By on January 19, 2011

You’d think that the zilch-o-torque characteristics of a Wankel engine wouldn’t be so great for hauling heavy loads, and you’d be right! Adding an automatic transmission to the mix, as is the case with this ’75 Mazda pickup, no doubt made for some interesting driving experiences when hauling, say, a dozen sacks of concrete mix in the back.

I can’t remember the last time I saw a Mazda rotary pickup on the street, but this one— which I spotted in a Denver self-service wrecking yard a couple days ago— survived long enough to stay out of The Crusher’s way until the second decade of the 21st century.

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24 Comments on “Wankel + Automatic = Ideal Truck Drivetrain?...”

  • avatar

    What a cute little pickup!  Love the round tail lights.  (I don’t remember this earlier version, my first awareness begins with the invasion of my neighborhood with the 79MY versions badaged as Ford Couriers after Ford’s equity buy-in to Toyo Kogo.)

    Regarding the interior … would look to be a deluxe model, what with the woodgrain trim and a/t.

    Something else about the interior … somebody was compulsive about pairs:  two blue oil filters, two blue jacks (hmm blue maybe too), two v-belts …

  • avatar

    You’d think that the zilch-o-torque characteristics of a Wankel engine wouldn’t be so great for hauling heavy loads

    In situations where you have low torque but high revs, can’t you just change the gearing to compensate?

    • 0 avatar

      In theory you’re right; given enough gears and the will to use them torque is largely irrelevant and power is what counts.  However there are plenty who insist on flooring it at 1500 rpm and having something happen.  They don’t want to rev at 4000+ rpm all the way up a long hill in order to maintain 70mph.  They are more comfortable with “low end torque”.  Good thing they are not Indy or F1 drivers!

    • 0 avatar
      Felis Concolor

      I forget what the torque and power curves were like for the old 13Bs, but set the torque converter’s stall speed to 5000 rpm and I’m certain you’d get decent pulling power, although standing start launches would be somewhat dramatic.

  • avatar

    Yo, we heard you liked wankel engines, so we put a wankel in the most useless application ever, yo truck. Enjoy!!!

  • avatar

    rotaries are not exactly for trucks et al. in those days mazda had nothing to lose, just stuff a wankel into everything.
    now as hear say, wankel is going into audis as aux power gen. for their hybrid.
    also heard the rot are better for hydrogen burning, less back fire, which is very dangerous.
    is no doubt a small foot print, light , compact, if spinning on high rpm it should work, also at high speed the centrifugal force could pin the seal much tighter than at slow speed.
    even in the days of nsu, some engines did much better if driven on autobahn more often, if it were driven on stop & go, the engine didnt do as well.
    a friend had a rx7, lasted 270,000 km on orig engine, then slowly lose compression, and needed a new rotary. she does a bit more freeway commuting than stop /go driving.

  • avatar

    I had one of those…great truck, a little slow off the line but the old 13B rotary would rev to 7k, great for embarrassing Fiats and even BMW’s of the day.  You just had to ease off the line at the stop lights, until you could get the rev’s up, catch them at their 2-3 shift.

    I taught my wife to drive a stick in an RX2.  It cost me a clutch.  While learning, she took a friend to the airport.  He called me, said I really had to talk to her.  She was driving on the freeway in second gear.  I had told her she didn’t have to shift until the rev limiter sounded at 6.5k.  She didn’t.
    Mazda needs to figure out the EPA issues and put a turbo rotary in a light platform.

  • avatar

    I remember a friend’s Dad had one in lime green.  It was a manual and had a audible red-line indicator.  My friend made it a point to demonstrate that particular feature.

  • avatar

    I don’t recall all those sacks of cattle feed and hay bales giving my dad much trouble in his ’74.  But then, it was West Texas and when you don’t have to deal with hills bigger than speed bumps you can haul heavier loads with less penalty.

