Brake question

[Bill Stevenson]

I am experiencing a slow deterioration of braking performance over time. Mine is a 2008 with ABS. The brakes get mushy about every 2-3 months. Dealer purges them and they are nice and firm at first. At the last service, 36,000 miles, dealer looked hard, but didn't find anything wrong. Possibly a slow leak in the master cylinder? Anybody else had this problem? Any suggestions would be appreciated.

Bill

[Bob Ain't Stoppin']

Suggestions: Replace any brake lines that are rubber, or non steel. Replace/rebuild the master cylinder to renew the rubber seals. I assume your brake pads are in good condition?

[Bill Stevenson]

All brake lines are steel. Brake pads, I dunno for sure, but my guess is they were marginal the dealer would have suggested replacement. They used to love to replace the brake pads on my previous R1150R, which pads wore out with the tires for reasons never determined. But I will take a look at the pads. I am thinking the master cylinder is the prime suspect.

[dbrick]

Bill,

I think Don's post of 1-24-2010 in this thread: viewtopic.php?f=20&t=19466 addresses the same issue.

[deilenberger]

Bill,

I think Don's post of 1-24-2010 in this thread: viewtopic.php?f=20&t=19466 addresses the same issue.

Just as an update to that thread - mine continues to have a slightly mushy feel on first use. This becomes more pronounced as the brake pads wear - again - I think a factor of piston retraction by the piston seals. Just put new front pads on yesterday (Carbone Leone from Beemerboneyard - $56 with BMWMOA discount and I had them within 24 hours) and it feels firm again, but I expect as the pads wear for the symptom to return.

Can't say it's a problem since I've never failed to stop the bike due to this. Since I have grip-puppies on the grips (increasing their diameter) it's a bit more obvious since the lever comes closer to the surface of the grip puppy.

After 77,500+ miles I've learned to ignore it.

[Bill Stevenson]

Thanks to all for the responses. It does not sound like my bike has the same symptoms that Don described. I have my dealer (a very, very good dealer BTW) do the brake bleeding with a purpose built vacuum pump. After bleeding all is well for 2 or 3 months, before the mushy thing crops up. This was not always the case, but started within the past year. I am the original owner and the bike has ~37K miles on it. Brake pads don't seem like a likely root cause, but I will check them. More likely there is a wee leak in the master cylinder, the more I think about it.

Assuming that I decide to put new brake pads on, to leave no stone unturned, is there any reason not to stick with OEM?

[deilenberger]

Assuming that I decide to put new brake pads on, to leave no stone unturned, is there any reason not to stick with OEM?

Price? Value?

BMW wants $120 per caliper - ie - $240 for the front pads. These are nothing special pads - simple sintered ones for Tockico calipers. BeemerBoneyard (Hi Mike!) has Carbone Lorraine sintered pads for around $65 for both calipers. If you're an MOA member - add that into the discount field. 10% off. I ordered new ones Monday and was installing them Tuesday afternoon.

http://www.beemerboneyard.com/cl2960a3.html

I've used these pads - and EBC-HH's. These give excellent stopping power without too much dirt/dust and aren't awful on the rotors. The EBC's offer a bit more initial bite but are harder on the rotors. Mike carries both.

As an update - my lever still is quite firm, and ALL I did was replace the pads. Didn't have to touch the brake fluid since it had been flushed last time when I replaced the pads (about 40k miles ago.)

IF your dealer has flushed the system and topped it up with partly worn pads in the calipers - you may have to remove some brake fluid from the reservoir when you push back the pistons to fit the new pads. Don't overlook this - dribbling brake fluid is awful on nice painted surfaces. FWIW - BMW has always been rather clever with their brake fluid reservoirs - it usually get to the MIN line about when the pads are gone (bikes and cars).. if you don't top it off (I don't because it's simply not needed and provides no benefit) it will go right back to the FULL line when you put new pads in.

At 37k miles - chances are your pads are getting thin anyway, so.. spend $65, satisfy your curiosity and get new pads at the same time.

[Bill Stevenson]

Thanks very much Don.