Suddenly less resistance in brakes...

[cosmouser]

So I got my K75 back from a repair shop/dealership and they replaced the brake pads and bled the front master cylinder about a week and a half ago. When I first got the bike back I barely had to pull back the front brake level for it to start braking. Day after day since, the level has been losing resistance gradually. This morning I felt more play in the lever than I was comfortable with... I'll be calling them tomorrow but I thought I'd see if anyone here is familiar. It still brakes but the pattern so far is a little disturbing.

[TimTyler]

... they replaced the brake pads and bled the front master cylinder...

It's not possible to just bleed the master cylinder. Either you bleed the front brake system or you don't.

Do you have ABS?  Did you go to a shop that specializes in BMW bikes?

I'd call the shop and file your complaint. If they don't offer to fix it immediately I'd go buy a brake bleeder and do it myself.

[cosmouser]

Oops.. Yes they bled the front brake system. No ABS. I did go to a shop that specializes in BMW bikes. They're closed today but yes, will call tomorrow. Thanks.

[K75RT Keith]

Any apparent loss of fluid in the reservoir? 
Have you found any signs of leakage? 
How old are the brake lines?  If they're old, take a look at the brake lines for swelling or deterioration.

[Motorhobo]

Before going back to the dealer I'd try removing the MC cover and doing the ol' turn the handlebars left & right while slowly 1/4 lever-pumping...there might be a bubble in there trapped. Then maybe crack the valve, wait for some gravity drippage and see if any air escapes. Who knows, maybe there's just a bubble in there aching to get out.

I always have an 11mm and a piece of tube in my case and it's seen a good deal of use over the past 10 years -- last time my MC failed it didn't do it all at once but rather got squishy on me over the course of a couple weeks and I was able to crack-n-bleed it back to hardness several times before I got a chance and the $$ to replace it.

[rbm]

Sounds like there is air entering the system.  You might try tilting the handlebars left to place the MC at its highest point and then strapping the brake handle to the bars to apply pressure in the system overnight.  This tends to force air out of the lines and firm up the handle.  If this procedure fails, then its time to take the bike back to the garage for them to diagnose and correct.

[cosmouser]

I went back to the dealership that did the repair and they checked out the bike. They said it was the fluid settling back to normal after the break bleed. Also, the whole front brake assembly is old, the brake pads are old and the rotor is under the specified thickness. Lots of things could hurt the braking ability, but they said it would not continue to lose resistance and they beveled the front pads to more accurately contact the front rotors for free as well.

[drut]

" They said it was the fluid settling back to normal after the break bleed. Also, the whole front brake assembly is old, the brake pads are old and the rotor is under the specified thickness. Lots of things could hurt the braking ability"

Hmmm!  :musicboohoo:

[K75RT Keith]

So, did they try to sell you a newer bike or just a "new"brake system?

[cosmouser]

So, did they try to sell you a newer bike or just a "new"brake system?

They sold me new rotors (which will be put in this September). Aside from that they didn't pitch anything else.

[johnny]

greetings...

i do not trust a single thing a dealer says... not the wordsmith service writer... not the certified technian with decades of exierience or the greedy owner... nobody...

j o