[Healeys] silicone brake fluid

Sun Jun 16 13:05:48 MDT 2019

 I have used Castrol LMA in all my British cars for over 40 years.  This year I rebuilt the complete brake system on my Bugeye I went to the local supplier of Brit car parts to buy another bottle of  Castrol LMA BF.  Even though she had it on the shelf the owner of the store told me to buy the Lockheed brand because Castrol BF is no longer made by the same people.  It is not the same stuff and I would be far better off with Lockheed Dot 4 BF.  She offered no explanation further other than the new Castrol LMA was crap and the Lockheed stuff can be trusted.  I tend to listen to someone that sells the stuff every day.  My BN2 is a completely new system with an original master that has been re-sleeved.   I guess I could start out with silicone fluid, but all my experience is with Dot 3/4.  I have managed to use it for 40 years and not removed too much paint in the process.
Mike MacLean

    On Sunday, June 16, 2019, 9:50:43 AM PDT, Kees Oudesluijs <coudesluijs at chello.nl> wrote:  

Entirely correct.

DOT4 will be perfect for most users. DOT5 for the silicone boys. DOT5.1 is similar to DOT4 but is upgraded to more or less the same properties (e.g. boiling point) as DOT5 but absorbs water and is compatible in practically all classic car braking components. It is better suited to extreme driving compared to DOT4. It may also have a harder pedal as it is non-compressable. DOT5 is slightly compressible and can feel a bit spongy when you are not used to it. Most won´t notice anything.

ALL brake fluids should be replaced on a regular bases, usually every 2 years, in very damp environments more often. 

Kees Oudesluijs

 Op 16-6-2019 om 18:15 schreef simon.lachlan at alexarevel.plus.com:

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When this came round last time, I did a little digging and came up with this, which I believe I may have inflicted on you before. It was written for our local (UK) club magazine but I’m sure that most of it, if not all, is universal. It’s more about what mixes with which rather than which rots  what. If you get my meaning….

   - All brake fluid is “synthetic”…it’s not a “natural” product.
   - Most synthetic fluids are NOT silicone. They are polyethylene glycol ether based.
   - DOT 3 & 4, which can be mixed, are not silicone. They are glycol.
   - DOT 5, which cannot be mixed with 3 or 4, is silicone. Can’t be mixed with anything!
   - DOT 5.1 is glycol based and cannot be mixed with DOT 5.
   - DOT 5.1 can be mixed with DOT 3 or 4, as both are glycol based.

Simon

From: Healeys <healeys-bounces at autox.team.net> On Behalf Of Bob Spidell
 Sent: 16 June 2019 16:34
 To: healeys at autox.team.net
 Subject: Re: [Healeys] silicone brake fluid

I've used silicone BF in my BJ8 for close to 30 years (and when I replaced the brake MC, 15-20 years and 80-100K miles ago, I disregarded the same warning).  As somebody mentioned, your problem is symptomatic of the 'check valve'--aka 'foot valve--malfunctioning or damaged.  I had similar problem with my brakes on a long road trip; had to pump the pedal a couple times on every application (for a couple thousand miles).

We put the highly-touted Castrol BF in our 100M after a thorough restoration--with all-new brake system--and the fluid jelled when that car sat for a couple years.

Side note: Most BFs are calling themselves 'synthetic' these days.  Are they a new formulation, or just jumping on the bandwagon as, AFAIK, BF has always been synthetic (the glycols used don't occur in nature)?

Bob

On 6/16/2019 7:44 AM, Team.net wrote:

I have used silicone in all my british cars for 25 years with no problems

 On Jun 16, 2019, at 09:31, HealeyRick <healeyrik at gmail.com> wrote:

Apparently, silicone can cause swelling of the seals in Girling and Lockheed systems:   http://www.gomog.com/brakes.html  I have a Howe hydraulic clutch in my Nasty Boy, and that also came with the advisory not to use silicone fluid.   

Rick Neville

On Sun, Jun 16, 2019 at 8:24 AM Brian Drab <bgdrab at redzone.ca> wrote:

Last week I completed a driving tour in our BJ8. It was a great tour and everything ran well except for one thing.  4 or 5 times, when I used the clutch, the clutch master cylinder bypassed. The rest of the time it worked well. As I don’t want to be caught without a clutch at a later date I am changing the clutch master cylinder. I have received a replacement and am preparing to install it.

On the box is a quick summary of the bleeding procedure under a warning – “Using Silicon Brake fluid will void  warranty”. I have used silicon fluid for well over 10 tears and never experienced any problems with it and have never seen or heard of this type of warning before. I have never heard of any destructive qualities of Silicon  fluid. 

My question is – does anyone have any idea what it is about. 

For me to change to Dot4 fluid is quite a big deal as I would be changing out the clutch as well as the brake system seeing  as they share a common reservoir. 

I’d appreciate any comments on the warning.

Brian Drab

BJ8

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