Date: Sun, 4 Jul 2010 02:11:01 -0700
Reply-To: neil n <musomuso@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: neil n <musomuso@GMAIL.COM>
Subject: Re: Pedal Pressure & Brake Lights
In-Reply-To: <4C2F9435.5070508@cox.net>
Content-Type: text/plain; charset=ISO-8859-1
Thinking about it again, it seems to me that the push rod adjustment
is there to provide a suitable amount of play between the MC piston
and pushrod end so it's not pushing on piston when pedal at rest.
Regardless, I see what you mean Mark et al.
To all. For sure. I understood that the switches were pressure
activated. Just didn't suspect them, as I couldn't see both of them
failing (or becoming less efficient?) at the same time. But I guess
that could be the case. I mean if one fails, the other should do the
job of closing at the right point right? Or, as per Marks comment,
maybe that's just how they operate.
If replacing the switches doesn't work, adding a pedal actuated
electrical switch seemed like a good idea to me too.
But if Marks anecdotal observation is correct, how hard would it be to
retro wire in some 2 contact switches? I likely have the parts.
Looking at my air cooled Haynes I see how the switches work in terms
of lighting up the brake lights, but am not overly clear about the 3rd
connection to the Brake Warning Light. Is there something in the
switch(s) that activates causing light to go on in the event of a
hydraulic pressure loss? Haynes says if light stays on, (all else
correct) then a fault lies in the hydraulics. I'll search that one.
I'm sure it's in the archives.
I'm guessing, but am just about certain that finger pressure alone
would light up the brake lights. I would have to have a helper confirm
this, but at night, keeping one eye on bumper or other reflective
surface of vehicle behind me, if using a light foot, I can slow down,
come to a stop, no brake lights on. What I don't want is to be warning
people that I'm slowing down by harfing down on the pedal more than
need be.
Neil.
On Sat, Jul 3, 2010 at 12:49 PM, mark drillock <mdrillock@cox.net> wrote:
> It is internal hydraulic pressure that turns on the switch, not pedal
> pressure. So whether that pressure comes from your foot or the booster makes
> no difference.
>
> Anecdotal evidence makes me think the early 3 wire switch takes more
> pressure than the 85+ 2 wire one. Don't really know.
>
>
> Mark
>
>
> neil n wrote:
>>
>> Hi all.
>>
>> It's likely that my brakes engage before brake lights come on. (need a
>> helper to confirm this)
>>
>>> From archives, 2 possible causes stuck out. Corrosion at bulbs, and
>>
>> rear shoes out of adjustment. i.e. fronts engage but rears too far
>> away so extra pressure is needed to actuate switch for rear hydraulic
>> circuit. But if one switch engages, all brake lights come on right? In
>> my case, brakes work fine, pedal height is good, and has stayed
>> consistent over several thousand miles, so the rears are working
>> right. I'll check for corrosion at bulbs but they are likely fine.
>>
>> I recall checking the push rod adjustment on the new booster I
>> installed ~4 years ago. Would an improperly adjusted push rod (on
>> booster) affect amount of pedal pressure needed to turn brake lights
>> on?
>>
>> What else would could be at fault here? Design flaw?
>>
>> Both brake light switches were replaced at time of booster install.
>> AFAIK, the switch wiring is fine (untouched by me)
--
Neil Nicholson '81 VanaJetta 2.0 "Jaco"
http://tubaneil.googlepages.com/
http://groups.google.com/group/vanagons-with-vw-inline-4-cylinder-gas-engines
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