Front brakes issue

[BamaJohn]

Wondering how many others have front brakes issues.

 

The Issue:  Long travel on lever b4 engaging pads onto rotors;  but pumping twice gets full pressure with short throw of lever.  Stopping power is ok.

 

Attempts to remedy:   1. zip tie lever o'night--no help;  2. flushed system, using GS-911 and multiple bleeds (I have speed bleeders on all calipers)--brake lever travel was good for one day, then back to long travel and the need to pump twice.

 

I'm wondering if the issue might be in the master cylinder instead of the calipers?   Anyone else seeing this kind of thing?

 

 

[9Mary7]

Had a similar problem in the past.... It was in the master cylinder.

[dirtrider]

5 hours ago, BamaJohn said:

Wondering how many others have front brakes issues.

 

The Issue:  Long travel on lever b4 engaging pads onto rotors;  but pumping twice gets full pressure with short throw of lever.  Stopping power is ok.

 

Attempts to remedy:   1. zip tie lever o'night--no help;  2. flushed system, using GS-911 and multiple bleeds (I have speed bleeders on all calipers)--brake lever travel was good for one day, then back to long travel and the need to pump twice.

 

I'm wondering if the issue might be in the master cylinder instead of the calipers?   Anyone else seeing this kind of thing?

 

 

Afternoon  BamaJohn

 

Some possibilities on this one. 

 

When did the problem start happening? (this could help us help you) 

 

Did the problem just occur one day or did it come on slowly?

 

Did the problem show up after any brake or tire service was done?

 

Do you have any slop or play in the front wheel bearings? 

 

Instead of guessing lets see if we can define the failure mode a little better first. 

[Boxflyer]

I looked at John's RT in the parking lot on Saturday when we were together in N.C.

 

When the bike is sitting still on the side stand and you squeeze the brake lever, you can hear a slight clicking sound coming from the LH caliper.  It sounds like the backing plates on the pads are dragging or hanging up on the calipers as they move towards the disk.

I suggested that the calipers be cleaned and lubed around the pistons and where the backing plates touch the caliper.

 

I use CRC Silaramic now as my "go-to" brake lubricant since it's compatible with brake pins and their rubber boots on the rear caliper, and has a very high "melting point".

For the cleaning of the pistons, I use a flat style shoe lace and loop it around the slightly extended piston and saw back and forth until all road residue is gone.

 

Good luck John.

[dirtrider]

2 hours ago, Boxflyer said:

I looked at John's RT in the parking lot on Saturday when we were together in N.C.

 

When the bike is sitting still on the side stand and you squeeze the brake lever, you can hear a slight clicking sound coming from the LH caliper.  It sounds like the backing plates on the pads are dragging or hanging up on the calipers as they move towards the disk.

I suggested that the calipers be cleaned and lubed around the pistons and where the backing plates touch the caliper.

 

I use CRC Silaramic now as my "go-to" brake lubricant since it's compatible with brake pins and their rubber boots on the rear caliper, and has a very high "melting point".

For the cleaning of the pistons, I use a flat style shoe lace and loop it around the slightly extended piston and saw back and forth until all road residue is gone.

 

Good luck John.

Afternoon  Boxflyer

 

While anything is possible my common sense tells me that a sticking brake pad or sticking caliper would more cause a dragging or overheating brake than cause a long initial lever travel condition.

 

If the brake pad or caliper is sticking then what is causing the brake pads to kickback  and cause the long initial lever travel?   

[Boxflyer]

I replied because I had touched and listened to this bike.

 

I'll keep out of it

[Skywagon]

DR, Box, Bama....Mine is a 14.  It has done that since new. I even asked the dealer about it on the test ride when new. Not sure if it is as pronounced as Bama, but it's there.  I don't get any fading of the lever when applying it.  It will hold solid as long as you want to hold it....even overnight tied down.  If you pump it a couple of times it will be a little shorter to connect.  I know all my front system is very clean so no issue there.  I've blead the brakes multiple times including compacting the pistons and making sure they were clean.  I've grown to accept it is just how it is and a non-issue.  Stops like crazy, never fades, and never goes more than about 1/2 way.  

