02' 1150RT Front brake not releasing

[Alba]

All,

 

I'm looking for some guidance. I removed the ABS system last year and all has been good.  Also calipers had new seals and pistons at the same time.

 

Recently I became aware that the front brake was not fully releasing, brake light remained on, and requires me to push the brake lever forward a milometer to fully release.

 

Bike on centre stand front wheel raised, wheel spins.  Apply brake release, wheel will not spin. Push the brake lever forward wheel spins.

 

Any thoughts?

 

For the UK team, would this be an MOT failure?

 

Many thanks

[dirtrider]

23 minutes ago, Alba said:

All,

 

I'm looking for some guidance. I removed the ABS system last year and all has been good.  Also calipers had new seals and pistons at the same time.

 

Recently I became aware that the front brake was not fully releasing, brake light remained on, and requires me to push the brake lever forward a milometer to fully release.

 

Bike on centre stand front wheel raised, wheel spins.  Apply brake release, wheel will not spin. Push the brake lever forward wheel spins.

 

Any thoughts?

 

For the UK team, would this be an MOT failure?

 

Many thanks

Morning  Alba

 

It sure sounds like something in the master cylinder is sticking. 

 

Possibly the lever itself is binding on it's pivot bolt, or the lever is rubbing on something, or possibly the master cylinder piston is dragging in the cylinder bore due to crud or corrosion.

 

Make sure the lever is free to move on it pivot pin, if the lever & pivot checks out then you will probably have to drain the master cylinder  (just the cylinder not the entire brake system), then remove the lever & piston rear retainer then slide piston out of the bore. 

 

Once the piston is removed you can address what you find, probably clean the piston & cups as well as polish the bore with fine Scotch Pad (clean the bore completely afterwards  if you use Scotch pad or fine wet/dry paper). Do not leave ANY abrasive in the bore. I do not recommend using a cylinder hone  in the master cylinder bore. Some do, I don't, & I don't recommended  using one. 

[Alba]

thanks dirtrider i'll work through you tips.

 

Is the "lever & piston rear retainer" the slotted screw directly behind the brake lever?

Edited July 10, 2020 by Alba
Full message was not initillay displayed

[dirtrider]

35 minutes ago, Alba said:

thanks dirtrider i'll work through you tips.

 

Is the "lever & piston rear retainer" the slotted screw directly behind the brake lever?

Afternoon  Alba

 

The lever is removed by removing the lever pivot screw.

 

The piston is removed by removing the little set screw that holds the piston in, do NOT mess with the slotted  screw (little pushrod) in the lever. 

[Alba]

Morning,

 

I'm struggling to find instructions/ video on how to remove the front brake master cylinder, does anyone have a link?

 

Thanks

[dirtrider]

2 hours ago, Alba said:

Morning,

 

I'm struggling to find instructions/ video on how to remove the front brake master cylinder, does anyone have a link?

 

Thanks

Morning  Alba

 

Check you messages on this site as I sent you some info.  

[Alba]

I have manage to remove 'dust cover' underneath the master cylinder housing and when I turn the pivot bolt a few turns the brake lever operates as expected i.e. does not need the forward push.  When I re-tighten the pivot bolt the forward push of the brake lever is required.

 

Should my next step's be;

- drain the master cylinder of brake fluid

- remove the pivot bolt (I am wary of damaging the piston as it appears the lever and piston is in one assembly)

- pull the brake lever out (i.e. in the  horizontal direction) 

- clean the pivot bolt

- clean the brake lever and master cylinder mating surface's

- reinstall and fill master cylinder with brake fluid

 

Thanks for any further guidance

[dirtrider]

16 minutes ago, Alba said:

I have manage to remove 'dust cover' underneath the master cylinder housing and when I turn the pivot bolt a few turns the brake lever operates as expected i.e. does not need the forward push.  When I re-tighten the pivot bolt the forward push of the brake lever is required.

