By on April 4, 2017

C1937 Cord 812 (Jane Nealing/Flickr)

DAG writes:

Why don’t automakers design front-wheel-drive cars with the transaxle in front of the engine? This moves the front wheels forward and improves weight distribution; offers better potential for aerodynamics and leaves space under the hood for pedestrian protection. With a turbo four-cylinder, the engine could have clearance from the firewall. Also, the engine and transaxle could be mounted on a pivoting subframe, hinged at the front, to drop down at the back for major maintenance; disconnect steering and exhaust to drop cradle.

The engine would sit in the space where rack and pinion generally resides; steering gear design would be a challenge for direct mechanical actuation. Perhaps traction would be reduced. Would crashworthiness also be affected?

Sajeev answers:

Interesting query! I’m happy to play devil’s advocate to your modern-day Cord powertrain layout:

  • Potential aerodynamic benefit is eliminated via pedestrian safety regulations. Larger front fascias increase surface area in contact with humans, thereby reducing physical damage from knee-bending.
  • Head protection isn’t likely, thanks to our cab forward designs — more cab, less hood and a greater chance the pedestrian’s head still slams somewhere needing 10 cm of space above the engine intake manifold.
  • Hinged subframes bring crashworthiness concerns. While I can’t google up proof, subframes are designed to prevent the engine from intruding into the passenger compartment in a head-on collision. They normally move down and/or under the firewall, and a hinge introduces a fail point in something that must not fail.
  • Not concerned about steering system interference; most vehicles use electric steering now.
  • V-shaped engines would be tough in this configuration. Perhaps one day we can have a V6 engine renaissance. Perhaps it will lead to something deliciously looney like a second-gen LS4. That’s not likely with this design.

This is probably another case of automakers doing their jobs by not reinventing the wheel, by protecting us from what we want. But hey, if it worked on the Cord …

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice. 

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24 Comments on “Piston Slap: The Case for the Front-Mounted Transaxle?...”


  • avatar
    OldManPants

    That Cord’s front end seems better suited to pedestrian processing than safety.

    “Get in my bellay!”

  • avatar
    JimZ

    because all of that adds cost, complexity, and zero value to the customer.

  • avatar
    cheezman88

    Isn’t this how Audi has their cars laid out? I never understood the advantage of this layout. All it does is shift the weight forward and now you have a car that understeers severely.

    • 0 avatar
      notapreppie

      Audi’s front-engine longitudinal FWD/AWD cars still have the gearbox behind the engine. They’ve gone to significant lengths to try to reduce the amount of weight forward of the front wheels but it’s still sort of a reverse-911 configuration.

      Given how much effort they’ve put into shaving a few ounces, I have a hard time believing they haven’t looked into spinning the whole assembly around.

      I don’t know about their transverse platforms.

      Right now, most transverse FWD layouts put the gearbox below/behind and slightly to the side of the engine. Spinning that around would let you move more weight between the wheels and improve weight distribution. You would either have to move the wheels farther forward (engine in the same position relative to the body) or passenger cabin farther back (transmission in the same position relative to the body) to make it work.

      Steering linkage could be solved with a few u-joints and creative routing (or going with the dystopic nightmare of a purely steer-by-wire system).

    • 0 avatar
      Scoutdude

      No Audi, and Subaru put the engine in front of the transaxle on their longitudinal FWD/AWD vehicles. That set up was also found in the Chrysler LH cars, original Toyota Tercel and the first couple of generations of GM’s E body FWDs.

      It was Saab that most recently (and Citroen before that) put the transaxle in front of the engine and that does shift the weight distribution to the rear, or at least it did when engine blocks were made out of iron and transmissions didn’t have more than 5 gears for a manual and 4 for an auto. With the MT almost extinct, ATs having more than 6 gears and engine blocks being aluminum that may no longer be the case.

      It is important to note that on most of those longitudinal FWD set ups the transaxle sat at least partially under floor as they would in a conventional RWD layout.

