Front brake sticking

[MoteroNC]

I have a situation where my front brakes are sticking. When I pull the brake lever at a stop light it stays engage with the rotor. If I push the lever forward the calipers are free again. Has anyone run into a similar situation? I plan to pull the calipers out and do some trouble shooting. Thank you.

[dirtrider]

1 hour ago, MoteroNC said:

I have a situation where my front brakes are sticking. When I pull the brake lever at a stop light it stays engage with the rotor. If I push the lever forward the calipers are free again. Has anyone run into a similar situation? I plan to pull the calipers out and do some trouble shooting. Thank you.

Afternoon MoteroNC

 

What are you working on?

 

Different BMW models have different braking problems so we need to know what model & year that you are working on.

 

The way that you explain  your problem it sounds more like it is in the hand lever/front master cylinder area than the caliper area.  

[MoteroNC]

I have a 09 r1200rt. Yes it feels like the lever unless I have too much brake fluid.

[dirtrider]

38 minutes ago, MoteroNC said:

I have a 09 r1200rt. Yes it feels like the lever unless I have too much brake fluid.

 

Afternoon MoteroNC

 

If the front reservoir is overfull that sure is possible. If you think it is overfull then open a caliper bleeder & let a little fluid out until the level drops to just below the full line.

 

If the reservoir was filled to the full mark with old worn brake pads, then new thicker pads installed, then it might very well be overfull now.

 

You don't have handguards on that bike do you? If so those are a major contributor to sticking brake levers.

 

I can't tell much from where I'm at here as I can't see or feel the brake lever  but the (2)  places that usually cause issues on the later 1200 I-ABS gen2 systems is the lever pivot curded up so the lever return sticks, or the master cylinder piston to bore gets curded up so the piston is lazy returning. About all you can do with this is to dig in & find out what is hanging up & why it is hanging up.

 

Your problem 'sounds' like it is in the master cylinder or lever area but that isn't cast in stone so don't focus on 'only' that area, but do clear that area as the cause before moving on to other areas.

[MoteroNC]

No hand guards. I will start by blending a bit to see if that helps. When the bike is resting the fluid on the eye glass in the cylinder shows a bit past mid point.

[dirtrider]

1 minute ago, MoteroNC said:

No hand guards. I will start by blending a bit to see if that helps. When the bike is resting the fluid on the eye glass in the cylinder shows a bit past mid point.

 

Afternoon MoteroNC

 

That doesn't sound overfull to me.

[MoteroNC]

No something is not allowing the lever to return to the most fwd position where no brake pressure would be applied by itself. If I push it myself then it does it.

[MoteroNC]

I took some brake fluid out, did a little bleeding, remove and reinstall brake pads and it all seems to work. My only concern now is that I hear a clicking sound but it maybe unrelated.

[dirtrider]

38 minutes ago, MoteroNC said:

I took some brake fluid out, did a little bleeding, remove and reinstall brake pads and it all seems to work. My only concern now is that I hear a clicking sound but it maybe unrelated.

 

Afternoon MoteroNC

 

Where do you hear the clicking coming from?

[MoteroNC]

I took some brake fluid out, did a little bleeding, remove and reinstall brake pads and it all seems to work. My only concern now is that I hear a clicking sound but it maybe unrelated.

[MoteroNC]

The front of the bike. 

[dirtrider]

10 hours ago, MoteroNC said:

The front of the bike. 

 

 

Morning  MoteroNC

 

Grab each front brake rotor & try to rotate fore/aft, see if the rotors are loose on the mounting bolts. Some rotation is normal, a lot of  rotation usually means worn rotor mounting parts.

 

If that is your clicking then a lot of the later 1200 hexhead bikes have that as they have semi-floating brake rotors.

[lkraus]

11 hours ago, MoteroNC said:

The front of the bike. 

 

You'll need to isolate the source a little more than that.  

It's normal to hear a slight click from the two switches at the lever. 

[dirtrider]

53 minutes ago, lkraus said:

 

You'll need to isolate the source a little more than that.  

It's normal to hear a slight click from the two switches at the lever. 

 

Morning Larry

 

The OP has a 2009 1200RT, that has the I-ABS gen2  brake system so no brake switch at hand lever or at foot pedal as the brake light switching is internal to the  ABS module.

 

The older (pre 2007) 1200RT with the I-ABS (wizzy) system did have a brake/cruise switch at the hand lever.

[MoteroNC]

I did check the rotors. A little bit of play but not much. I would have never thought of checking it so great inside. Not sure why the design allows that play. I just apply a bit of brake caliper lube to the back of the pads and the retaking pins. I will test ride carefully in the morning and see if the clicking noice is gone.

[dirtrider]

13 hours ago, MoteroNC said:

I did check the rotors. A little bit of play but not much. I would have never thought of checking it so great inside. Not sure why the design allows that play. I just apply a bit of brake caliper lube to the back of the pads and the retaking pins. I will test ride carefully in the morning and see if the clicking noice is gone.

 

Morning  MoteroNC

 

Floating the brake rotors on the mounting bolts is a cheaper way of giving the customer semi-floating brake rotors than the more complex & expensive 2 piece brake rotors using bobbins between the inner & outer rings. (floating, or semi-floating, brake rotors prevent rotor warping as they heat up during repeated hard braking).

