Its hard to admit when you make a mistake. Big mistake.

I rebuilt my power brake system on my 75 with new lines, rebuilt calipers from Lonestar with O rings and rebuilt Master cylinder by White Post Restorations. I chose to use Silicone fluid because, 1. I had used it before on my restored 62 with no issues for over 10 years, 2. Less need to re-bleed periodically and 3. Because it is more paint friendly.

Pressure bled the system with Motive Products pressure bleeder and the brake system worked perfectly---- for about a week. Started seeing some wet spots on the ground under the power brake booster. I believe the master is leaking at the pushrod and running down the booster. After two more drives of 20 miles or so I noticed wet spots by inside of two tires. Next drive I took the brakes pull to the right and now all four calipers are leaking to some degree, two a lot. Pads and rotors are contaminated with silicone fluid.

If anyone has a similar experience I am wondering if I can flush the system with denatured alcohol or brake fluid and replace with DOT3 or do I need to remove the calipers and master cylinder to send them back to be rebuilt again while I flush the lines.

I need some advice on how to proceed. I just finished cleaning up the engine compartment and getting the car back on the road after being out of commission for six months. I am sick about this turn of events.

 

I have used DOT 5 for decades and have never encountered your issue. Return the parts and ask for an explanation for the failures before condemning the fluid.

 

Beautiful engine compartment.

 

I researched which fluid to use and there were many who had your experience. I was influenced by stories like yours. As well as my past experience. There are also many who say to not use silicone to avoid problems. I just don't see how all four calipers and the master cylinder, rebuilt by two different companies, can be at fault. There is no denying your success with silicone. I just know it is not working for me this time.

Also, both rebuilders discourage the use of silicone.

 

Thank you. Lots of time and effort.

 

Been using it for years here too - never had any issues at all.

As far as the naysayers, some of the "old folks" (yes, I AM one) condemn stuff they have no experience with or knowledge of. Right up there with all the "Ban Synthetic Oil" crew!!

 

 

Sorry to hear of your troubles.
I was one of SSBC's first customers when they started stainless steel sleeving calipers back in 1979. I made the switch to silicone brake fluid at that time. It's been trouble free all these years and I'm around 155K miles on the car now including many high speed events. I'm a firm believer in silicone on these cars for the exception of track cars. The only difference I see is I rebuilt my calipers with GM lip seals/pucks/springs as opposed to the o-rings. You say LoneStar discourages silicone fluid with their o-ring calipers?

 

I also have SSBC sleeved calipers for over 25 years, still the same Dot 5 fluid, never had a leak, never had to add fluid.
I rebuilt the MC at that time as well. Used an ACDelco kit.

 

Sounds like the silicone is attacking the seals in your system. Is silicone brake fluid compatible with all commonly produced synthetic rubber seals?? I am sure that many of today's aftermarket seals are made of questionable materials.

 

what I read about silicone is while it doesn't like some seals never put it in a system that had old style fluid, dad ( an old timer amd aircraft tech ) did that in his avanti and did flush it but it still leaked silicone,
but yours was new, I know the cat who owns lone star why not call him on this one....

 

Well it sure shows. Looks like it just rolled off the assembly line.

 

I have used silicone brake fluid with lip seals for over 37 years in my 68. Sorry that you are having problems. Where did you buy the silicone brake fluid from? With all of the crap that everyone is selling now a days, that may be the problem. I have never heard of silicone bothering seals before this. Lou.

 

What I have seen and learned doing online research is guys who run silicone and have it work for them love it and think the guys who have leaks are nuts or in some way it's their fault or the parts but never ever the silicone,
I have also read more times than I can count do not mix fluids, a no brainier or should be and in the case of a system that ran standard fluid and flushed and swapped to silicone it very well might effect seals and leak..the reason I didnt swap on my vw trike....the world is bigger than one cats garage or one forum, take a trip around the net and read up on the subject....

 

I am one of those guys with no drips in 8 years since rebuilt calipers and master, as well as new short lines and all new hoses. If there is a leak, especially with flared stainless...silicone will certainly find it. I find it interesting the OP's leaks began almost immediately. Since he obviously knows what he is doing, I would bet on the parts. Throwing the baby out with the bath water and going to DOT 3 is not the solution to his problem.

 

Like I said, calling the owner of lone star is the first move, he is a great guy and will do what he can, I too would bet on hard parts with this one, "IF" I was starting with a fresh system I would run silicone but that is not the case with me so I will not take the chance that it would likely leak on me....

 

I am waiting for a call back from Lonestar tech service. I will report on what I find out.

Silicone was from Napa.

It is encouraging to hear from those who have had success with silicone in disc brake systems. My single line drum brake 62 worked great with silicone but I was beginning to have doubts about calipers. The operator who took my call at Lonestar this morning said the type of brake fluid shouldn't matter. Lonestar has been very responsive to me with great customer service so I have my fingers crossed that they can help solve the problem.

Picture is of left front caliper. Notice blac crud that seems to be a mix of brake pad dust and silicone. Also center vanes are wet.

 

Well, Lonestar was very empathetic and helpful. I will need to send the calipers back for evaluation. Don't know for sure but it is possible there is contamination with DOT3. I flushed all the lines with Denatured Alcohol but did not flush the master with alchohol. The master was rebuilt and sleeved by White Post and they bench tested it with DOT 3. White Post said they empty the master before shipping but I would guess that the DOT3 won't all come out. I assumed it was clean. I will report in a couple of weeks as I lear

 

My anecdote:

I got rid of the Delco cast iron calipers. Today, it's really gross to have these heavy slug cast iron masses on your unsprung wheels. I replaced them with Stainless Steel Brake Corporation (SSBC) calipers. They look almost like the Delco cast irons, except they are aluminum. They weigh 1/2 as much. They are expensive. Wilwood is less expensive I believe.

My 68 MC was rebuilt by Paragon. It's been sleeved.

All new stainless steel lines and stainless steel line fittings, all new brass blocks.

I have silicon brake fluid. I have a rock solid brake pedal and no leaks at all.

Just my experience. I think a big help was that I started off with all new.
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BTW: Replacing the brake lines looks very difficult. It's NOT. I've replaced about 4 brake line sets that lie along the driver's side frame. The first one was time consuming. I think I took about 30 minutes to replace the fourth. This time includes jacking up the car and placing jacts/supports under it.

 

Wooden surprise me one damn bit..........seems that everything is junk today, right off the shelf....like my LED house lightbulbs, two of them failed already, not 2 months old.....

I have had this '72 for 20 years now, went Silicone right away, with lip seals, went O rings years ago, not an issue....