Hi all,
As I am putting fresh fluid in a brand new brake system, does brake fluid exist that don't eat your paint these days like years gone by?

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1968 Morris Mini Deluxe - members gallery
1970 Morris Cooper S - members gallery
Mini's I grew up with
Slot car couch

I believe silicone brake fluid won't harm paint, however its more expensive than normal stuff, more compressive, has a shorter life, and a few other drawbacks that means for most people's cars: its not really worth it.
Its just easier to keep a rag wrapped around the mastr cylinders and fill them with a funnel.

I have a piece of 1" silicone hose I use when filling master cylinders, fits snugly over the thread on the reservior so no messes.

Thanks Harley,
I will try to keep it clean then

I do remember seeing some kind of pump you can use similar to a auto transmission box oil fill pump? Will see what my local auto shop has when the time comes.

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1968 Morris Mini Deluxe - members gallery
1970 Morris Cooper S - members gallery
Mini's I grew up with
Slot car couch

You could always used a big syringe with a bit of plastic tube on the end.

Yep, that sounds like a good idea.

Cheers

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1968 Morris Mini Deluxe - members gallery
1970 Morris Cooper S - members gallery
Mini's I grew up with
Slot car couch

Whats your source on that? what other drawbacks?
Silicone brake fluid is non nonhygroscopic and in a sealed system would never need changing unless you purposely added like air/rust/water and the only way of doing that is by putting it in a dirty brake system. It also has higher temp ratings so I cant see any draw backs other than the cost.

Silicone fluid has a known problem of being slightly compressible. A lot of people are turned off by the soft spongy feel in the pedal.
I have never used it but a lot of Americans on other forums have tried it and some have given up for this reason.

Water will still enter the system. Where there is air there is water. So just like any brake fluid you still need to change it at set intervals.

I use 5.1 grade silicone brake fluid (racing motorbike spec) and it is fine, the current lot is 3.5 years old and still looks/behaves the same.
Like Kirby said, it costs a lot more but he also outlined the benefits.

I got it to prevent the possibility of the strengthening rail rusting where the RH brace attaches (just in front of and below the fuses), also so the paint around the hydraulics doesn't turn to rust.

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Dean Hutton's first car was a Mini.

Normal brake fluid is the same, in a clean sealed system it would never need replacement.

Okay so I cocked up before when I said it has a shorter life, it has a very long life, the problem is the components around it. If moisure or other contaminents get into the system, it will stay there, so regular changing of silicone fluid is still recommended, as a means of 'flushing out' these contaminents.
It may not be universally accepted, but it makes sense to me.




It'll still look the same in ten years, doesn't mean its not past its useby date.

One of the thigs we used to do was religiously bleed the brakes on race cars before each race so that the calipers and wheel cylinders always had fresh brake fluid in them when you needed to stand on the brakes.

I still periodically do a brake bleed on all the cars we have.

The theory - true or not - is that the fluid at the working end becomes affected by heat and contaminants. At flat chat, thirty metres before a corner, with one big stab on the brakes to get down to corner speed you want the brakes to wor. Especially in close company with other race cars.

I have never silicon fluids though.

Mike

Ill say again: non nonhygroscopic, The reason normal brake fluids need changing so often is they absorb water even from the air, Yes no mater what fluid you use they are both a sealed system but in the case of normal brake fluid it is soaking up the moisture in the air like a sponge every time you push the pedal down.

Silicone brake fluid has no such problem, yes air may still enter the master cylinder by condensation but it would be an inconsequential amount and that tiny (less than a drop*) amount would float on the reservoir not dilute the whole system.

I understand that it might be hard for old guys to give up their religious maintenance schedules but the fact of the matter is modern oils have a massively longer service life.

*rough maths based on service life and Victorian humidity

Kirby I'm not one of the old guys but can you explain this for the uneducated amongst us?

My understanding of the issue (as things relate to oils not brake fluid) is that service intervals are reliant upon the equipment more than the lubricant. Or do you mean brake fluids when you say "modern oils" above.

And a general question to all about silicone brake fluid, aside from being a hydraulic media, is the fluid meant to be lubricating the system as well? My understanding of silicone is that it is carp as a true lubricant.

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Cheers
Alec
1275LS - July 78 - XNFAD18Y/102918

I've had silicon brake fluid in one of my cars and it's been there since the late 80's or early 90's. Never changed it (been there around 20 years now!) and never had a problem as a result of not doing so. I can check, but I think it has a Dot 4 or 5 rating.

Before it was used, every single rubber part was changed, and I had stainless pistons made for the brake calipers, rear brakes wheel and master cylinders, so essentially, it was a new system, never had glycol base fluid in it.

I cannot comment as to any apparent sponginess as I never drove the car with glycol based fliud, but it does feel fine to me.

At that time, the only place I could get it from was Fraser Motorcycles down on Parramatta Road, next to American Autos. It was very expensive back then and I think it is just as expensive these days. It seems it is a little more widely available these days, but not overly so.

It doesn't attack paint like normal brake fluids do, however, if you do spill any on there and it needs touch up latter, I think you need to take it back to bare metal as the paints won't take to the silicon, or there maybe some cleaning agent available? I'm no painter so I don't know what's out there these days.

Worth it? Well, it did - back then - cost about $75 for the fluid and about $50 for the rubbers and hoses. I don't run it in any of my other cars only because it is not easy to come by, nothing wrong with it as such, but to get the best benifit from it, you do need to go to some trouble.

In my other cars, I just change the brake fluid out every 18 months.

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