Has anyone tried to use silicone dot 5 fluid with wagner (american made) brake components? I have a 1957 444 which I want to convert the system to silicone, I have a new master cyl and rebuild kits for the wheel cyls. I was going to takeall the cylinders off and blow out the lines w/air then put it all back together w/ the silicone. But I cant find any info on the compatabillity.
thanks
Pete

Here is the update on the conversion. I have soaked a wagner seal in the silicone fluid, and it seemed to survive just fine. It did not grow or get soft. I Then cleaned and rebuilt all the wheelcylinders (they say wagner/Lockheedon them), and blew out the lines w/air. and installed the master cylinder. The silicone seemed to bleed better than the dot 3. It took less since I knew that all the dot 3 was out of the lines. I still have to bleed it once more, and it will be ready for the road. Many of the articles that I red on the net warned about the silicone getting air in it from pouring or shaking it, It really does not seem to bubble if you are fairly carefull. The pedal seems just as good as the before the conversion. I still have to look the whole system over to make sure there are no leaks. I found one rather dangerous thing, one of the bolts for the driverside top a arm was missing and the shock rubbers worn out. If anyone has a bolt, let me know (M11X50X1.5).
thanks
Pete

Sounds like you were MUCH more careful than I was when I did the changeover!

Glad you found the naughties in the suspension. Yet another reason to do a "complete" job instead of just a quickie-get-it-on-the-road type repair.

You should be able to find an appropriate bolt at a local shop that sells hardware. The NAPA here has 'bout everything.

M11 ????? I thought FER SURE these used standard "inch" hardware everywhere but for the steering box. (guess I wasn't looking hard enough).

Mike!

The '59 PV I'm working on these days uses at least 3/4 metric hardware, which surprised me. Everything in the front suspension is metric.

That may explain why some of my flare wrenches don't actually fit the fittings?
Darn, I was sooooo confident too!

Mike!

Some time ago, I made a bibliographic review about the possibility of use DOT 5 on my 121 Amazon. Please, read:

http://www.vtr.org/maintain/brake-fluids.html

http://www.minimania.com/MM/BRAKES___Silicone_brake_fluid__to_use_or_not_to_use___that_is_the_question__785.htm

http://www.geocities.com/MotorCity/3122/DOT5.html

http://www.356registry.org/Tech/brake_fluid.html

http://www.vtr.org/maintain/brake-fluids.html

http://www.vintagebrake.com/tips.htm

References are on no order.

Btw: At last, I remain on DOT 3, replacing it every 6 months (cheap, more available, we've too much humidity on my city - need check to prevent external rust on calipers and brake cylinders, plus a afternoon of joy and work shared with my eldest son).

Joaquin
Rojo 121 Amazon
Lima Peru

I have used silicone fluid in a 1966 Ford (acquired in 1968) for about 20 years, with complete satisfaction. Before then, I had two episodes of suddenly failed rear wheel cylinders and two of leaky non-power master cylinder due to rust. I replaced the wheel cylinders and rebuilt the m/c and the undamaged front calipers, and flushed out and drained the hydraulic plumbing. I did not disturb the proportioning valve. There's only a fair chance the new rubber parts were Wagner's.

In my 1978 VW Rabbit(Golf) bought new, the non-boosted m/cyl got rusty and leaky after about 6 years and I rebuilt it with Ate parts. I refilled the m/c and reservoir with silicone fluid without ever draining or servicing the wheel cyls or calipers. Nothing bad ever happened with the hydraulics since then. This car went out of service for cumulative reasons 6 years ago, but oddly, the brakes still work and the fluid remains topped up.

This VW is German-made and uses two brake fluid pressure-activated brake light switches in parallel, one for each part of the tandem m/c. After a year or two of silicone fluid exposure these switches no longer would pass enough amps to light up the brake lights. But they would brightly light a little test bulb and operate a relay, which I then wired in permanently to restore brake light function.

Silicone fluid is said to be more compressible and give a softer pedal. This effect isn't dramatic and hasn't bothered me. The stuff is vastly more expensive, and its advantages over modern conventional fluids would not be decisive during a new car's warranty period, hence not any mfr's choice. Spilled or leaked silicone fluid however will not take paint off.

Charles Greenlaw, Sacramento California

Why do you want to use silicone brake fluid? It's performance is inferior to the real thing. The only reason I can think of for using it is if you can't be bothered to do the periodic maintenance recommended by the manufacturer. Personally I prefer to have a proper look at my brakes once a year.

