Author Topic: Braking issues - bleeding and grip  (Read 386 times)

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Offline Wantabeach

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Braking issues - bleeding and grip
« on: September 16, 2018, 08:10:44 pm »
My son and i haven working on his 1992 Concours and doing some deferred maintenance. The calipers were leaking brake fluid and the disc was black with it. We just did a caliper rebuild and now pressure feels soft but even after it firms up the grip seems even weaker than before. Here are a few additional facts and questions I’m hoping you seasoned riders can help us with.

I took took the brake lines off the calipers and pumped the fluid out with the handle injecting air in the system. In retrospect this was probably not a good idea. I was planning to flush all the fluid out with my pump bleeder tool so I thought it would not matter.

The seals were in pretty bad shape and left stuff in the groves which we cleaned but not perfectly.

There was some piston pitting oddly enough on the side that was NOT leaking.  Cleaned it up with fine steel wool but some pits remained.

Everything else came together pretty well. We pulled a lot of fluid through both calipers with my brake pump kit and then manually bleed them old school also.

We pumped the hand brake and a few bubbles came out of the reservoir also.

I reread the manual regarding bleeding and have a few questions:

Should i be bleeding with the reservoir top off?

The manual says to bleed the calipers first and then the anti-dive and then using the bleeding valves on the junction blocks. Where are the anti-dive and junction bleeding valves?  What are those anyway?

Since i probably sucked some air into the master do people also bleed it through the banjo bolt?

I wiped the pads the pads a bit and cleaned the disc with brake parts cleaner and steel wool.

We really appreciate your advice.

Paul and Eric.



Offline WillyP

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Re: Braking issues - bleeding and grip
« Reply #1 on: September 16, 2018, 08:53:40 pm »
There's no bleeders other than on the calipers, what manual are you reading? There is a junction block, you could bleed using the banjo's on the junction block, Ive done that but it's very messy and I found it not helpful.

Once you introduce air in the master, you might find it helpful to crack the bleeder on the master to bleed the master, but it's better to do that off the bike.

I tried several different methods to get a firm lever but the only method that worked for me was tying the lever to the grip overnight.

As far as bleeding with the cover off, you must monitor the level of fluid in the master so you don't introduce air and have to start over. It can get messy with the cover off, so I usually lay the cover on top but that doesn't work well. I think I'll try a spring clamp next time.
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Re: Braking issues - bleeding and grip
« Reply #2 on: September 16, 2018, 09:01:45 pm »
A connie doesn't have an anti dive, and the junction block does not have bleed valves.
So, for now, only use the bleed valves on the calipers.
Cap must be off of the reservoir, and "NEVER" "EVER" let the fluid level drop to the point that your sucking air.
   If you do suck air at the reservoir, you have to start all over again.

Your system is just full of air and a C-10 brake system can be a real pain to get all the air out.
The main reason for this is, the system is so small that you can't push it out quickly enough.
I think the air that is trapped in the lines/calipers, floats up as you try to push it down.

One thing that helps is; compress the lever and leave it overnight.
  (Use a tie wrap or tape to hold it compressed).
This seems to help the trapped air migrate out.

Do you have a vacuum pump?
If so, pulling the fluid thru is your best option.

Bottom line: I think your doing it correctly. It just takes a lot of effort to get all the air out.

I'm not a guru on this. Others will add info and suggestions to what I've said.

Ride safe, Ted

PS: If you got brake fluid on any painted surface. Clean it off immediately!
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Re: Braking issues - bleeding and grip
« Reply #3 on: September 17, 2018, 02:06:21 am »
the anti-dive he is speaking about what never a Concours (ZG/GTR) feature, this was a system found on the 900 Ninja Model (I have a set of those specific forks, and they do physically fit the early Conni, I purchased them many years ago as a possible "upgrade", but never did install...), but that does not apply to the Concours.

during the rebuild process, it's imperative to get a clean, smooth, finish on the pistons... this can be achieved by using a wooden dowel and a wooden plug, wrapped in tape, and jambed into the hollow end of the brake caliper's piston, and when the dowel is chucked into a drill press collet, and locked with minimal clearance on the bottom between the piston and a piece of wood, and spun at slow to moderate speed,  the piston can be cleaned, and 'Honed" externally to provide a 'crosshatched' fine honed finish, similar to honing a piston cylinder before replacing rings, 600 grit wet/dry pper is sufficient to provide a nice surface, free of pits, and longitudinal "scratches"... when finished, clean everything using solvent, then denatured alcohol, before assembly.

as for the fluid reservoir, the screws can be removed, and rubber diaphragm lifted out to fill, then set both back into place, and cover with a rag, to allow the repeated fillings of the master, while preventing the spurts during the bleeding process from shooting all over. also' this limits any contamination from moisture to a minimum, during the process.

