By on June 8, 2017

Renault 5, public domain

The late Janet Reno once described herself thusly: “The fact is I’m just an awkward old maid with a very great affection for men.” Similarly, I think of myself as a liberal-arts type with a very great affection for engineering. I’ve designed a few bicycles in my time, and I’ve earned most of my bread by programming in various languages, but I’m not qualified to draw a bridge, create a capacitor, or invent an engine. Those are special and particular disciplines that attract special and particular people. I ain’t one of them.

Nevertheless, even as an outsider it seems plain to me that there are two kinds of automotive engineering: the inventive kind, as practiced by Henry Ford and Colin Chapman, and the iterative kind as practiced by the vast majority of engineers currently working in the business. When Jim Hall put a wing on the Chaparral, he was doing inventive engineering; when the Mercedes F1 team runs through ten thousand CFD calculation sequences to remove crosswind drag by 0.5 percent, that’s iterative engineering.

Inventive engineering gets the headlines, but iterative engineering pays the bills. Which leads me to today’s question, which asks? Can’t we be inventive when it comes to front-wheel drive?


James asks,

Maybe you can answer a question for me that I haven’t been able to figure out:

Why in a transverse FWD setup is the engine hung out in front of the wheels?

Every auto journo (with good reason) complains about two things in a FWD car — the proportions (huge front overhang) and the weight balance (huge front end bias). In a longitudinal setup I get it (easier to run the front half shafts directly off the transmission) but can’t figure out why it needs to be that way in a transverse setup. Why can’t the “drive unit” (engine, transmission, half shafts, front wheels) just be rotated 180 degrees in place? I can’t see that it would affect packaging (same stuff in the same space) which is the big reason to go FWD transverse. Is it a crashworthiness thing? Is it a cost thing?

I think the reductive answer to this is, “It wouldn’t fit.” Take a look at any FWD car from the side. Measure the distance from the center of the wheel to the other side of the engine. Then look at what that same measurement gets you if you face it the other way — you’re well into the passenger compartment. As someone who races a FWD car and therefore has the hood up on it all the time, I can tell you that there isn’t actually a lot of space between the back of a transverse engine and the firewall.

“Ah,” the inventive engineer replies, “then we move the front wheels forward, the way they were on, say, a BMW E36!” You could also lengthen the nose, Zimmer Quicksilver style. It’s certainly possible to flip the engine around if you have that kind of room.

The iterative engineer will point out that doing so leads to all sorts of problems. In order to pass a modern crash, the engine has to “submarine” a bit in a front-end impact. This is easily engineered with a systeme Panhard car, like a RWD Bimmer, and it’s been figured out with conventional transverse FWD cars. But an FWD car with the engine hard up against the firewall? Tougher to do.

There’s also the minor matter of servicing the thing, which would be a nightmare even with a Saab-style reversed hood. Getting the air in and out of the engine will be frustrating, which doesn’t mesh well with the idea of a flopped-front-driver as a performance car. There are a thousand iterative challenges to solve with this idea.

Last but not least, there’s the fact that if you’re going to put this much effort into engineering a unique platform for an FWD performance car, you might as well do an RWD performance car! So I think it’s safe to say that nobody is going to waste their inventive time and iterative effort into doing an FWD car with the engine behind the front wheels.

Except, of course, for the fact that it’s been done.

The first-generation Renault 5, known as “Le Car” in the USA, had a longitudinal FWD setup much like the Audi 80 aka “Fox” that appeared next to it in 1972. But the better mousetrap had already been invented by Sir Alec Issigonis; the transverse-engined Mini was an authentic revolution compared to the Renault and Audi which were merely Thirties FWD designs in square bodies.

Renault’s second-generation 5, known as “Supercinq” in France but never sold in the USA, utilized a transverse engine placed behind the transmission. Euro-snobs will recall that the Renault 5 was also available as a mid-engined RWD car, making for three separate and distinct layouts in what was more or less the same body.

And we could end the story here, except that the “Supercinq” actually took its layout from the Renault 11, which we know as the Encore/Alliance. Yup, the AMC/Renaults also had their engines mounted against the firewall. The performance model of the Alliance was the Renault GTA.

So now we have the real answer to the question posed by James, and it goes like this: Sure you can do it! But nobody’s gonna buy it.

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93 Comments on “Ask Jack: Can We Flip the FWD Script?...”


  • avatar
    JimZ

    “Every auto journo (with good reason) complains about two things in a FWD car — the proportions (huge front overhang) and the weight balance (huge front end bias).”

    the vast- VAST- majority of car buyers don’t care one whit about the things auto journos dislike.