  • avatar

    I still remember the jingle on TV back in the day…”the piston engine goes boing diddy boing diddy boing, but the Mazda goes mmmm!

  • avatar

    “You’d think that the zilch-o-torque characteristics of a Wankel engine”

    What? 600 Nm out of a naturally aspirated 2.6 is hardly what you’d call ‘Zilch’ torque. Diesel rotaries have proven to have very favourable torque characteristics for heavy vehicles.

  • avatar

    Wow, I haven’t seen one of these in decades. I never drove one, or even rode in one but I do remember seeing a few around. The word on them was that the truck body was designed to hold together for the life of the engine-about 18 months. Every one I ever saw was rotted out from nose to tail and belching oil smoke, and I’ll bet I haven’t seen one since they were 3 years old max. Detriot wasn’t the only outfit peddling junk back in the day.
    A school mate’s Dad owned the Mazda dealer in our town at the time. To his dying day he swore Mazda rotaries were why he switched to a Honda franchise in ’77. Ended up a millionaire….

    • 0 avatar

      This junkyard dog looks better than some of the 15 year old stuff I see the local-yokels driving into town in the morning. Somebody ought to rescue that critter. Would be a fun weekend parts getter.

  • avatar

    That would make awesome Le Mons racer (once you ditch the auto)
    Light weight + Rotary goodness.
    And they already have a good racing pedigree!!

  • avatar

    Nothing like a rotary at high RPMs. They live for that. I once had two RX-7s. Darn fun cars (and I’m sure pickups) to drive!

  • avatar

    My dad had a mid ’70’s (’76?) B1600 (a nice blue) with the four pot. Air shocks meant that we could load it with a ton of liquid fertilizer, it road dead flat and we’d wind that engine tight and it’d haul ass. Hills were always a 3rd gear attack but it never wavered. An incredibly durable rig that was last seen in the early 90’s in our area with 300K on the clock (though the body was going to hell). It was one small tough truck that consistently got over 30 mpg.

  • avatar

    Actually an AT is a good thing for a engine w/o low end torque. That little thing called a torque converter multiplies the torque more so the higher the stall speed. There is a reason that drag racers use ATs and that is the torque multiplication and a high stall speed to get the engine in it’s power band when it leaves the line.

  • avatar

    Scoutdude, actually the gearing multiples torque, not a torque converter.

    I would think that either the original tailgate has been replaced or this one had a 4 cyl originally. The mazda rotary pickups had “ROTARY POWER” stamped into the metal in huge letters and painted white.

    i know quite about about rotaries and the different models because I used ot buy a lot of parts off these things. My first track car was a 1981 rx7 that was originally a spec 7 racer. I swapped to the 5 lugs, big brakes, hubs, axles from the newer GSL SE, swapped the engine to a built s4 turbo motor with s5 irons. The turbo charger was a switzer off a case tractor, ghetto sumped original fuel tank wiht the biggest external fuel pump you’ve ever seen. It all ran on a haltech. People used to laugh when I’d be plugging away on the old DOS powered laptop tweaking the fuel injection on the “turbo turd”

    • 0 avatar

      A torque converter does multiply torque when it is slipping.
      However, a torque converter is able to multiply torque when there is a substantial difference between input and output rotational speed, thus providing the equivalent of a reduction gear.
      The torque converter is one of the reasons back in the day a vehicle with an AT would come with a much steeper rear end ration than the same vehicle with a MT, of course nowadays MTs are pretty rare.

    • 0 avatar

      That’s right. In fact Issigonis once experimented with doing away with the gearbox entirely and using a torque convertor as the transmission.

    • 0 avatar

      Or not all REPUs had that tailgate. ID plate in photo #5 clearly indicates “13B”, so it’s reasonably safe to say this one was factory built with the Wankel.

  • avatar
    Mr Carpenter

    Correct; hence the name, “torque convertor”. 

    Otherwise, without a torque conversion stator, the device is called what it is when it can only slip and slide (wasting energy all the while) – a fluid coupling. 

