Dot5 synthetic silicon brake fluid on MK1 single line

[65MK1S]

Is anybody using the Dot5 on their MK1 single bake line setup? This
will be my last mini build and will go to kids and grandkids. Any problem
with squisssy pedal? This car, 65 MK1 S does not have a vacuum assist
brake system, only simple master cylinder. All new lines and brake cyls with
rebuilt disk pistons.
Thanks
Kent

[Daz1968]

I have it in my mk2 Cooper on clutch and brakes, not had any issues at all, may even change my mk1 over to it.
I think only issue is in newer cars with abs.

[LarryLebel]

I've been using DOT5 for years without any problems but mostly with servos. I don't think a single line system makes any difference.

[Peter Laidler]

Been using it since the early 80-'s in clutch and brakes on my Mk2S. Never had any probs with it. Drained the old stuff from my brand new 2001 Rover Cooper Sport the day it went into my garage. Filled it with silicon and never had a prob with that either.

Contrary to popular belief by some, you CANNOT compress a liquid so ignore comments that silicon fluid gives a spongy feel. If the brakes are spongy, it ain't the silicon fluid.............

[MrNoo]

Always used silicone fluid and Performance Friction Carbon metallic pads on my Mini Se7en race cars, never had an issue, used S master cylinder and no servo, good pedal and silicone also wont lift your paint if you spill any

[Gary Schulz]

Silicone is the way to go especially when you consider what it does to paint when you have the inevitable leak or mess to clean up (It does nothing to the paint except make it shine!). When people refer to spongy brake feel I believe they are referring to the relatively lower boiling point which may cause some compressibility issues under extreme situations. For general use and light competition it is so much better than dealing with the other stuff... I have been using it for decades and have never had a single issue with it.

[Peter Laidler]

All I can say in reply to your quoted web site minisprinter is that it's not actually me saying that you can't compress a liquid. It's the laws of physics, The world would be a better place if we could. No cars with hydraulic brakes, no torpedoes to destroy ships, no tsunamis. Your quoted web site have got around their argument with weasel words. I wish I could have told Prof Harrison!

[paul7]

I was always told that if the brakes felt spongy, you had air in the system.

[InnoCooperExport]

On the subject of compressible liquids I would like to weigh in with my 2 cents. Once was a time I was an engineer on high pressure liquid chromatography systems in the Space Industry, the pumps we used had to be programmed to take the compressibility of the various liquids (mixtures of water and organic solvents) we pumped into consideration so as to not to create any fluctuations in mixing and flow rate which would affect our analyses. So yes, there is a degree of compressibility in a liquid, however it is in orders of magnitude 10^-10 Pa^-1. These things didn't really become a problem until we were working at the sharp end of 500 bar (and even then you'd barely notice it). You'd be struggling to get over 100 bar in a servo assisted system less so in a direct brake system so I doubt you'd ever notice.

[Alex]

Compressible or not, what I do know from personal experience is that silicone fluid will operate the brakes with a brush of the pedal but not operate the hydraulic brake light switch until the line pressure rises.

[Peter Laidler]

Surely, that''s how it's meant to be! The brake light switch operates only when the brake line pressure reaches a certain point...... silicon or not!

[Dearg1275]

Whether silicon dot 5 is good or bad a cautious thought. Should you have an accident and your insurers are involved and they notice the little sticker saying silicon fluid only, they may very well check against the brake manufactures specifications and those would be for DOT 4 fluid. I would not want to have to wriggle out of that situation especially if injury had been caused. I think I would rather have some damaged paint work.

D

[gazza82]

I used this in my Alfa 156 for several years .. Castrol React Performance Dot 4  .. (it was previously called Response).

I was persuaded to try it by the Lotus partsman at the Alfa dealer* I used ... and glad I did. It made everything feel firmer. Later I replaced all the hoses with braided and went to Ferodo Performance pads and transformed the braking .. it was never great from new!

* They sold Alfa, Mitsubishi, Lotus and Morgan ...

[Peter Laidler]

There was a certain condition when young men joined their university Junior Common Rooms, fraternal societies, Messes and other clubs. Convention ruled that they never discussed politics and religion while inside those hallowed walls. Lately it has been no discussion about being pro-EU or anti-EU. There should be another set of rules to add for classic car owners.
Never discuss silicon brake fluid or waterless coolant!
Whatever side you're on, you just can't win.........

[Dearg1275]

There should be another set of rules to add for classic car owners.
Never discuss silicon brake fluid or waterless coolant!
Whatever side you're on, you just can't win.........

Surely it’s not about winning? Having an opinion is not about winning and if we all kept our opinions to ourselves what hope of reflection, thought and progress.

D

[Herbert]

Can anyone tell me which Synthetic brake fluid is best ? and where can I buy it ?

[Peter Laidler]

Just my opinion. AUTOMEC. It's a light purple colour and been around since probably the late 70's as we used it in our modsports Midget at the time. Used it in all my own private cars since, MGBGT, Dolly Sprint, Norton Commando, MBG GT V8, current Cooper S following restoration and last-of-the-line 2001 RCSports. Been perfect in all. So that is only my humble limited experience, from shopping cars to the fast, faster and xxxxing fast, racing cars and bikes. So pretty limited spectrum I agree.

[1071 S]

Don't know if things (formulas) have changed but.... Way back when, silicon fluid was notorious for causing squishy pedals.

While its true fluids are (to all intents nd purposes) incompressible, silicon fluid was prone to collecting micro bubbles of air when disturbed. This meant is was a gas fluid mix. And hence compressible.....

Having bought your bottle of fluid home you would place it carefully on the shelf for a couple of days ..and then gently pour it into the system and then gently as possible bleed the obvious air out. Some always seemed to be left behind.....

Cheers, Ian

[Peter Laidler]

NEVER happened to me or any vehicles I know of Ian. The chemical composition - as at lunchtime yesterday - is the same as it always was according to my classic car fiend and pal James the Chemist, who also uses it in his Midget

[Dearg1275]

Here is an “opinion” from the brake manufacturers.

A079F172-21A5-416A-9960-66E67F1ACBD8.jpeg

For information only.

D