my fingers than my left foot.

Illustration for article titled Sequential Shifting Is The Best Thing About My Motorcycle Powered Car
Photo: Matt Brown

This whole setup is pretty great, but I think the part that I enjoy the most is the sequential shifting. I think it is much better than the H-pattern shifting you typically see, and I think it’s a little odd that we haven’t seen sequential shifting more in cars, especially high-performance cars. There are companies that sell kits that turn an H-pattern shifter into a sequential shifter with some mechanical wizardry. Also, lots of racing transmissions are sequential, and basically all motorcycles have the same sequential shifting pattern.

There are some drawbacks of sequential shifting. The obvious one is that you don’t know what gear you are in without a separate gear indicator. You can’t just look at the shift lever and see where it’s at. This is also true with paddle shifters and is easily fixed with a sensor and a small digital readout on the dash. You also can’t shift over gears, meaning that you can’t go from fifth to first without going through fourth, third, and second. I see this as a minor inconvenience that has almost never been an issue for me.

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H-pattern shifter
H-pattern shifter
Photo: Vetatur Fumare ( (Flickr)

Some would say that a drawback of the mechanical sequential lever over steering wheel paddles is that you can’t have both your hands on the wheel while shifting. However, even if the shifter paddles do move with your hands, the steering wheel almost always travels farther than you can rotate your hands around without repositioning them, so the paddles are not always right there with your fingers.

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Still, there are good reasons why you don’t often see a manual sequential lever in a car. A typical motorcycle or racing sequential transmission is a different fundamental design. Instead of helical cut gears and synchromesh that nicely joins the gears, they have straight cut gears and dog engagement. Straight cut gears are louder, and the dog engagement is a less fancy way of engaging gears where you kind of just shove a moving peg into a moving hole and hold on. It’s louder, it doesn’t shift as easily at low speeds, and it isn’t robust for a high-mile road car.

If you’re sitting there trying to figure out what the hell I’m talking about, this video explains it pretty well.

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Helical cut gears.
Helical cut gears.
Photo: adogcalledstray ( (Flickr)

You could have a standard road car gearbox with sequential shifting a couple of ways: either with the aftermarket kits I mentioned at the beginning or by using the same system that a paddle shift uses but have the switches on a lever in the console. The Toyota MR2 had this option at one point, as well as the E46 M3. The reviews on those are mixed.

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BMW “sequential manual gearbox”
BMW “sequential manual gearbox”
Photo: The Car Spy (Flickr)

Either way, both options lose the direct feel of the engaging gears and I’m not sure I would feel the same way about them as I do about my sequential shifter.

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A lot of people just don’t like sequential transmissions, either because of the drawbacks above or because they’re just used to the H-pattern. And that’s fine, I’m not telling you that you should like it, or to go find a racing transmission for your road car (but, you know, maybe?). It doesn’t much matter anyway; there are fewer mechanical links between you and the powertrain every year, and manual transmissions are few and far between. But, if you ever get the chance to put a motorcycle engine in a car, I highly recommend it, if only for the shifting.

Matt Brown is an automotive engineer, writer, and builder of unconventional things. Mostly vehicles.

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DISCUSSION

americarocks212
AmericaRocks212

This sounds like a really cool project! Can you put up some pictures of the car?