    GM’s Hydramatic division didn’t utilize any torque convertors at all until 1964 when the Turbo-Hydramatic 400 came out in Cadillacs and a few other GM cars (and no, it was NOT GM’s first 3 speed Hydramatic – that was the bloody awful “slim Jim” which it had introduced in about 1959 or 1960).   The original 4 speed Hydramatic was introduced in 1938 with a crash box reverse and was only semi-automatic between two manual ranges; the 1939 ‘box was automatic. 

    Now, Buick Division of GM did nothing BUT torque convertors, and in fact, the earlierst Dynaflow automatics didn’t shift at all.  “Low” (a planetary set, with manual selection) was for mountain use or emergency use only.  The Powerglide (built by Chevy) was a copy of the Dynaflow and yep, performance with the Chevy 6 in early 1950’s Powerglide cars was dismal – until they re-engineered the thing to shift 1-2 and then it was only somewhat dismal.

    When I was a boy in the early 1960’s a friend’s grandpa lived right across the street from my parent’s house and he had a 1948 Buick with Dyaslush – I mean Dynaflow.  The big inline eight ran at about 2/3 maximum RPM’s (or so it seemed) and the big black sedan quite literally crawled to the corner – about 5 mph.  Absolutely awful. 

    Tucker originally experimented with a massive 589 cubic inch boxer six sitting between the rear wheels with the crankshaft turning two torque convertors directly on the stub driveshafts to the wheels, though soon got rid of it (and yes, THAT experimental chassis which never gained a body DIDN’T have reverse – the later cars did).  I have to wonder if he was planning on having an electric motor for reverse (but I suppose that would have mandated 24 volt electrics, like a military truck, instead of the 6 volts then common for cars). 

    Mercedes-Benz is another company which eschewed torque convertors for decades, and only started adopting their use (in lieu of fluid couplings) in the 1980’s.  Very late. 

    Typically torque-convertor automatics shifted (as later Dynaflows did) with 2 ratios, or sometimes 3.  Fluid coupling transmissions typically had 4 ratios, due to the lack of torque multiplication in the fluid coupling. 

    Nowadays, all our cars shift, shift, shift, shift, shift.  My wife’s Sonata 5 speed automatic actually acts like a 6 speed since the torque convertor clutch locks up after it goes into 5th. 

    James Nance, the President of Packard (then Studebaker-Packard for awhile, also) had John Z. Delorean (yes, the Pontiac man – who started out as a Packard man) engineer the Twin-Ultramatic (which was a sort of copy of the Dynaflow).  The Twin-Ultramatic came out late in 1954, and shifted from low to high then the torque convertor clutch locked up (yes Packard WAS way ahead of their time).  Likewise, the likewise independly developed Studebaker Automatic Drive, which was also introduced in 1951 (before the merger of those two companies) had 3 forward ratios, a lock-up torque convertor and generally started out in 2nd, shifting to 3rd then lockup.  Some 1956 SAD’s (Studebaker Automatic Drives) started in 1st, and this transmission was no longer affordable for Studebaker due to miserable sales levels, and Borg-Warner, which had bought up the sub-contractor for Studebaker (i.e. Detroit Gear) sent the transmission packing to England in 1957 where it was built and installed in many cars until 1967.  Including Jaguars, pre-M-B 4 speed automatics of 1963, and many others.  It is called the “3-band” automatic by knowledgeable automotive historians. 

  • avatar

    I love REPU’s.  I would love to add one to the fleet, but this on is a bit far away I think.
    Very cool truck, and have a huge following amongst Rotary fans.  I’m amazed this one got junked.
    There were two at the Deal’s Gap Rotary Rally last year, and were crowd favorites.  One of them was still original paint/unrestored.

  • avatar

    I learned to drive in a ’75 mazda B1600. That truck was absolutely indestructible. And, having a manual choke in hand was a great “feature”. I always loved the sorta military look of the rear end.

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