By on July 26, 2013

Your humble E-I-C pro tem recently had the chance to rallycross a WRC-engined Subaru in Texas and I enjoyed myself like you wouldn’t believe. More importantly, I met the Texas Rally Sport crew, which is even cooler than Toretto’s crew in the first F&F, although not quite as cool as any crew containing both Ludacris and Sung Kang.

TRS is full of people building everything from off-road Pinto wagons to B-Spec rally Mazdas, but they really love their Subarus.

The Subaru you see above is in the process of being rebuilt to something very interesting… and when it’s finished, you’ll be right there with me to check it out. In the meantime, please feel free to absolutely foam at the mouth about DOING THIS SORT OF THING ON A PUBLIC ROAD WITH PUPPIES AND CHILDREN NEARBY. Don’t worry. There were no puppies or children around. They were methodically slaughtered in order to clear the road.

Just kidding, everybody! Go out and have a great weekend!

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22 Comments on “Wheels Up, Nose Down, While You Rallycrossers Bounce To This...”

  • avatar

    Jack Baruth Likes Hip Hop.

  • avatar

    She’s doin’ the Bertha Butt Boogey!!!

  • avatar

    This was fun to watch .


  • avatar

    In the words of James Hammond, “I just learned what proper brakes are! It’s like hitting a wall!”

  • avatar

    Remove the rear shocks, who needs ’em anyways? Remove the rear brakes to while you are at it. Good heavens, who needs the back wheels on the ground while under heavy braking? It’s not like any one ever needs to brake on a corner… Ever!
    Seriously, we forget how important the rear brakes are on a car. aside from slowing down they keep the back of the car on the ground. There is a devise on most cars that powers up the rear breaks first under hard braking. Take note next time you have to nail the brakes… subtle but it’s there.

    • 0 avatar

      I’d be interested to learn how you think this “devise” works. Although I have little knowledge of the newer, higher-end fancy-pants electronic systems, I’ve never seen anything beyond a mechanical proportioning valve controlling pressure to the rear brakes, and that has no ability to do what you describe.

      Depending on the rear suspension design, application of the rear brakes can settle down the rear, though. I’m not sure how much this effect is there on multi-link or other independent designs, but on a torsion beam you can definitely feel how applying the rear brakes causes the suspension to squat, if rolling forward, and jack up, if rolling backwards.

      • 0 avatar

        Sounds like Beerboy has a few too many. The rear brakes don’t really keep the rear wheels on the ground though they can’t by definition lift themselves off the ground, the front brakes have that responsibility but doing stoppies in a car is pretty hard.

        I think he is referring to the proportioning valve, replaced by electronic proportioning systems run through ABS. It does no such thing as “power up rear brakes under hard braking” in fact the harder you brake the less rear braking you get…

        • 0 avatar

          The proportioning valve was used on disc front drum rear systems. Normally it is included in the combination valve except for vehicles with dual diagonal split braking systems. It does not cause the rear brakes to provide less braking the harder you apply the brakes though it does reduce the pressure to those brakes. Drum brakes are self energizing so their braking force is not linear in regards to line pressure like it is with disc brakes. So it alters the pressure to the drum brakes to achieve a linear response similar to that of the front discs.

          Now there are aftermarket devices sold as proportioning valves that allow you to adjust the pressure to one half of the system to balance the braking effect but they don’t work quite the same as the factory valves.

          • 0 avatar

            Scoutdude, you obviously have an in-depth knowledge of how these systems work, but I do take issue with your contention that a proportioning valve doesn’t reduce brake pressure the harder you brake.

            While no expert in the matter, I do know for a fact that my ’92 Jetta (rear drums) had a mechanical linkage from the torsion beam to the valve, which would change the rear brake pressure depending on rear ride height. It therefore would both increase rear brake pressure with increased load (such as passengers sitting in the rear), and reduce brake pressure during hard braking when weight would shift to the front.

            Many proportioning valves also have a spring in them, whose force, once overcome, will reduce pressure to the rear brake lines. You can find graphs online of when this “knee point” happens vs. brake line pressure. The result is that when you brake harder, less percentage of line pressure goes to the rear to compensate for the fact that there will be less weight on the rear wheels. I know that my Miata (rear disks) functions this way, and it’s common for the track guys to mess with this for two reasons:
            1) To overcome the conservative factory setup which ensured that the front brakes locked up way, way before the rears – a boon to stability and safety, but left some braking performance on the table.
            2) To adjust for aftermarket brake setups, which will likely have different front-rear biasing requirements than stock.

            In the case of the Miata, it is true that they dropped this mechanical proportioning valve in 2004 when the ABS computer took over control of rear proportioning.

