C2 ('63) Brake System dilemma!

[David Van Weele]

Re: C2 ('63) Brake System dilemma!

I installed Silicone brake fluid in my 1963 Z06 in 1980 and it is still there. I am sure I did not get it all out, I used the original brake lines, slave cyliners and a new M/C. The braking feel is a little softer than with the normal brake fluid not so much as to be uncomfortable. Silcone seems to trap air to a greater degree and I think that is the reason for the softer feel.

I am not an expert on this but these are my observations so take for what it is worth.

Dave

[Ed Driscoll]

Re: C2 ('63) Brake System dilemma!

Hey Guys,
As far as the best way to flush systems, I leave that to the pro's. However, as to the question of what to use, silicone or not, here's an email I received from someone in the know.

Hey Ed,

We've never been able to get a truly HARD pedal with silicone fluid. Owing
to its very chemical nature, the stuff is too springy to satisfy a Barber
racer for example.

We'll bet that with the Skippy cars where heat is really not that big a
problem,( the brakes are in the open air after all - and just how much do
you use the pedal in those things anyway) that the boys are using a good
DOT4 fluid like Castrol or Motul.

Best regards,

Tom Hnatiw
Dream Car Garage

Toms an old racer, and from what I can gather, most race cars (including the Barber Dodge RT cars) run DOT4. I guess the thrust of this is, if it's good enough for a race car, it's probably good enough for your Vette. Just keep that cap on.

As an aside, when I race the RT's, the pedal is very consistent, and I sense no brake fade when driving the car hard. You should never be driving that hard on the street. I've never seen a boilover related brake failure at the track.

Hope this helps.

Ed

[Mike Cobine]

Re: C2 ('63) Brake System dilemma!

The simple reason that the racers don't run it is that in the real world, it is compressible and it can change size (volume) with temperature differences. Maybe in a lab it doesn't, but in a race car, it does.

This may well be due to air that is trapped, but unfortunately, the heat you generate in a race can bring them to boiling, and then you have air no matter how hard you try not to when pouring it in.

This has been known to racers as far back as the mid/late '70s when the DOT 5 silicone fluid was first making the Corvette rounds.

You brake hard in a corner, you heat up your brakes, fluid expands, fills (overfills) the MC, and the pedal gets high. You run down a straight, force a lot of cooling air over the brakes, cool down the fluid, the fluid contracts, and suddenly you have a very low pedal. Now you have your next corner at 160 mph.

Simply put, you ain't got time to pump the pedal!

Wilwood tried a synthetic that was possibly based on the silicone to increase the temperature about 10 years ago to replace their famous Wilwood 560. It was Wilwood 750 or 780 or something like that. Many bought it and threw it in the trash the same weekend.

A lot of things will work in an 1100 lb. formula car. My favorite was Motul in the red can. Good stuff, dual pin brakes would actually brake, and no fade. And if it stopped a 2700 lb 180 mph '66 Vette, it will stop your street Vette.

[Clem Z.]

Re: C2 ('63) Brake System dilemma!

mike maybe this what explains the "altitude" problem you hear about with DOT 5.you use your brakes hard coming down steep hills and you heat up the fluid and when it cools off after you get to less steep hills you loose pedal.