    • 0 avatar
      newenthusiast

      ^ This. In a daily drive vehicle, which is probably never getting close to a vehicle’s limits as it goes about its typical usage, would 99% of drivers even know or feel weight distribution and how it affects their car? And if they even knew what it was and how to recognize it…..would they care?

      I know I have never given it any thought while getting groceries, transporting kids, driving to work, etc. I HAVE given it thought when I was younger and had a series of compact FWD drive vehicles in my native Pennsylvania and the winter driving I had to do. I knew that FWD plus a set of winter tires was my best safety bet for the price range and size of vehicles I could afford at that time. That’s about the only time I thought about it.

    • 0 avatar
      RichardF

      Jack’s question is fun to discuss – BUT, it’s based on a completely false premise.

      The Renault Supercinq’s engine is in the normal place for a transverse engined supermini, ie, ahead of the axis of the front wheels. Just Google for pictures of Supercinq engine (sorry, I don’t know how to attach a picture here), and it finds plenty of under hood pictures, which clearly show the engine block ahead of the strut towers.

      The large air cleaner assembly is right back against the firewall, perhaps this has caused a misunderstanding

  • avatar
    chaparral

    There are two other reasons to hang the engine forward in a FWD car.

    1) Traction. If the engine moved back a foot it would take a typical car from 62% to 56% of the static weight on the driven wheels. An FWD car only gets worse at acceleration the harder it accelerates, the inverse of a 911 or a dragster lifting its front wheels free of the ground.

    2) Maneuverability. If the front wheels moved forward a foot, it would increase the wheelbase by a foot. This would have the same detrimental effect in tight quarters as adding another foot to the wheelbase for any other reason.

  • avatar
    JEFFSHADOW

    The RIGHT way to do Front Wheel Drive: See “GMXP784”
    1966-1985 Oldsmobile Toronado
    1967-1985 Cadillac Eldorado
    1979-1985 Buick Riviera
    Longitudinal Engine, TH425 transmission, Hy-Vo Chain.
    Daz All, Folks…!

    • 0 avatar
      la834

      And don’t forget the GMC Motorhome!

      What I really want to know about the ’85 and earlier Toro/Riv/Eldo is how they were able to get a completely flat floor front and rear into those cars for real 6-passenger capacity in two rows of seats, something that seems to elude automakers today.

      • 0 avatar
        JimZ

        they were body-on-frame and the only major components which needed to run front to back were the exhaust pipes. And those could run alongside the frame rails.

      • 0 avatar
        JEFFSHADOW

        I have a 1976 GMC Motorhome. LOW to the ground!
        From what I learned at the GM Training Center, the reason today’s cars have the floor tunnel is because they are uni-body designs and when you bend metal (like the center part of the chassis) you get more strength. Torsional Rigidity…
        Seems to work for my Auroras!

  • avatar
    Messerschmitten

    Thank the mythical early-60s Cadillac V12 for the Toronado/Eldorado/GMC/UPP longitudinal-engine layout.

    https://ateupwithmotor.com/model-histories/oldsmobile-toronado-1966-1970/2/

    • 0 avatar
      Kyree S. Williams

      Hmm! That says a lot. Thanks for that fact. I’d wondered why they drummed up that particular engine layout, and a V12 was why. If they were going to use a giant V12 (and V12s back then were pretty big), they either had to add a lot of length to the front, or do what they did…which was place the transmission beside the engine, and link the two by chain. Then, the engine itself had more space for length, since it didn’t need to accommodate a transmission behind it.

      • 0 avatar
        Messerschmitten

        I have a 1967 Cadillac Eldorado. Maybe the GM Heritage Center would allow me to “borrow” the sole remaining V12 prototype to see if it would bolt right in?

        https://macsmotorcitygarage.com/a-cadillac-v12-that-never-was/

        • 0 avatar
          Kyree S. Williams

          Sounds like a plan. I’ll distract the guards with my killer good looks, and you can sneak up behind them and wheel the engine away. Then we can test it.

        • 0 avatar
          wumpus

          I remain convinced that the Cadillac V-8/6/4 was originally conceived as a V-12/6, neutered by manufacturing and then forced through engineering. If it weren’t for the giesel 350 it would probably be remembered as the worst GM engine ever, but it probably would have made plenty of sense in 12/6 format.

          • 0 avatar
            JEFFSHADOW

            The 1981 V8-6-4 was a wonderful engine. Simply disconnect the electronic solenoid and you have a constant V8 from the 472 CID heritage.