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Offline Wantabeach

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Re: Braking issues - bleeding and grip
« Reply #4 on: September 17, 2018, 01:15:56 pm »
There's no bleeders other than on the calipers, what manual are you reading? There is a junction block, you could bleed using the banjo's on the junction block, Ive done that but it's very messy and I found it not helpful.

Once you introduce air in the master, you might find it helpful to crack the bleeder on the master to bleed the master, but it's better to do that off the bike.

I tried several different methods to get a firm lever but the only method that worked for me was tying the lever to the grip overnight.

As far as bleeding with the cover off, you must monitor the level of fluid in the master so you don't introduce air and have to start over. It can get messy with the cover off, so I usually lay the cover on top but that doesn't work well. I think I'll try a spring clamp next time.

I’m using a period correct Kawasaki service manual for a 1000 GTR that we purchased online although our bike is an American ZG 1000 but I don’t think that matters.

How do you bleed the master when its off the handlebars?

Offline Wantabeach

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Re: Braking issues - bleeding and grip
« Reply #5 on: September 17, 2018, 01:23:21 pm »
A connie doesn't have an anti dive, and the junction block does not have bleed valves.
So, for now, only use the bleed valves on the calipers.
Cap must be off of the reservoir, and "NEVER" "EVER" let the fluid level drop to the point that your sucking air.
   If you do suck air at the reservoir, you have to start all over again.

Your system is just full of air and a C-10 brake system can be a real pain to get all the air out.
The main reason for this is, the system is so small that you can't push it out quickly enough.
I think the air that is trapped in the lines/calipers, floats up as you try to push it down.

One thing that helps is; compress the lever and leave it overnight.
  (Use a tie wrap or tape to hold it compressed).
This seems to help the trapped air migrate out.

Do you have a vacuum pump?
If so, pulling the fluid thru is your best option.

Bottom line: I think your doing it correctly. It just takes a lot of effort to get all the air out.

I'm not a guru on this. Others will add info and suggestions to what I've said.

Ride safe, Ted

PS: If you got brake fluid on any painted surface. Clean it off immediately!

I will try the compress the lever over night trick and get back to you as that was suggested twice now. I do have a pump and did pull a lot of fluid through it initially but the hose does not fit that well over the bleeder screw so i can tell when air is gone as air gets sucked around the screw.

Thanks everyone.

Offline Brooke_Benfield_OR

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Re: Braking issues - bleeding and grip
« Reply #6 on: September 17, 2018, 08:39:09 pm »
I've been able to get air out of the front brake system by turning the forks full left and tapping on the master cylinder banjo bolt with a screw driver handle. After a few taps, squeeze the front brake lever very S-L-O-W-L-Y and watch for the bubbles (of course the cover is off the MC). You could also tap on the other banjo bolts. If the bike was on its side stand that could also help get the air moving up while tapping.
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Offline WillyP

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Re: Braking issues - bleeding and grip
« Reply #7 on: September 18, 2018, 02:42:55 pm »
How do you bleed the master when its off the handlebars?

Same way you do on the bike, but do it off the bike so if when you spill brake fluid it's not all over the bike. Make sure the inside of the master is spotless clean first.
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Online connie_rider

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Re: Braking issues - bleeding and grip
« Reply #8 on: September 19, 2018, 01:13:54 pm »
I haven't tried Brooke's suggestion, but it sounds like a good idea.
Certainly worth trying.

