By on March 24, 2011


Ralph Nader’s Unsafe at Any Speed was published in 1965. For the 1967 model year, cars and light trucks sold in the United States were required to have a dual-circuit brake system, so that a single hydraulic leak anywhere in the system would not result in total brake failure. Real drivers knew that they could come to a complete, safe stop using the emergency brake— that’s right, for emergencies— but that wasn’t enough for the feds. They rammed dual-circuit brakes down the throats of the American public, adding at least several dozen dollars to the cost of a new car. My Dodge van is a ’66 model, which means it was the last year for the single-circuit brakes that gave our forefathers their moral strength (though not as much strength as their forefathers, who relied on mechanical brake actuation instead of hydraulics), and a lifetime steeped in Naderite propaganda has convinced me that I’m better off with some margin of hydraulic safety. Upgrade time!

Rocket Surgery Racing Renault 4CV team captain Rich gave me a coupon for brake-line assistance for my birthday, so I decided it was time to take him up on the offer.

The new 1967-grade dual-circuit master cylinder cost well under 50 bucks, and new brake hoses plus some line and fittings didn’t add much more to the cost of the project. This would be an all-sweat deal.

More sweat than we expected, because the A100′s forward-control setup necessitates a funky linkage-and-backward-mounted-master system. The master cylinder, which is actuated by a system of rods and pivots that appear to have been adapted from a piece of 1897 mining equipment, is located directly below the driver’s seat.

I’d assumed that Chrysler, once all their lobbyists had failed to fend off the dual-circuit brake demands of the US government— headed by arch-liberal integrationist Lyndon Johnson at the time, as if I needed to spell that out for you— would have found some cheap, bolt-in way of installing the slightly longer dual-circuit master cylinder, but it turned out that the ’66 master cylinder’s tack-welded-in-place splash shield didn’t have room for the ’67-and-up components.

So, the Sawzall had to be brought into play. This involved jarring loose 45 years of built-up crud, not to mention the opportunity to slice important stuff ranging from the wiring harness to the throttle cable.

Hacking this piece of sheet metal away means that some air destined for the radiator will slip past, so I might fabricate a replacement that fits the new master. I’ll see what happens when summer heat comes along; for now, the engine runs quite cool with this small opening next to the radiator.

With the help of a $2.99 tube bender and some coat-hanger wire as a template, Rich starts work on the replacement brake lines.

I’ve never been able to do a double flare correctly, in spite of several very frustrating afternoons spent trying to do so in the past, so here’s the part I was especially glad to have Rich take on.

Modifying the plumbing was pretty straightforward; plug one port on the original four-way tee that once split the line from the master cylinder into one line to each front corner and one to the rears, using it for the front circuit only. Add another tee to send pressure to the rear brakes and signal pressure to the hydraulically-actuated brake light switch.

Bench-bleeding the new master cylinder.

To add fluid to the master cylinder in an A100, you must remove an access panel located on the floor just in front of the driver’s seat. Naturally, the access panel doesn’t quite fit the larger dual-circuit master cylinder, so a funnel must be used to get fluid to the rear reservoir. This process got brake fluid all over everything beneath, which made finding leaks a real challenge.

I didn’t trust the parked-for-12-years brake hoses, so I sprang for new ones all the way around.

After some bleeding, the new setup works fine. I’ll probably convert to front discs at some point, but for now I’m satisfied with drums that are less likely to fail. Anybody want to buy a genuine single-circuit A100 master cylinder?

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47 Comments on “Buying Into Nanny-State Safety Diktats: Dual-Circuit Brakes For the A100...”


  • avatar
    Educator(of teachers)Dan

    Ah Murilee, your taking me back to my teenage days of helping my dad do repairs on his 1967 Mustang.  You haven’t lived guys till you’ve held a long screwdriver across two wires to see if the “bypass” will make the car start and prove that’s the bad part.  (While your old man is behind the wheel cranking and cussin’.)

    • 0 avatar
      Lumbergh21

      I’ve lived.  Purchased a ’68 Mustang a couple of years ago as a project, and I have a ’58 Chevy, still with a single circuit master cylinder.  The only difference with my bypass experience is I was praying while my wife was behind the wheel cranking (no cussing required).

    • 0 avatar
      texan01

      I did that with mom’s 92 Le Sabre once, when the pass-key system went out. it wouldn’t read the key so I hotwired the starter and took it to the dealer. They were not amused when the writer went to shut it off and it wouldn’t restart.

  • avatar
    jmo

    Random question:  Was the emergency brake ever really intended to be used in emergencies?  Or, is parking brake a more accurate name.
     
    Is there any functional difference between a parking brake and an emergency brake?

