Brake Bleeding Nightmare

I've just overhauled my rear brake caliper. Soda blasting, new pistons, new seals, new banjo joint washers. Also overhauled the rear master cylinder. Clean up, new piston and seals kit and new banjo joint washers. Now I'm trying to bleed them.

Bought a vacuum pump system which seems to doing the job of sucking the fluid through. Did the front caliper first then the rear. The system has been drained of all fluid so I'm starting with empty lines.

The front one kind of went OK, I think, but the rear one just keeps pouring air bubbles out. The brake lever is offering 'no resistance' at all. I've used half a litre of fluid so far and I would have expected at least some resistance from the lever by now. The only result so far is that the caliper pistons have moved from the fully home position to resting against the pads, but no pressure from the lever.

Does anyone have any experience of this or have any tips or tricks. I don't want to waste any more fluid until I'm sure I'm doing it right.

Did you bleed both the upper and the lower valve on the front brake caliper before starting on the rear brake?

After a similar struggle with a Hornet900 I found 'back bleeding' with a large syringe worked for me. If you do try it use a turkey baster to remove fluid from the brake reservoir otherwise it could spill over and of course dont re-use the fluid.
JB

Loosebearing wrote:

I've just overhauled my rear brake caliper. Soda blasting, new pistons, new seals, new banjo joint washers. Also overhauled the rear master cylinder. Clean up, new piston and seals kit and new banjo joint washers. Now I'm trying to bleed them.

Bought a vacuum pump system which seems to doing the job of sucking the fluid through. Did the front caliper first then the rear. The system has been drained of all fluid so I'm starting with empty lines.

The front one kind of went OK, I think, but the rear one just keeps pouring air bubbles out. The brake lever is offering 'no resistance' at all. I've used half a litre of fluid so far and I would have expected at least some resistance from the lever by now. The only result so far is that the caliper pistons have moved from the fully home position to resting against the pads, but no pressure from the lever.

Does anyone have any experience of this or have any tips or tricks. I don't want to waste any more fluid until I'm sure I'm doing it right.

Since air is a lighter fluid than other liquids it tends to remain on the surface, It does not like to flow down. Rig up a support for your IV appearing device so that your resevoir is higher than your master cylinders. Your clear tube line should fit the caliper bleeders securely. Fill your IV reservoir with sufficient fluid so that air is never allowed to enter your down tube. Remove the tops of your master cylinders so that you can see the levels.

Open the bleed screw you have attached the down line to, I find starting at the rear works best. Allow fluid to flow from your IV reservoir backward into your rear reservoir, Slowly working the brake lever as the fluid back flows removing the air from the system.

Do not allow the level in the master cylinder to overflow, Remove the excess fluid as you progress.

Repeat this procedure on all bleed screws front and rear until you are sure that all air has been removed and you have hard levers.

Brake fluid is available in quart containers or larger, Use DOT 4 or 5 Do not use cheap 3 or bargain fluid.

Thanks guys,

Meldrew, I didn't bleed the upper nipple as I thought that the front brake is a completley separate line. Is this right?

Jolly Bodger, I think 'black bleeding' will be my next attempt but I'm concerned about air being sucked through the threads of the bleed screw 'into' the system ??

These are things I've picked up from surfing the subject. Of course not much of it is generic. It's a minefield out there

I've never gone wrong with going to auto parts store, they sell a little bottle with a magnet attached with hoses that attach to your bleeder nipple. Just keep adding fluid to the upper reservoirs until the little bottle is full.

Wow, that sounds like a magic trick !

I'll start googling the web right away

BTW, lloyd193,

I didn't quite get your procedure but I'm trying to use a vacuum. Is your method gravity fed or pressurized by a compressed air supply?

I didn't have any problem with air leaking past the bleed nipple but you could always put a little smear of copper grease on the threads before you start.
JB

Loosebearing wrote:

BTW, lloyd193,

I didn't quite get your procedure but I'm trying to use a vacuum. Is your method gravity fed or pressurized by a compressed air supply?

Gravity feed like an IV in a hospital, From the bottom up so that all air in the system is forced up into the master cylinders and out of the Calipers, lines and proportioning valves.

Happy motoring lloyd 193.

Just a little clarification on fluid types.....Honda spec is DOT 4 (DOT 3 is obsolete)
DOT 5 is Silicon based, and is NOT compatible with DOT 4 systems or fluid.