      In the case of many of those aforementioned longitudinal set ups it was done at least in part to make driving the rear wheels easy.

      • 0 avatar
        Jesse

        Saab put their transaxle in the c900 under the engine. The engine ran longitudinally, albeit backwards, with the output shaft in front. It connected with the input shaft of the transmission via chain. It can be a little tricky reaching the belts (against the firewall), but a clutch job takes like 2 hours because it’s up front and easily accessible.

    • 0 avatar
      heavy handle

      Not quite. Audi has their driveshafts near the transmission bell housing, so the engine is ahead, but the transaxle is behind.

      The Renault 5 (“LeCar”), and previously the 4, used the transaxle-ahead layout.

      Others, according to Wikipedia (en.wikipedia.org/wiki/Front_mid-engine,_front-wheel-drive_layout), include the Citroen DS, Acura Vigor and Scion iQ.

      The fact that it’s such a short list tells me that it’s probably too much of a compromise.

      • 0 avatar
        Scoutdude

        I’d forgot about the LeCar and its transaxle forward design.

        The Scion IQ is a transverse set up but the differential is to the front instead of the rear so the engine does sit behind the axle centerline.

        The Vigor used a system similar to the early GM E body and Tercel where the differential is strapped under the engine and is separate from the transmission.

    • 0 avatar
      Cobrajet429

      Citroen did it with the Traction Avant and the DS.

  • avatar
    Jack Denver

    Didn’t some old Saabs have this layout, with the output shaft facing the front of the car and the transaxle in front?

    • 0 avatar
      Scoutdude

      Yes, makes for fun changing the accessory drive belt or the belt driven accessories. Thankfully the water pump was in the block, not, since you had to pull the intake to access it on that Triumph engine.

  • avatar
    Ermel

    Citroen DS. Or even Citroen SM, with a V6.

  • avatar
    npaladin2000

    ” But hey, if it worked on the Cord …”

    Yeah, someone please remind me how well Cords sell these days? Oh, wait….

  • avatar
    indi500fan

    Over time, designs tend to coalesce around the optimum configuration for performance, cost, etc.
    In the case of fwd autos, the transverse engine with the transmission on the crankshaft axis is the winner.

  • avatar
    Sam Hall

    I think manufacturers have landed on the front engine/mid-mounted transaxle for space efficiency and maintainability.

    The transmission is small and doesn’t require much if any regular maintenance, so it makes sense to put it under the front footwell. The engine is large and does need belts, fluids, spark plugs etc changed on a regular basis, so it makes sense to put it in front of the transaxle where it’s out of the way of the passenger compartment and easy to reach for maintenance.

    Even RWD cars have these considerations, which is why the Nissan Skyline/Infiniti G coupe “front-mid engine” setup isn’t more common.

  • avatar
    someoldfool

    Read somewhere, might have been the Auburn-Cord-Duesenberg Museum, that Cords struggled to get up hills when the road was icy. The incline transferred too much weight to the rear wheels. The engines are positioned well behind the front axle. This is really obvious in the early 30s Cords, the loooooong straight 8 engine, the front of which is well behind the front axle.

    • 0 avatar
      ToddAtlasF1

      Exactly. The front-mid-engine-FWD layout of Cords, Citroens, and Renault R4s was good for practically nothing. The cars didn’t enjoy the packaging advantages of every other FWD car and they didn’t enjoy the traction advantages of FWD. Acceleration unloaded the driven wheels.

    • 0 avatar
      OliverTwist78

      Yes, that would be gargantuan L29 (1929-1932), not nimble 810/812 (1936-1937).