    • 0 avatar

      How do you think it got its name? Over time, it evolved into the parking brake. But, yes, way back when new drivers were taught to reach for the emergency brake, if need be. Especially so in Europe, where the ubiquitous floor mounted brake handle could be used quite effectively, for other purposes, as I explored repeatedly in my VW,

    • 0 avatar
      Kosher Polack

      Yeah, but on just the rear wheels on a fully-loaded van…well, maybe you’ll crash into something at 55 mph instead of 60. Hey, that could make all the difference in the world, to your cargo.

    • 0 avatar
      mcs

      Wait a minute. I thought it was called the “rear steering assist lever.” You mean there are other purposes for it beyond U-turns on narrow snowy roads and quick parallel parking! On an 02 to 06 MINI it’s a precision instrument – at least in the snow. Pull the level and the back comes around, but as soon as you put the lever back down, the rotation stops cold.

    • 0 avatar
      Lumbergh21

      I imagine if I adjusted the emergency brake just right in my truck it would actually work to stop the thing, as it has a decent lever action to provide adequate leverage; however, on first gen Mustangs the emergency barke has no leverage and the handle is difficult to even grip while maintaining eyes on the road and a hand on the wheel.  So, in some vehicles, an emergency brake is an emergency brake; in others it is a decoration or parking brake at best.

    • 0 avatar
      Felis Concolor

      Back when drums were all that were used, the “emergency brake” truly was effective in emergencies. For a few years when manufacturers thought they could get away with all discs in their automobiles, the manually operated system truly was a “parking brake”; clamping the disc brake pads via a small lever arrangement was not especially effective, especially when the car was in motion. It’s why today, even on vehicles with disc brakes at all corners, you’ll still see a miniaturized drum brake assembly in the rear disc, put there solely for adequate clamping power when the vehicle is stationary. And they still work well in emergencies today.
       
      And please, please, please don’t pull the big black hook in my Pinzgauer when it’s moving: that’s the actuator for a very powerful drive line brake. When stopped, it ensures I gain the holding power of any wheel which is engaged and in contact with the surface, but if used while moving can send some very nasty shocks down the torque tube.

    • 0 avatar
      MBella

      There are still plenty of manufacturers that use the caliper based parking brake setup. I never had an issue with on my VW. It comes down to the design of the system, cost and other engineering factors on which parking brake design they use, but the caliper based setup hasn’t gone anywhere.

  • avatar
    BigOldChryslers

    Anybody want to buy a genuine single-circuit A100 master cylinder?
    Same MC was used on 66 Chryslers.  I have 3 more good ones available if there are any takers.  :)
    Converting my cars to dual-circuit brakes was much easier than converting your van.

  • avatar
    skor

    You bet a parking brake will get you stopped from 65mph, provided that you have a couple of thousand feet to do it in.  According to Mush Limpblow and Sean Insanity,  that’s not a problem, because ‘Merica is big, not like those tiny countries in You-Rope that ain’t even a thousand feet wide.  All this safety business is just more tree-huger meddling.  Damn capitalism hating commies.  Go to Libya and kiss Muammar.

    ETA: Nice job on the refit.

  • avatar
    Detroit-Iron

    a lifetime steeped in Naderite propaganda has convinced me that I’m better off with some margin of hydraulic safety
     
    Coward!

  • avatar

    My ’66 F-100 is still on a single circuit MC. And the crappy MC rebuilds in this day and age last about 6-10 years, before they start to leak internally. It manifests in the pedal dropping to the floor under very low pressure, like waiting at a light. A quick hard pump, and it’s hard again. I’ve learned to swap mine out in under a half hour. Of course, in a Ford truck, it’s a bit easier to get to.
    But that’s why I never lend my truck out: I did it once when the MC was a bit soft, and scared the piss out of the driver. “Just pump it a bit harder”.

  • avatar
    geeber

    Cadillac and AMC/Rambler offered dual-circuit braking systems as standard equipment before 1967. AMC made it standard equipment in 1962; I believe that Cadillac made it standard that same year.

  • avatar
    Zackman

    Access plate in the floor? How long does it take for that and the screws holding it to rust up and be impossible to remove without a torch?

    • 0 avatar
      Lumbergh21

      Same set up in my 58 Chevy truck.  It’s inconvenient as you have to pull the floor mat back, but as long as you check your brake fluid more frequently than every time you replace the master cylinder, there is no real impediment to doing it other than laziness.

    • 0 avatar
      nikita

      “Naturally, the access panel doesn’t quite fit the larger dual-circuit master cylinder, so a funnel must be used to get fluid to the rear reservoir.”
      Chrysler never changed the floor stampings. My dad’s ’69 Sportsman had the same problem. The other “fun” with this arrangement is avoiding contamination via dirt and rust particles falling in during fluid level checks.