HOWEVER, there is a new DOT 5.1 fluid that is compatible.
It also has a higher boiling point than either DOT 4 or 5!

The gravity feed system is interesting, I'll give it some thought.

I'm gonna have a another attempt today with my vacuum system. I'll put some copper grease on the nipple threads too, just in case.

I'm sticking with DOT4 fluid. Seems to be the obvious choice.

Thanks all, I'll update later

What ive found is tying the brake lever to the handlebar overnight helps get stubborn air out of the lines and restores a lever pressure.Sounds like black magic but its worked on at least 5 different scooter and bike brake overhauls

Well folks, I give in.

The bike is going to a garage to have the brakes bled. I figured that if they can't get any joy then I have a problem.

It's going in on Thursday so let's see. I'll keep you posted. I don't know about you but I'm curious !

Well, the garage has done it. It was straight forward in the end, I guess I was a bit impatient. There's a little too much lever travel for my liking but I'll try the overnight lever tie to see if it improves things and then rig up the IV system for the future. Next job: the front brake. Will it be a dream or another nightmare?

FWIW, The rear brake lever has more travel (feels a bit spongier) than the front brake. The reason being that the left lever also must travel far enough to activate the start switch circuit.

After all you've been through to sort the rear brake the front brake should be easy peasy.

Loosebearing wrote:

Well, the garage has done it. It was straight forward in the end, I guess I was a bit impatient. There's a little too much lever travel for my liking but I'll try the overnight lever tie to see if it improves things and then rig up the IV system for the future. Next job: the front brake. Will it be a dream or another nightmare?

Now that you have hopefully gotten all the air out of your rear brake. If you gravity feed thru Both front bleeder valves, One at the time. All the air will be forced up into your front master cylinder and out of the system.

Be sure that you use sufficient fluid so that you have removed all the old fluid, Do not allow that master cylinder to overflow.

Happy motoring lloyd193.

I arrived back in town to late on this one. Hopefully you have your problem solved. After buying the same brake bleeder you purchased and having the same problem I tied the levers down with good success and suggested it here.You are right the bleeder screw threads allow air to be drawn in on some vehicles. One more suggestion,after doing a lot of disk brake work on the older Vetts I would suggest never to open up the complete system all at the same time. It can be very time consuming to bleed the complete system. Howard

Thanks all,

Thanks for your comments and wise words. The rear brake is biting better now so less pressure on the lever but if I had to pull up at high speed?......mmmmm?

Meanwhile, it's time to get some miles clocked up before winter......then, the front brake.......

With all this talk of bleeding brakes I decided it was time for mine too.
Complete flush and fill.

I bought a vacuum bleeder from harbor freight, $21 and a coupon got it to 17 bucks!

That, and a $4 bottle of DOT4 and I was ready...

I started with the L/H side, I suctioned off the old fluid from the reservoir and filled to the top.
Next, connected suction line to the lower bleed valve and pumped the vac pump, opened the bleeder.
I continued adding fluid and pumping the vac pump till I got completely clear fluid in the collector. Then moved to the rear caliper and repeated.
With both bleeders tight I repeatedly pumped the rear brake lever for a couple of minutes.  
I repeated the process to remove any remaining air.
The front brake was the same procedure, but only one valve.

When I test rode it, both brakes were flawless!

Total time was about a half hour, but without the vacuum bleeder it would have taken half the night!

I have a feeling that refilling the system without draining it may present less problems.

As I had removed the rear caliper the system had to be dry (well, as dry as possible!). I expected lots of air to come out while bleeding but after 500ml of fluid and half an hour with no result I suspected something was wrong. I never did figure out what.

I am going to re-bleed the system now that it's full. I'm going to try the old one-way tube and depressing the brake lever to about half travel only. Let's see what happens....

First I loosened the sliding bolt as this can be awkward with the caliper off the bike.



Then I disconnected the fluid journal.....



And rested it in a jar



Then I took the bracket to swing arm bolts out



Then the pad retaining pin



Here is the slide bolt.



The pads had seen better days



Pistons not looking good either.

