I am changing my silicon brake fluid back to dot 3. Have changed master cylinder, and filled it up with dot 3. I have the calipers off and would like to know if there is any special thing I should run through them before I flush them with dot 3??? Thanks

 

UHHH...why?? if you have a mechanical problem, or a runout problem....changing to 3 will not help one bit, but it will encourage rust deposits, and sludge in the brakes......no disadvantage to 5 fluids that I know of...not for street/storage anyway...

GENE

 

If your going to change back. be sure to flush the lines and all parts with denatured alcohol, any synthetic left behind will not mix, and it will probably cause you problems later.

 

there IS a major disadvantage to silicone fluids, even for street use. IT's in the fact that it's NOT hygroscopic, this is in fact a good thing but theres a downside to it. With out calipers pumping air and moisture when there's runout ot something leaking the moisture will not be absolrbed but it will sit at the lowest level, the caliper. The stuff will start to rust, pistons will seize.. and so on. Dot 5 is not the answer to all problems. I don't see the benefits at all, regular changes of Dot 5.2 or DOT 4 and you will have a firm pedal and no moisture problems. Just my 2 cents.

 

TT, after running 5 for years, when the front and finally rear calipers leaked like 5-6 years later....the calipers showed only one pin head sized rust spot in the back of the caliper, where the iron was.....you do 5-6 years in a high humidity like Wash dc or Jax Florida...and I can guaran-freaking-tee you that system will be a sea of rust, and the lines will suffer as a result.....I can put up with a slightly softer pedal , but that terminating rust has to go....

GENE

 

IT can't be worse than here, we have rain 364 days of the year, I'm at sea level, inland winds most of the time.. cars rust in the brochure here :D

Was just meaning to point out that Dot 5 is not the solution to all problems. A properly maintained and functioning brake system is. Brake fluid is clear, not dark brown in color, try to find a car that has ncie clear brake fluid in it (I know of one, it's standing in my driveway)

 

....And I thought the Great Lakes region was considered the RUST BELT!!! :cheers: :D :D

Seriously, I've been considering silicone fluid thinking it was the end all to brake corrosion problems. Then I talked with a brake system designer who told me that silicone fluids tend to entrap air bubbles that will not dissipate from the fluid. That is why they are a no-no for anti-lock systems because the rapid pumping action of the brakes stirs the silicone fluid up into a froth. I guess if you have a bit of rotor runout that might act the same way. That is why it is also difficult to get a system filled with silicon fluid bled properly. I still like the idea of not having to be overly concerned if a little bit drips on my paint --unlike the glycol based fluids which I've seen wreek havoc on a nice paint job.

I don't know. I'm still undecided as to which way to go :confused: .

 

twin Turbo I agree with you. Silicon brake fluid doesn't absorb water so the moisture sits in concentrated droplets, never mixing while coroding the line or where ever it sits. I was bleeding brakes and had about 1/2 inch long collection of water come out.
Silicon brake fluid also doesn't give as good a pedal feel, it is slight compressable.
This said I use it because I am constantly doing something to spill the stuff on painted surfaces.
So other then is doesn't attack paint that is the only reason I use the stuff. Forgot to mention I get it for free.

 

At the risk of ruffling some feathers, I’ll add my two cents…

I’ve been using silicone for about 20 years in everything from Corvettes to Harley Davidson’s. I’ve used it most recently to replace the brake fluid in my hydraulic clutches with great success as well. As far as I can tell there are only two drawbacks to silicone (Dot 5).

The first is that silicone does aerate easily, so along with not working well in some ABS’s, it does require patience when bleeding the brakes. If you pump the brakes slowly to minimize this, they bleed just fine. I usually do it again a couple of days later to ensure I’ve gotten all of the air out.

The second and more significant drawback is that it does expand when heated excessively. Therefore it’s not a good idea to use it for all out race machines that use heavy braking. (The fluid expands, begins to apply the brakes, gets hotter, expands more,… well you get the picture.) Having said that, I’ve used it in two of my cars that I autocross regularly with absolutely no problems.

As for the compatibility of silicone and hydraulic brake fluids, this is really a myth. (Not unlike the myths associated with mixing synthetic oils with petroleum based oils.) They are completely compatible and as long as the hydraulic fluid has not deteriorated they will function together just fine. Having said that, you need to keep in mind that hydraulic fluid is hydroscopic. This simply means that it will absorb moisture when exposed to the air. This is why corrosion is such a problem in brake systems in vehicles that see little use. This is also why most hydraulic fluid containers will caution you to use it from an unopened container, to minimize the amount of moisture in the fluid. It is also why most vehicle owners’ manuals call for flushing the brake system ever couple of years.

When converting from hydraulic to silicone, it is imperative to remove all of the hydraulic fluid from the system,… to remove all of the latent moisture. Mixing silicone with hydraulic will still expose your brake system to any moisture in the remaining hydraulic brake fluid. To get all of the benefits of using silicone, you want a clean system. The best time to do this is when you change out your calipers. Because of the dual master cylinders on most cars, I’ve even done the fronts or backs separately. Just remember which side you put the silicone in.

I was initially skeptical about the claims for silicone when it first became available. Then I learned that the Defense Department was using it in all of its’ equipment with hydraulic brakes. Because so much of their equipment sits idle for extended periods of time, switching to silicone has saved a lot of tax dollars in maintenance cost, not to mention the increase in equipment readiness. By the way, we were paying $20 a gallon when the commercial stuff was selling for $20 a quart. Of course we were also buying it in 55 gallon drums.
GUSTO