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Investigating the failure of brake switch with DOT 5 brake fluid (silicone).

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  • dpson
    replied
    How about the opposite approach; is there something in DOT 3 fluid that helps to prevent corrosion of the switches, perhaps by absorbing moisture, oxygen or ozone out the switch chamber, that DOT 5 doesn't do?

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  • nels
    replied
    I once had installed silicone fluid in a disc brake 63 GT Hawk. The vacuum assist was sucking a small amount of silicone fluid through the booster and into the intake manifold then down the number seven cylinder. The end result was a severely fouled number seven plug. The electrode was totally chocked off with white powdery sand or silicone. Sounds like the same thing with the switch.

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  • BILT4ME
    replied
    Thank you John!

    I hadn't really thought about what could happen to chrome when parked under a tin shed due to galvanic reaction due to ionized water dripping off of the tin down onto the car or even the proximity of the car in an electric field generated by the tin roof on a shed and the electrostatic charges developed by the wind, etc.

    Maybe there is some reality to it, I'm not sure.

    I deal with "poison pads" and galvanic reaction in the support structures we design for industrial use in marine environments, so I understand the process, but had not applied it to a car being parked in a building.

    I grew up in a rural area in northern Iowa and it was not uncommon to build lean-to's out of galvanized steel sheets left over from grain bins or even have all the walls of the building made from similar materials. I have seen examples of other things that resulted, such as plant life dying due to the high zinc content washing off the roof of a tin shed, but hadn't thought about others.

    When I bought my 59 Lark in 1981, the front and rear bumpers were hazed, as if they never got finished during the chrome process. All of the pot metal trim was VERY bubbled under the chrome. I know it's possible that it was a bad batch from the factory, but the car only had 28K miles on it and it was only 22 years old then. I compared it to a 60 Lark that we sitting outside of a wooden building for all of its life (never garaged) and all of the chrome on it was in MUCH better condition. It's possible that my 59 was stored in or under a tin shed that had ionic water dripping on it for most of its life previous to me.

    Just a possibility.

    Thanks for the thoughts!

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  • jclary
    replied
    Originally posted by jclary View Post

    Just as parking your Studebaker under an exposed galvanized tin roof seems to promote corrosion of your chrome bumpers, oxidation (electrical activity) accelerates under certain atmospheric conditions.
    Originally posted by BILT4ME View Post
    Do you have more information about this? I have often wondered why my Lark has had really bad chrome on the bumpers as well as the pot metal trim around the windows when I bought it 34 years ago with only 28K on the odometer and this may provide some insight......
    Sorry it has taken me so long to respond to your question. I saw it yesterday but had to contemplate and try to remember where I first heard the idea. Unfortunately, I couldn't recall where I read it. I can't recall if it was merely an (unscientific) offhand comment, or anecdotal observation in an article (as in Turning Wheels), here on the forum, or some other source. However, it struck home to me because I have so much chrome stored under a drafty tin roof pole barn over an exposed southern red clay floor.

    In this environment, I have observed chrome and aluminum degrade, and corrode. Similar parts, kept in my house, and in another building with a real floor, and no exposed tin roof, have survived much better. Therefore, I have concluded that (especially here in the hot, humid, thunderstorm prone south) electrically charged humid atmosphere, plays a role in promoting corrosion, and degradation of chrome plated metal. Also, that it is possible that proximity of certain other materials (Zinc) could play a role in the process.

    Here is a Wikipedia link that my be of value. http://ccs.dogpile.com/ClickHandler....35F2A29B6D57F5

    However...The following paragraph, didn't take long to rise above my level of comprehension/formal education, or motivation to grasp mastery of the subject.

    "Dissimilar metals and alloys have different electrode potentials, and when two or more come into contact in an electrolyte, one metal acts as anode and the other as cathode. The electropotential difference between the dissimilar metals is the driving force for an accelerated attack on the anode member of the galvanic couple. The anode metal dissolves into the electrolyte, and deposit collects on the cathodic metal."

    Stuff like this is where my eyes tend to glaze over and I either start daydreaming or wander outside to tinker on something interesting.

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  • Xcalibur
    replied
    Interesting info on what actually happens to the switch. Years ago I reported in Turning Wheels on the Ron Francis switch and its extremely disappointing performance (early failure), along with the snippish reply I got from RF when I wrote (in the old days) asking about this, given his ads at the time. Ultimately, I simply converted all my silicone equipped vehicles to mechanical switches... VIOLA, problem solved once and for all! None have needed replaced since.

    Just for info sake I found the switches that lasted the longest with silicone fluid were from NAPA, greatly outlasting the RFs of the time. But, today who knows!

    Leave a comment:


  • BILT4ME
    replied
    Originally posted by jclary View Post
    Just as parking your Studebaker under an exposed galvanized tin roof seems to promote corrosion of your chrome bumpers, oxidation (electrical activity) accelerates under certain atmospheric conditions.

    Do you have more information about this? I have often wondered why my Lark has had really bad chrome on the bumpers as well as the pot metal trim around the windows when I bought it 34 years ago with only 28K on the odometer and this may provide some insight......

    Leave a comment:


  • jclary
    replied
    Originally posted by ivorydan View Post
    John, how long was the dot 5 in there before the switch failed?
    Dan
    Honestly, I can't recall, except to say that it had been in there for years. Even then, I can't recall how long it was NOT working. Only that I replaced it after discovering it was not working.