 

Should my next step's be;

- drain the master cylinder of brake fluid

- remove the pivot bolt (I am wary of damaging the piston as it appears the lever and piston is in one assembly)

- pull the brake lever out (i.e. in the  horizontal direction) 

- clean the pivot bolt

- clean the brake lever and master cylinder mating surface's

- reinstall and fill master cylinder with brake fluid

 

Thanks for any further guidance

Morning  Alba

 

You might start by removing the lever pivot bolt then pulling the lever (with push rod) out of the master cylinder assembly.

 

Then clean the lever, pivot bolt, & inside the lever operating area of the master cylinder assembly, then  reinstall the lever & pivot bolt with a very light lubrication on the pivot bolt.

 

See if it still sticks. (it shouldn't if all is good with the parts & piston isn't sticking in the cylinder bore)

[Alba]

Thanks dirtrider for giving me the confidence to fully remove the pivot bolt, unfortunately I was not able to remove the throttle twist grip thus allowing the lever and push rod to be removed.  However on a positive note the movement after removing the pivot bolt allowed what ever was restricting the lever to be dislodged as when I reassembled the lever was working as expected.

 

Success, thanks again.  

[Alba]

The front brake has started not fully releasing again, so I have decided to replace the front brake hoses with SS, after watching a Chris Harris video. I'm not replacing the pipe between the callipers so hopefully I will be able to unscrew the unit which has not been touched in 19 years.  If this does not work the only remaining part of the front system which has not been replaced/ refurbished is the reservoir.  Does anyone have any guidance or YT links to help me?  

 

Thanks in advance .... 

[Alba]

Is replacing the front brake lines likely to work or am I wasting my time and cash with the root cause being the reservoir?

[dirtrider]

6 minutes ago, Alba said:

Is replacing the front brake lines likely to work or am I wasting my time and cash with the root cause being the reservoir?

Afternoon  Alba

 

It could be a one way restriction in the front hose but that probability is pretty low.

 

The usual cause is something sticking on the brake lever or in the master cylinder OR the master cylinder internal piston not fully returning. 

[Alba]

That's what I am thinking i.e. more likely the master cylinder. When I unscrew the pivot bolt quite a bit the level returns as expected, to me this suggests the internal piston is ok, but I don't understand, when I tighten the pivot bolt the brake level does not want to fully open.

[dirtrider]

16 minutes ago, Alba said:

That's what I am thinking i.e. more likely the master cylinder. When I unscrew the pivot bolt quite a bit the level returns as expected, to me this suggests the internal piston is ok, but I don't understand, when I tighten the pivot bolt the brake level does not want to fully open.

Evening Alba

 

Does the lever have the bushing still in place? Does the lever have the correct pivot bolt? (it's special)

[Alba]

 

Does the lever have the bushing still in place? --- Yes

 

Does the lever have the correct pivot bolt? (it's special)  --- I believe so, it's an opaque hard plastic bush?

[dirtrider]

20 minutes ago, Alba said:

 

Does the lever have the bushing still in place? --- Yes

 

Does the lever have the correct pivot bolt? (it's special)  --- I believe so, it's an opaque hard plastic bush?

Evening Alba

 

If you have the correct parts then you will have to try and figure out why it is sticking when you tighten the bolt. 

 

This is kind of a hands-on deal to figure out.  

[Alba]

Update: All resolved, the lever is perfectly returning to the stop position

 

For those who have never done this wee job remove the cover from directly underneath and at the side of the master cylinder (screw location ID'd). 

 

 

Unscrew the pivot bolt and gently pull out the lever.  As you can see my unit was extremely dirty, so I thoroughly cleaned, lube'd the pin and gently sanded the aluminium area. I also used a cotton bud to gently clean the housing the pin goes into.  Result a very smooth returning brake lever.

 

[Gary E Reynolds]

Tap on it with a non-destructive hammer.