> I've had very good luck with DOT 5 silicone and think the key
> is to having
> the system free from any other fluids, and would always recommend flushing
> with alcohol if necessary.
> I'm concerned about why someone is stating to stay away from it
> for racing.
> What is the problems associated with racing that would not be good for DOT
> 5?
I've no personal experience, but here are the reasons I've heard :
1) DOT 5 has more of a tendency to foam when agitated in air ... that is,
form tiny bubbles in the MC reservoir that are hard to bleed out if they get
into the lines. All it takes to sidestep this problem is to let it
'breathe' a bit after adding to the MC and before bleeding again, but this
may not be convenient if working on brakes between races.
2) I believe (1) is the reason DOT 5 has a bad rap for 'soft' pedal ... but
it is very slightly more compressible than glycol fluids, especially when
hot. This may result in slightly more travel at the brake pedal, maybe 1/2"
or so when the brakes are hot & you really stand on them. Some people feel
this is a problem.
3) There are racing brake fluids that have higher dry boiling points than
DOT 5. Of course, they have to be changed frequently to keep them dry
(glycol will suck moisture out of the air, and even through soft brake
lines). But, that means DOT 5 is not the ultimate for racing.
YMMV
Randall
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