Front lever slow brake fade at stoplights

[Crisco Brown]

I have a 96 R1100r which I recently bought after it had sat for a few years. When test driving it I noticed that the front master cylinder had a slow leak so I ordered a re-build kit and installed it.

This eliminated the fluid leak and the brakes continued to function well as they had all along.

now Ive got a new problem… if Im at a stoplight or for any other reason hold the front brake on for any period of time the lever slowly but steadily moves back until it almost touches the grip.

at this point the brakes no longer work and the bike will roll on a hill.

as soon as I release the lever and pump it a couple of times the brakes are completely back and work great until the next time I stop at a light and the same thing happens again.

could it be that there is a problem with the master cylinder which the re-build kit alone wont solve?

Do I need a new or good used master cylinder unit and if so does anyone have one they could sell me? In the interest of full disclosure a previous owner had by-passed the abs unit and installed a set of Galfer braided steel lines and I have replaced the fluid entirely and re-bled the brakes several times.

any and all ideas and suggestions will be gratefully accepted.

In the meantime this otherwise great running unit with only 30 thousand miles on it  is sitting idle as I dont feel comfortable riding it with dodgy brakes… the riding season is short up here in Canada so the clock is ticking if I want to get out and see the fall colours!

thanks in advance Crisco

 

[dirtrider]

38 minutes ago, Crisco Brown said:

I have a 96 R1100r which I recently bought after it had sat for a few years. When test driving it I noticed that the front master cylinder had a slow leak so I ordered a re-build kit and installed it.

This eliminated the fluid leak and the brakes continued to function well as they had all along.

now Ive got a new problem… if Im at a stoplight or for any other reason hold the front brake on for any period of time the lever slowly but steadily moves back until it almost touches the grip.

at this point the brakes no longer work and the bike will roll on a hill.

as soon as I release the lever and pump it a couple of times the brakes are completely back and work great until the next time I stop at a light and the same thing happens again.

could it be that there is a problem with the master cylinder which the re-build kit alone wont solve?

Do I need a new or good used master cylinder unit and if so does anyone have one they could sell me? In the interest of full disclosure a previous owner had by-passed the abs unit and installed a set of Galfer braided steel lines and I have replaced the fluid entirely and re-bled the brakes several times.

any and all ideas and suggestions will be gratefully accepted.

In the meantime this otherwise great running unit with only 30 thousand miles on it  is sitting idle as I dont feel comfortable riding it with dodgy brakes… the riding season is short up here in Canada so the clock is ticking if I want to get out and see the fall colours!

thanks in advance Crisco

 

 

Afternoon  Crisco Brown

 

Your lever "creep" pretty well points to a leaking master cylinder piston to bore seal (fluid slowly seeps back past the piston seal).

 

This can be caused by a rough/pitted master cylinder bore, or a burr on the bore side of the small take up port.

 

You didn't use a brake hone on the master cylinder bore did you?   That can leave the bore rough enough to have a seal leakage.

 

Did you clean the master cylinder bore to remove all the junk stuck to it? 

 

It is also possible that your piston is corroded, pitted, or damaged so your piston seal leak is between the piston seal & the piston body.  

 

Unless you can find & repair the smoking gun (point of seepage)  then you should probably replace the master cylinder. 

 

 

[Crisco Brown]

Thanks so much any ideas about where I can get a new master cylinder? When the kit was installed it was cleaned out but at this point this seems to be a better way to resolve the issue once and for all rather than guessing at which of those issues might be the cause and end up wasting good money after bad and end up doing it eventually anyway… thanks so much Crisco

[dirtrider]

2 hours ago, Crisco Brown said:

Thanks so much any ideas about where I can get a new master cylinder? When the kit was installed it was cleaned out but at this point this seems to be a better way to resolve the issue once and for all rather than guessing at which of those issues might be the cause and end up wasting good money after bad and end up doing it eventually anyway… thanks so much Crisco

Afternoon  Crisco Brown

 

The two places that come to mind are:

 

E-Bay, this can be a crapshoot but usually a vendor with a good reputation will make it right with you.

