Grrrrrrrrr! Arse! etc etc.

[Captain Bean]

Its me again.

Looking for a bit of advice.

Fitted a gorgeous set of ACE/clubman bars at the weekend, so controls and brake fluid reservoir sits at a bike of an angle when bike is upright.....

Is it likely then that this new position of reservoir has led to some starvation (or related misery) of brake fluid that has led to my brake binding on?

Struggled the 300 yards home and slacked off the bleed valve on caliper which released pads enough to push bike around.

Then found it impossible to bleed brakes-pushed pistons back in easy enough but lever offers absolutely no resistance to squeezing and would not push fluid to caliper.

Suspect the brake lever assembly is nadgered but it seems weirdly coincidental to its new orientation on bars.

Any thoughts? Should I by an ebay cheap and cheerful replacement with a remote reservoir? Should I swear and menace "helpful suggestion" neighbour with a big spanner again?

I am relying on my good chums out there in Forumshire.

Thanks.

Rich.

 

[coyote13]

Sounds like you may have been a tad low on the brake fluid in the first place. Set your front end so that the reservoir is sitting vertical, top off your fluid, then re-bleed. May not be the "kosher" way to do it, but it ought to work.

 

[Captain Bean]

Cheers Coyote.

Will give it a go tomorrow.

Thank you.

Keep smiling.

Rich.

 

[Tim]

The MC orientation aside, what did you do with the brake line routing when you fit the lower, narrower clubman bars (assuming you started with stock). Brake lines need to be routed in a nice, smooth fashion or you'll run into trouble. You may want to invest in shorter, braided steel lines at some point soon (chances are your lines are 40 years old anyhow).

Lots and lots of people have done the same, and have had success. So running clubmans does not necessarily mean you need a different MC with angled or remote reservoir. So long as its kept topped up.

When you're bleeding your brakes, make sure you turn your bars to the left and put the bike on the side-stand. This will get the MC more or less level (play with it).

Keep in mind the angles motorcycles get to while on the road - the MC is designed to work at some extreme positions. So the angle of a clubman bar shouldn't pose any major hurdles.

 

[devilishdesigner]

As others have said, First check that the brake line is smoothly routed and the master cylinder is well topped up. Once those 2 things are right give it a bleed, but personal experience is that once air is in the system on an Ace it is a prick to get out. I usually remove the caliper and raise it up above the reservoir to make sure that the bleed nipple is the highest point, otherwise I have found an air bubble can get caught in the brake line and never quite make it down to the bleeder or up to the reservoir.

 

[jpmobius]

As others have already said, orientation of the master cylinder is almost certainly not an issue. Its orientation is definitely not the problem with the extra pressure activating your brakes. Likely the lower mounting position has made a more tortured routing for the line, and the extra curls have either reduced the line volume or made a kink, which will cause either less volume containing the same fluid, adding pressure, or reducing the tiny back flow resulting in extra pressure. You may know the only mechanism for retracting the brake pads after you brake is the actual piston seals relaxing to their undistorted shape, which means there is only the tiniest force keeping the brake from being partially activated when the brake is not applied. So it takes very little to go awry to partially activate some brake. Old lines also very commonly go bad and collapse inside, turning into sort of a one way valve, so it may be as simple as that (and they can absolutely look good as new on the outside, so if you think there is any chance of this, replace the line - no matter how good you think it is). The rubber diaphragm under the mc cap (properly installed and in good condition) will enable the master to work perfectly even if nearly upside down, but serious angles can make them aggravating to bleed. The problem is that the highest point can easily be the banjo fitting (or whatever you may have) that bolts the line the mc. There is enough volume there that the air bubble just goes back and forth when you pump the lever, so you never get another "bite" of fluid. Wrap a rag tightly around it, and crack the bolt while pumping the lever. That blows out enough trapped air to get the pumping action of the mc going 99% of the time almost instantly. Once you get past that, bleeding is usually easy because as long as the mc can pump, you can drive all the air out through the bleed at the caliper(s). I have this situation all the time (like everyone else), and usually I don't spill a drop of fluid except at the caliper. I have never had to use a vacuum pump (though it does work like others have described) nor any kind of special tool or contraption to perfectly purge any hydraulic system. The key is to get the mc to have no air involved in it. Same with cars, and everything else. Inside the system, the diameters are usually small enough that bubbles of air don't "bubble" up the line. They just travel down the line with the fluid, otherwise brake bleeding would be nearly impossible regardless of technique. New lines are strongly advised. Plan carefully. There must be no strain on them at any time, from full compression to maximum extension of the suspension. Good luck!

 

[Captain Bean]

Crikey!

Thank you all so much for your very informative replies-I will have a determined effort after work.

Cheers for taking the time to pass on your thoughts.

Regards.

Rich.

 

[giantclam]

It sounds to me, the brake fluid isn't able to travel back through the master cylinder to the reservoir as it heats up (this only takes a few applications of the brakes). The most likely culprit of this is the piston in the m/c is not returning all the way after the brakes are applied. Take the lever off and check it.
This happened to me when I fitted chinese pazzo copy levers to the GSXR radial master cylinder on my SV650.
If you find bleeding loathsome, try reverse bleeding. get a big syringe and slowly push fluid up from the caliper, up the line, through the m/c and into the res. I use this method first always now and you get a solid lever straight up. I got a vacuum pump but found the syringe worked better. if the m/c piston isn't sitting right the fluid will not pass, you will know your problem lies here.
Good luck.

 

[Tad]

Also another thing to check is that your front brake lever isn't been fouled on something like the flasher as the lever has to return all the way and have a couple of mm's play in it to let the piston completely back or the brake is still held on and as the disc gets hot the brake system expands meaning that the only thing it does is push the pads further on.
PS, sorry for the lack of comers and full stops.
Tad. X

 

[Captain Bean]

Hey there.

All good advice heeded and hoiked off caliper and lever set up, clamped lever to old bars held in vice, converted old Mr Muscle squirty bottle to syringe using bit of tube off that discarded emission/crankcase abomination. Squirted fluid back through bleed valve and bazinga! We have brakes-well sort of, by that I mean that they as good as they ever were....

Can recommend the bars that 00racing supply, the little blue box sweetens things a bit and will fit new sprocket and jet at the weekend.

Cheers for your sage advice, everyone.

Rich.