These are the only pictures I took but I hope it gives an insight for other DIYers

To stop air leaking into the system and before you try to bleed the brakes remove the bleed nipples and wrap PTFE tape around the treads of the bleed nipples , this will stop air leaking when you try either the pump or vacuum method. When I bled my brakes the front bled easily but the back was time consuming, wrapping PTFE tape around the threads certainly helped but still took quite a bit of time and used quite a lot of brake fluid to completely remove all the air from the rear caliper. By the way I used a vacuum bleeder coupled to the compressor to bleed all brakes on the Silverwing and my Sym 400i with success but it failed miserably bleeding the front brake on my 81 Virago and had to resort to operating the front lever slack the tighten the nipple until all the air was removed. Pud

Interesting insight vmaximus.

I wonder if I should take a degree in Hydraulics and get to the bottom of this thing. It's strange how different bikes have different behaviour, even when the bits we're dealing with are essentially all the same.

I haven't tried to bleed the rear brake since the shop got it working, I'm almost scared but curious.

Can someone tell me which bleed nipple I need to loosen on my front brake calliper for bleeding my front brake ? There is two and I'm not sure which one to bleed from.
Thanks in advance
Neale

I think I read somewhere here on the forum that the upper bleed nipple is for the front brake lever and the lower one is connected to the back brake lever.

If you're bleeding just your front brake then it's the upper one.

And yeah...where is Tandrgee?

Thank you very much Loosebearing your advise is much appreciated.
By the Way Tandragee is in N Ireland .

I am prompted to return to this nightmare by an unusual event which happened today.

Whilst trying to make a low speed 180 degree turn from a standing start, I leaned over a bit too far and nearly dropped the bike. Naturally, my instinct was to grip both handlebars to hold the bike from simply dropping to the floor. Once I had righted the bike I noticed my left hand had hold of the brake lever which was tight against the hand grip.

From the posts above you'll see that I have never been happy with the amount of travel on the left lever but surely it shouldn't come in that far?

I've bled this system from time to time using the pumping method but have had no air coming out.

Does tying the levers back overnight really work?

Let it set overnight then grab a good handful of both break levers, neither should go to the grips, if they do then there is air trapped somewhere providing both reservoirs are full.

Loosebearing wrote:

Does tying the levers back overnight really work?

Worked for me when I had problems bleeding the rear calipers on my 2004 Swing. I think that I used a bungy cord to hold the lever as close to the handle grips over night. Seems like the bubble came up through a hole in the brake reservoir.
Also remember that the left lever also controls the center piston on the front caliper.

Loosebearing wrote:

 Once I had righted the bike I noticed my left hand had hold of the brake lever which was tight against the hand grip.

From the posts above you'll see that I have never been happy with the amount of travel on the left lever but surely it shouldn't come in that far?

I suspect you have very little if any problem with your lever movement bud, go out & pull the lever until you hear the second microswitch click, now look at the minimal amount of airgap between the lever & the grip, now imagine how much extra pressure you applied to the lever when 'righting' the bike.

When was it last MoT'd ?  the brake function will have been tested on the rolling road at that point.

Just did my brakes on a 2012 wing with 15800 miles, rotors in spec, had a little trouble with the bleed procedure from manual but phils a winger advice worked great, put zip ties on brake handles and let them set for 6 hours, like new again.MAGIC!

Thanks Guys, I'm gonna give it a go. The brakes 'are working', in fact there is more resistance in the rear lever when used in conjunction with the right lever. I've tested them at speed and the tyres will lock up. It was MOT'd OK last September.

My SW needs a clean before I do anything else. Riding in the rain for two days running has left it's mark. Yuk!

The theory on holding the brake lever in over night is that it pressurises the system, and by definition warms the fluid up as well. So any air bubbles are also compressed. Then when you let the lever go the next day the few compressed air bubbles which by them should have risen to the highest point, just under the master cylinder if you are really lucky, will expand and "pop" intot eh brake reservoir.

I've done this for years, and a few people poo poo the theory, but it's always worked for me.

I'm sorry to keep bangin' on about this brake issue but it's weird!

When my SW in stationary, engine on or off, the rear brake lever has very little resistance and a lot of travel, as mentioned above. But, when in motion the rear brake lever has much more resistance and the brake is much more efficient. When used along with the front brake it has even more resistance and the combined braking is comfortably reassuring.

I can understand combined braking being better because of the front/rear combination valve acting on both brakes, but it doesn't explain why the rear lever alone should be more efficient when actually 'on the move'.

