Topic: Anyone here ever tried Silicone Brake Fluid???

[gnarlycharlie4u]

As you indicate, these fluids WILL NOT successfully (safely) mix.

not only that but you could potentially damage parts of your brake system, especially the switch for the light.

[TwoTired]

Would not also have to junk the M/C as well as the caliper and start over with a complete new system, not just new lines?

Not if you continue to use DOT5 Silicone fluid for the life of the system.
But yes, if you wish to convert back to DOT 3,4, or 5.1 fluid.  This is why the US military doesn't stop using DOT5.  It can't be 100% removed from the vehicles unless ALL the brake components are replaced as well.

The military was sold on the conversion because of silicone's wide operational temperature range, and the promises that the more expensive fluid would result in reduced maintenance (no fluid change) and longer lasting components (preventing internal corrosion).
They found that unless they returned to the routine flushes that the DOT3, 4 needed, wheel cylinders were still rusting/corroding (with DOT5 Fluid).  When the maintenance costs were seen to rise and the cause found, the yearly or bi-yearly flushes were reinstated.  With the availability of DOT5.1, the operational temperature range problem was solved.  But, as there is no way to effectively flush all the systems for conversion, it is cheaper to continue to use DOT5 than replace every existing vehicle's entire brake system.  So, they are stuck with it.

There is the further problem of waste disposal.  Silicone fluid isn't exactly environment friendly.  While not particularly toxic to humans, it is quite persistent and quite illegal to dump into common drainage, land fill, or sewer systems.  It's contamination possibilities are quite disconcerting.  All you can do is store it or move it from place to place.  In California, waste silicone fluid must be handled by a licensed recycle facility.  Personally, I don't want to find it in my drinking water, whether from the city treatment plant or from ground water supplies.

All the other DOT3, 4, 5.1 brake fluid types are relatively easy to break down and convert their chemical structure, so handling this fluid is routine.
  Even nature has a way of breaking down glycol over time, so spills have a limited toxic life span.

Hope this helps,

[gnarlycharlie4u]

They found that unless they returned to the routine flushes that the DOT3, 4 needed, wheel cylinders were still rusting/corroding.  

That's because there's not a problem with the brake fluid, it's the brake components that allow moisture in the system.
Herp-a-derp.

In fact silicone brake fluid doesn't absorb moisture like dot 3/4/5.1 so you're more likely to cause moisture in the system to create steam under pressure resulting in corrosion and/or premature brake failure.

[TwoTired]

They found that unless they returned to the routine flushes that the DOT3, 4 needed, wheel cylinders were still rusting/corroding (with DOT5 Fluid).  

That's because there's not a problem with the brake fluid, it's the brake components that allow moisture in the system.

Yes, as I relayed in a prior post.  But, you are using the same brake components regardless of the fluid used.  Water still gets in.

In fact silicone brake fluid doesn't absorb moisture like dot 3/4/5.1 so you're more likely to cause moisture in the system to create steam under pressure resulting in corrosion and/or premature brake failure.

If you change the fluid as you are supposed to, any absorbed water gets removed with the fluid replacement, when using DOT3,4, and 5.1.

With DOT 5, you have to get the water that has settled in the low points of the brake system, like the wheel cylinders/calipers.  Most bleeders are at the top of the cylinder/caliper to allow air bubbles to escape.  To get at and remove the water collected in a DOT5 system, you have to disassemble the wheel cylinders/calipers.  So, there is an argument that states even flushing a DOT5 system routinely, won't remove the collected water inside the brake system to prevent internal corrosion.

[Steve_K]

I think I read that DOT 5 has more drag in the system.  I mean it is not as slick as DOT 3.  Seals need to be made for DOT 5.  Systems that are designed with DOT 5 in mind work well.  Maybe in our older bikes it may work.  I think I am staying with DOT 3 or 4 in my bikes. 
Steve

[TwoTired]

I'm NOT trying to pick on anyone here.  I'm just trying to separate the science from the lore, using what little knowledge I possess.
Certainly no need for Gaither to apologize for his post.  I think everyone learns from a discussion topic.  Why else be here?

I think I recall several Posts involving difficulty in bleeding CB brakes using DOT3. Evidently some folks tie the lever back and give it time to allow air to work its way into the M Cyl with some success - DOT3 fluid.

The physics involved would indicate that tying the lever back was superfluous.  The bubble(s) will rise to the exit port regardless of whether the lever was tied back, or not.  I have allowed the SOHC4 brake system to "self bleed" just by waiting overnight for the bubbles inside to rise to the master cylinder.  Night before - spongy lever.  Morning after - firm lever with only the passage of time effecting the system.

A parallel rationale:
A man successfully whistles and walks to work 100 times.  If the man doesn't whistle, will he still be able to walk to work?  

