Bleading brakes on BMW R1100

[chunkolini]

Good grief, sorted out the back wheel woes, in the end I drilled the heads off the bolts and left the stems as studs to centre the disc. Sorted. See previous post.

Next.
Help.
Tomorrow I am meant to be taking my boy off on a jolly (and a day of school) to the seaside with a bunch of mates.
Front brake was binding a bit, so I bled it which made no difference.
Then I pumped the pistons out a bit to get any grotty deposits off them that might be stopping them returning into the caliper. (pads are badly worn, but no time to replace them today). Of course two of the pistons popped clean out, but went back in no problem.

Since then I have spent hours trying to blead the brake with no joy. I have bled the ABS thingy under the seat, still no joy.
At present there is almost no pressure to be felt at the lever even pulled back to the bars. Let the lever off and the wheel can be turned by hand, pull the lever and it cant. So obviously something is happening but not much. I have ridenit up and down the drive, some braking but not enough to go out on the road.

No signs of serious fluid leakage.

I have strapped the lever to the bar to see if that will help as I have heard that this can sometimes improve things.
Edit, 1/2 hour later. Odd this, pull the lever to the bar, there is a feeling of pressure for a few seconds and then it goes away and I can turn the disc by hand, let the lever out to refill the piston and the same happens again.

Anybody else got any ideas?

Chunko'.

 

[gordon stephenson]

Hi Chunko,
Had loads of trouble bleeding land cruiser brakes after replacing some pipes,
Problem turned out to be a bleed nipple we were missing which was on the rear axle load proportioning valve, once we bled that it took only minutes to get a good pedal again.

Hope this might help Gordon.

P.S. Sorry just realised you are talking about a motor bike, so I'v proberbly been no help at all.

 

[wobblemonster]

You should have bought a Honda
Had this problem a few times, the way I overcame it was a bit long winded but it worked,
Get an oil can ( the type that you pump with your thumb)
Clean it out and fill with new brake fluid
Use a piece of pipe ( windscreen washer pipe is the right size) and push one end on the oil can spout and the other end on the bleed nipple
Undo the bleed nipple a couple of turns
Pump the oil can
What you are doing is "back bleeding" your pushing the air into the master cylinder rather than pushing the air into the caliper.
When there are no bubbles coming into the master cylinder nip up the bleed nipple and you have brakes
The big down side of this is fluid will come out of the master cylinder, so lots of rags required.
Good luck
Rick

 

[shenion]

Bikes are difficult as the brake lines are vertical usally with a manifold or ABS unit in the middle (for left/right front.) Bubbles will just sit there. As you bleed they will move down the line a bit but by the time you pump them back up they have moved back up the line. Or when you pump up, they will move down the opposite line you are bleeding.

The only way is to use a vacuum bleeder. You can pull a large volume of fluid continuously and get out all the air.

 

[kev234]

Have you tried using g-clamps to push the pistons all the way back. Leave them on (pistons pushed right in) then bleed again. This sometimes helps push trapped air from behind the pistons.
Kev

 

[gavuk]

From cars ,sometimes by moving the master cylinder to a posistion where it has never run,pedal to the floor,or lever to the handle bar,u can damage the master seals due to slight corrosion of the bore .I try to do 1/2 pumps now or use a pressure bleeder,vacuum is the way to go i think.I also prefer to use a bleed pipe which is plugged at the end and has a small vertical slit cut in it,this i place in a jam jar with enough fluid to more than cover the slit,this way i can see bubbles and only fluid can re-enter the nipple.Hope you get it sorted ,for the youngsters sake...Gav

 

[peterd51]

Hi,

I had a similar problem with the clutch on my Mondeo. The trick there is to use the front brake to back-bleed the clutch similar to Wobblemonsters suggestion...

but could you connect the the front and rear brakes together, assuming that they have separate levers to operate them? So you'd push fluid from the reservoir and down to the front or rear brake, across a temporary transfer pipe to the other brake and back up to the reservoir. No spills as you're not adding any fluid, if it's possible to do it that way.

Regards
Peter

 

[hotrodder]

Another trick which sometimes helps is to tap calipers/cylinders/lines with a small spanner or similar to dislodge trapped air. Good job for the boy while you're (trying to) bleeding the system

 

[ngt]

We use pressure bleeder. 1 - 1.5bar

 

[Porschemaniac]

Bike brakes can be a nightmare (I speak from experience).

Air tends to 'hide' at the highest point in the system - which is very often the union between the master cylinder and the pipework.

It is possible to bleed from this union - although, this does take some care. Basically, squeeze the lever, whilst (carefully) cracking off the banjo bolt on the mater cylinder a fraction. Make sure that you have plenty of rag wrapped around the banjo bolt, at this point - otherwise you'll end up with brake fluid (A.K.A. paint stripper) all over your paintwork.

A couple of good squeezes on the lever usually does it - and don't forget to tighten the bolt again between squeezes (just like the bleed nipple when bleeding the brakes conventionally).

Sounds a little extreme, but it can work.

Hope you get it sorted.

 

[MrFluffy]

I have strapped the lever to the bar to see if that will help as I have heard that this can sometimes improve things.

That trick really works best if you leave it overnight Im afraid. The idea is all the active pressured ports in the brake systems are open because the brake is lightly applied by the strap, so over time the air bubbles all return to the highest (sealed) point, which is the master cylinder piston. When you release it in the morning, the returning fluid is actually the air thats risen during the night.
Its very effective even against the most naughty of brakes (used goodrich hoses, refitted are the worst), but you do have to leave it overnight...

If all else fails tonight, last thing, pop the strap back on and give it another go

 

[michael1703]

Bleed the brakes from their fittings if you cant dislodge the air

Pull the front lever half in, crack open a fitting whilst applying gradual pressure and nip the fitting up before you let the lever out again

Bleed nipples are'nt always cited where the air wants to sit

Sports bike with clip ons are a pain as the m/cyl is angled down and the banjo bolt is the highest point, so its better to bleed from there first

starting at m/cyl work towards the nipple with flow of fluid

some brakes are linked, some have bridge unions bolted to the bottom yoke etc

Have to say that i havent worked on a beemer for years so can only remember they are heavy brembo's and most fittings are double flare as opposed to banjo

 

[gordon stephenson]

Had a Vauxhall years ago that the only way to bleed the system was to clamp all piston right down in the cylinders, when the pisons were in normal operating position they trapped a pocket of air ABOVE the bleed nipples.

 

[pedrobedro]

Have you bled it with the ignition on to activate the ABS ? I think you need the ignition on and pull the lever to pump the ABS system up to pressure then open the bleed nipple.

 

[^neo^]

Another thing that works (with cars, but brakes is brakes) is to bleed them with the caliper off the bike (chock it with a piece of wood so the piston doesn't pop out) and the bleed nipple vertical. As said above, can get an air pocket above the nipple

 

[bawjaws]

You should have bought a Honda

whit!, he shouldve bought a vespa

 

[Robotstar5]

I,ve found dropping the caliper off (still connected) so the system has a slope in it - stops the air getting trapped in any high points.

Or how about one of these?

 

[chunkolini]

Hi guys
cheers for all of that (except bawjaws comment about a S*****r we all know that they belong in the canal).
I borowed a big syringe from a mate. bled them from the bottom and just as I was about to give up the brakes came back to life.
So Chunko and junior did go to the ball. Ha Ha!!
I tested them out before heading off by almost running over an old coffin dodger who jumped in front of me.

Chunko'.