Brake fluid changing, it’s a thing now but why?
Discussion
Just got a price for my Triumph bike service and at 2yrs old they said it would require new brake fluid ! Seems the same for cars and everything now ! Recommend changing every 2 years .
I’ve owned cars for 8 yrs and never even thought of changing the brake fluid .
Is this just the latest conn to up the service price or maybe an ‘ass covering’ exercise .
I understand moisture absorption etc but the bike has a sealed system so moisture cant get in !
Out of interest I bought a testing probe , I tested the bike and my 2018 Isuzu which has never had a fluid change . Both Dot4 and both tested fine .
I’ve owned cars for 8 yrs and never even thought of changing the brake fluid .
Is this just the latest conn to up the service price or maybe an ‘ass covering’ exercise .
I understand moisture absorption etc but the bike has a sealed system so moisture cant get in !
Out of interest I bought a testing probe , I tested the bike and my 2018 Isuzu which has never had a fluid change . Both Dot4 and both tested fine .
R TOY said:
Just got a price for my Triumph bike service and at 2yrs old they said it would require new brake fluid ! Seems the same for cars and everything now ! Recommend changing every 2 years .
I’ve owned cars for 8 yrs and never even thought of changing the brake fluid .
Is this just the latest conn to up the service price or maybe an ‘ass covering’ exercise .
I understand moisture absorption etc but the bike has a sealed system so moisture cant get in !
Out of interest I bought a testing probe , I tested the bike and my 2018 Isuzu which has never had a fluid change . Both Dot4 and both tested fine .
Call me cynical, but when I first started driving cars needed to be service every 6 months and didn't need the brake fluid to be changed, then annual servicing came along and all of a sudden, brake fluid starts needing to be replaced...I’ve owned cars for 8 yrs and never even thought of changing the brake fluid .
Is this just the latest conn to up the service price or maybe an ‘ass covering’ exercise .
I understand moisture absorption etc but the bike has a sealed system so moisture cant get in !
Out of interest I bought a testing probe , I tested the bike and my 2018 Isuzu which has never had a fluid change . Both Dot4 and both tested fine .
FWIW, I had a Mondeo 2.5T I bought at 3 years old and kept for 8 years, always serviced it myself and measure the percentage moisture of the brake fluid every year, it was always <1%.
There used to be a automotive engineer on here who went by the name of Max Torque and he always said brake fluid change in a temperate climate, such as the UK is a waste of time because the humidity is not high enough to effect the fluid.
R TOY said:
Just got a price for my Triumph bike service and at 2yrs old they said it would require new brake fluid ! Seems the same for cars and everything now ! Recommend changing every 2 years .
I’ve owned cars for 8 yrs and never even thought of changing the brake fluid .
Is this just the latest conn to up the service price or maybe an ‘ass covering’ exercise .
I understand moisture absorption etc but the bike has a sealed system so moisture cant get in !
Out of interest I bought a testing probe , I tested the bike and my 2018 Isuzu which has never had a fluid change . Both Dot4 and both tested fine .
It's been the case for quite a few years - Lotus recommend annual brake fluid changes on the S2 Exige (first built 20+ years ago) for example. I’ve owned cars for 8 yrs and never even thought of changing the brake fluid .
Is this just the latest conn to up the service price or maybe an ‘ass covering’ exercise .
I understand moisture absorption etc but the bike has a sealed system so moisture cant get in !
Out of interest I bought a testing probe , I tested the bike and my 2018 Isuzu which has never had a fluid change . Both Dot4 and both tested fine .
My understanding is that moisture can form in the system through condensation etc, plus the brake fluid acts as a lubricant for your braking components (seals etc) so if it's got years of crud in it (even if your moisture meter says it's fine for water) then you could have premature wear on those components, which are far more expensive to replace than fluid.
I must admit my cars and motorbikes invariably felt better after a brake fluid change, possibly only because the systems are properly bled after the changes. Seems a no brainer to stick to the service book to me, given it's not expensive.
