Re: IML: Brake Light Switch on '56

[randalpark@xxxxxxx]

That sounds like a plan to me. It still shouldn't be necessary. Those 
switches were the primary way to activate brake lights for over 30 
years in the automotive industry when hydraulic brakes first became 
common place. They were very dependable, and were easy to replace.

I'm with Kenyon in that you may have gotten a bad switch. Even with all 
new parts and no dirt, an air bubble is still a possibility, although 
as I stated earlier, I have never had to bleed the switch. Since I am 
not there to feel your pedal, I am still concerned that possibly there 
is something else going on, and it doesn't sound electrical. If there 
is a hydraulic problem effecting the lights, then it could eventually 
effect the brakes. That would bother me.

Paul W.

-----Original Message-----
From: jcantor791@xxxxxxxxxxx
To: mailing-list@xxxxxxxxxxxxxxxx
Sent: Wed, 2 May 2007 6:18 PM
Subject: RE: IML: Brake Light Switch on '56

Paul, 
 
Both the fluid incompatibility and the dirt issue make at least some 
sense to me however, there are two important points that I probably 
should have mentioned in my original post. First, the entire hydraulic 
side of the brake system was replaced with new components two years ago 
with the exception of the two brass junction blocks which I cleaned 
very thoroughly with alcohol and compressed air. I think this makes the 
dirt scenario rather unlikely. Second, while I did upgrade from the 
"original" spec DOT 3 fluid, I did not go with the silicone DOT5. 
Instead I used ATE's DOT4 fluid which seemed to me to be a nice 
compromise (it also has the advantage of being available in different 
colors to make flushing the system very easy). 
 
Therefore the jury is still out as to exactly what might be causing the 
problem. However, in the interest of protecting the car's very nice 
tail end while also avoiding the potential for whiplash, I'm going to 
install the "modern" pushbotton brake light switch that I've purchase 
at least as a temporary solution. This will allow me to safely drive 
the car this season while still puzzling over what else might be going 
on. In the fall when I'm planning to flush the brake fluid anyway, I'll 
probably take the switch off and see if I can determine what the issue 
is/was. 
 
Thanks, 
Jeff 
'56 Sedan 
Trenton, NJ 
 
Subject: Re: IML: Brake Light Switch on '56 
Date: Mon, 30 Apr 2007 23:41:57 -0400 
From: randalpark@xxxxxxx 
Reply-To: mailing-list@xxxxxxxxxxxxxxxx 
It sounds to me like the switch is clogged with foreign material. I 
would suggest replacing it again. 
 
I saw the post about the hydraulic switches possibly not being 
compatible with DOT 5. I haven't found that to be the case either. That 
type of switch was used through 1961. I have that type of switch in my 
1948 L.C., as well as my '55, '56, and both '60 Imperials. The switches 
do go bad, and they don't always leak. I had the most trouble with the 
one in my 1960 LeBaron, and that was before I changed everything over 
to Dot 5. Apparently, there was some crude in the lines on that car. 
Eventually, it worked its way into the switch. I was lucky that I 
didn't lose my brakes. I didn't know then that a switch problem like 
that could be a warning sign of a more serious problem. 
 
Knowing what I do now about brakes, rotten Dot 3 fluid in old cars, and 
changing to Dot 5, I would consider a light switch problem like you 
describe, especially if it should continue after replacing the switch 
the second time, to be a possible indication of dirt in the system. On 
your car, it would likely be from it entering the reservoir during 
removal of the lid to check the level. It would be very easy for that 
to happen, and then work its way into the switch. If there is enough 
dirt in the system, it will also eventually cause the brakes themselves 
to not work either. A sign of this would be good brakes when the pedal 
is depressed gradually, with a super hard and non-responsive pedal when 
pushed suddenly for a panic type stop. It doesn't take very much dirt 
or very big clog to effect brake action seriously. 
 
I apologize for saying that I thought you should look elsewhere, and 
then not suggesting what else to check. It has been that sort of a day. 
I would replace the switch, and see if that fixed the problem. If it 
happens again with the new switch, I would suspect foreign matter in 
the lines. That would indicate the need for a complete flush, or 
possibly replacement of all the lines, including the metal ones. The 
junctions should all be cleaned and inspected as well. 
 
If a car sits long enough, and heaven forbid that the brake system was 
some how left open, such as if the master cylinder had been off for a 
few years, the fluid will turn gloppy and finally solid in the lines. 
Flushing them doesn't always get it all out. 
 
I hope this helps. 
 
Paul W. 
 
 
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