Brake Fluid

onerare39

Ok, so I'm tired of having Dot 3 eat away paint and I want to switch to Silicone. From the research I've done it does not seem to be a problem to just flush the system with the silicone fluid.



Article from another site:



The single most common brake system failure caused by a contaminant is swelling of the rubber components (piston seals etc.) due to the introduction of petroleum based products (motor oil, power steering fluid, mineral oil, etc.) A small amount is enough to do major damage. Flushing with mineral spirits is enough to cause a complete system failure in a short time. I suspect this is what has happened when some owners change to DOT 5 (and then assumed that silicone caused the problem). Flushing with alcohol also causes problems. Brake systems should be flushed only with DOT 3 or 4.



If silicone is introduced into an older brake system, the silicone will latch unto the sludge generated by gradual component deterioration and create a gelatin like goop which will attract more crud and eventually plug up metering orifices or cause pistons to stick. If you have already changed to DOT 5, don't compound your initial mistake and change back. Silicone is very tenacious stuff and you will never get it all out of your system. Just change the fluid regularly. For those who race using silicone fluid, I recommend that you crack the bleed screws before each racing session to insure that there is no water in the calipers.



Is it truly this easy?



Inquiring minds want to know!

Jon B

I changed over to silicone in my 1937, back in the early 90's. No problems, and I'd never change back.

mdwhit

onerare39 wrote:

Ok, so I'm tired of having Dot 3 eat away paint and I want to switch to Silicone. From the research I've done it does not seem to be a problem to just flush the system with the silicone fluid.



Article from another site:



The single most common brake system failure caused by a contaminant is swelling of the rubber components (piston seals etc.) due to the introduction of petroleum based products (motor oil, power steering fluid, mineral oil, etc.) A small amount is enough to do major damage. Flushing with mineral spirits is enough to cause a complete system failure in a short time. I suspect this is what has happened when some owners change to DOT 5 (and then assumed that silicone caused the problem). Flushing with alcohol also causes problems. Brake systems should be flushed only with DOT 3 or 4.



If silicone is introduced into an older brake system, the silicone will latch unto the sludge generated by gradual component deterioration and create a gelatin like goop which will attract more crud and eventually plug up metering orifices or cause pistons to stick. If you have already changed to DOT 5, don't compound your initial mistake and change back. Silicone is very tenacious stuff and you will never get it all out of your system. Just change the fluid regularly. For those who race using silicone fluid, I recommend that you crack the bleed screws before each racing session to insure that there is no water in the calipers.



Is it truly this easy?



Inquiring minds want to know!

Three years ago, I completely rebuilt the brake system in my 1953 Nash. I replaced or rebuilt all components including the replacement of all brake lines.

At the time, I used DOT 5. Recently, I had to replace a rear wheel bearing, so I had to disconnect the brake line in order to do the job. When I attempted to bleed the air out of the brake line, the piston in the master cylinder became stuck at far end of the master cylinder. Upon disassembly, I realized that the rubber cups; the one on the piston and the one before the piston had swelled. I then checked the rubber cup in one of the wheel cylinders. It was ok. I had bought modern wheel cylinders with modern rubber. The master cylinder, I had re-sleeved and then used an old NORS rebuilding kit. The rubber that was in the kit was not made to stand up to DOT 5. The moral of the story is to make sure that you use materials that are made for modern chemicals. The new master cylinder kit that I purchased actually stated that it could be used with DOT 5.

Even though I solved the problem with the swollen rubber cups. I do not intend to put DOT 5 back in the system. I believe that I can flush the DOT 5 out completely out of the system with alcohol. I am going to use a synthetic DOT 4 made by Valvoline.

If you Goggle for Silicone Brake Fluid, you will get a lot of "Pros" and "Cons" on it's use. One thing I noticed was that my brakes seemed softer with DOT 5.

BTW, if you do use DOT 5 make sure that you clean the assembly fluid off your brake internal componets, because it does not mix with DOT 5.

tigermoth

my '35 has cables so that is no help, but i switched my '51 MG TD over 5 years ago to DOT 5 and i have had no problems. regards, tom

[Deleted User]

onerare39 wrote:

Ok, so I'm tired of having Dot 3 eat away paint and I want to switch to Silicone. From the research I've done it does not seem to be a problem to just flush the system with the silicone fluid.



Article from another site:



The single most common brake system failure caused by a contaminant is swelling of the rubber components (piston seals etc.) due to the introduction of petroleum based products (motor oil, power steering fluid, mineral oil, etc.) A small amount is enough to do major damage. Flushing with mineral spirits is enough to cause a complete system failure in a short time. I suspect this is what has happened when some owners change to DOT 5 (and then assumed that silicone caused the problem). Flushing with alcohol also causes problems. Brake systems should be flushed only with DOT 3 or 4.



If silicone is introduced into an older brake system, the silicone will latch unto the sludge generated by gradual component deterioration and create a gelatin like goop which will attract more crud and eventually plug up metering orifices or cause pistons to stick. If you have already changed to DOT 5, don't compound your initial mistake and change back. Silicone is very tenacious stuff and you will never get it all out of your system. Just change the fluid regularly. For those who race using silicone fluid, I recommend that you crack the bleed screws before each racing session to insure that there is no water in the calipers.



Is it truly this easy?



Inquiring minds want to know!

To use dot 5 fluid you have to start with a completely new system. Brake lines, flex lines, master cylinder and all wheel cylinders. You can never get all the old fluid out and using alcohol ruins the flex hoses and cups. I started with all new parts in my 53 and after 119,000 miles of travel, replaced front and rear shoes at 70,000 miles and wheel cylinders, rubber cap remove were still shinny and clean. The brake pedal is at the top and toe pressure is all I need to stop. Walt.

[Deleted User]

onerare39 wrote:

Ok, so I'm tired of having Dot 3 eat away paint and I want to switch to Silicone.

I've finally found an advantage to having the master cylinder under the floor...no paint to damage!!!!

J Spencer

Jon B wrote:

I changed over to silicone in my 1937, back in the early 90's. No problems, and I'd never change back.

I also have Dot 5 fluid in my 51 Pacemaker. I did the brakes on this car in 1986 or 87 before I bought the car in 1988. All cylinders were rebuilt, new shoes,springs etc. I am just now experencing a pull to the right (front) so I will have to pull the wheels to check it out, so I guess 20 plus years with out problems ain't to bad!! I have experienced no leaks either. Remember silicone brake fluid does not absord water like Dot 3 or 4 does and the boiling point is at least100 degrees higher also.



J Spencer