  • avatar
    Alex L. Dykes

    I’m one of those crazy safety-obsessed people that actually liked Nader’s ideas. Dual circuit brakes just make sense to me. As do energy absorbing dashes, crumple zones, air bags, seat belts, pretentioners, stability control, etc. It’s not that I need it 99% of the time, it’s that 1% of the time when I actually do that I don’t mind the cost of safety innovations.

    • 0 avatar
      mnm4ever

      Alex, as much as we all joke, its not that we dont appreciate safety developments.  Many of today’s safety features are a blessing to all of us… ABS, crumple zones, etc.  Its the idiot-proofing that bothers me.  Remember automatic seat belts?  How about the CHMSL?  Pointless expenses aimed at the lowest common denominator of drivers.

      My problem is that the single biggest safety improvement that can be made is to improve the nut behind the wheel.  If Nader would focus his energy on getting the US to mandate better driver training, improving driver skill, stepped licensing, minimizing the idiotic factors behind crashes, then we would all be safer without the idiotproofing.

    • 0 avatar
      jmo

      <i> If Nader would focus his energy on getting the US to mandate better driver training, improving driver skill….</i>

      None of that has ever been show to do any good.   We’ve been through this 100x on TTAC and there is scant evidence to support your theory.

    • 0 avatar
      psarhjinian

      If Nader would focus his energy on getting the US to mandate better driver training, improving driver skill, stepped licensing, minimizing the idiotic factors behind crashes, then we would all be safer without the idiotproofing.

      Nader doesn’t advocate that (much) because, quite frankly, it’s a lost cause.  You cannot train bad drivers to be better ones.  Heck, you can’t really “train” drivers at all, outside of “what a stopsign means” and “how to read speed limit signs”.

      Driving a car is something you’re conditioned to do, not trained to do.  There is a big difference between the two concepts.  For example, you can train someone to clean a gun or aim at a target at a shooting range, but you have to condition them to, in a panic situation, pull out a gun, deliberately aim, and shoot someone.  It’s akin to teaching someone people skills: you can’t, not really, and certainly not when the pressure is on.

      How you react in extremis isn’t something that’s trainable**. It’s is something you can condition someone for, but that’s a far more intensive process: it’s what we make soldiers, commercial pilots (and race-car drivers) do, not what we could expect Joe Sixpack to do unless driving was his day-to-day job.

      So instead you minimize the harm that people can cause and/or suffer by taking the human factor out of the equation.

      Countries that do have safer drivers have the benefit of cultural conditioning.  Much as I’d like to change some aspects of North American culture, that probably won’t happen.

      ** this is why the current trend to use training as a kind of CYA tactic when something bad happens is bullsh_t.  You can’t train someone on, say, “sensitivity”, and you can’t say someone “has been trained in emergency procedures” and expect it to work.  At best you can fire them because they’re been trained and you, management, can wash your hands of the matter because you’ve done your bit.

    • 0 avatar
      Zackman

      “Pointless expenses aimed at the lowest common denominator of drivers.”

      mnm4ever: I think you answered your own question. Problem is, the “lowest-common denominator” are usually those that survive the accidents they cause.

    • 0 avatar
      mnm4ever

      Yea yea I know we are too far gone to fix the bad driving now.  I can still bitch about it though!

    • 0 avatar
      aristurtle

      I’m fond of the CHMSL, myself: when driving at night it’s quite nice for cars to have a brake light that doesn’t also double as a tail light. It’s also far lighter than a crumple zone and far less expensive than an airbag. What’s the beef?

  • avatar
    relton

    Actually Hudson had a dual system, half hydraulic and half mechanical, from 1936, when they went to hydraulic brakces, until the end of Hudson. Very simple and effective.

  • avatar
    Birddog

    Hey MM! If you’re willing to put your John Hancock on that cylinder I’d gladly make it a desk ornament in my office! 

    No joke!

  • avatar
    HoldenSSVSE

    And somewhere along the way the emergency brake has become a pitiful parking brake that is incapable of stopping the car in a total brake failure scenario.

    • 0 avatar
      Kosher Polack

      Yes, and the pedal you get in most cars lacks any modulation at all, plus you would have to take one of your hands waaay off the steering wheel and stick your head under the dash just to reset it if you make some kind of mistake or enter a spin. It’s amazing how reliable brakes are in everyday service in hundreds of millions of cars around the world, but if they really do bail on you for some crazy reason, how many average drivers even know to raise their left leg and fumble around for some tiny ratcheting pedal? Or clunk the automatic into a lower gear? Hell, many cars don’t even let you do that anymore.
      I wish to modify my hand-mounted parking brake lever so you press a button to lock it, and otherwise you can pull it to slow down whenever you want (which I do, frequently, because the brake lights don’t come on when I do it).