 

Some of the later  1200 hexhead bikes do seem to  have a lot of rotational play in the brake rotor mounting area, they still work good plus the extra play doesn't seem to cause any harm other than a little  low speed clicking.

 

The BMW design of floating the front brake  rotors at the mounting bolts does seem to work good as I regularly turn my front brake rotors purple when I ride hard (I am a fast rider, late braker, late apex type rider) so do abuse the front brakes at times. And the brakes always seem to return to normal smooth braking operation. I just don't sit with the front brakes clamped on at the first stand-still stop after super heating them to prevent pad deposit to the red hot rotor surfaces.

 

[MoteroNC]

Thank you for the explanation DR. I will commute today and see how it goes.

[MoteroNC]

Good afternoon DR

 

Everything was working well today so appreciate the guidance

[MoteroNC]

Good evening DR,

 

After a week of normal use the condition came back on Friday. I noticed the pins the hold the pads have some rust. Do you think this could be preventing the pads from sliding more freely and why the pads may stick a bit. That would not necessarily explain that if I push the lever forward it frees up again. 

I want to troubleshoot the lever and master cylinder. Any guidance or procedure on how to do this. I am thinking on taking everything apart in the morning, cleaning rust and re lube the guide pin. Thoughts?

[dirtrider]

11 hours ago, MoteroNC said:

Good evening DR,

 

After a week of normal use the condition came back on Friday. I noticed the pins the hold the pads have some rust. Do you think this could be preventing the pads from sliding more freely and why the pads may stick a bit. That would not necessarily explain that if I push the lever forward it frees up again. 

I want to troubleshoot the lever and master cylinder. Any guidance or procedure on how to do this. I am thinking on taking everything apart in the morning, cleaning rust and re lube the guide pin. Thoughts?

 

Morning  MoteroNC

 

If the pins are corroded then it sure wouldn't hurt to clean & lube (or better yet replace, as once they start rusting then even cleaning & lubing probably won't keep the rust from eventually returning).

 

But, with the  (moving lever thing) that  pretty well points to something sticking in the front lever/master cylinder area.

 

As for troubleshooting the lever/master cylinder?-- Not much to tell you as about all you can do is start disassembling then looking for the root cause  of the sticking.  

 

Personally. I would start by removing all the brake fluid from the master cylinder reservoir then making sure that the (very small) take-up port in the bottom of the reservoir  is not restricted or plugged with crud.

 

One thing to caution you on: COVER EVERYTHING around & under that master cylinder as brake fluid is a GREAT paint remover & plastic destroyer so even cover the plastic dash (I use large plastic garbage bags over the surfaces,  with some old newspapers placed over the plastic bags under the most likely to spill areas). (REALLY! respect brake fluid around paint or clear plastics)

 

 

[MoteroNC]

Well. This intermittent problem has come. I am pretty sure it is isolated to the master cylinder. The brake lever does not fully retract intermittently.

 

Q1. Is there a spring that normally helps the lever retract full forward? If so any tips to acceess it.

Q2. I noticed a set screw or bolt with red paint in the inside of the lever assembly? Does this set any spring back setting on the lever.

 

I have done new bleeds, clean calipers, pins etc so that is why I am almost certain it is in the lever assembly or the master cylinder. I also looked and tried to clean inside the cylinder but see no obstructions there. Appreciate any help or advice.

[dirtrider]

Morning  MoteroNC

 

 

Well. This intermittent problem has come. I am pretty sure it is isolated to the master cylinder. The brake lever does not fully retract intermittently.

 

Q1. Is there a spring that normally helps the lever retract full forward? If so any tips to acceess it.-- Yes, there is a light spring inside the master cylinder bore to push the internal piston back & that then pushes the lever back. That spring isn't very strong so in some cases it isn't strong enough to push back a master cylinder piston if it is really cruded up, or  if the master cylinder bore is corroded, of if the lever pivot is binding.

 

Q2. I noticed a set screw or bolt with red paint in the inside of the lever assembly? Does this set any spring back setting on the lever.-- NO, DO NOT mess with that screw as that sets the lever to piston position as well as  allows the piston to uncover the take-up port.  

 

I have done new bleeds, clean calipers, pins etc so that is why I am almost certain it is in the lever assembly or the master cylinder. I also looked and tried to clean inside the cylinder but see no obstructions there. Appreciate any help or advice.-- Well it sounds like SOMETHING is still preventing return or preventing the caliper pistons from returning fully.

 

What happens if you use the lever enough to get  brake hang-up, THEN open a bleeder to allow the pressure out?  If the drag goes away then then something in the ABS module, or brake lines,  or master cylinder is retaining the pressure. If the problem or drag doesn't go away then your problem is more than likely in the caliper area.

 

[MoteroNC]

I will try that but I think it is in the cylinder but from the inside I see no blockage or corrosion and the fluid couldn't be cleaner. One more clue. In the am after cold soaking at night it works fine but then gets worse as day goes by. I must admit it is a very small amount of pad contact and lever movement left. Do you think it could be the spring?