MR FX: Dual Drivetrain Lemons Build Update

MR1When last we left our group of idiotic racing enthusiasts, they had just taken a dull sawzall blade to a rusty MR2…

It’s at this point of a project that many ambitious and enterprising folks take a step back, assess the situation, and realize they this thing will never run and that they were morons to take even a single step down this insane path.  Our team is certainly not that smart, so onward we go.

The plan with this car is to build the whole thing on Saturdays between now and the race at the end of March in Sonoma.  Can it be done?  Well, if we keep getting attendance like we have the first two weeks, I think it may well happen.  We’ve had 6 guys thrashing on both of the first two Saturdays and the net has been a nicely disassembled MR2 and a torn-down engine (needs a head gasket, maybe more).  Go team!

Skinned

This is what is left of the MR2.  As I mentioned in the first post, this car will end up looking much more like the FX, and will carry most of that sheet metal when it is completed.  So, from the MR2, we’ll have what you see above, plus engine and transmission, fuel tank, wiring, gauge cluster, and cooling system.  Everything else will be FX. 

Oh, and it’ll have two drive trains.  That’s the part that makes me a little giddy every time I think of it. 

The folks at 24 hours of Lemons HQ reportedly had twice the number of applications for this particular event than it had room for.  Luckily, both of our cars/teams were accepted.  So now all we have to do is turn what you see in the above photo into a running race car in two months. 

We’ll make it, or we’ll be committed, or both. 

Bonus mystery car:  Name the vehicle behind the MR2 carcass? 

 

Scott Ith is an Associate Editor with Hooniverse.com, but he also contributes to his own site NeedThatCar.com.  Head over there for more hooniganism.

50 Comments

  1. So how do you rig up the throttle cable, to control both engines, and how do you sync them, so one drivetrain isn't pulling against the other one (different speeds)?

    1. It's been done before in LeMons. That team used an automatic for the front drive portion, and, thanks to the torque converter, and "road coupling", the different engine speeds didn't present an issue.
      Even with 2 separate manual transmissions, the road coupling effect would just keep the engines at whatever RPM they need to spin at to match wheel speeds. It really feels like it should be more complex than it really is to have 2 different drivetrains in one car.
      The biggest problem with 2 manual transmissions would be coupling both clutch linkages and shift linkages to work in tandem.

      1. This is the same team, Stick Figure/Volatile Ram Racing (ZomBee's sister team). They just decided one dual engine'd car just wasn't enough "crazy" in one bucket.
        I drove their first car, the MRolla and it was pure genius. Neither drivetrain pulls against the other, They simply help push each other along, kinda like getting an extra kick from the car behind you.
        What it actually feels like, is as if the hand of god came down and gives you a nice push. The 4 wheel drive makes a hero out of you, and I've never laughed so hard on a track.
        Until one of the motors blew. Then it was like running around with a dead engine in the trunk. But the fact that we kept running with a completely dead engine also made me laugh like a madman.
        Pure genius, these guys.

        1. So, you're saying that they know what they're doing, having done it before. That means that this one should be better, right?

        2. I'd like to experience that kind of laughter. The only time Ive come close was when I built a 17 foot tall trebuchet that worked far more dramatically than expected. Some of us enjoyed the punkin gut hailstorm more rhan others.

      2. I think you should link the clutches and then have to shift both transmissions like the old twin-stick transports.

        1. Alright, here's how I understood it from context:
          Let's start with manual transmissions, since they are tightly coupled. The crank shaft is hooked to the flywheel, which (when in gear) is attached to the input of the transmission via friction on the clutch. The transmission input to the wheels gets geared down by the selected gear and the final drive, right?
          So, the clutch-flywheel is 1:1, the transmission depends on selected gear, and the diff depends on the ring and pinions. Which means, the wheels have to turn at a fixed ratio (transmission gear * final drive) to the crank shaft of the engine. The rotation rates are coupled together. Road coupling is a bit of jargon to point exactly at this phenomenon.
          Automatics experience road coupling too, but it's a loose coupling rather than a direct coupling thanks to the torque converter.
          It's the reason when you shift gears, the engine goes to a specific RPM, even if you blip the throttle wrong during the gear change. It's also the reason why automatics kind of suck at engine braking while manuals are awesome at it.
          (NOTE: I could be horribly wrong. I have a physics degree. Physicists have a nasty habit of deriving things from context/principle and then passing off that knowledge as if it is something they've known for years. I might have done that in this post.)

          1. That's a good explanation.
            The nuances are in the transients.
            (Re: NOTE This is not an instance, but I also have the ability to pass on things I've just learned, or even hypothesized on the spot, as if I've known them for years.)

          2. It's a great ability for arguing with and tends to convince the average Joe. Here in my family, we call it the MacLeod Book of Knowledge, as we all seem to do it, more or less.