My SW seems to be a bit of an enigma. It is a 2001 model without ABS but with just 30,000 miles. I suspect it had been left standing for some time before I bought it and I've had to do some pretty extensive work on it to get it up to a safe standard. This brake issue is niggling me. I've bled the brakes from time to time without any signs of air in the system. What's going on...?

Just asking are you bleeding in the correct order? if you are using a Might Vac go slow don't over draw, as always use fresh fluid from a newly opened bottle. One other are you sure your hoses are all in top shape and not ballooning when pressure is applied

You might want to take it in to a Honda motorcycle shop. Not worth worrying about it. How much is your life worth? At least you can take it back if brakes still seems bad.

I'm sure I'm bleeding in the right order. I must admit, the age of the hoses may be ballooning as the possible cause. I'd like to put braided hoses on but that's a big job.

Sending it to the Honda dealer makes me shudder when I think of labour costs so I think I'll consider that as another job for the winter. Why it should make any difference when on the move is still pretty odd though.

As has been mentioned before re this thread, you've zip-tied the brake levers overnight and achieved some success with that. You also reported success trying the "IV drip" method. What did / how did you rig up a drip feed bottle and how was it connected to the bleeder screws? Did you connect the drip feed to both front caliper bleeders at the same time? Did you connect all three bleeders at the same time?

I think you are 'over thinking' this bud, I can get my left lever within 3/16" of the handlebar, brakes work or they don't, but I see ............

Loosebearing wrote:

Sending it to the Honda dealer makes me shudder when I think of labour costs

All I can say to that is, is your life worth less than the dealers fee for an hour to confirm/deny the efficiency of your brakes ?

When I bled my breaks last fall I first bled the rear - I did NOT take the hose off the caliper. There is a bleeder valve covered by a piece of plastic I unscrewed, then loosened the bleeder valve. I simply stuck a piece of fish tank air hose on it (has a bulge but no threads - expand the end with a screw driver to get the hose on). The hose ran to the bottom of a bottle. As I pumped the handle the bottle filled preventing back flow or air getting in the line. I just filled the open reservoir as it got almost empty, making sure it did not go dry until I saw cleaner fluid coming out. Close the valve before disconnecting the hose.
Then you have to open one of the front caliper valve and repeat using the rear lever. If nothing is coming out you have the wrong valve - that is the one you use for the front break bleeding.
If you are getting air, use teflon tape anything you disconnected. If you took out the valve because you unscrewed it too far, use teflon tape but not too much, just a couple winds on the threads. When you close the valve be careful not to strip the threads but you have to close it firmly. Pump the breaks hard to make sure you don't have a leak. Remember to cover the valve with the little black rubber nipple. Think of it as a little black dress for the nipple... Running away now.

One thing to be careful with is keeping the bleeders just open enough for the fluid to flow. These things can leak air around the threads when the bleeders are a bit open so only crack them open when you have a bit of pressure on the brake handles. Also remember that the brakes are linked so you have to work on both brakes bleeders when bleeding the rear brake circuit. One thing some folks forget is that you have to keep the lever squeezed down and held until you close the bleeders. It's possible to suck air back into the caliper if you release the handle before snugging the bleeder.

Plumbers PTFE tape wrapped round the bleed nipple thread helps prevent air sneaking past threads during bleeding. The eesibleed people also sell a very thick loctite type sealer for the same purpose.

I confess, I haven't tried the IV bleed method but I'm sure I bled them in the conventional manner 'in the right order'.

I'll try the lever tie-back again. Maybe I am over thinking this whole thing. I'm pretty convinced that there is no air in the system and that hose ballooning could be the problem. As I said, the brakes are working but why they should be more powerful when riding than when stationary will remain a mystery

Loosebearing wrote:

As I said, the brakes are working but why they should be more powerful when riding than when stationary will remain a mystery

But are they actually more powerful when riding bud ? I'd lay you a pound to a penny, that if when riding you applied as much pressure to the lever as you do to activate the starting isolator switch when the machine is stationary, you would have a completely locked rear wheel.
If there was an actual problem with the brake, surely it would have become more apparent over the two years that this thread has been running

The lever reaches the isolator switch with hardly any resistance and the brakes definitely have more resistance when riding, (not so much with the front brake) but the difference while riding is noticeable.

