rear brake bleed problem

[sroby]

need some input on bleeding  my rear caliper.  Just finished up installing my new rear caliper modified by Mr Jim snyder.  While I am pumping up the pedal to bleed,The pedal will bleed down usually before I have a chance to undo the caliper bleed screw. I can  pump it up real fast about 10 t0 20 times and hold it down and feel it bleed off.  Is this bleeding off in the master cylinder that i can feel with my hand while holding presure on the pedal?  Does that mean I am going to have to rebuild the master?  Any suggestions. Thx in advance STeve

[T Cro ®]

Bleeding the rear caliper has always been tricky and if your trying to refill an empty or dry caliper it will be even more difficult. A MitiVac will help. I've also heard of success with reverse flush where fluid is forced through the caliper to the master cylinder.

[Motor Head]

 Even with Air in the system, you should be able to pump it quickly and get a Non Traveling Pedal. As you have Air Pressure as well as fluid. Are you sure you don't have an external leak? If there is no external leak, then like most bleeding problems, its probably the Master.
 You could have some junk that was in the cylinder, and when it was pushed full stroke, it has collected up under the seal lip. Normally you would only get a small amount of travel on your Master Cylinder, it when bleeding it gets a full stroke.

[Boomer343]

There is the possibility that in going beyond the usual stroke length of the master cylinder piston that roughness or debris ripped the piston cup seal. Considering the

master components are set up for short strokes at intervals pumping away full stroke like a mad man won't be doing anything any good but your right arm.......

Time to clean and do a rebuild on the master......more work for that right arm.......

So after the rebuild, short, slow strokes ....anything else and you're just pumping air into the fluid.

As always your experience may vary.....

[sroby]

Good deal folks, I am off work the next 2 days and I will dig into it and keep you posted. My sincere thx Steve

[markk53]

need some input on bleeding  my rear caliper.  Just finished up installing my new rear caliper modified by Mr Jim snyder.  While I am pumping up the pedal to bleed,The pedal will bleed down usually before I have a chance to undo the caliper bleed screw. I can  pump it up real fast about 10 t0 20 times and hold it down and feel it bleed off.  Is this bleeding off in the master cylinder that i can feel with my hand while holding presure on the pedal?  Does that mean I am going to have to rebuild the master?  Any suggestions. Thx in advance STeve

My solution...  , Harbor Freight vacuum brake bleeder



http://www.harborfreight.com/brake-bleeder-and-vacuum-pump-kit-92474.html

The best $30 I ever spent.  Double disc originally took a bit of work due to learning process and needing someone to make sure the reservoir didn't drain dry.  I was drawing the vacuum too high and sucking air in at the fitting showing bubbles all the time.  I went lower vacuum and wife kept the master cylinder full -  all went great.  I did my rear brake, which is probably very similar to the Concours, by myself, using low vacuum and an eye on the master cylinder, shutting off early and refilling.  Less than 15 minute bleed for virtually  perfect brake feel, like new. 
Either find a store near you (maybe use the 20% coupon in a bike magazine if needed) or order one.  You won't regret it, consider it mental thearapy when it takes out all the mental stress out of brake bleeding.  Recoup some of your costs - charge your buddies beer and pizza to help them with their brakes.

Oh, and I also learned EBC pads were far superior to the pads I had in the caliper - low buck ebay.  Cost twice as much, but I will pay twice as much per set when I do the front end.  They are great.

[Motor Head]

 The Vacuum/ suction process is great for fluid exchange. Just remember that the design of the cup seals in your brake system is to hold pressure in, not vacuum. So always finish with a pressure bleed, as Air can be sucked into the system past seals that were meant to hold Pressure. Especially around the Master rear cup seal, or on a Car the Wheel cylinders.

[sroby]

Thx folks, I picked one up yesterday will give the try tomorrow. keep ya posted, Thx againSteve

[WiConnie]

Also take a look at a set of Speed Bleeders....well worth the cost in my opinion. I have them on all brake calipers and clutch. Easy Peasy.

[T Cro ®]

Also take a look at a set of Speed Bleeders....well worth the cost in my opinion. I have them on all brake calipers and clutch. Easy Peasy.

No what's "Easy Peasy" is Speed Bleeders, a Miti-Vac and DOT 5 Brake Fluid..... Between the SB & the MV flushing the fluid is so dam easy it's near silly not to do it yearly.

[WiConnie]

No, no, no, no, no...what's REALLY easy peasy is Speed Bleeders, a Miti-Vac and DOT 5 Brake Fluid, a cold 6 pack of Miller Genuine Draft, and a Packers game on TV!
You'll want to bleed your brakes every weekend!

[T Cro ®]

No, no, no, no, no...what's REALLY easy peasy is Speed Bleeders, a Miti-Vac and DOT 5 Brake Fluid, a cold 6 pack of Miller Genuine Draft, and a Packers game on TV!
You'll want to bleed your brakes every weekend!

No TV in my garage just yet only got music..... But I do got a 25 CF refrigerator with all sorts of refreshments and enough heat to keep Santa stripped down to his skivvies to keep from breaking a sweat while working on the bike when it's snowing and blowing!

[markk53]

The Vacuum/ suction process is great for fluid exchange. Just remember that the design of the cup seals in your brake system is to hold pressure in, not vacuum. So always finish with a pressure bleed, as Air can be sucked into the system past seals that were meant to hold Pressure. Especially around the Master rear cup seal, or on a Car the Wheel cylinders.

Never thought of that!  Thanks for your comment.  That is probably why I ran into issues with bubbles in the fluid when I was using too much vacuum on the front brake set.    I may just redo them this summer.  When I did minimal suction on the rear brake I ended up with an extremely solid pedal when done. 

I've kind of wondered if I could reverse the process, filling the vac set up and clamping a hose to the bleed screw then pressure feeding fluid through the system to the reservoir or doing a modified cap and reversing that flow.  I've not looked at the vac set up though to see if the gun could presurize as opposed to vacuumize (a real word?) the chamber.  I know a back feed is better than a draw.

I would have done the six pack of beer method, but it was too early in the day and I did a test ride.  Next time I'll do it in the evening and save the test ride for the morning.  I did have a stogie though.  I hope that partially compensates for lack of beer. 

[sroby]

Harbour frt version of the mighty vac, worked out perfectly. Brake caliper bled allis well with the earth again. Much thx. Regards Steve

[markk53]

Worth every penny, wasn't it?  Even if you never used it again, it was worth it.  I know it was for me... and then I used it again.  SWEEEEET!


A fan of the Flying Pig Farmer, huh? 

[goatmar]

Easiest way is to have someone else do it.    But what fun is there in that. 

[sroby]

Yes sir theres always that!