      L29 had a massive flaw (no pun intended) with differential axle in front of gearbox, which was in front of the long straight-eight motor.

      https://s-media-cache-ak0.pinimg.com/736x/31/aa/52/31aa5217e333149564aa22090c05cfeb.jpg

      810/812 solved the weight distribution problem by putting the gearbox in front of differential axle, which was in front of V8 motor. That is a true transaxle gearbox.

      http://theoldmotor.com/wp-content/uploads/2014/11/cord5-760×457.jpg

  • avatar
    Stumpaster

    Aside from ease of assembly, I think there is a real structural benefit in tying the shock towers to the firewall. Notice how in the modern cars they almost merge.

  • avatar
    Goatshadow

    The front overhangs on modern can be pretty ridiculous. Thanks to RWD BMW and Benz get it right more than anyone else. Audi gets it pretty wrong.

  • avatar
    relton

    Anyone who says, “it worked on the Cord” has never driven a Cord.

    FWD cars have transverse engines for space efficiency. Audis don’t worry about that too much since they are premium priced cars whose owners aren’t concerned about the last mpg or cubic inch of interior space.

    Engines are ahead of the axle because it was a styling choice many years ago. in fact, it is still a styling choice.
    The axles/wheels could be at the front of the car simply by turning the current powerplants around. I have been in planning discussions where that was seriously studied. The reason for considering it revolves around the definitions of size in the proposed EPA regulations. The larger the vehicle, the lower the mpg requirements. The definition of size is solely the wheelbase. Making the wheelbase longer, in the same size car, makes it easier to meet a lower mpg target. This is somewhat of a simplification; the rules go on for hundreds of pages, all of which I have read in excruciating detail. So, in the future, it is very likely that we will see more FWD cars with the front wheels at the front of the car.

    • 0 avatar
      OliverTwist78

      “Audis don’t worry about that too much since they are premium priced cars whose owners aren’t concerned about the last mpg or cubic inch of interior space.”

      What about the first generation Toyota Tercel, which is one of the smallest cars with longitudal mounted motor and transaxle? Citroën GS? Brazilian-built Volkswagen Gol (not to be confused with Golf)? And so on…

      “Engines are ahead of the axle because it was a styling choice many years ago. in fact, it is still a styling choice.”

      Nope, it’s more effective to package the engine ahead of front axle for the increased collision protection without enormous strengthening of firewall and subframes as to prevent the engine intrusion into the passenger compartment.

      Mercedes-Benz switched from engine behind front axle in its first and second generation A-Class to engine mounted ahead of front axle in its third generation.

      A representative offered the explanation: the first two generations had a double sandwich floor with strong brace to jut the engine out of the body in an event of frontal collision. Thus, tilting the engine over the transaxle. The third generation A-Class (and its larger derivation, second generation B-Class) has none of double sandwich floor and brace. Placing the engine in front of axle offers better collision protection.

      In addition, engine in front of transaxle makes it easier to add the all-wheel-drive system. Case in point, Mercedes-Benz could never offer AWD version of its A-Class and B-Class until the third generation A-Class (W176), second-generation B-Class (W246), and first generation GLA-Class (X156) were introduced.

  • avatar
    Greg Locock

    “Not concerned about steering system interference; most vehicles use electric steering now.”

    They still have steering columns and steering racks.

    Main reason I know of is that the space in front of the engine is wasted for crash because it is resisting engine mass as well as the rest of the cabin. If the engine hits the crash barrier immediately then you can use the space behind the engine to decelerate the safety cell.

  • avatar
    JamesGarfield

    Doesn’t anyone remember the RUXTON?

    It used a reverse Inline-8 engine-transaxle, FWD design:

    https://en.wikipedia.org/wiki/Ruxton_(automobile)

    And it actually slightly pre-dates the Cord.

    They are VERY rare. Only 33 of them known to remain, with only about 16 in running condition. The latest restored one auctioned for about $370,000.

    If you want a really fascinating read, check out this thread on its insanely immaculate restoration:

    http://forums.vwvortex.com/showthread.php?6206837-1932-Ruxton-build-thread-or-quot-How-I-became-an-unwitting-restorer-quot


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