    • 0 avatar
      Big Al from Oz

      When I was a kid (12?) my parents had an Austin Kimberley.

      It had an OHC inline 6 with twin SU’s.

      I remember them always complaining about sh!tty mpg’s and lack of power.

      For a FWD of its time it sure was wide and roomy inside.

      • 0 avatar
        Kyree S. Williams

        That’s because I6s are long. You’re taking a long engine that’s normally mounted front-to-back and mounting it side-to-side. The car has to be able to accommodate that, and still have a transmission beside it.

        Up until recently, Volvo was using transverse I6s in its cars. Thee was the 3.2-liter I6, which was the base engine, and then the T6, a turbocharged I6. (and likewise, the transverse-I5 powertrain was designated as T5).

        Now, T5 refers to a turbocharged I4, T6 is a turbocharged and supercharged I4, and T8 is a turbocharged, supercharged and electrified I4.

        • 0 avatar
          NeilM

          Kyree writes: “That’s because I6s are long. You’re taking a long engine that’s normally mounted front-to-back and mounting it side-to-side. The car has to be able to accommodate that, and still have a transmission beside it.”

          Nope. The Austin Kimberly was based on the BMC’s Austin Maxi. These cars, like the original Mini, had the gearbox in the engine sump (and sharing engine oil). Because this arrangement didn’t add any length, even an inline-6 could be mounted transversely.

          The Lamborghini Miura used the same arrangement with its mid-engine V12, although very late SV cars isolated the gearbox so that it no longer had to use engine oil.

          • 0 avatar
            Kyree S. Williams

            You’re right. I’m wrong. Although, in general, transverse-mounted engines do have their transmissions mounted beside them.

          • 0 avatar
            Big Al from Oz

            NeilM,
            I do know the vehicle was wider than most other British cars of the time. By US standards, no.

            It would of been as wide as a Holden HQ.

  • avatar
    Kyree S. Williams

    Yeah, longitude-FWD is still a thing at Volkswagen Group. Every Audi from the A4 and up (with the exception of the Q7 and R8) is longitude-FWD. VW in particular slings the engine way further ahead of the front axle than in most cars, with the transmission directly behind the engine (as in a RWD car) and in line with the front axle. Shafts come out of each side of the transmission, connecting to the front wheels. If the car has Quattro, Audi’s AWD system, it gets an additional driveshaft going out of the back of the transmission to the rear differential, as in a RWD car. In fact, the most recent iteration of this is Volkswagen Group’s “MLB” architecture. The Volkswagen Phaeton (now defunct) and Bentley Continental GT and Continental Flying Spur / Flying Spur also use this arrangement. This is probably why VW chooses to use a W12 instead of a V12 in these flagship cars. A V12 wouldn’t fit lengthwise, but a W12 is no longer than a V6 and fits quite well at the very front of the engine bay.

    To some extent, Subarus could be longitude-FWD, because the newest ones are front-biased (with the exception of the RWD BRZ) and could be FWD instead of AWD if the rear driveshaft was disconnected and some light re-engineering was done. I believe at one point you could get them in FWD-only.

    And then there were the E-body cars, specifically the early versions of the Cadillac Eldorado and Oldsmobile Toronado. They were longitude-FWD, with the RWD-like transmission sitting beside the engine and being driven by a chain. Since the transmission was closer to one front wheel than the other, these cars obviously had unequal-length half shafts, so I believe GM initially used telescoping shafts that could change length, in order to mitigate torque steer. This arrangement was known as GM’s Unitized Powerplant Package (UPP). This was at a time when FWD was thought of as exotic and high-tech, so it made sense to put it on these cars. Weirdly enough, the Buick Riviera from generation 2 (1966) to generation 5 (1978) was on the same E-body platform, although it remained RWD and had a full frame, unlike the other cars, which were partial unibodies. In 1979, for generation 6, the Riviera finally adopted its E-Body siblings’ FWD-longitude setup, but this was to be the last generation in which any of those cars would be longitude-FWD, because they switched to transverse-FWD when they were redesigned in 1986.

    • 0 avatar
      JimZ

      the UPP also found its way into “pusher” motorhomes.

    • 0 avatar
      Scott_314

      Great post!

    • 0 avatar
      Scoutdude

      Yes Subaru started their current architecture as FWD and it wasn’t until later that the added the ability to drive the rear wheels and then finally dropped the FWD versions as people stopped buying them.

      The GM vehicles with the UPP had equal length shafts, which interchange from side to side, to minimize torque steer. There is an intermediate shaft that hangs under the engine and the passenger side axle shaft bolts to that. Telescoping CV joints are the norm in FWD, the overall length changes with suspension travel so it is required.

