At 01:13 PM 2/22/2000 -0800, Skye Poier wrote:
>.... I have the earlier hydraulic switch. It usually doesn't come on
unless I'm REALLY pressing on the brakes. .... Is it possible to make the
switch more sensitive or to fit the later type of pedal-actuated switch?
There's not much you can do to make the switch more sensitive, as the
switch is sealed as a crimped assembly. However, the heavy pedal to
actuate problem is not terribly uncommon, and is just the sign of a tired
switch. If you install a new pressure switch it should work with just
light toe pressure on the pedal (should). In fact the brake l;ights should
operate just pressing the brake pedal with your thumb.
FWIW, I ran silicone DOT-5 fluid in my MGA from the day it was restored
with all new hydraulics, until 12 years and 135,000 miles later when I
changed the hoses and repacked all the hydraulic cylinders. During that
time I flushed fresh silicone fluid through the system every two years, and
never had a speck of trouble with it.
When the system was repacked I switched from silicone fluid to Casterol LMA
DOT-4 fluid, just out of curiosity. Shortly thereafter the brake pressure
switch failed. I wouldn't say that had anything to do with the DOT-4
fluid, any more than it had anything to do with the DOT-5 fluid. It was
just time for the switch to expire, that's all.
Otherwise, I think maybe I don't like the DOT-4 fluid. After about six
months I had to R&R a short section of steel brake line at one front wheel
while I was replacing a worn lower swivel link. When I bled the brakes
afterwards the fluid was pretty black with disolved and suspended rubber
particles, so I flushed the whole system. Because of this, about six
months later I bled the brakes again just to check, and sure enough the
fluid was quite dirty again, and so I flushed the entire system again. I
never had this problem with the silicone fluid, so naturally I'm a litle
concerned about this. Would anyone care to venture a guess whether this
condition may be an effect of the DOT-4 fluid, or maybe some inferior
rubber products having gotten into the system with the last rebuild? And
FWIW, all the rubber hydraulic parts came from Moss Motors.
Barney Gaylord
1958 MGA with an attitude
http://www.ntsource.com/~barneymg
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