[TEWKS]

16 hours ago, Boxflyer said:

I replied because I had touched and listened to this bike.

 

I'll keep out of it

I was hoping to hear more between the two of you. Both extremely competent wrenches which could only up the game for us regular hacks.  

 

Now, I was going suggest to John that he take his stich fixing Duct Tape and wrap that brake lever till it felt just right. But then thought better of it, it’s a BMW damnit not a Harley! 

[BamaJohn]

Thanks again Brad for looking at it with me and I'll work on that.  And thanks DR for your reply.  I mainly wanted to see how many others have a similar problem, since about 3 of us at Sparta had it.

 

For the record:  The problem developed slowly.  Not associated with anything I can identify in the way of maintenance.  The front wheel is without "wiggle".

[BamaJohn]

3 minutes ago, TEWKS said:

Quote

Me too.....and I appreciate both replies!   

 

And no duct tape will work on this issue Pat.....  But I DID buy a new supply today for the bike!

[Bernie]

My brake fading happened on Thursday and Friday afternoons, while being chased by you guys.

I think it had something to do with heat buildup and old brake fluid. On Friday morning (cold 40-50F), I normal brake pressure and brake lever travel again. 

After @Boxflyercleaned the system, flushed and bleed the system, the brake pressure was back to normal, even when hot.

@BamaJohn your problem sounds almost like DR suspects, that something is causing the brake pads and pistons, to retract too far into the calibers. Maybe a disc out of round? Or bad wheel bearing, too much play in the brake disc floating washers?

[9Mary7]

Suzuki had this problem which resulted in the recall and replacement of front master cylinders on all GSXR's from 2004 thru 2014(?) IIRC. Turns out with age, the master would get some crud in it and bypass internally, causing exactly what BamaJohn is experiencing. Suzuki changed the location of the compensating port to cure the issue.

I'm not saying that BMW has this problem, only that an internally bypassing master will exhibit these symptoms. My son's GSXR track bike did this and the brake system was perfectly maintained, with no crud in it. 

It is because of this personal experience that I recommended focusing on the master cylinder, I should have expounded a bit more.  

[Bernie]

Is it possible that if the lever is adjusted too close to the grip that it may not release completely? 

[BamaJohn]

I should have mentioned that I've tried adjusting the front brake lever from 1 to 4 with no change, other than the distance of the lever from the grip.

 

Still wondering how many people are having this issue......

[Boxflyer]

John, 

l have a spare master cylinder I can send down to you if you want to swap it out for troubleshooting. 

[Boxflyer]

1

[BamaJohn]

9 hours ago, Boxflyer said:

John, 

l have a spare master cylinder I can send down to you if you want to swap it out for troubleshooting. 

That's a very kind offer and I'd like to take you up on it.  I'll pay shipping both ways.  Thanks Brad!

[dirtrider]

17 hours ago, BamaJohn said:

 

For the record:  The problem developed slowly.  Not associated with anything I can identify in the way of maintenance.  The front wheel is without "wiggle".

Morning  BamaJohn

 

OK, that most likely eliminates a maintenance issue.

 

Still not enough info to tell you anything conclusive but it does sound (on the surface anyhow) like an internal master cylinder issue.  

 

Can you confirm that-- if you ride the motorcycle home with a properly functioning front brake  are you able to get that long lever travel the next time you use the front brake (at first usage)  after sitting overnight or longer?  

 

If so then that does point to a master cylinder issue. 

 

If you can duplicate the conditions that produce the long lever travel (motorcycle sitting period  etc) then you might remove the front master cylinder cover & remove about 3/4 of the fluid, then allow the motorcycle to sit the required length of time it takes for the problem to show up. 