      This page has a good picture of the final drive assembly of the early UPP. https://classicoldsmobile.com/forums/toronado/73300-69-toronado-drive-train-picture-drawing.html Note most of the later downsized UPP’s was also the front driving axle for the 4wd versions of the S-10 including half shafts and much of the suspension.

    • 0 avatar
      Ermel

      Longitudinal FWD with the engine behind the transmission: Citroen ID, DS, and SM.

    • 0 avatar
      Featherston

      Ate Up with Motor has an interesting description of the UPP’s halfshafts:
      – – –
      The original halfshafts, developed by Oldsmobile and GM’s Saginaw Division, used permanently sealed Rzeppa-type constant velocity (CV) joints at each end, but the inner CV joints telescoped, allowing the halfshaft’s length to change slightly in response to lateral forces. Interestingly, the telescoping CV joint was actually invented by Pontiac’s John DeLorean, who patented it in 1959, and was originally intended for the rear suspension of the rope-drive Tempest, where it was supposed to reduce acceleration and braking squat. Oldsmobile used it, along with careful attention to steering geometry (including a slight negative scrub radius), to almost completely eliminate torque steer. (The telescoping halfshafts were replaced for 1967 by three-ball-bearing CV joints, which worked almost as well and cost less.) The right halfshaft also incorporated a rubber torsional damper that could twist up to 7.5 degrees to absorb driveline shocks and vibration.
      – – –
      Interesting picture here, as well (right halfshaft on top): http://www.breznick.com/toronado/brakes/HalfShafts%20-%201.jpg

    • 0 avatar
      OliverTwist78

      The W12 motor is the same length as V8, not V6. I know because I have seen both 6-litre W12 and 4-litre V8 Audi/Bentley/Volkswagen motors on display at IAA Frankfurt auto exhibition.

      The W12 is not technically a W-form despite what Audi/Bentley/Volkswagen say on the contrary. W-form means three banks of cylinders. Look at Bugatti W18 motor concept before it magically became ‘V16’ in the production version. Ditto for the stillborn Amati W12 motor.

      The Audi/Bentley/Volkswagen W12 motor is technically a V12 with two banks of six cylinders on each bank. The cylinders in each bank are staggered as to shorten the length.

      Why Volkswagen didn’t continue to use VR moniker for its successive range of motors with eight, twelve, and sixteen cylinders, i.e. VR8, VR12, VR16.

  • avatar
    WallMeerkat

    The Renault 21 – aka Eagle Medallion – was offered with both a Transverse and Longitudinal FWD – as well as 4WD.

    The station wagon was longer still, which meant that the model was offered with FOUR different wheelbases!

    At least it was symmetrical though, earlier Renaults used to have different wheelbases on each side due to suspension packaging.

  • avatar
    sportyaccordy

    Honda did this with the Legend and Vigor, which infuriated me because had the Vigor/Legend been RWD the whole course of the Acura brand would have been different. But yea, it’s pointless. All the sacrifice with none of the dynamic benefits.

  • avatar
    redapple

    Automotive Engineering 101.
    Bending the power 90 degrees cost you 3-6% in efficiency. Transverse engine placement instead of north south saves you that.

    • 0 avatar
      TonyJZX

      I assume the ultimate extension of this is the north south awd/4wd platform like those seen in some departed and not yet departed japanese sports cars?

      in response to this article i would say… a bear is a bear, a bull is a bull, dont make a bull into a bear, dont expect a bear to behave like a bull

      i expect an FWD platform to behave like one and I dont expect it to do something it was never intended to do.

      If you need a bear, buy a bear. If you need a bull, buy a bull.

    • 0 avatar
      Big Al from Oz

      reapple,
      Accounting 101;
      Installing an engine traversely saves weight and manufacturing costs.

  • avatar
    Shane Rimmer

    Doesn’t the Scion/Toyota iQ mount the engine further back?

    • 0 avatar
      Kyree S. Williams

      Yes, but that’s a car with very tidy dimensions, and it has no real overhang to begin with. What little overhang it has is pretty much occupied by the crash-protection structure. Plus, the engine is so small that the powertrain package can basically fit neatly on top of the front axle assembly…which is interesting, because the iQ’s inspiration, the Smart ForTwo, is rear-engined and RWD. Of course, the ForTwo doesn’t have to accommodate a third occupant in the rear.

    • 0 avatar
      Scoutdude

      Yes the iQ has its engine “behind” the transaxle or to be more accurate behind the axle shaft.