          3. My family, by each knowing every single dirty trick of argument, knows better than to use them on each other.

        2. Road coupling is actually just a bit of industry jargon stating that since the front wheels are in contact with the road, and the rear wheels are in contact with the road, the front and rear drive are "coupled" by the road, forcing them to turn at the same speed, and since there is no hard coupling (like a transfer case) within the drivetrain to fight this, there is no undue stress on components. This is opposed to a conventional 4WD setup, which, if it had different final drive ratios, would create terrible stress at the transfer case, since the transfer case and the road are both fighting to turn the same engine at different RPM.
          Basically the road is the only thing telling either engine what RPM to spin, and without any other connection, they each spin at whatever RPM is necessary. If the gearing means that at 70 mph, one engine spins at 2000 rpm, the engine will be spinning at 2000 rpm, regardless of throttle opening, and if the other drivetrain has to spin at 2500 rpm, it can and will.

          1. Great explanation.
            Also, the two engines do in fact spin at different RPMs all the time. Which is weird, because you are shifting a 5-speed up front, but all you can hear is the automatic doing it's own thing behind you. Very bizarre.
            It's like that game of rubbing your belly and patting your head then switching, all while trying not to die at 95mph surrounded by gasoline, rusty heaps and 180 other idiots.

  2. I think you should take the front of the MR2 and the back of the FX and make a car with NO DRIVETRAIN!!!
    I don't know why.

  3. The car behind the MR2 carcass was their previous entry that Lemons HQ deemed too insane.
    And I was going to drive it. I won't spoil the fun and say what it is, but Paul says he's gonna put it on the street instead.
    And I'm gonna beg to drive it.

    1. A jackal Multipla!
      jackal Multipla!
      It looks like a jackal Multipla!
      jackal Multipla?
      jackal Multipla!
      It's a jackal Multipla!
      jackal Multipla?

    2. "I won't spoil the fun and say what it is…."
      Ditto. I assume this is the one discussed at Oregon Raceway Park in 2011.
      "And I'm gonna beg to drive it."
      I may have to do the same.
      I won't, however, be making it to Sonoma this time, even though that now means missing both the Saturday-Sunday race and the Monday race. My job instead requires me to be in the middle of the Black Rock Desert launching weather balloons and rockets that week.

      1. It is indeed.
        Sorry you won't be at Sears Point! The thought crossed my mind that you outta be there to participate in all our madness. But you can't compete with launching rockets…
        And now that you mention it, I don't recall any rules specifically stating "no rockets" in the race.
        We should talk.

        1. Okay, so maybe YOU GUYS should buy the front end of the MR2 and the rear end of the FX, build the Toyota Breadvan, but give it rocket propulsion!
          (Hint: if you use rubber + laughing gas rockets, you actually have some control over the power produced and it's less explodey)…

  4. Is that a Thames or Bedford van from the 60's? I'm too lazy to go look it up but it's either that or that truck Maxichamp spotted a few months ago. Yeah..still too lazy..

  5. Someone needs to make the import fighter version of this: Pontiac Phoenix + Pontiac Fiero. Iron Dukes Glory! Or maybe it's one of those funny ones where you pluralize the first word: Irons Duke!
    Add a Faux Ferrari Body Kit. There are 8 cylinders and at least one flat plane crank!
    /Days my wife is glad I don't have a garage to myself.
    EDIT: Please read the above as that the MRolla and MR FX are two of the greatest LeMons cars, ever. There should be a class. I wonder what you could bolt to the front of an X1/9, and whether that would improve your position for IOE or halve it (twice the chance of an eye-talian basket case making over the line…).

  6. an answer to jeepjeff X1/9 plus CRX = axis of semi-evil. i have a friend with a fiat x1/9 he adores and drives across the country in! he has -scores- of photos of his escapades in that silly faded banana yellow car. i think its fun but constantly dread his first major mechanical "roadblock" and how he will find parts to fix it. so far its had a throttle cable failure and a rain induced italian wiring gremlin come out of the woodwork, not to mention that i seem to believe there is a very old and large rodent living within the chassis delicately severing or plain removing choice wires at random every summer. PS. he calls it "honey badger"

  7. Why only dual drivetrain??
    I mean, for only 50% more in costs and time, you could have a six-wheel three drivetrain beast!

    1. 2.1: Vehicle Eligibility: Entry limited to mass-produced, four-wheeled vehicles legal for US highway use at the time of their manufacture….
      At some point LeMons HQ might draw the line and refuse to grant a waiver on top of another waiver. Perhaps.

      1. Are you saying that my de-tired dualie pickup would be ineligible? Unacceptable! We can discuss which tires…

  8. There was a Saab 96 VW bug combo around St. Johnsbury Vt. in the late sixties early seventies. I got a ride and ran the VW rear with a hand throttle, cobbled together clutch(on the passenger side and the standard floor shifter with my left hand. The driver ran the Saab front with all the standard controls including 4 on the tree. It was an incredible dirt road and snow car, unstoppable.

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