brprider679
New member
Does it help or hurt to only replace the brake fluid at the handlebar reservoir?
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02 K1200LT - Brake fluid question
- Thread starter brprider679
- Start date
I'd say it doesn't help.
Brake fluid is hygroscopic, i.e., it attracts and absorbs moisture. Moisture in brake fluid is bad because:
a) compromised brake fluid can, if sufficiently heated, form pockets of steam. Steam is compressible, so the brakes get spongy; and
b) moisture will cause corrosion of brake system components. Because brake fluid is lighter than water, the moisture collects in the lower parts of the system: the calipers and flexible lines. Down low in the system is where the most severe effects will be found.
Changing the fluid in the reservoir will prevent neither of these results. The reservoir doesn't get hot, and if the reservoir's rubber bellows gasket is OK water doesn't collect there.
My anecdotal evidence is this: in bikes and cars since the early 70s, I've regularly changed brake fluid as recommended. In none of these vehicles (with multiple hundreds of thousands of miles on both types) have I had to rebuild or replace any hydraulic brake system component except pads.
I wouldn't be surprised if someone chimes in with "I haven't changed brake fluid in 6 million miles and my brakes are fine." This is a YMMV situation; I choose to flush the systems regularly.
That's what I thought the OP was asking.
Brake fluid is hygroscopic, i.e., it attracts and absorbs moisture. Moisture in brake fluid is bad because:
a) compromised brake fluid can, if sufficiently heated, form pockets of steam. Steam is compressible, so the brakes get spongy; and
b) moisture will cause corrosion of brake system components. Because brake fluid is lighter than water, the moisture collects in the lower parts of the system: the calipers and flexible lines. Down low in the system is where the most severe effects will be found.
Changing the fluid in the reservoir will prevent neither of these results. The reservoir doesn't get hot, and if the reservoir's rubber bellows gasket is OK water doesn't collect there.
My anecdotal evidence is this: in bikes and cars since the early 70s, I've regularly changed brake fluid as recommended. In none of these vehicles (with multiple hundreds of thousands of miles on both types) have I had to rebuild or replace any hydraulic brake system component except pads.
I wouldn't be surprised if someone chimes in with "I haven't changed brake fluid in 6 million miles and my brakes are fine." This is a YMMV situation; I choose to flush the systems regularly.
That's what I thought the OP was asking.
Last edited:
bikerfish1100
New member
as opposed to...?
changing brake fluid never hurts. it should be done at least every 2 years, tho some prefer annual.
changing brake fluid never hurts. it should be done at least every 2 years, tho some prefer annual.
pglaves
#13338
I don't understand the question, and I also don't remember for sure what brake system that year model has.
But, if it is an ABSII system with a single fluid circuit then pouring in the reservoir and bleeding out the wheel caliper flushes the whole system, with the bit remaining able to be extracted at the bleed nipples atop the ABS unit. So if that is the system then yes, that's the way I do it.
If it is whizzy (power) brakes then there are two seperate fluid circuits. In at the handlebar reservoir and out at the ABS unit will do half the job. But in at the unit and out at the wheel calipers is also necessary - along with a special reservoir at the add point. In this case the OP question would be the easy half of the job.
And if, perchance, the OP question is can I suck it out of the reservoir and just refill the reservoir, the only time that really does any good is when a dishonest seller just does it that way so it isn't obvious to a buyer that the fluid in the system looks like old coffee or chocolate syrup and is junk.
But, if it is an ABSII system with a single fluid circuit then pouring in the reservoir and bleeding out the wheel caliper flushes the whole system, with the bit remaining able to be extracted at the bleed nipples atop the ABS unit. So if that is the system then yes, that's the way I do it.
If it is whizzy (power) brakes then there are two seperate fluid circuits. In at the handlebar reservoir and out at the ABS unit will do half the job. But in at the unit and out at the wheel calipers is also necessary - along with a special reservoir at the add point. In this case the OP question would be the easy half of the job.
And if, perchance, the OP question is can I suck it out of the reservoir and just refill the reservoir, the only time that really does any good is when a dishonest seller just does it that way so it isn't obvious to a buyer that the fluid in the system looks like old coffee or chocolate syrup and is junk.
I'd suggest checking out the BMWLT.com forums on this issue; my 2003 K12 has the integrated braking system, a totally different thing from the ABS2 systems on my K11s...
There's a lot of insight there for K12 owners.
Larry Johnson
El Paso TX
2003 K12LT
1995 K11LT
1993 KllLT
199l K75RT
There's a lot of insight there for K12 owners.
Larry Johnson
El Paso TX
2003 K12LT
1995 K11LT
1993 KllLT
199l K75RT
You have to replace the brake fluid for the ABS circuits as well as the wheel circuits. Make sure that you do not get any air in the lines or you will have to reset the codes and your brakes will not work correctly presenting you with a dangerous situation. Replacing the brake fluid is not a difficult task. There are numerous articles in the Tech section (BMWLT.com website) describing the process.
Also you need to replace the Fluid in the Clutch reservoir. That is a much easier process because the Clutch is not monitored by the on board computer system and flushing it is very simple. But you also need to make certain that you do not cause air to get in the lines.
Pop off the reservoir caps of both the brake and clutch (not at the same time though) have your bike on the center stand and level! Place quarters over the hole in the bottom of each reservoir (this prevents fluid from spraying all over your bike when you squeeze the levers) also remember to remove the quarters before putting the reservoir caps back on.
Good luck and have fun! I flush my circuits every year.
If you do not flush your circuits, the water that is absorbed by the fluid gets into the reservoirs, the ABS circuits and the calipers and the corrosion will ruin your components. You do not want to have to buy a new ABS circuit! About $1,000 new! And the repair requires running the diagnostic analyzer to check for faults and to clear the codes! No problem if you have the GS-911 device, but a dealer trip if you don't.
Also you need to replace the Fluid in the Clutch reservoir. That is a much easier process because the Clutch is not monitored by the on board computer system and flushing it is very simple. But you also need to make certain that you do not cause air to get in the lines.
Pop off the reservoir caps of both the brake and clutch (not at the same time though) have your bike on the center stand and level! Place quarters over the hole in the bottom of each reservoir (this prevents fluid from spraying all over your bike when you squeeze the levers) also remember to remove the quarters before putting the reservoir caps back on.
Good luck and have fun! I flush my circuits every year.
If you do not flush your circuits, the water that is absorbed by the fluid gets into the reservoirs, the ABS circuits and the calipers and the corrosion will ruin your components. You do not want to have to buy a new ABS circuit! About $1,000 new! And the repair requires running the diagnostic analyzer to check for faults and to clear the codes! No problem if you have the GS-911 device, but a dealer trip if you don't.