  • avatar
    PrincipalDan

    Well the Skyactiv system due to its long “tri-Y” header design forced the wheels forward and the hood to be elongated on Mazda vehicles but the enthusiast crowd kvetches about the “awkward proportions.”

    Make up your minds.

    • 0 avatar
      Kyree S. Williams

      I think the new Mazdas have flattering proportions. I’m not going to keep the Lincoln forever, and that new CX-5 is looking really nice these days.

      Another automaker with flattering FWD proportions is Volvo. But Volvo just removed the front overhang altogether, because with its new I4-or-smaller doctrine, it doesn’t need to accommodate V-shaped engines that take up engine space (not that Volvo was really using V6s to begin with; it tended to use I6 engines).

      • 0 avatar
        PrincipalDan

        FWIW I love the proportions of the Mazda 6 sedan. Plus the old Hot Rod Magazine subscriber in me loves that someone slapped a tri-Y header on an I-4 after decades of me reading articles about how to build a set for your V8.

    • 0 avatar
      Pete Zaitcev

      Alex Dykes was quite positive about Mazda’s proportions, saying they were more “RWD-like”.

  • avatar
    Bangernomist

    Renault 5: “Oui, btdt.”
    Renault 4: “Enfant ingrate!”
    Citroën Traction Avant: “Bitches, s’il vous plaît.”

  • avatar
    someoldfool

    Take a look at practically any fwd Cord and you’ll see the engine is set behind the front wheels. Legend has it the fwd Cords could not climb a hill if the road was slick due to weight transfer.

    • 0 avatar
      Kyree S. Williams

      Yeah, you want the weight over the driven wheels or at least vectored that way. In a RWD front or mid-engined car, even though the weight is not over the rear wheels, when you go up a hill, the force of the weight is directed toward the back of the car, due to gravity.

    • 0 avatar
      Jack Baruth

      Yes but the Cords have a longitudinal mount.

    • 0 avatar
      OliverTwist78

      You are referring to L29, not 810/812.

      The L29 has a severe design flaw, which caused the difficulties with hill-climbing. Cord chose to place the long gearbox and even longer and heavier straight eight motor behind the front axle. That shifted lot of weight to the back when going up the hill.

      Side photo of L29

      http://theoldmotor.com/wp-content/uploads/2013/04/ACDIII-600×289.jpg

      810/812 has shorter V8 motor behind the front axle with gearbox ahead of front axle. Same layout as Citroën Traction Avant and its subsequent progeny, DS.

      Side photo of 810

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

  • avatar
    deanst

    What I want to know is why front wheel drive cars no longer seem to offer any more space efficiency than RWD vehicles – with the exception of subcompact or maybe compact cars. Audis don’t seem to have more room than their comparable BMW competitor, and likewise the Buick LaCrosse versus Chrysler 300. When first introduced in North America, the Chrysler k cars and GM x cars seemed to offer huge amounts of space versus their RWD competitors.

    • 0 avatar
      tommytipover

      Now days, the center console is 3 feet wide and the door panels take up a foot and a half each. In the olden days, the center tunnel was only big enough for the exhaust and the trans linkage, and occupants were separated from the outside world by the door skin, a 3/4 inch impact bar and a cardboard inner panel.

    • 0 avatar
      Kyree S. Williams

      Don’t negate the benefit of not having to straddle a big driveshaft hump if you’re the rear-middle occupant in a FWD-only sedan, like you do in a RWD sedan. But, yeah, a car these days just has a giant, wide center console, whether or not there’s a transmission beneath it.

    • 0 avatar
      Ermel

      Audis have a longitudinal engine (except the small ones), so they’re comparatively crampy if compared to a Passat or a Skoda Superb, which have a transversal layout.

      • 0 avatar
        Kyree S. Williams

        They shouldn’t be. Because the transmission and engine are pushed so far forward in an Audi (the transmission is pretty much in line with the front axle), not much of the powertrain should intrude into the cabin space.

  • avatar
    Robert Ackley

    To accomplish traditional steering geometry, the rack and linkage must be placed ahead of the axle. If the engine layout is reversed the steering shaft must go around the engine/trans unit. Not desirable.

    • 0 avatar
      cdotson

      You can do traditional steering with “front” steering – rack low ahead of the axle centerline, or “rear” steering – rack high behind the axle centerline.

      I’ve seen setups run both ways, and can see how one situation or the other would work regardless of engine/transaxle configuration.

      • 0 avatar
        Robert Ackley

        “You can do traditional steering with “front” steering – rack low ahead of the axle centerline, or “rear” steering – rack high behind the axle centerline.”