On a separate note, without the brake fluid change I'd say your nearly-new Triumph doesn't have a "full" service history, and if I was buying a car or bike that hadn't had the brake fluid changed for years at a stretch, rightly or wrongly, I'd be questioning what other aspects of maintainance the owner had skimped on.
phumy said:
Brake fluid is hygroscopic (readily taking up and retaining moisture) and as the reservior cap is open to the atmosphere, it will absorb moisture, moisture (water) is not what you want in your brake fluid, hence it normally needs a change every 2 or 3 years.
The reservoir cap is open to atmosphere, but the fluid is covered with a rubber diaphragm.the cueball said:
Got my first bike 26 years ago and it's always been change the fluid every 2 years, so certainly not a "new thing".
Also just had a quick look at the service book for my 1990 bike and it's down as 2 years in there too...
I always thought bikes would be even more sensitive to fluid changes/brakes not fully bled than cars given the much lower volume of brake fluid they have, so I'd always be erring on the side of caution. Also just had a quick look at the service book for my 1990 bike and it's down as 2 years in there too...
Pre- and post- fluid change and bleeding on my Ducati Monster 821 was absolutely night and day in terms of performance, for example, and the fluid that came out was noticeably dirtier than the new stuff. Also note that ABS-equipped bikes often need dealer diagnostics to bleed the ABS pump (Ducatis certainly can do, for sure) so even if you think it's a scam (which I don't think it is) I'd be bleeding the brakes every couple of years anyway, in which case you may as well change the fluid.
This is the real-world reality of materials - eventually any flexible seal is slightly permeable. Moisture wicks into the system past the seals in the calipers and through the hoses, no matter how good the quality.
If you drain some directly out of the caliper (where it's furthest from the lid, and point of most-cited contamination) you'll find with a hygrometer that the fluid has a certain percentage of water, even on a bike that never gets ridden in the rain.
If you don't change the fluid you a) reduce the boiling point and b) have corrosion inside the system. Ever have a brake caliper that had good seals but a corroded piston? That's why.
It's not just a scam for dealers to pad their bottom line. Granted they might take the piss with the frequency, but ultimately brake fluid is a single point failure that's probably worth spending the tiny amount of money on.
If you drain some directly out of the caliper (where it's furthest from the lid, and point of most-cited contamination) you'll find with a hygrometer that the fluid has a certain percentage of water, even on a bike that never gets ridden in the rain.
If you don't change the fluid you a) reduce the boiling point and b) have corrosion inside the system. Ever have a brake caliper that had good seals but a corroded piston? That's why.
It's not just a scam for dealers to pad their bottom line. Granted they might take the piss with the frequency, but ultimately brake fluid is a single point failure that's probably worth spending the tiny amount of money on.
_Neal_ said:
I always thought bikes would be even more sensitive to fluid changes/brakes not fully bled than cars given how much less volume of brake fluid they have, so I'd always be erring on the side of caution.
Pre- and post- fluid change and bleeding on my Ducati Monster 821 was absolutely night and day in terms of performance, for example, and the fluid that came out was noticeably dirtier than the new stuff. Also note that ABS-equipped bikes often need dealer diagnostics to bleed the ABS pump (Ducatis certainly can do, for sure) so even if you think it's a scam (which I don't think it is) I'd be bleeding the brakes every couple of years anyway, in which case you may as well change the fluid.
Yeah I would agree... I rebuild my calipers every 2 years, so do the fluid at the same time... my wee "dip-o-meter" always says it's fine... but for what it costs, and what it does.. it's a no brainer for me.Pre- and post- fluid change and bleeding on my Ducati Monster 821 was absolutely night and day in terms of performance, for example, and the fluid that came out was noticeably dirtier than the new stuff. Also note that ABS-equipped bikes often need dealer diagnostics to bleed the ABS pump (Ducatis certainly can do, for sure) so even if you think it's a scam (which I don't think it is) I'd be bleeding the brakes every couple of years anyway, in which case you may as well change the fluid.
