• Hi Guest!
    If you appreciate British Car Forum and our 25 years of supporting British car enthusiasts with technical and anicdotal information, collected from our thousands of great members, please support us with a low-cost subscription. You can become a supporting member for less than the dues of most car clubs.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

silicone brake fluid

Share this page

Hi,

A simple way to determine whether you have silicone or glycol based brake fluid in an unknown system, is to place an ounce or two of fluid in a jar, and then add a drop of water. If the water droplet becomes absorbed in the fluid, then it's glycol based, if it doesn't mix, it's most likely silicone.

Scooter
 
Hi Jay

I agree with Mark. If it was good enough for Geoff it's good enough for me.

Cheers
savewave.gif
england.gif
savewave.gif
 
Its late again but this time Iam awake and have facts
1.DOT 3 minimum boiling point 401 deg f
polyalklene glycol ether (hygroscopic)
2.DOT 4 minimum boiling point 446 deg f
polyalklene glycol ether (hygroscopic)
3.DOT 5 minimum boiling point 500 deg f
silicone (synthetic) (nonhygroscopic)
4.Dot number referes to the type of tests done
on the fluid
5.Hygroscopic-strong attraction to water
6.PGE based brake fluid absorbs water rapidly,
reducing the boiling point alot
7.boiling water causes gases which do not
compress well leading to a soft pedal
8.silicone and water remain seperated but water
is heavier so it settles to the lowest points
normally the calipers where it boils at 212degf
9.silicone fluids compressibility is unstable
thru temperture ranges causing a ever changing
pedal feel
10.brake part rubber can be ethylene propylene
which gets soft when exposed to silicone
11.do not use mineral based cleaners
12.DOT 5.1 not enough research yet
Hope this was better and cleared up some of the questions.For more information try www.thebrakeman.com/fluid_tech I have read his articals for many years and they always seem to hold up.
 
Valvoline recently introduced a Synthetic Brake fluid. This product seems to address all the concerns.
It's rated Dot 3 / Dot 4.
It will not absorb moisture - eliminates internal corrosion.
Will not attack rubber components.
AND it's more economical than silicone at $ 5.00 / litre in lieu of $30.00, and available at most auto parts stores [Autozone. PEP Bros, etc].

I put it in my Healey when I put it together, then I flushed out replaced the brake fluid in all the other vehicles [7] of my family which I also maintain.

Regards, Bob
 
Bob,
The Valvoline prouduct sounds interesting.

Having Put up a few posts on this brake fluid subject I realized that after a life time of working on brakes there was a lot more to learn.So alot of research and reading followed.Knowing how people feel when things have worked for them with no aparent problems I hesitated to add this post to a already long subject post list.However there was one outstanding caution in every artical. DO NOT USE SILICONE BRAKE FLUID.At best it was suggested for show or museum vehicals only due to its properties.From the previous post there seems to be alot of people using silicone.From a safety stand point my suggestion is do not. I am not a expert and do not expect any one to make changes based on my information.If you use silicone in a driver please take the time to do some research and then draw your own conclusions.It could make a difference.I have come to enjoy the people on the forum and have always loved Austin Healeys,lets do our best to keep both in good shape.
Thanks
CDK
 
Back
Top