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Discussion Starter #1
I just purchased my first bike since 19--, 2003KLT with 17K miles. Back then it was a honda 450CL. Great bike when young and immortal. This beast is unbelievable. I just can't get off. I am, however, curious about this brake fluid change stuff. I was in the automotive repair business for many years and my first vehicle was a 1958 Rambler - yes to all you youngsters, there were real live ramblers made in the USA. I have NEVER heard about changing brake fluid until I bought this vehicle. Is this a BMW service dept. gimmic? What can possibly cause the fluid to become a problem - less a leak? I plan on doing most of the routine maint. myself over the winter and can't for the life of me figure out why I should change the brake fluid. Is there an unusual chemicle reaction that occurs in motorcycles that does not occur in automobiles? They are both closed loop systems.

Thanks for the help.
 

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BigGeo said:
I I have NEVER heard about changing brake fluid until I bought this vehicle. Is this a BMW service dept. gimmic? What can possibly cause the fluid to become a problem - less a leak? I plan on doing most of the routine maint. myself over the winter and can't for the life of me figure out why I should change the brake fluid. Is there an unusual chemicle reaction that occurs in motorcycles that does not occur in automobiles? They are both closed loop systems.

Thanks for the help.
Brake fluid is hydroscopical, it absorbs water easily and holds it. This water contaminates the brake systems and causes corrosion to the internals of brake components.
I always change the brake fluid in my vehicles every 2-3 years. Did you ever notice how clear brake fluid is when new then look at it a few years later? Ever wonder why it gets so dark in color? That is the moisture contamination.
 

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ABS brake systems in-general seem very sensitive to old brake fluid. Toyota says every two years is their standard. So its not just a BMW "thing."

A few dollars on brake fluid is a fair tradeoff to avoid replacing costly ABS pumps & such...
 

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Think he wants to know how the water gets into the closed system when there isn't a leak.

COme to think of it, I'm curious also.

Does the heat from the pads break the fluid down making water?

Bob 0h 0h LT
 

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Fifteen or so years ago when I was spending all of my money at the track, everyone told me to use Motul synth. fluid for the higher heat range.
However, synthetic attracts moisture better the regular DOT4.

Though you think your brake system is sealed, is it?

Moisture can seep into the system at the banjo bolts through the res. seals and even through the brake lines themselves.
Not to memtion that the brake fluid itself will attract moisture.
Just because the fluid doesn't leak out doesn't mean smaller molecules can't get in.
 

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2005 K1200LT
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BigGeo said:
I have NEVER heard about changing brake fluid until I bought this vehicle. Is this a BMW service dept. gimmic? What can possibly cause the fluid to become a problem - less a leak?
Thanks for the help.
Almost all vehicle manufacturers recommend changing the brake fluid on a regular basis. Almost eveyone doesn't do it. I garantee if you had drained the fluid out of that 58 Rambler (yeah I had one too), it would have been BLACK from rubber contamination and moisture. No system is completely closed loop. Since I have owned the LT I have started flushing all my other vehicles as well. It is amazing what came out of the system the first time on a 10 year old car.
 

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Discussion Starter #7
Thank you all for the input. I've put over 200k miles on vehicles and with the rare exception of forced fluid changes - blown cylinders- I've been pretty fortunate to escape without changing the fluid. I believe this may be a little like government spending - more is always better than less. Would schools be better if we spent $20k/student/year, would unemployed be more comfortable if the unemployment payments were $2000/week, would we all be safer if we stayed home instead of riding? Would an engine last longer if we changed the oil every 500 miles, would we be safer if we changed all the cables and connectors yearly? Probably yes to all. So what is the cost benefit to changing the fluid, are there safety issues I'm likely to encounter? Perhaps if it turns dark I'll consider it.

Thank you again for helping this new rider with his, perhaps, inane questions.

Incidentally, I love the word hydroscopical and will attemt to use it in future conversations.
 

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Discussion Starter #8
Jzeiler, Thanks for the info. I checked my Lexus RX service manual and they forgot the brake fluid change schedule as did my Subaru Tribeca. Perhaps this is a German phenom.

I did drain virtually all fluids out of the "bler" but the push button tranny still let go on me. Replaced it with a 1959 galaxy 500. Now that was a machine.
 

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BigGeo said:
So what is the cost benefit to changing the fluid, are there safety issues I'm likely to encounter? Perhaps if it turns dark I'll consider it.
The "cost benefit" to changing the brake fluid is not trashing a $2500 ABS unit. If you wait 'till it turns dark it may be too late.
 

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Try the chit chat section for the stuff that isn't related to the LT.

At the first indication your brakes might be spongy, change the fluid.

Bob
 

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BigGeo said:
Thank you all for the input. I've put over 200k miles on vehicles and with the rare exception of forced fluid changes - blown cylinders- I've been pretty fortunate to escape without changing the fluid. I believe this may be a little like government spending - more is always better than less. Would schools be better if we spent $20k/student/year, would unemployed be more comfortable if the unemployment payments were $2000/week, would we all be safer if we stayed home instead of riding? Would an engine last longer if we changed the oil every 500 miles, would we be safer if we changed all the cables and connectors yearly? Probably yes to all. So what is the cost benefit to changing the fluid, are there safety issues I'm likely to encounter? Perhaps if it turns dark I'll consider it.

Thank you again for helping this new rider with his, perhaps, inane questions.

Incidentally, I love the word hydroscopical and will attemt to use it in future conversations.
You pays your money and you takes your chances.

I have had to change at least 5 master cylinders that leaked from RUST in the bore from the absorbed moisture on vehicles I have owned over the last 40 years (I never used to flush). As far as cost benefit, I gladly pay 3 bucks for a pint of fresh fluid that will prolong the life of a $2,200 ABS unit.

But then to each his own.
 
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