What's better than a manual transmission? Two manual transmissions!

(Photo likely stolen from MurileeMartin.com)

Some of you may remember the FX32, a twin-engine Corolla/MR2 mashup that the insane crew of Stick Figure/Volatile RAM racing put together back in 2013. Well, it still runs, and it’s still racing – now with MOAR manual transmissions!

The original design was sort of a “soft-coupling” system where the rear engine had an automatic transmission and the front was manual. We would just put the rear in “Drive” and then drive the car as if it was a single-engined manual car.
The problem with that approach was it didn’t maximize the power of the rear engine. It would get all confused about what it was supposed to be doing, as the driver had the throttle wide open through second gear, then closed for a beat then wide open again. It would shift up when the throttle was lifted, then downshift again, etc…

So, I, because I hate automatic transmissions, and because I wanted to know if it could be done, converted the rear to a manual transmission. A double-standard, if you will.

The additional clutch master cylinder was mounted under the dash in the driver compartment, with a reversing mechanism to depress it with the one clutch pedal. It has functioned perfectly since it was tuned to exact (precise-ish) specifications.
The shifters were the biggest hurdle. I originally come up with a design that just attached two stick shifts together, and had a sort of pantograph arm for the side-to-side movement. It worked very well for 3-4 shifts, but not great for dropping into second gear. Our drivers ended up abandoning second gear, using third out of slow corners and being patient waiting for the torque-less 4AGEs to wind up to their happy place, which is well over 4000 RPM. That setup lasted through most of day one, when we blew a head gasket in the rear engine and finished the race on only the front.

The latest iteration can be seen in this video.  As you can see, it’s much more sophisticated (in much the same way that a cassette tape is more sophisticated than an 8-track).  The shifter cables need to do exactly the opposite action for either end of the car, so I built reversing mechanisms, and with precise accuracy, I fabricobbled them together.

This setup will be race-tested this weekend at Thunderhill. Stop by and say hi and feast your eyes on this amazing feat of engineering. Or just have a beer with us and try to figure out why it failed so hard.

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14 responses to “What's better than a manual transmission? Two manual transmissions!”

  1. mdharrell Avatar

    “So, I, because I hate automatic transmissions, and because I wanted to know if it could be done, converted the rear to a manual transmission. A double-standard, if you will.”
    That may well be the noblest automotive paragraph ever to appear on this site.

  2. theskitter Avatar

    Nice work.
    Keep iterating.

  3. onrails Avatar

    Double standard. That was beautiful…

  4. Kiefmo Avatar

    Oh man, I would have taken advantage of the automatic’s difference in shift points from the manual in one of these ways:
    1) Link the automatic engine’s throttle to a ratcheting lever — like a handbrake. You can have it delivering some power all of the time, and modulate speed with the manual engine. Then ratchet it wide open on the straights and other sections when you can use all the power both engines can muster. Difficulty: a throttle that can be locked open probably wouldn’t pass safety.
    2) Add a servo-activated locking mechanism that grabs onto the auto engine’s throttle cable and holds it in position. Activate the servo via a button on the steering wheel that can be thumb-activated. So, for maximum acceleration, go WOT and press the button. When you lift off the throttle to shift the manual, the auto engine will remain pegged. Difficulty: this only works for WOT, since the lock on the cable would prevent the throttle pedal from being depressed any further for either engine.
    3) HAND CONTROLS. Control the throttle of the auto engine with a go kart-style, steering wheel-mounted hand lever. Bonus points if you make the lever a ring that sits behind the steering wheel and moves with it, so you can use either hand, and any hand position on the wheel. Difficulty: the learning curve.

    1. mdharrell Avatar

      I see the appeal in that third option but it would probably be far easier and nearly as wrongheaded just to add a cruise control unit to the automatic end of the car. Bonus points for using a FoMoCo steering wheel, circa 1978, for the sake of its stylish built-in controls.

      1. Kiefmo Avatar

        That is a damned snazzy steering wheel, ahmustsay.

        1. mdharrell Avatar

          Yup. My father’s ’78 F-150 XLT Ranger Lariat Edition had the same wheel, with cruise control. It even worked.

    2. caltemus Avatar

      I just saw a 4 turbo supra on youtube that had dual throttles and the second butterfly was controlled by a hand lever. Definitely had the cool factor

  5. outback_ute Avatar

    I was wondering whether we were going to be talking twin engines or series gearboxes. I saw a story about the latter a couple of years ago, where a guy had taken a 1950’s Hillman Husky and effectively turned it into a tractor by installing a second gearbox and twin rear wheels for use on a rural weekender, including clearing trees and grading tracks. They called it the Dam Buster.

  6. Rover 1 Avatar
    Rover 1

    My new favourite word.

    1. Monkey10is Avatar

      “ghettofettled”, as they call it in Yorkshire.

    2. caltemus Avatar

      That’s an term AvE uses frequently. Don’t forget your safety squints!

  7. Ol' Shel' Avatar
    Ol’ Shel’

    Take the bend out of that square rod before it breaks. Bends are bad. Bends increase stress and fatgue in a mechanism like that.
    Neat work, though!

  8. needthatcar Avatar

    Update: We broke the rear engine on practice day. Despite repacing it, we couldn’t get it running. So we disconnected it and just raced on the front engine.
    The real news, however, is that the front frabricobbled shifter worked absolutely perfectly the whole weekend. It never missed a shift. I forgot that it wasn’t just a normal shifter.