Author Topic: Brake fluid change  (Read 5066 times)

Offline Finglonga

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Re: Brake fluid change
« Reply #10 on: 20 October 2017, 10:06 »
What amazes me, and please don't take this personally, is that people will spend a lot of money on the actual car, and then not take the manufacturers advice on maintaining it.  For £60 (or whatever it is) every 2 years, it is worth it for a bit of piece of mind and the fact a full and complete service history will demonstrate the car has been looked after when selling on.

I found this explanation on another forum:

With time the brake fluid takes on water - you can see this happen by watching the fluid become darker with time (color change is by design and due to water uptake) - as the fluid takes on water, two things happen - first, the boiling point of the brake fluid decreases (the fluid boils at a lower temperature, which will show up as fade under conditions of repeated, hard braking like you might go through at a track) - the second thing which changes is the corrosiveness of the fluid - as it takes on water, it becomes increasingly aggressive towards the caliper and piston - this results in corrosion the end result of which is the caliper seal is no longer able to seal the bore (fluid gets around it), getting fluid all over the place (this is a gradual thing) - this is why if you live in a humid region and have been neglecting the brake fluid, you need to hone out the cylinder bore (so that it is uniform and smooth) or replace the pistons, or both.




Like I said about taking a car on the track you will not notice it. Pay what you want but you do not realise brake fluid is not like a sponge. When working in the car trade it was common to see cars come in that are driving around with brake fluid that is well over 10 years old. Not in a humid country so not even an issue. Any change in the brake feel then by all means get it changed.

Dealers play on the fact people are not mechanically minded and use the Hygroscopic word to scare people into thinking their cars brakes will suddenly fail and need fluid changes when not needed. It is recommended but not necessary otherwise dealers would insist it is done.

Offline brettblade

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Re: Brake fluid change
« Reply #11 on: 20 October 2017, 13:36 »
What amazes me, and please don't take this personally, is that people will spend a lot of money on the actual car, and then not take the manufacturers advice on maintaining it.  For £60 (or whatever it is) every 2 years, it is worth it for a bit of piece of mind and the fact a full and complete service history will demonstrate the car has been looked after when selling on.

I found this explanation on another forum:

With time the brake fluid takes on water - you can see this happen by watching the fluid become darker with time (color change is by design and due to water uptake) - as the fluid takes on water, two things happen - first, the boiling point of the brake fluid decreases (the fluid boils at a lower temperature, which will show up as fade under conditions of repeated, hard braking like you might go through at a track) - the second thing which changes is the corrosiveness of the fluid - as it takes on water, it becomes increasingly aggressive towards the caliper and piston - this results in corrosion the end result of which is the caliper seal is no longer able to seal the bore (fluid gets around it), getting fluid all over the place (this is a gradual thing) - this is why if you live in a humid region and have been neglecting the brake fluid, you need to hone out the cylinder bore (so that it is uniform and smooth) or replace the pistons, or both.




Like I said about taking a car on the track you will not notice it. Pay what you want but you do not realise brake fluid is not like a sponge. When working in the car trade it was common to see cars come in that are driving around with brake fluid that is well over 10 years old. Not in a humid country so not even an issue. Any change in the brake feel then by all means get it changed.

Dealers play on the fact people are not mechanically minded and use the Hygroscopic word to scare people into thinking their cars brakes will suddenly fail and need fluid changes when not needed. It is recommended but not necessary otherwise dealers would insist it is done.

Oil changes aren't strictly needed either, but as with any fluid in the car it's common sense (and I include coolant, gearbox oil etc).  On a normal use road car, changing the brake fluid means that you'll keep your calipers in the best condition and you are less likely to run into ABS issues.  Anything approaching "fast road" use will benefit from new fluid in enhanced pedal feel because reducing the moisture content has the biggest impact when the car is under heavy and/or prolonged braking.  Anyone running regular DOT4 on a track isn't using it properly.
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