Incidently, FWIW As an experiment, I have a partially used bottle (plastic bottle) of DOT5, (with the cap on it) that has been in my garage for almost 15 years. There is absolutely no moisture or any other type of contamination in the fluid.

The plastic bottle of DOT5 was not sealed with the same type of rubber seals used in the braking system, was it?  Could there not be a different function relating to osmosis of the seals?
We don't know what the humidity of the air was in the bottle, or the differential temperatures between the inside and the outside of the container.  Condensation on the outside of a glass doesn't always occur.  But, it does when the temperature differentials are right and the air has humidity in it.  Can you say that the conditions for storage of the DOT 5 container were the same as the conditions experienced by a vehicle in regular service and exposed to random weather conditions?

Another factor to consider is that plastic containers do not conduct heat the way that metallic components do.  Internal condensation would be effected by this, no?

And while I'm here and in the spirit of "giving"....  
Contrary to what many believe, liquids CAN be compressed.  The accepted engineering description of this material property is called Bulk Modulus, (which is the inverse of compressibility).
http://www.engineeringtoolbox.com/bulk-modulus-elasticity-d_585.html
Now, you would think that with such an accurate description of a property, it would be easy to compare the bulk modulus of Dot 5 to some other DOT brake fluid.  HAH!
However, be aware that the Bulk Modulus of silicone fluids is less than that of normal brake fluids, and because of this slight compressibility difference, it can lead to a slightly spongy pedal feel (even without any entrained air).
In my search, I did find the table below, which illustrates the compressibility comparison of DOT 5 to DOT 4.  I can't corroborate that table.  But, I thought it interesting, and offer it for all to sneer at.   Do note that silicone gets more compressible as it heats up.  So, while DOT 5 probably won't boil while you are driving around the inside of a volcano, you'll need more pressure to make the vehicle stop.  

Consider if you will:
Arthur C. Clarke 3rd "law": "Any sufficiently advanced technology is indistinguishable from magic."
I would add that, if the physics/chemistry of a technology isn't understood, products using the technology often take on a "magical" aura.

Just some things to think about...

Cheers,

[MRieck]

DOT5 sucks. MotoGP bikes do not use it.

[bwaller]

Well just a minute Mr Rieck, do you mean no means no? 

           

[Gaither]

Ah, Two-Tired, who can argue with your informed, elaborate reasonings? Again, I'll admit I do respect your knowledge and appreciate your willingness to share it with us.

I will say, I doubt compressibility is a problem on these ol' bikes. I doubt that my foot (car) or hand (bike) would notice it enough to be a problem or feel spongy. IMHO, If the lever feels spongy, get the air out of the system. (I do hope that guy makes it to work.)

Obviously, there are pros and cons, successes and failures and, as always, various opinions related to brake fluid and many other matters. But, the discussion of them is both fun and informative. Happily, I learn new things on this Forum each day - thanks to folks who obviously know more than I. As Two-Tired said, "Why else be here?"

I've had good luck with DOT5 in cars. As I said to start with, I have not yet tried it on the 550. However, since I'm not selling DOT5, I have no desire to persuade anyone to try it. I do think it is good to have options and that each can do as he/she pleases. Having these ol' bikes like we want 'em is what it's all about.

Without a "hand count" it appears to me there are more on here that don't like DOT5 than do - and for logical reasons. Some have had good luck with it. As a result of this discussion, I admit I will give it a lot of thought before I put it in the 550 when he time comes. However, if I ever again have an old car I think is worth a DOT5 conversion, I will not hesitate to do it.

One other thing, I put DOT5 in that GT Mustang in '76. I drove it hard 7 years with no problem. I sold it in '83 to a buddy in Callif. His son still has the car. I called him tonight to see if they had any brake problems. They live 600 miles apart but will be together in Jan. ***I've asked him to get me an update on the brakes. If he does so, I will post it here - regardless of the results. It isn't a CB but it should still be of interest (to me, at least).

Meanwhile, thanks to all who took part in this discussion and/or anyone who may have more to say on the matter.

This has to be the best Forum going. I appreciate and enjoy having even a small, insignificant part in it. Further, you guys have saved me a bunch of money and enabled me to turn a usless bike into a good-running, dependable motorcycle. for that, I am grateful.

Gaither

 



 

[HondaMan]

I do not have a brake problem at present. However, I can't recall seeing a Post involving Silicone Brake Fluid. So, I'm curious. Has anyone tried it on these ol' bikes?

It's not bad with salt and lemon, but I wouldn't ride after drinking too much of it. 

Merry Christmas!

[Don R]

I used it on my 40 chevy coupe, it had 56 chev rear and 54 chev front drums and a stock master cyl under the floor. The brakes were spongy unless I let it sit and warm the engine. The engine heat would cure the spongy problem and it was fine until it was parked for a while. I switched to regular fluid and the problem was solved. today it has 73 mustang rear and 74 nova fronts with a corvette master cyl under the floor. Not so sure it stops any better that the old drums.