Converting to Silicone Brake Fluid

[Jerry K.]

Re: Converting to Silicone Brake Fluid

After cleaning the old fluid out of system and I MEAN Cleaning. I started with all new lines and new wheel cylinder kits and brass sleeved master cylinder. Reassemble with dot 5 coating on parts, bench Bleed master cylinder. After all lines are tight, gravity bleed system. Gravity bleeding is what worked for me as nothing else did. Patience: Fill MC and open bleeders (clear Plastic tubing at each bleeder with a clean receptacle at each wheel cylinder) do not pump brake pedal as this puts more air in the line. Open valve bleeders one at a time starting farthest from MC, watch MC fluid level , adding when low. The bleeders are on top of wheel cylinder so air in line escapes with a few a bubbles seen in the clear plastic tubing. I watched a movie and ate lunch and periodically checked MC level. Did this at each wheel, lost very little fluid. Its been 5 years since I bleed the breaks and still have solid pedal. PATIENCE!!!

[Gary C.]

Re: Converting to Silicone Brake Fluid

I converted to silicone in my 65 a year ago...Initally the pedal was a little spongy compared to how it was prior to the conversion....I just ignored it and some time later (I forget how long) the pedal was just as firm as ever...so the soft pedal resolved itself..I do not know how but that is what happened in my case.

[Paul J.]

Re: Converting to Silicone Brake Fluid

New pads, especially if the rotors aren't turned, may have a somewhat soft pedal until the pads break-in/seat, which usually takes 200-300 miles of normal road driving. That's why brake shops always turn rotors when installing new pads. The pads will bed very quickly, but turning shortens rotor life. As long as the rotors aren't warped the pads will seat, but it takes time. The rotors on all my cars are severely scored from race track hot lapping. Most brake shops guys would say they are junk, but they are not warped. It just takes a little time to bed in new pads, and once done the brakes are superb. The vented Monza rotors on my Cosworth Vega are on their sixth set of OE Delco semimetallic pads, severely scored, but well over the minimum thickness. I could outbrake Porsches at Riverside and Willow Springs back in the eighties/nineties when I ran four track events per year. Duke

As recommended by all of the service literature, I used to always turn my rotors when I installed new pads. But after years of doing this I noticed that once the pads bed it makes little difference whether you turn rotors or not as long as they are not warped. I also noticed that scoring on the rotor increases friction surface area, although very, very slightly. I haven't taken any measurements as to whether this shortens pad life or not. Paul

[Duke W.]

Re: Converting to Silicone Brake Fluid

The last new car I took to a track event was my '91 MR2. It was near new, but everything was broken in. On a race track you have to hit the brakes hard at a very precise point if you are looking for lowest lap time. The MR2's brakes were very grabby on initial application, but it got better as the day wore on. By the last session the grabbyness on initial application was absent because the rotors were scored. Modulation characteristics went from poor in the first session to very good in the last session and excellent in subsequent events. Fade was never an issue.

About a year later a buddy with a Gen I MR2 did a track event with me. A week before the event he installed new brake pads. I highly recommended that he do a specific break-in procedure, but he didn't think it was necessary. In the first session he was black flagged due to smoke coming out of the wheel wells. He ran the rest of the sessions, but by the end of the day the pads were worn out, and brake performance was poor all day.

New pads on old rotors, especially if scored, will require more pedal effort and more pedal travel until they are bedded, which takes 200-300 miles of normal light to medium braking in typical road driving. The average driver will not accept this, so shops always turn rotors and the pads are bedded after the first few applications, so there are no comebacks with complaints about poor brake performance, but these folks pay in the long run with rotor replacements as most are only good for only one turn.

I can't say for sure if new pads on old rotors wear more, but with proper break-in, I don't think they do. My estimate is that my typical track events, which were about 120-150 miles of hot lapping wore the pads the equivalent of about 10,000 miles of normal road driving.

A car that doesn't have very consistent and adequate response to brake applications on a race track is no fun to drive!

Duke