    • 0 avatar
      psarhjinian

      Mostly because there’s very little need.  It’s very hard to induce total brake failure in such a way that the emergency brake is required, and even harder to do it without the car screaming brake failure warning at you well beforehand.
       
      It’s like complaining that your appendix can’t help you break down cellulose.  Since there’s very few situations in which humans will be eating grass, grass and nothing but grass, it’s moot.

    • 0 avatar
      Birddog

      Two years ago I lost a rubber brake line on the right front and the main metal line running to the rear on my 97 Ram. I never in ten lifetimes even considered something like this happening.. 
      I can assure you that at the very least one vehicle can come to a safe stop by downshifting and whacking the “Oh S#!+” pedal.

  • avatar

    I’ve got a scarebird kit on my ’62 Comet. They aren’t *quite* bolt on and will require some tweaking of components to fit. However the ability to buy replacement parts at any auto parts store and not only from the company that made the kit is what sold me.
    Not getting stuck for days in East Bloodynowhere Nebraska because I can just buy a Cavalier caliper at the local NAPA instead of having to have a custom one shipped to me from 5 states away does wonders for my peace of mind.

  • avatar
    LTDScott

    I’m happy to see that I’m not the only home mechanic who can’t make a double flare worth a damn.

  • avatar
    Scottdb

    I’m curious:  If/when you convert the van to front disks, will that have to include a proportioning valve, as well?  Would installing one with the four drums be helpful?

    • 0 avatar
      Uncle Mellow

      Either a proportioning valve or a different spec master cylinder – or both maybe. I have to fit a replacement proportioning valve on my wifes’ car at the weekend , so I’m hoping for fine weather and someone to pump the pedal for me.

    • 0 avatar

      What Mellow said, plus maybe the appropriate “residual pressure valve” or rpv.  Disk brakes use a lower pressure rpv, so if you use a master for drum brakes (10psi rpv) your disks will drag.  Wilwood and others sell 2 & 10psi in-line rpvs, most master cylinders have them built in for their original application.  That should confuse things a little more. 

      Before you take on any project like this do some research.  Many hotrod & racing forums have this covered ad nauseum. 

    • 0 avatar

      Supposedly I will be able to use the same master with an adjustable proportioning valve, though I might have to drill out the drum residual pressure valve and add an inline disc-friendly one.

  • avatar
    mzs

    I wonder about my ’67 Volvo. It has single circuit brakes and only a frangible (not collapsible, it’s supposed to bend/break at this rubbery mount) steering column. Does anyone know, was it something like early ’67s were still exempt? Also good work on this MM! I’d like to do a dual circuit upgrade, but worry I don’t have a prayer to get a double flare right.

    • 0 avatar
      mechimike

      That’s odd, because my ’67 Volvo wagon does have dual circuit brakes.  It may have been a running change, and back then with records as bad as they were its possible a ’66 car may have been tagged as a ’67.  At any rate, I can tell you from experience the Amazons are very safe cars- the emergency yank-up handle will stop the car (provided it is in place and functional) and that steering column will buckle in an accident.  Our race car (’66 Amazon) was in a front end wreck and the steering column neatly buckled, and did not impale the driver.  Unfortunately, part of the reason for the wreck was a loss of brake pressure due to a hose leak, and since it was a single circuit car, and the E-brake had been removed, the driver had no braking.  Luckily, the unibody structure took the impact well and the driver was unhurt (except for his pride).  Of course, avoiding an accident is far better than surviving one, so a dual circuit mod may be a good idea- and its not hard to do on the Amazon. 

      I can’t do a double flare either- I’ve bought 3 different flare kits and can’t do it on any.  I just buy pre-flared lines and couplings from NAPA. 

  • avatar
    Feds

    It’s taken me too long to do this, but better late than never: Murilee, I’ve been lurking here for a couple of years.  You showing up as a writer was enough incentive for me to get a WP account for the sole purpose of posting up how much I like reading your articles.

  • avatar
    MrFixit1599

    On my 1981 Subaru GL, the Emergency Brake was actually connected to the front brakes.  Sadly, if the brake pads decide to remove themselves from the front drivers side caliper (due to damage from a previous offroad excursion), not only will the regular brakes not work worth a damn, neither will the Emergency Brake.  Needless to say this caused an airborn offroad excursion.  Still drove the damn thing about a mile home with a nice trail of oil and antifreeze behind me. 

    • 0 avatar
      MarcKyle64

      Ah yes, the Subaru HillHolder emergency brake.  It would activate a little valve in the master cylinder that held the brake pressure until the clutch pedal was released.  It was quite handy on hills where you wanted a hand on the wheel and the other on the shifter.


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