When I bought the SW the rear brake was very good and this thread all started when I overhauled the rear caliper...my god, was it two years ago? I couldn't get any resistance from the rear lever at all after extensive bleeding as explained above. I took it to local garage, who also specialises in bikes, and he managed to get the rear lever to work but it was never very reassuring. I've lived with it all this time but it's still niggling me. I've tested the brakes with emergency stops from time to time and the tyres skid as if they are about to lock up but I can't help thinking that it's mostly dependant on the front brake.

I would feel better if the rear lever alone would haul the bike up before the lever runs out of travel. However, with Autumn approaching I will give it another look and maybe replace any weak hoses etc.

I hope I have a revelation during that time and find the cause...it's just weird, a bit like it's owner?

Have to assume that the rear caliper rebuild means the pistons slightly retract into the bore when the brakes are released over time, as they are supposed to? Which would give you the "lot of play" symptom when you come to start the bike. And which would also go some way to explaining why the brakes feel much better when the bike is in use, the pads expand with heat as well as the disc and that will bring the lever up as well.

Does the bike stop well when you are going for it? If it does, it kind of suggests there's not much wrong with the brakes. If the lever is coming back to the bar when using the bike, then yes there's a problem.

Interesting points Lost it. Glad to hear from you again. The brakes pull the bike up quite reassuringly when going for it, I've tested them at around 75 - 80mph and I hear tyre squeal as if they're about to lock up and the front end judders a bit (no ABS remember) like the front tyre is about to hop a little bit.

The rear lever stays well away from the bar so I guess the brakes are working. I will concede to the general consensus from all here and enjoy the ride. It's always reassuring to get more opinions from others 'in the know'.

Just wanted to put this problem to bed, I had a scare the other day whilst going downhill at speed and decided once and for all to see what happens if I grab the the rear lever with all my might.

The brake lever touched the hand grip and the bike was still moving quite freely
...YIKES!

Tied back the brake levers over two nights and then cut them loose and slowly let them settle into their natural open position...didn't touch the levers after that. Let the bike stand for a day without touching the levers. Tried the brakes tonight and the rear lever now has some real resistance behind it with much less travel for effective braking. Conclusion; tying the levers back worked. Both brakes are now the best they've ever been. Bad news... the front reservoir is manky inside but the fluid looks clear.

I've topped up the fluid but that's the next job for the winter along with inserting the little 'blowback' cover thing. A brake bleeding nightmare all over again? I need a lye down

A lot of folks believe the pistons in disc brakes retract from the pad similarly to the way shoe brakes operate. In disc systems they don't retract. The master cylinder (if in proper condition) doesn't "suck". Releasing the brake lever just takes the pressure off the fluid allowing the pad to relax but doesn't retract the pad from the disk. It couldn't even if the fluid was sucked back since the piston isn't attached to the disk.

In normal operation there's really very little fluid moving in the system. If you get too much lever movement it's either air in the system, old soft brake lines, or a warped brake disk. A warped or bent disk will push the brake pad back into the caliper which means the next time you press the lever more fluid will be needed at the caliper to push the pucks against the pad before the brake pad can begin to press the disk.

An easy way to check the disks for runout (wobble) is to hold something snugly the fork and just barely touch the disc surface. Then turn the wheel or better yet spin it, and if the pencil or whatever you use shows a varying gap between it's point and the disc surface you have some runout. There is a maximum value for that in the service manual if you have one for your bike.

The very best way to bleed brakes is with a pressure or vacuum bleeder. I've had a Mity Vac for years I use on all of our vehicles. You hook it to the bleeder nipple on the brake cylinder, take the lid off the brake reservoir to make sue you don't suck it dry, then suck the fluid out of the brake cylinder while adding new fluid sufficient to keep the reservoir full until you see new clean fluid come through at the nipple.

Linked brakes on some motorcycles can be a bear because the rear brake line comes from a low point on the bike up and over in an inverted U to get over the steering head and then down to the front caliper. A vacuum bleeder really shines with coupled or linked brakes. Harbor Freight or Amazon lists these tools. Here's a source for a mity vac:

https://www.amazon.com/MV8000-Automotive-Tune-up-Brake-Bleeding/dp/B00265M9SS?SubscriptionId=AKIAILSHYYTFIVPWUY6Q&tag=duckduckgo-ffab-20&linkCode=xm2&camp=2025&creative=165953&creativeASIN=B00265M9SS