Ride safe, Ted
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Offline Victor Salisbury

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Re: Braking issues - bleeding and grip
« Reply #9 on: September 19, 2018, 01:56:37 pm »
When I changed out my calipers, I did the same thing as Brooke mentions, even after doing the mity-vac and 'manual' bleed. I was surprised at how many bubbles I burped out that way. Did this procedure a couple days in a row, with compressing the brake handle over night, the 2nd time had quite a few bubbles, the 3rd day, was back to ops normal.

HTH

I've been able to get air out of the front brake system by turning the forks full left and tapping on the master cylinder banjo bolt with a screw driver handle. After a few taps, squeeze the front brake lever very S-L-O-W-L-Y and watch for the bubbles (of course the cover is off the MC). You could also tap on the other banjo bolts. If the bike was on its side stand that could also help get the air moving up while tapping.
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Offline Wantabeach

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Re: Braking issues - bleeding and grip
« Reply #10 on: September 20, 2018, 04:26:03 pm »
I've been able to get air out of the front brake system by turning the forks full left and tapping on the master cylinder banjo bolt with a screw driver handle. After a few taps, squeeze the front brake lever very S-L-O-W-L-Y and watch for the bubbles (of course the cover is off the MC). You could also tap on the other banjo bolts. If the bike was on its side stand that could also help get the air moving up while tapping.

I tried compressing the brake lever but did not help much.  I will try this method and report back. 

Additionally, since the disc was black with burnt brake fluid and I did not thoroughly clean the metal pads with something like Acetone, I think I may need to do that.  Anybody ever "sand" the pads down?  Although I probably have 4mm of pad left, the wear pattern was uneven.

Thanks everyone!
Paul

Offline Brooke_Benfield_OR

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Re: Braking issues - bleeding and grip
« Reply #11 on: September 20, 2018, 10:34:09 pm »
Yeah...i tried sanding the pads one time. It was a while back and I don't remember if I actually ran with them or not.

If the pads got soaked with brake fluid I would consider them toast and go buy a new set. I know it bites the budget but you'll probably not ever have optimum braking performance with the old pads and your safety is at stake. With new pads you will be pushing the caliper pistons farther back in their bores so you might dislodge some of that air you've been trying to exorcise from your system.
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Offline Wantabeach

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Re: Braking issues - bleeding and grip
« Reply #12 on: Yesterday at 04:27:58 am »
When I changed out my calipers, I did the same thing as Brooke mentions, even after doing the mity-vac and 'manual' bleed. I was surprised at how many bubbles I burped out that way. Did this procedure a couple days in a row, with compressing the brake handle over night, the 2nd time had quite a few bubbles, the 3rd day, was back to ops normal.

HTH

I've been able to get air out of the front brake system by turning the forks full left and tapping on the master cylinder banjo bolt with a screw driver handle. After a few taps, squeeze the front brake lever very S-L-O-W-L-Y and watch for the bubbles (of course the cover is off the MC). You could also tap on the other banjo bolts. If the bike was on its side stand that could also help get the air moving up while tapping.

Wow. I could not be more frustrated. I done what has been suggested except bleeding banjo bolts. I have pump at least a few pints of dot 4 through the front brakes alternating sides and they are still very spongy. I must have reLly suck a lot of air through. May need to take it to a shop if i can’t fix it in a few days.

Anybody have trouble with old bleeder screws or crush washers letting air back in?  I have not replaced these items.

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Re: Braking issues - bleeding and grip
« Reply #13 on: Yesterday at 09:50:04 am »
When I rebuilt the calipers on my 1983 GL650 Silverwing, I got frustrated with the standard bleed method that you've been using.  Just couldn't get anywhere that way.  I changed to the reverse bleed method and got it done pretty quickly.  If you're concerned about leakage at the bleed screw, you can put a small amount of teflon thread sealing tape on the threads of the bleed screw, and that should reduce any leakage there.  Try this method and I think you'll be back soon reporting success.
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Offline WillyP

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Re: Braking issues - bleeding and grip
« Reply #14 on: Yesterday at 02:48:53 pm »
Whatever method you use it is going to take a lot of patience and perseverance... don't get frustrated, and don't give up.
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Offline Wantabeach

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Re: Braking issues - bleeding and grip
« Reply #15 on: Yesterday at 03:26:59 pm »
When I rebuilt the calipers on my 1983 GL650 Silverwing, I got frustrated with the standard bleed method that you've been using.  Just couldn't get anywhere that way.  I changed to the reverse bleed method and got it done pretty quickly.  If you're concerned about leakage at the bleed screw, you can put a small amount of teflon thread sealing tape on the threads of the bleed screw, and that should reduce any leakage there.  Try this method and I think you'll be back soon reporting success.