 

BeemerBoneyard,  they stand behind their used parts but don't always have stock on parts. Mention being a member of this website & BBY usually gives a discount.  https://www.beemerboneyard.com/

 

Also, BeemerBoneyard usually has new master cylinders in stock but @ around $400.00

[Crisco Brown]

Thanks I will follow up on this suggestion thanks Crisco

[Michaelr11]

1 hour ago, Crisco Brown said:

Thanks I will follow up on this suggestion thanks Crisco

 

The MC leak is probably right, but before you go for replacing it, try bleeding the front brakes again.  Pump through the master cylinder at least three refills of fluid.  See if that makes any difference.

[Crisco Brown]

Thankyou for your idea I will try that again

[dirtrider]

20 minutes ago, Michaelr11 said:

 

The MC leak is probably right, but before you go for replacing it, try bleeding the front brakes again.  Pump through the master cylinder at least three refills of fluid.  See if that makes any difference.

Evening Michaelr11

 

Crisco says "

This eliminated the fluid leak and the brakes continued to function well as they had all along.

now Ive got a new problem… if Im at a stoplight or for any other reason hold the front brake on for any period of time the lever slowly but steadily moves back until it almost touches the grip"

 

How is bleeding 3 fills or 3 gallons of fluid through it going to stop the lever creep?  Even if it had some air in the system once the pressure is built up it should NOT leak down sitting still just holding the brake lever on.  

 

Air gives a long lever pull at first apply not while holding it on steady.  

 

 

 

 

[Hosstage]

The symptom is a classic sign of a bad master cylinder. I've owned a lot of crappy old cars, and every one that had pedal fade while stopped that was not caused by a leak was a bad master.

Also, $400 for a new master cylinder? And I thought Harley parts were expensive.

[MichiganBob]

BMW = Bust My Wallet

[Crisco Brown]

Lol

[Skywagon]

If you want to try one more thing before you cough up dough for a new MC....maybe take it to a real brake shop where they have the tools to properly hone, clean, and rebuild.  I'm not sure what that would cost or if the result would fix the job, but might be worth a shot to at least inquire.

[Crisco Brown]

Great advice as the $400 us price is a bit daunting to spend on a bike which I only paid $2000 for especially for a retired guy just trying to keep riding as long as he can.

maybe somewhere out there someone would be willing to part with a used one for a more reasonable sum…..thanks to all who chimed in with their ideas…. Crisco

[9Mary7]

I'll look thru my spares.....

[Crisco Brown]

Thanks so much Crisco

[9Mary7]

Struck out, sorry.

[Crisco Brown]

Thanks for taking the time to look… Crisco

[Lowndes]

Crisco,

 

There may be a similar model BMW with a complete front master cylinder unit with throttle and switches that would work on your bike, maybe an R1100S (see pics below).  That would expand your search options considrably, but would require some search and comparisons to find units similar enough.

 

Just a Google search turned up this:

 

 

Bob's parts diagram ( https://www.bobsbmw.com/store/microfiche/BrowseParts.aspx?GroupName=Handlebar%2c+Control+Fixtures%2c+Cables+(32)&MBike=51672&GroupID=32 ) shows :

 

 

#11 refers to the diagram, the number 32722352190 is your part number.  Use it to look for that unit on similar era BMW's.  Bob's also has used parts.

 

These are pics of my '99 R1100S right handlebar control pod.  Looks like it may have more more buttons and be longer than your R1100R pod.  

 

 

Hopefully you can find something that works for your bike.  Keep searching, it's out there!!

 

 

 

 

 

 

[Crisco Brown]

Great idea thanks… Crisco

[dirtrider]

Morning  Crisco/ Lowndes

 

Be careful  in using the 1100S as the source as most (that I know of anyhow) 1100S master cylinders won't work.

 

About all the 1100R, 1100RT, 1100RS, 1100GS & some K-bikes of that era used the same  32722352165 master cylinder. 

 

Try searching E-Bay, or on-line, for a  ( BMW 32722352165 ), lots of hits should come up on that part number . 

 

Even BeemerBoneyard has an aftermarket 32722352165 (way lower price than a BMW OEM unit).    https://www.beemerboneyard.com/32722352190n.html

 

The 32722352190 is a BMW late (superseded) replacement part so that will limit you to mostly new BMW retail or at least expensive new. 

 

 

 

 

[Crisco Brown]

Thanks great advice