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Brake light switch

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peteatgr

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I have replaced my hydraulic brake light switch several times and always seem to end with the same result. After a fairly short time the brake lights come on later and later in the stopping process unti they finally only come on when the car is just about stopped. I purchased a Watson Street Works mechanical brake switch but can't seem to find a good spot to mount it. Anyone have a good idea on either; making the hydraulic switch more relaible, mounting the Watson mechanical switch, or another simpler approach to brake light reliability? At this point I'm reduced to hand stop signals and I'm not even sure most younger drivers know what I'm doing with my arm and hand.
 
A man named Dave Braun (not sure of the last name) makes a relay setup with a capacitor for this that takes the electrical load off the very weak hydrolic switch so the switch just activates the relay and the relay takes the electrical load. He lives in Washington state and sells the unit for about $15. Very easy to install. I have this on all my cars and have had no problems. I can get you his information if you are interested. Have a good day!

John
 
That would be a perfect solution. Easy installation works for me. If you can get me a contact I would really appreciate it, and my car might not get rear ended!
 
Pete, I had the same experience with the poor durability of the replacement hydraulic brake switches. I also bought a Watson Street Works mechanical switch and mounted it as shown in the picture.
I made a simple right angle bracket and attached it with two screws to the bottom of the heater duct, just in front of the heater door.
 

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In the early 60s my Dad had a problem with the hydralic switches in the British cars. He found the 50s Chevrolet switches actully screwed into the threads and wired easily and were very reliable along with cheap back then.
 
 
The only time I've heard of AH owners having that problem is after they've switched to synthetic DOT 5 brake fluid. Is that what you've done?

If you've decided to switch to an all electric system consider the MGB brake light switch which can be bought from MOSS motors.
 
I did switch but I don't remember if the problem started before or after.... I think after. You may be right. I plan to install Dave DuBois ugrade to the pressure switch and the mechanical Watson switch in parallel. Someone has a good wiring diagram for this on the internet that I have seen... I just have to find it again. In this way if one fails the other acts as a full backup. Too many close calls with "rear enders". Taking no more chances.
 
John has a point, what is the cause of break pressure switch failure and does it have something to do the use of DOT5?

In my case the new switch worked quite well in its DOT 5 environment for many years before I was informed at a stop light that I had no brake lights. Returning home, I found that by pressing on the peddle very hard, I could get the brake lights to light. Since I very seldom, if ever, actually observed MY brake lights, I can’t say whether the condition came on quickly or the lack of light response got progressively worse over an extended period. I can say that now I look for a brake light reflection every time I back my Healey out of the garage.

So, did the switch fail because:

  1. It could not handle the electrical draw and deteriorate to failure?
  2. It becomes less sensitive and the softer peddle produced by DOT 5 (as compared to DOT 3) exposes the growing unresponsiveness sooner?
  3. DOT 5 deteriorates a component in the switch which results in switch failure?

Let me first state that I have no idea what the actual cause of brake switch failure is, however, if the above list has any validity and #1 is the culprit, then installing a relay would reduce the power through the switch and extend its life considerably. If #2 or #3, or a combination, are the cause of the switch failure, then the installation of a mechanical switch seems, to me, to be the alternative.

Pete, I totally agree. Although I replaced the pressure switch, I wired a mechanical unit in parallel with the hope of not having 2 failures. Since then, at least 1 switch has provided good break light response. I have no idea, however, if one or both are delivering as I have never again checked.

Ray (64BJ8P1)
 
Ray,

I started searching for a way to insure the activation point reliability of my brake lights which had become just like yours - came on at about the time I'm fully stopped. I searched around the internet and from one person to another to another I came across Dave Dubois who offers a simple kit to prevent the "burn out"/failure of the hydraulic pressure switch. I contacted him and he quickly replied with the quoted response below. I checked around and have found several people who have used the kit and it seems to have given everyone long term reliability of their brake lights. The absolute cause of the orignal problem of switch failure (currrent overload or Dot 5 fluid) seems to be up for debate a bit - but the switches do seem to fail with disappointing frequency for whatever reason. i'm determined to not get rear ended as I have almost had happen all to frequently.

"If by that you mean not having to push the brake peddle harder to get the brake light to come on, the answer is no. If you have to press harder on the brake pedal to get the brake lights to come on, you need to install a new brake light switch. My relay/arc suppression circuit will only insure that the replacement brake light switch will not fail again in a few months. In that regard, the circuit does make the system vastly more reliable. The addition of the relay/arc suppression circuit will also allow you to add whatever power third brake light you wish to the circuit without fear that it will cause the brake light switch to fail."

I did see a nicely diagramed wiring diagram on the internet for making Dave's kit/pressure switch mod operate in parallel with the Watson Street Works mechanical switch and that's what I intend to do .......as soon as I can find it again.
 
Hi Peter and thanks for the information. I have known Dave for years but never had a conversation on this subject so I am a little surprised to learn he addressed and designed something for this issue. Did Dave’s kit references indicate if they are, or were, DOT 5 users?

I appreciate that your BJ8 P2 has separate brake and directional lights so placement of a relay after the switch would be appropriate, however, my P1 (as well as all previous models) requires a Flasher Relay to mediate between brake and directional lighting for single dual-purpose rear bulbs. When considering the installation of a relay to reduce load on the pressure brake switch, it became clear that I may be making additional demands on the flasher relay.

Brake%2520Switch%2520Light%2520Relays.jpg


Since this relay is relatively complex (a black box to me for many years), I decided to see if I could also offload some draw on this unit as well. To do this, I decided to move my previously planned relay location from feeding the flasher relay to feeding the lights after the flasher relay. Although this approach required an additional relay, it now offloads 2 critical electrical units while improving power to rear lighting.

Thanks again,
Ray (64BJ8P1)
 
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I installed a Watson brake switch on my Jaguar Mark 2, and Dave Dubois may have been the person who recommended it. Ultimately, it worked beautifully and could be adjusted to switch on the brakes with just a touch of the pedal. I had already installed a generic third brake light in the rear window (excuse the non Brit term). That enabled me to see exactly when (and if) the brake lights came on. It was connected to the original wires at the hydraulic brake switch, which remained in place. It could be reconnected with no problem. However, this switch was designed to work in cars with brake pedals that penetrate the fire wall--yes, something found on old car. I had to mount the switch backward and held it in place with a short piece of angle iron fastened to the steering column. This looked a lot better than it sounds. However, if I had it to do over again, and hadn't invested in the Watson switch, I would explore the MGB switch or some generic switch that would work by simple depression of the brake pedal.
 
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