Fork oil is the other fluid that is usually forgotten about with bikes... again.. should be changed every 2 years, but most people wait until a seal is leaking..
The amount of bikes I've went to buy with "full service history" without these 2 things being done is staggering.
phumy said:
Brake fluid is hygroscopic (readily taking up and retaining moisture) and as the reservior cap is open to the atmosphere, it will absorb moisture, moisture (water) is not what you want in your brake fluid, hence it normally needs a change every 2 or 3 years.
But the system on my bike is sealed so it’s not exposed to the atmosphere , any more than a litre tub sat on a garage shelf . R TOY said:
phumy said:
Brake fluid is hygroscopic (readily taking up and retaining moisture) and as the reservior cap is open to the atmosphere, it will absorb moisture, moisture (water) is not what you want in your brake fluid, hence it normally needs a change every 2 or 3 years.
But the system on my bike is sealed so it’s not exposed to the atmosphere , any more than a litre tub sat on a garage shelf . You could perhaps come up with a mechanical auto-adjustment mechanism between the pedal and the hydraulics, or even in the slave pistons, but no-one has ever done that as far as I know. Probably because the upfront cost would be greater for something no-one really cares about when buying new. It would also probably break expensively.
That said, the manufacturer-recommended intervals tend to be a bit on the ridiculous side. Under normal conditions, the fluid should easily last as long as the pads. I tend to change mine at the same time (which ends up being about every five years).
I agree that it makes no sense to have regular fluid change intervals on the bike with a sealed system, though.
Edited by kambites on Friday 21st February 15:39
Is there a reason why manufactures don't use DOT 5 from day one of a new car ?
Also DOT 5 is no good as a paint stripper, unlike DOT 4.
When i restored my Mk3 Cortina 16 years ago, i replaced all the braking system and stuck in DOT 5. Gave it a bleed a couple of times a few years later but it seems a waste of time, as what came out was as good as new and still purple in colour.
Also DOT 5 is no good as a paint stripper, unlike DOT 4.
When i restored my Mk3 Cortina 16 years ago, i replaced all the braking system and stuck in DOT 5. Gave it a bleed a couple of times a few years later but it seems a waste of time, as what came out was as good as new and still purple in colour.
I first became aware of the concept with my son's Golf Mk5 about 20 years ago.
They had a two year service interval for changing the brake fluid but because it required doing via the ECU/OBD2 system it was often missed by garages doing the service. Usually after 8 or 10 years, the ABS pump would flag up a fault and often was diagnosed as needing a new ABS pump when most of the time all it needed was the fluid change that had been missed.
The fluid at the wheel end of the braking system degraded more than the stuff at the pump because it was subject to more heat changes so the sensors at the wheels read a different pressure to the ones at the pump. This showed up as a faulty ABS pump.
I had a mate who worked at a VW garage and he says they lost count of the number of ABS pumps they replaced before they realised that in many case they just had to change the brake fluid.
I guess with most vehicles (cars and bikes) having ABS nowadays, it's a pretty normal thing.
They had a two year service interval for changing the brake fluid but because it required doing via the ECU/OBD2 system it was often missed by garages doing the service. Usually after 8 or 10 years, the ABS pump would flag up a fault and often was diagnosed as needing a new ABS pump when most of the time all it needed was the fluid change that had been missed.
The fluid at the wheel end of the braking system degraded more than the stuff at the pump because it was subject to more heat changes so the sensors at the wheels read a different pressure to the ones at the pump. This showed up as a faulty ABS pump.
I had a mate who worked at a VW garage and he says they lost count of the number of ABS pumps they replaced before they realised that in many case they just had to change the brake fluid.
I guess with most vehicles (cars and bikes) having ABS nowadays, it's a pretty normal thing.
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