>Joe Flake wrote:
>>
>> Anybody have insight into the workings of the brake booster
>> unit for a TR6?
>>
>> My understanding is that at rest (ie no pressure to the
>> brake pedal) both sides of the diaphram are exposed to
>> the same airspace. This means no motion, since there's
>> no pressure differential.
>>
>> When you press on the pedal, you upset this, and allow
>> the master cylinder side of the diaphram to be exposed
>> to engine vacuum, and the other side gets exposed to
>> atmospheric pressure. This differential pulls the
>> diaphram and thus provides the boost.
>>
>> And so I thought that there was never a time when
>> there was an "open" flow of air into the vacuum hose
>> back to the engine. (perhaps a bit of movement as
>> pedal/valve moves, but not a continual flow)
>>
>> Is this how it's supposed to work???
>>
>> If so, why does a good steady pressure on my brake pedal
>> kill the idle of the engine? Idle is about 900-950 rpm,
>> but with brake applied, it will stumble down into the
>> 600-700 range, and threaten to die. Removing my foot from
>> the pedal immediately restores smooth idle. My assumption is
>> that it opens an air flow into the vacuum line to the
>> booster.
>>
>> Does this mean a bad diaphram? Or maybe something else?
>> If it's the diaphram, what are repair options? I've
>> heard in the past that the replacements weren't available,
>> but I'm not sure whether that's true or not.
>>
>> Currently avoiding brakes to keep the engine running :-)
>>
>> Joe
>> flake@a3115jmf.atl.hp.com
>> '72 TR-6 CC75128
Hi Joe,
Maybe there is a short in your brake lights or your battery is low. When
you apply the brakes there is more draw on the alternator causing the engine
to slow. Not normally . . . but if there was a problem?
Could be electrical. Just a thought.
CC51493LO
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