        That’s where the engine/trans would be.

  • avatar
    jimble

    My first car was a Renault Encore but I never knew about the unusual FWD layout. What I did know from owning one was that handling was pretty good and the ride was excellent for such a tiny car — if you could keep the thing from falling apart. The Alliance and Encore sold well at first but people soon learned that the combination of legendary French reliability and legendary AMC build quality was about as miserable as you’d expect, and sales dried up. My car’s trade-in value after only 5 years was a whopping $50.

  • avatar

    If I’m not mistaken, Alec Issigonis’ original Mini was the first modern transverse engine FWD car (Walter Christie made a series of FWD racing cars in the first decade of the 20th century that had transverse engines and used the crankshaft as the front axle). Sir Alec’s main design brief was about packaging, making enough room for all the mechanical bits and four adults. The Mini transmission’s gear set actually sits underneath the engine, in the sump, with just the final drive sitting behind the engine. While not great for either engine or transmission lubrication (engine oil isn’t really thick enough for gearboxes and those gears do a nice job of mechanically chopping up the long polymers in the oil and degrade it vis a vis engine lubrication – it was bad enough with the manual gearbox cars, but for the automatics, like they put in the Austin America / MG 1100 it was even worse), it does result in a fairly compact unit. Flipping the drivetrain around would be a less efficient use of space, both in front of and behind the engine. With the Mini layout, they can tuck the final drive under the bottom of the firewall which allows the engine itself to be close to the firewall, as Jack pointed out in the original post. Flip it around and you don’t get the engine much closer to the firewall while having a lot of wasted space above the now front mounted final drive.

    Modern transverse FWD cars have the same general layout of the original Mini, though transmissions don’t share cases and fluids with the engine.

    https://i2.wp.com/www.aronline.co.uk/images/engineaseries_01.jpg

    • 0 avatar
      JuniperBug

      To be fair to the Mini’s lubrication design, many modern high performance motorcycles are still bathing their gearboxes in the engine oil. They let the clutch splash around in there while they’re at it, and here we’re talking about engines larger and much higher-performing than what the Mini came with, and they seem to get away with it. I’ll grant that you won’t likely get away with the long oil change intervals and powertrain durability that most modern cars enjoy, but six digits are totally possible for the few riders who use their bikes that much.

    • 0 avatar
      allythom

      Interestingly (or not), the early Mini designs had the engine mounted transversely, but the other way. However, if I recall correctly, the SU carb would ice up when at the front of the car, so they flipped it around (brilliantly putting the coil and spark plugs at the front right behind the grill) and introduced an idler gear into the gearbox -to ensure 4 forward gears, which is why transverse ‘A series’ engined cars (Minis, Metros, Austin/Morris 1100/1300s and some Allegros) have a characteristic gear whine.

    • 0 avatar
      Messerschmitten

      GM was working on transverse-engine FWD in 1958-59 for a Corvair- or F-85-like vehicle.

      https://ateupwithmotor.com/model-histories/oldsmobile-toronado-1966-1970/

      Another important design aspect for the Mini is that it had to use as many off-the-shelf pieces as possible. Many of the compromises were not optimal.

      In the mid-1970s, my “daily driver” was an ex-race 1966 Cooper S 1275. The lubrication (and general durability) problem was no joke: I rebuilt the transaxle every 10k miles.

    • 0 avatar
      TR4

      “If I’m not mistaken, Alec Issigonis’ original Mini was the first modern transverse engine FWD car ”

      First with a mainstream four cylinder four stroke, perhaps. The SAAB 92, produced from 1949-1956, had a transverse two cylinder two stroke as did the DKW model whose engine SAAB used. SAAB then went longitudinal with the 93 and subsequent models.

    • 0 avatar
      Scoutdude

      Engine oil certianly is thick enough for use in a transmission. Chrysler recommended 10-30 in the transmission section of some of their FWD manual transaxles. ATF is also common in manual transmissions. In a purely spur gear application there isn’t a lot of shearing forces that is what happens in a Hypoid gear set which is why they need a different type of oil.

      Additionally the scales for viscosity are different for gear oil and engine oil. The viscosity of a 10W40 motor oil is essentially the same as 75W90 gear oil.

  • avatar
    cdotson

    Hard to describe without CAD or diagrams, but one of the contributing reasons is steering geometry. Typical CV axles have a limited range of articulation that limits the overall steer angle of each wheel in a FWD/AWD vehicle.

