Classic cars forum & vehicle restoration.

[Keith D]

This started off as "what I did to my car today", and then I thought maybe I should expand it into a thread.

I topped the brake fluid reservoir up on my A40 today. Big deal!

Back in 1990, yes, 28 years ago, I had to rebuild my entire hydraulic brake set up on the A40. A mechanic in the VCC told me to do the job using silicone brake fluid. (DOT 5) I did, and haven't needed to touch the hydraulics since, although we generally spend about three months a year overseas and the car can lay up for months unused and without the brakes being pumped in that time.

I cleaned out the lines thoroughly. From memory I used white spirit and then blew through with dried compressed air. I had each pitted wheel cylinder and the master cylinder bored out and sleeved with a stainless steel sleeve. I fitted new standard sized rubbers and bled the system. Twenty eight years ago.

Silicone rejects water and therefore it cannot pit the cylinders (glycol brake fluid is hydroscopic and can contain 10% water) and destroy the rubbers. Hence your only replacement costs are the actual brake linings.

It must never be mixed with DOT 3 or DOT 4 fluids or with DOT 5.1.

I have heard all sorts of stories about the silicone boiling and doing other undesirable things, but have never experienced anything nasty myself, nor from others over here who have converted to silicone.

Is anybody else out there using silicone in their brakes, or does everybody use it in the UK?

Keith
_________________
1926 Chrysler 60 tourer
1932 Austin Seven RN long wheelbase box sedan
1950 Austin A40 tourer
1999 BMW Z3
Its weird being the same age as old people.
You are either part of the problem or part of the solution

[ukdave2002]

This topic came up recently on a Morris Register forum; people like you, who have used it 20 years ago and it's still going strong, some folk undertaking a full brake rebuild are using it for the first time today. It's never had universal take up in the classic market in th UK.

I suspect it's never got universal uptake because it's not that often one rebuilds an entire brake system.

Harley Davidson fitted as standard in the 90's

It's always seemed odd to me that Silicone is dot 5 yet the powers that be used dot 5.1 to label the latest stuff which is not silicone

Dave

[Brent29]

Just heard of using silicone brake fluid. It is surprising they last that long.

[Ashley]

The dodge is that some rubber seals swell with silicone fluid and jam up everything. A Rolls-Royce specialist in Australia managed to destroy the brakes on the Governor General’s Phantom VI by using it, so best check your car is suitable.

[Bitumen Boy]

[Ashley]

Shadows with self levelling suspension us RR363, but not the old Phantom with a mechanical servo.

[Keith D]

I was rather surprised to read Ashley's comment regarding seals swelling when used with dot 5 fluid. I used the word 'rubbers' as a generic term for seals. Replacement seals in Oz are neoprene and are not affected by the silicone fluid. I'll repeat my earlier point however, that new seals must be fitted and the whole system thoroughly cleaned out. I used white spirit followed by compressed air. I have had no problems at all.

It sounds to me as if the RR had dot 5 fluid put straight in onto an existing dot 4 filled system without the vital preparation.

Keith
_________________
1926 Chrysler 60 tourer
1932 Austin Seven RN long wheelbase box sedan
1950 Austin A40 tourer
1999 BMW Z3
Its weird being the same age as old people.
You are either part of the problem or part of the solution

[47Jag]

What do modern cars use? My wife's 16 year old BMW Mini recommends changing the brake fluid every two years, I've no idea what my Jaguar needs. I would have thought they would be the latest DOT 5.

Art

[ukdave2002]

[MVPeters]

You might like to read this (long) article on brake fluids. Like all internet data, take it with a grain of salt, but it looks pretty credible to me.

https://new.minimania.com/The_ABC_s_of_Brake_Fluid

Safety note: DOT 3, 4 & 5POINT1 are all to a large extent compatible - as has already been stated, DOT5 is Silicone & must not be mixed with the others. Whoever used that number 5 should be shot!

I have a BMW MINI & apparently, I can buy the correct brake fluid for anywhere from $9 to $84 per litre. I only use what MINI recommend, DOT4 & from the local parts store.
_________________
Mike - MVPeters at comcast.net
2002 MINI Cooper 'S'

[Keith D]

I read with great interest Mike's Minimania article. I was not aware of the erosion possible at the lowest part of the system using dot 5 fluid and will certainly check my brake pipes that are made of steel.

In the case of my A40, the front brakes are hydraulic but the rear brakes are mechanical, so if I were to have a fluid corrosion problem, I would not be without brakes entirely. However, I must stress that in 28 years there has been no problems at all with any of the brakes.

The car will not be used for the next several months due to my travel committments, but I will check everything out ASAP and post the results.

Keith
_________________
1926 Chrysler 60 tourer
1932 Austin Seven RN long wheelbase box sedan
1950 Austin A40 tourer
1999 BMW Z3
Its weird being the same age as old people.
You are either part of the problem or part of the solution

[Penman]

Hi
I remember back sometime round the 60s/70s that tyhere were dire warnings about the dangers of mixing Lockheed and Girling brake fluids. This was before the days of universal fluids and was purportedly because of incompatability of one type of fluid with the other makers rubber seals.

Then a strike at one of them, Lockheed or Girling resulted in one car maker fitting a mixed system (eg Lockheed front and Girling rears, or different Master cylinder and Wheel cylinder.
_________________
Bristols should always come in pairs.

Any 2 from:-
Straight 6
V8 V10

[ukdave2002]

I recall my father talking about the time he bought some RAF surplus brake fluid in the 50's and it destroyed all the seals in his car..

Dave

[MikeEdwards]