 

Then with the cover still removed, & using enough light to see to the bottom of the fluid reservoir, slowly pull the brake lever while looking into the bottom of the reservoir.   If you see a stream of brake fluid coming back out of the take-up port hole in the bottom of the reservoir right up until you start getting a firm lever then that tells you that you have an internal master cylinder problem. (a  very small squirt back as very first lever movement is normal but it should be very small & quit squirting back as the lever is moved just a little)

 

This isn't conclusive as you can get internal fluid by-pass & not have the fluid squirt back through the take-up port hole but IF you do get the squirt back it pretty well points to a failed (or failing)  master cylinder. 

 

CAUTION: do not pull the brake lever fast as that can cause a stream of brake fluid to squirt up & out of the reservoir & get all over the motorcycle paint or dash. Brake fluid can quickly ruin paint or dash plastic so I also suggest that you cover  under & around your dash & paint with a couple of plastic garbage bags just as a precaution.   

 

 

[BamaJohn]

Thanks DR....IF the master cylinder is possibly failing, that would make this issue far more serious in my mind.  So, I'm gonna approach it this way:

1. Clean the bike to remove the road grime/grit from my 1800+ miles last week;

2. Remove (one at at time) the front calipers and clean/lube pistons & pad slide points;

3. Rule out rotor warp;

4. Follow your points above;

5. If all this fails to remedy the situation, then I'll swap the master cylinder with Brad's;

6. If the swap remedies the issue, then I'll know what causes it and make a permanent fix.

 

I appreciate all suggestions/comments...thanks everyone!

[dirtrider]

24 minutes ago, BamaJohn said:

Thanks DR....IF the master cylinder is possibly failing, that would make this issue far more serious in my mind.  So, I'm gonna approach it this way:

1. Clean the bike to remove the road grime/grit from my 1800+ miles last week;

2. Remove (one at at time) the front calipers and clean/lube pistons & pad slide points;

3. Rule out rotor warp;

4. Follow your points above;

5. If all this fails to remedy the situation, then I'll swap the master cylinder with Brad's;

6. If the swap remedies the issue, then I'll know what causes it and make a permanent fix.

 

I appreciate all suggestions/comments...thanks everyone!

Morning  BamaJohn

 

Just a quick observation: 

 

If you ride that motorcycle home & park it with a good functioning front brake, then next morning try the front brake lever without riding or moving the motorcycle & you get excessive lever travel then you can pretty well rule out sticky front pads or pad kick-back as the root cause. 

[Boxflyer]

Sorry, but you can't rule out sticky pads and or hanging pistons.

I had John squeeze the brake lever and there were clicking and popping sounds coming from the caliper/rotor area.

 

Cleaning and lubing are essential as a first step in solving this issue.

 

I'm sending John a master cylinder today if doing basic preventative maintenance don't improve the problem. 

[dirtrider]

35 minutes ago, Boxflyer said:

Sorry, but you can't rule out sticky pads and or hanging pistons.

I had John squeeze the brake lever and there were clicking and popping sounds coming from the caliper/rotor area.

 

Cleaning and lubing are essential as a first step in solving this issue.

 

I'm sending John a master cylinder today if doing basic preventative maintenance don't improve the problem. 

Afternoon Boxflyer

 

Help me understand this-- If the motorcycle isn't moved or ridden after a working front brake then WHAT is causing the brake pads to kick back causing the long lever travel.  What am I missing on this?

 

I ride a GS off-road in quicksand mud & in clay mud that builds up so bad you can't identify the brake calipers & I haven't ever had a severely dirty brake caliper or pistons cause a long lever travel.  I have had it stick the brake pads/pistons enough to cause brake overheating & purple brake rotors but even that didn't lead to a long lever travel.  

 

 

[Boxflyer]

D.R.

I just want to help John, not get into our skills at diagnosing online and routine maintenance.

Take care

[dirtrider]

9 minutes ago, Boxflyer said:

D.R.

I just want to help John, not get into our skills at diagnosing online and routine maintenance.

Take care

Afternoon Boxflyer

 

OK,  keep helping him I will back out so you can work with him. 

[Bernie]

It is strange that his brakes make noises when standing still. 
 

[RTinNC]

So then is the answer just don’t stand still? 
 

[9Mary7]

[Toter]

Any update on the solution??