    In order to maximize maneuverability you want to use as much of the available CV articulation as possible which requires the transaxle output to be somewhat forward of the front wheels’ centerline. Looking at the layout from above the shaft angles toward the rear of the car as you follow it out from the transaxle toward the wheels. This allows for steering geometry more closely approximating Ackermann steering to reduce tire scrub. In Ackermann steering the inside tire turns a sharper angle to follow the smaller radius around the center of steering. Because the inside tire turns a higher angle away from straight ahead you need more tire clearance inside the wheel well to the rear of the tires’ centerline.

    The engine is typically the wide portion of the transverse engine/transaxle. Placing the engine behind the transaxle not only forces the front axle forward but further cramps the engine width-wise by wedging it between the narrower section to the rear of the front wheel wells as the halfshafts have to trail back towards the tires for steering geometry.

    Longitudinal FWD? As described above, this may only work for inline engines. Between this limitation and worse weight transfer under acceleration it just isn’t worth the trade-offs.

    • 0 avatar
      Scoutdude

      “Longitudinal FWD? As described above, this may only work for inline engines. Between this limitation and worse weight transfer under acceleration it just isn’t worth the trade-offs.” Somebody better tell Subaru and Audi as well as go back in time to tell GM this since they all use(d) non inline engines in longitudinal FWD and FWD based AWD cars.

      ” Because the inside tire turns a higher angle away from straight ahead you need more tire clearance inside the wheel well to the rear of the tires’ centerline.” Again somebody needs to tell the MFGs, for all these years they haven’t been making the wheel well deeper in the rear than they do in the front. Also any angling of halfshafts is very minimal if present at all. Fact is that the mfgs don’t care about Ackerman much anymore. With the same sausage different length strategy that gives different wheelbases with the same front suspension Ackerman looses out to the cost savings of one knuckle fits all.

      • 0 avatar
        cdotson

        I can’t speak to Audi, but Subaru’s powertrain protrudes to the front of the front axle rather than flipped behind it as posited in the article. I don’t know what FWD wheel wells you’ve seen but most of the ones I’ve looked at appear to my eye to have noticeably less space between them toward the firewall than they do at the tire’s leading edge.

        And you’re right about Ackermann, although I’ve heard “percent Ackermann” bandied about as if it means something. I suppose it’s a relative measure on how badly screwed up the geometry is relative to true Ackermann. Not that true Ackermann is always desired; there are any number of dynamic situations where intentional deviation from Ackermann is preferred due to the handling characteristics with significant weight transfer. Back when I had to worry about steering geometry all they were concerned about was minimum scrub to reduce turf damage at full-lock under almost no power while minimizing turning circle.

  • avatar
    gvera

    Nobody remembers the Citröen Traction Avant?
    It had a longitudinal engine rotated 180°, the engine was placed behind the front axle with the gearbox in front of it.

    From Wikipedia:

    The Traction Avant used a longitudinal, front-wheel drive layout, with the engine set well within the wheelbase, resulting in a very favourable weight distribution, aiding the car’s advanced handling characteristics. The gearbox was placed at the front of the vehicle with the engine behind it and the differential between them, a layout shared with the later Renault 4 and 16 and first generation Renault 5

  • avatar
    ConBrio

    How about shortening the engine via a V configuration a-la the Lancis Fulvia of the 60’s and 70’s? Front to back space less compromised than an inline configuration, leaving more room for movement.

  • avatar
    Pete Zaitcev

    BTW, you know what else had Toronado architecture with longitudinal engine and FWD? Dodge Intrepid, at least in the 2nd generation with tall trunk. I didn’t realize that all throughout its production run, and only found out when I came upon one in a wrecking yard. The driveshaft went right through the engine’s bellhousing, and the steering linkage was actually on top of engine’s driveshaft.

    • 0 avatar
      PrincipalDan

      That was the layout for the cab-forward cars (both generations).

    • 0 avatar
      Scoutdude

      No the transaxle in the Windshield forward cars was “behind” the engine. The UPP had the transmission partially behind and partially beside the engine, and had a separate differential that sat next to the engine.

      The LH cars were designed that way as the original intention was to make that chassis accommodate FWD, 4WD and RWD but Chrysler ran out of money to tool up for the 4wd and RWD versions. The LX platform is just a warmed over LH platform and they had actually dusted off the rear axle drawings for refresh but then Mercedes stepped in and mandated the use of their components, setting back the introduction of the vehicle.

      Lots of other vehicles have mounted the steering rack high on the firewall and to a top steer knuckle.

    • 0 avatar
      JimZ

      The LH cars were designed that way partially because they were going to be built at the plant which was then building the Renault 25-based Eagle Premier and Dodge Monaco, which had a similar powertrain layout.

      the 42LE transaxle in the LH cars was simply the A604/41TE guts in a new case with a different final drive design for longitudinal placement.

