Do you use silicone brake fluid

Due to a rather traumatic time with some brake fluid and a freshly painted kit car 30 years ago I have used expensive silicone brake fluid on my build.

It has taken a lot as I had a few leaks, and even more now as after a recent rolling road session they undid the brake union to see if it was a stuck caliper causing a rear lockup.

My former garage owner friend advised me that modern normal brake fluid does not appear to damage paint so badly as in the past. Also, it would help with pressure bleeding the brakes if required as I doubt any garage would have a silicone filled pressure bleeding system as well as a normal one.

As far as I understand you can go from silicone to normal fluid but not back.
 
Be careful. Regular brake fluid is hydroscopic and will absorb water - lowering the efficiency of the fluid and the temperature at which it will boil and fail. Silicone fluid is not hydroscopic and does not absorb water. The problem arises when water gets into the silicone system and is not mixed with the other fluid. Now you have two separate fluids and when the water arrives at the caliper piston its low boiling point will give immediate failure. As the regular brake fluid mixes its efficiency slowly reduces but does not cause sudden and complete failure. You are better off using a quality brake fluid and flushing the system every couple of years to keep it fresh.
 

Randy V

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Bud speaks the truth... However, one thing needs to be added about silicone fluid... It is extremely difficult to get the air bubbles out of it as it is more viscous than normal brake fluids. If trying to bleed the brakes in a cold or even cooler shop, you'll be busy for days..
 
Bud speaks the truth... However, one thing needs to be added about silicone fluid... It is extremely difficult to get the air bubbles out of it as it is more viscous than normal brake fluids. If trying to bleed the brakes in a cold or even cooler shop, you'll be busy for days..


Thanks Randy,

Don't want to be ungrateful but, now you tell me! that explains a lot as well. Don't tell my daughter she was in the car for hours, "peddle to the floor, stop, let it up" repeat :)
 
Rule number one when bleeding brakes NEVER fully stroke the M/cyl half way is plenty other wise you will be there all day.

kaspa
 

Rick Muck- Mark IV

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What does a full stroke "break"?

Some masters when bottomed out will cause the seal to be "nicked" on the transfer port and cause failure.

We saw it very often on the Bendix masters used on the 61-66 Thunderbirds and other Fords. Guys would bench bleed and jam the piston until it bottomed and then have a leak into the booster.
 
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