          • 0 avatar

            I guess I didn’t word that quite right. Yes the proportioning valve reduces line pressure once it reaches a certain point. So yes you can find graphs that show input pressure vs output pressure and you will find they are a straight line of in = out until you reach a point and then they become a cure where the output pressure is a decreasing percentage of the input pressure. If Mazda has slipped one into the Miata that is not the norm for most vehicles.

            The purpose is to make the brake force of the drum brakes increase in a linear fashion like discs do, because drum brakes are self energizing while discs are not. That is why power brakes were not really needed on drum/drum systems and those that were fitted provide less assist than those on disc/drum systems.

            The Load valve as seen on the rear of some vehicles, mostly trucks, is a separate, additional, device and it does reduce the brake force across the board from what the proportioning valve up front did. The both serve the same purpose of trying to prevent the rear brakes from locking up prematurely.

        • 0 avatar

          I know about the older distribution valves. I guess I refer to electronic break distribution systems. I am not that technically clued up but… please look at what is happening to the car in the video, it is quite clear that it is a combination of missing brakes and shocks so I really am not talking out of my @ss.
          Oher… an eye shtar… (hic)… ted drinknin roun umm… then… (hic)

    • 0 avatar

      Years ago when front disc rear drum systems were the norm vehicles did have a hold off or delay valve in the front disc circuit. However that was so the brakes would apply at the same time. It prevented pressure to the front circuit until it had built to the point where that same pressure in the rear system was high enough to overcome the return springs for the shoes. One of the big reasons got back to the days or RWD vehicles. If someone had fitted studs or had chains on the rear in ice/snow the front brakes would lock up with light pressure while the rears would keep propelling the vehicle on automatic equipped vehicles. On vehicles with 4 wheel discs that valve was not present.

      Google how a “combination valve” works. The common disc/drum ones include that delay valve for the front circuit, a proportioning valve (explained above) and a residual pressure valve (to keep the lips of the wheel cyl sealed and help that delay valve do it’s job) for the rear circuit and the differential pressure shuttle valve between the two circuits to turn on the warning light when the pressure in the two halves of the circuit are not the same.

      Some modern cars do have Electronic Brake Force distribution to adjust the front to rear pressure to achieve equal braking despite the normal weight transfer.

    • 0 avatar

      Perhaps I should explain a bit better. I don’t intend to say the rear brakes are the be all and end all of control.
      The driver of this car is nailing the brakes, releasing and nailing again in a pattern. Watch how the back of the car lifts and then sinks again, it “bounces” higher the second time and even higher after that. The bouncing is caused by the missing shocks but the lifting is aggravated by the inactive rear brakes.
      My intention was to illustrate, often underestimated, rear brake importance. I may have overstressed the action of EBD but I do not think I was far off the mark.

    • 0 avatar

      To all you doubters… Please read the first paragraph to it’s end.

  • avatar

    Rollin down the street, in her subie, shakin her eyeballs loose…laid back, with her mind on her lesbos and her lesbos on her mind.

    • 0 avatar

      Lesbos is a nice island in the Aegean Sea. I don’t remember seeing any Subarus there. Some lady named Sappho came from there….I think she was a poet or a blogger or something.

    • 0 avatar

      Dammit, you beat me to the lesbian jokes. I was going to say, damn, I love a woman that can drive a car like that, too bad she’s a “Subaru buyer”, if you know what I mean.

      I am a huge fan of most everything that Subaru makes. And I am especially a huge fan of the fact that they will let you buy a large AWD wagon with 6-speed stick. But the lesbian jokes never get old. They are disempowerment empowerment for anyone that’s watched “Chasing Amy”. Sure, people should expect better from blog editors, but not blog commenters.

  • avatar

    Little ditty, about Jack and Brianne, two racin’ drivers rallycrossin’ the best that they can…

    Hopin’ for a rental rally-x story out of this. And very much hoping that this meeting of two talented people turns into something good for both of them!

  • avatar

    Nail the brakes and the rear end rises. Release the brakes and it sinks. Repeat at the natural frequency of the suspension and watch the amplitude increase with each cycle. Nothing more complicated that what a kid does on a swing set.

  • avatar

    Well as the Yakko, Wakko, and Dot would say: “Boingy, Boingy, Boingy.”

    Or alternatively as Tigger says: “Their tops are made out of rubber, their bottoms are made out of springs…”

  • avatar

    “puppies and children were methodically slaughtered in order to clear the road.”

    Don’t forget them Bunny rabbits. Pesky critters are always plugging the radiator and their remnants cook on the headers. Gawd! Awful smell.

  • avatar

    Jumped into this post only because that was the best Subject line ever. Call me a sucker for 90’s rap, I guess. Very nice, Jack!

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