Well..I can't imagine why vacuuming 3 pints of dot 4 through the bleed screws would not get it but at this point I'll trying it and report back.  Has anyone on the forum had success with this method?  Just curious because I have not read this yet and have read quite a bit so far. 

Thanks everyone
Paul
« Last Edit: Yesterday at 03:33:14 pm by Wantabeach »

Offline Wantabeach

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Re: Braking issues - bleeding and grip
« Reply #16 on: Yesterday at 03:34:50 pm »
Whatever method you use it is going to take a lot of patience and perseverance... don't get frustrated, and don't give up.

Thanks....I really don't want to have gone through all this and then take it to a shop for what is suppose to be the easiest part in theory.  I appreciate the encouragement. 

Paul

Offline MikeH_OH

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Re: Braking issues - bleeding and grip
« Reply #17 on: Yesterday at 03:58:41 pm »
Stick with it. I bled and bled and bled. Air in the master cylinder was killing me. I help the brake lever open for multiple nights before I got the air out.
As for the brakes not feeling as tight; you had a bad caliper to start. Are you wanting to feel a sticky piston creating additional braking force? My lever pressure was much lower. Once on the road I realized i had plenty of brake pressure.
You'll get there. It just takes more time than anyone wants to put in!

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Re: Braking issues - bleeding and grip
« Reply #18 on: Yesterday at 04:22:30 pm »
After reading through this I am thinking that a backwards bleeder would make this job a lot easier.  There are a few backward bleeds out there  Phoenix comes to mind. These bleeders push up from the calipers to the master taking advantage of the air naturally wanting to migrate up.
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Offline MikeH_OH

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Re: Braking issues - bleeding and grip
« Reply #19 on: Today at 11:09:25 am »
The backwards bleeding Grant refereed to will work. just make sure you seal off all points of potential leak; bleeder screws and bleeder hose connections. push the fluid into the calipers from the master cylinder, left caliper to the clutch slave cylinder. Fluid will exit the clutch master cylinder. Or some reverse that and pressurize the clutch to brake system.

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Re: Braking issues - bleeding and grip
« Reply #20 on: Today at 11:57:27 am »
After reading through this I am thinking that a backwards bleeder would make this job a lot easier.  There are a few backward bleeds out there  Phoenix comes to mind. These bleeders push up from the calipers to the master taking advantage of the air naturally wanting to migrate up.
Just go to tractor supply and buy the biggest syringe you can find. Use the tubing of your choice. Don't need a fancy bleeder system.

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Re: Braking issues - bleeding and grip
« Reply #21 on: Today at 01:58:43 pm »
Being of simple mind, I have a thought.
Any air he has, must be in the hoses? (he's not getting any air out, and the air should have migrated up)

So, couldn't he just fully push all the pistons into the caliper's to reverse the fluid?

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Offline MikeH_OH

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Re: Braking issues - bleeding and grip
« Reply #22 on: Today at 03:22:53 pm »
the air will move up the hose to the point the piston can push it. If it is too low it won't make it back through the master cylinder. I will just be in a different location in the hose.

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Re: Braking issues - bleeding and grip
« Reply #23 on: Today at 06:47:51 pm »
This was just something to try while he buys syringes/other.. may be  waste of time, but only takes a few minutes.

My initial thought was the same as yours. But then I recalled pushing the pistons in to remove a caliper on 1 side.
The fluid from 1 side, overflowed a normally serviced reservoir.
My guess is; in most cases, the air is in the hoses, not the calipers,,,  so you only need to push the fluid out of the hoses.
Pushing all 4 pistons in is probably a lot more fluid than the volume of the hoses?

Ride safe, Ted
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Re: Braking issues - bleeding and grip
« Reply #24 on: Today at 07:15:35 pm »
Might help, but then, might drag dirt into the seal area and cause a leak.

And you might still have tiny air bubbles trapped in the banjo fittings.
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