  • avatar
    Garrett

    Go big or go home!

    Instead of just flipping the engine around, flip it around and move it to the back of the car. To keep some weight at the front, put a front mounted gearbox/transaxle. Basically, the same layout at the Porsche 924, but with things swapped around.

    I’m sure the handling would be…interesting.

  • avatar
    Bangernomist

    I dunno about the claims for the Renault cars. Murilee’s own junkyard pics show the Alliance’s engine packed in pretty close but still definitively ahead of the shock towers and presumably the front wheel centerline.
    http://www.thetruthaboutcars.com/2010/12/renault-alliance-still-on-the-scrapheap-of-history/

    Now, as far as who did it first, here’s your unicorn, though it wasn’t exactly a triumph of packaging efficiency. Imagine how much less Audis would understeer if they stuck to tradition: http://myautoworld.com/audi/cars/history/1931-dkw-f1/1931-dkw-f1.html

  • avatar
    relton

    The new EPA CAFE rules give cars with longer wheelbases and wider tracks an advantage. Their numbers, in absolute terms, are lower.

    I have sat in a number of planning meetings where reversing the engine/trans positions were actively discussed. In other words, the wheelbase of the car would be increased, but the overall length would stay about the same. Any handling advantages would be incidental to the main purpose of meeting the new CAFE rules.

    Of course, with the new administration, those CAFE rules may be out the window, and a whole new set of paradigms for design may take place. I’m retired now, so I can only watch from the sidelines.

    • 0 avatar
      chaparral

      Bob,

      I suggested in planning meetings at the same company that one of our sedans should switch to a mid/rear engine architecture for that exact reason.

      You should unretire. There are spots open at the Tier-1 I work at now.

    • 0 avatar
      OliverTwist78

      I spoke with the representative at Mercedes-Benz exhibition a few years ago about the latest generation of A-Class along with its van sibling, B-Class. The first two generations of A-Class had engines behind the gearbox, but the current generation adopted the ‘mainstream’ engine and gearbox in front of axle.

      The answer was the ‘better crash protection’, putting more distance between the engine and firewall in transverse mount application.

      I am not wholly convinced of this argument because there are so many vehicles with transverse-mounted V6 and V8 motors whose rear banks were very close to the firewall. I know because it is very frustrating to replace the spark plugs due to tight and almost inaccesible space.

  • avatar
    KitaIkki

    What’s surprising is there are so few mid-engine cars based on relocating the ubiquitous transverse-FWD power-train to behind the driver seat. FIAT, Pontiac, Toyota (plus JDM Honda and Mazda) all tried that. All except Honda are gone. Now it’s just a few Lotus models (with Toyota FWD packages) and JDM Honda S660. Seems such a no-brainer to compete with Miata on the cheap, using mostly existing FWD parts. 300hp V6 from a crossover should do wonders in a mid-engine 2-seater.

    • 0 avatar
      Kyree S. Williams

      There’s more to it than that. A vehicle like that would essentially have to go on its own platform, making it a very expensive endeavor.

    • 0 avatar
      JimZ

      “What’s surprising is there are so few mid-engine cars based on relocating the ubiquitous transverse-FWD power-train to behind the driver seat. ”

      Why is it “surprising?” Who the hell wants to buy two-seat cars?

  • avatar
    Shortest Circuit

    Also, funny things happen when you try to 180 engines… Opel had the great idea not to try to re-engineer the venerable 1.7DTL diesel for the third time to try to keep the dinosaur rolling. Instead they turned to the Japanese (Isuzu, to be correct) and got their 1.5 turbodiesel, which was smaller and stronger than the 1.7!. Only problem, the crank turned the other way around, in comparison to the DTL. No worries, just flip it! The result: open up a DTL-engined Corsa and be presented with the HP pump, the alternator and the glowplugs. Open up the Isuzu engined one and be presented… with the exhaust manifold, a tiny turbo,and… that was it, really. To do any sort of maintenance was at least a 2-mount-out, better yet, a full engine-out job. Yuck.

  • avatar
    bjarnetv

    Sorry jack, but as a super5 owner, i can confirm that the engine is indeed mounted slightly in front of the wheel centerline.

    (how do you post pictures on this site?)

    http://i325.photobucket.com/albums/k368/bjarnetv/IMG_0417_zpswmtobrsx.jpg

  • avatar
    WildcatMatt

    What exactly makes Henry Ford inventive as opposed to iterative?


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