    As we can tell from posts to this thread, there seems to be a wide variation as to how long a switch lasts until it fails. The main theme is that switch failure appears to be related to the use of DOT 5 much more than the traditional DOT 3. The suggestion to fill the switch cavity with silicone, dialectic grease, etc., is problematic (in my opinion) due to how the switch is constructed and how it operates. The "dry side" cavity must allow about 1/4" movement of the copper washer when pressure is applied so that it makes contact and closes the circuit. One other thing to keep in mind...this is a "live" circuit. It is "open" only by a very short space. Garyash and Altair have made good points regarding materials, and reactions in the presence of electrical charge (Electrical discharge creating corrosive OZONE). Just because a direct circuit is not being completed when the switch is NOT activated, does not mean that electrical reactions are not taking place.

    Although electrical science has made huge leaps, there are still "phenomenons" in the field. Just as there are huge electrical reactions very obvious (lightening) in electrical storms...I believe the same is occurring (mostly unnoticed) microscopically. I view this entire orb we call earth, as a living organism. If you've ever experienced "foxfire," you know what I mean. That is why I think that in the tiny atmosphere in the switch, there is probably electrical activity, even when the switch is not activated. Just as parking your Studebaker under an exposed galvanized tin roof seems to promote corrosion of your chrome bumpers, oxidation (electrical activity) accelerates under certain atmospheric conditions.

    As to what role the chemicals of DOT 5 plays, I don't know, but under certain conditions, it could be serving some catalytic role.

    Leave a comment:


  • StudeNorm
    replied
    I have to agree with post #5. The issue may be quality. I have a switch that was brand new in the box hanging around on my shelf for a few years but had never been installed. Since the switch on my '63 seemed to be getting sluggish I installed the new switch and now I had total failure. It didn't matter how hard I depressed the pedal, nothing. I placed the old switch back in and all started working again so my conclusion was...BAD SWITCH! Personally, I like the mechanically activated idea. BTW, my '63 Avanti has had DOT 5 fluid in it for many years (since before I got it) and the brakes and brake lights all work fine.

    Leave a comment:


  • Robert Crandall
    replied
    I had unending switch problems after I changed a 1957 Buick to DOT 5. Switches from Harley Davidson, from manufacturers that claimed DOT 5 compatibility - none worked for very long, in some cases not long enough to make a 100 mile trip. I followed as was done by post #7. I looked at the under dash switch on my 1978 C20 for the suspended pedal, bought one just like it, made brackets, and installed it on the Buick. Close to 15 years later, it still works.

    For my 1949 2R5 I did what was done in post #9. The original mechanical switch on my 1950 GMC still works. I bought a replacement switch for that truck and installed it on the 2R5. It looks just like the one in post #9, but without the adjustable arm, and works without problem.

    It will be good if Mr. Clary's research leads to an answer because a switch that lasts is the easiest fix. I changed both of the cars above to a dual master cylinder, so I already had to come up with a different method of having a switch.

    Leave a comment:


  • altair
    replied
    I sometimes think outside the box and ozone comes to mind in this application. Each time the switch is opened (after application) there will be an arc created, that arc will generate a minute molecule of ozone gas. Ozone gas is a form of oxygen. Molecules of ordinary oxygen are made up of two oxygen atoms joined tightly together. Ozone molecules have a third oxygen atom loosely attached. The third atom can easily separate from the molecule and combine with other substances. Ozone is a chemically reactive gas. This could explain the corrosion. Just an out of the box thought FWIW.

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  • 345 DeSoto
    replied
    OR...drill two small holes in the opposite sides of the switch, and fill the switch full of silicone grease...

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  • ivorydan
    replied
    John, how long was the dot 5 in there before the switch failed?
    Dan

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  • BILT4ME
    replied
    What about using a dab of silicone caulk on the exterior of the switch where the phenolic meets the aluminum body in order to prevent moisture from entering from the exterior. I am guessing that since the DOT3 would ABSORB the moisture, it was less of an issue because it would draw the m,oisture AWAY from the contacts, whereas, now, it allows the moisture to stay inside the switch and corrode the contacts.

    Just my $0.02.......

    Leave a comment:


  • jclary
    replied
    I like your thinking Bob. Another thing has occurred to me. When I switched over to DOT 5, I drained and cleaned everything. I replaced the flex hoses, and fabricated new metal brake lines. I either rebuilt, or replaced, the master cylinder, and all four wheel cylinders. However, I think I merely re-installed the brake switch. It is possible that the brake switch was the one that left the factory in 1951. At the time I did the conversion, the car only had around 58,000 miles.

    It is easy to see how incorrect assumptions can be concluded from such crude unscientific observations. I like the alternative mechanical switch solution that Paul and others have made. I have several of those switches. Surely, with the early automatics like my Land Cruiser, having those wide double brake pedal shafts...room to safely install the switch shouldn't pose a problem.

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  • garyash
    replied
    Ideally, a pressure switch with a welded stainless diaphragm would solve this. Someone must make one for the automotive market. Otherwise, there are lots of industrial switches to use - at a price.

    Adding the relay seems to be a common way around the problem. Here's a link to a page where the guy used a relay with a capacitor across the contacts and a diode on the coil to prevent arcing.
    http://www.omgtr.ca/technical/brakel...lightrelay.htm

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