As far as I know no car manufacturer uses silicone brake fluid, nor are the seals specced for it. Why don't you ask Wagner Technical for their advice, if you do let us know what they say.

Regards


Pete

Walrus and JohnMc both have very valid points. A few more and a plug

"Brake grease" as used inside component assemblies is NOT hygroscopic. It is silicone based (surprise!).

Plug: I've used silicone (DOT 5) for many years (before DOT 4 was widely available) and have been nothing but happy. It is COMPLETELY inert so it is compatable with anything.

Caveats/points.
It will not mix with any other type of fluid, i.e. they will separate in the line/cylinders somewhere. Not a particular problem but neither will water mix and the "blobs" of water or water saturated "other" fluid can cause local corrosion if not bled out (eventually). It can be bled out over time (like months) or until you are happy it is all out.
It is prone to entraining air bubbles. If the brake system has any air in it, the bleeding is done with too much vigor, or the system has both high volume of flow and small lines (high velocity) a soft pedal can result and the bubbles are a major pain to get out. The only real way to accomplish it is to be VERY patient. Pour slow and with as little vertical drop as possible. Bleed out major air then let system sit 24 hours. Bleed out remainder of bubbles.

DOT 5.1 seems to be a better fluid for people "on the go" as it can be added to top-up a system or at the semi-annual flush very easily. DOT 5 is good for us who like to "fix and forget" which is a mis-nomer as you can NEVER turn your back on a mechanical system.

Mike!

I have used silicone brake fluid in both the brake and clutch hydraulic
systems of a 122 wagon and also in the dual braking system of a 164, both for
almost 20 years. I have had to change the brake light switch in the 122
wagon (just yesterday, in fact - it didn't leak, just didn't make contact)
but the switch was at least as old as the DOT5 fluid.

I have had NO problems with the DOT5 fluid and in fact have not even had to
put in a cylinder/caliper kit in the 122 brake system over that 15 years.
I did have to replace the clutch master cylinder on the 122 but I believe
that I got grit into it somewhere along the way. That was last spring, btw,
also after 15 years.

No problems with the 164 either. I put in the DOT5 when I replaced the
master cylinder in about 1987 and flushed out the lines and calipers but
have not replaced any rubber components except the brake booster, which
is not supposed to be exposed to fluid.

I was involved in testing silicone brake fluid for the army in a wide variety
of vehicles in Panama back in the early 80s and conclude that it is one of
the greatest boons to brake systems in humid environments that there has ever
been. No evidence whatever of any water contamination of any part of the
systems.

I have heard claims that "since water doesn't mix with DOT5 it will settle
to the bottom of components because it is denser than DOT5." I suppose if
you deliberately introduced water into the system that might eventually
happen but since it is hydrophobic (like wax) water is not attracted to it
like it is to the alcohol in conventional brake fluids, so the problem only
exists if the system is contaminated by water. My guess is that even then,
unless there were a large amount of water, it would be completely surrounded
by the DOT5, with its very low surface tension, while water, having high surface
tension, would probably remain in spherical drops or tiny beads.

The one problem you might have with DOT5 is air entrainment. Air bubbles don't
come out as easily so you don't want to shake it or handle it roughly.
If you do get tiny air bubbles entrained in your system they will make your
brake pedal soft. I have exercised reasonable care and have never had this
problem.

So I'd say, "Go for it!"
--
George Downs, Bartlesville, Oklahoma, Central US

I have used silicone brake fluid once, but that was not in a PV. I can't think of any reason why it shouldn't be compatible with any new component, regardless where it's made. However new components may be assembled with brake grease which is as hygroscopic as conventional brake fluid, in which case the benefits of SBF will probably be less.
Keep in mind though that you will have to renew your brake light switch at least once every year when using SBF. Installing a mechanical switch is an option to consider.

Hopefully someone else with experience will comment on the DOT 5 brake fluid, but I thought I'd mention the new (ish) DOT 5.1 brake fluid. Never mind the confusing DOT nomenclature, it is a modern version of the DOT 3 and 4 fluid. It has the temperature handling capability of DOT 5 (probably why it is rated with a 5) and greatly improved moisture control. I think they make a long life version that is safe to leave in a car for 10 years, as opposed to the 2 year (I think) recommended life span of DOT 4. You can add it straight do a DOT 3 or 4 filled car and just bleed until new fluid comes out the bleed valves.
--
I'm JohnMc, and I approved this message.