In a message dated 2/21/00 9:25:28 PM Eastern Standard Time,
tkvezina@bellsouth.net writes:
<< I've always used a fresh, unopened can of brake fluid for flushing the
system. A quality DOT3 like Castrol LMA is fine. DOT4 is also compatable
with DOT3. It has a higher boiling point and absorbs less moisture, but it
is MUCH more hazardous to paint.
My experience with DOT5 (silicone) brake fluid is limited, but all bad. Two
weeks after I changed over to DOT5, I was picking pieces of master cylinder
seals out of my front calipers! >>
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A coupla points here. Castrol LMA is DOT 4. Do not use any DOT 3 in your B,
unless you buy British spec DOT 3 which is really DOT 4. (Confused? So was
I until I figured it out.) US spec DOT 3 will eat any natural rubber seals.
Check out the tech page at www.vtr.org for lots on brake fluids. (I know,
its a Triumph page!)
You are correct about DOT 5. Silicone brake fluid can be used if you rebuild
the entire brake system and replace every seal. It does not eat paint, but
it doesn't work as well as DOT 4 either, and it really doesn't mix with other
brake fluids. Also, because it doesn't absord water, it allows any water in
the system (from humidity in the air) to pool and will rust out your brake
lines unless you change it annually.
If the brakes were working correctly before, but you want to rebuild the
calipers, I wouldn't worry about the MC. Rebuild or replace it with a rebuit
if you want to make sure. (That's what I did.) Rebuild the calipers,
replace the rear wheel cylinders because they are fairly cheap, replace the
flexible brake hoses (I recommend braided hoses), flush the system with
denatured alcohol, then blow compressed air thru it to dry it. Flush it once
with new Castrol LMA, then fill and bleed all.
The gunk in the calipers is probably because the fluid wasn't changed.
(Probably ever!) Change the brake fluid by opening each wheel cylinder and
bleeding it until fresh fluid comes out. Do this every two or three years.
Racers use two different color brake fluids so they know when the new stuff
gets thru the syste. Pretty neat idea! We just had this discussion on the
Spridgets list. Check the archives for that thread.
Allen Hefner
SCCA Philly Region Rally Steward
'77 Midget
'92 Mitsubishi Expo LRV Sport
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