more on bleeding brakes

[north49]

.....after 8 attempts at bleeding my front brakes, I'm now a believer in the saying " if you do the same thing over and over but expect different results then you're insane".
On this site we have the Stator Papers and a brilliant discussion of carburetor over hauls ! ! How about a brake guru sharing his knowledge on how to bleed brakes effectively and efficiently the first time . There has to be a better methodical approach than just pumping bottles of fluid through hoping to get the air out.
Ya....I've bled lotsa brakes in my dubious career but haven't encountered anything like the Suzuki front hydraulics that seem to have some mystery space that hides air........so hoping to hear from someone that knows how to do it right the first time.

cheers all

 

[Steve]

How far apart did you have the system?

Did you start by bleeding the banjo bolt at the master cylinder?

What method are you using? "just pumping bottles of fluid through hoping to get the air out" isn't much of a description.

If you have a Mity-Vac, the procedure is rather simple.
1) Open the master cylinder and suck all the fluid out, then clean any debris from the reservoir.
2) Fill the master cylinder with fresh fluid.
3) Attach the suction hose of the Mity-Vac to one of the bleed nipples on the caliper.
4) Apply a bit of suction, open the nipple. Watch the air bubbles in the tubing, keep squeezing for vacuum as necessary.
5) Keep an eye on the level in the master cylinder. A second person is a big help here.
6) When the bubbles stop, tighten the nipple, repeat on the other side.

If you don't have a Mity-Vac, it's still not very hard.
1) Open the master cylinder, use a suction bulb (you can use an infant model found in the pharmacy or a turkey baster) and suck all the fluid out, then clean any debris from the reservoir.
2) Fill the master cylinder with fresh fluid.
3) Rig a small catch can (I use baby food jars) and a drain hose from the caliper bleed nipple. Put enough brake fluid in the catch can to cover the end of the hose.
4) It helps to have a helper, but the sequence is: open the bleeder, squeeze the lever. Close the bleeder, release the lever. Repeat as necessary. This will move fluid (and bubbles) through the hose quicker than repeated squeezing, then opening the bleeder to have everything squirt out under pressure. Some have said that you don't need to close the bleeder every time, as long as the end of the drain hose remains covered with fluid.
5) Keep an eye on the level in the master cylinder. A second person is a big help here.
6) When the bubbles stop, tighten the nipple, repeat on the other side.

 

[TooManyToys]

Step backwards slowly away .......

Step backwards slowly away .......

.. is ringing in my head.

I qualify as a brake expert, but more towards auto then bikes. And I've lived with my '82 1100e Suzy brakes for 25 years so I'll give it a try.

I've rebuilt my calipers every few years and I'm about to do it again along with the masters, but I've never had an issue.

When I rebuild calipers, before I install them I prefill the caliper body with brake fluid, tapping lightly on the sides to dislodge any air that may be trapped. I then use new copper washers (but you can anneal them with heat if you don't have new) to ensure a good seal at the banjo bolts.

Once attached to the hoses, I'll take off the master cylinder cap, then re-tap both the calipers and work my way up the hose to try to dislodge any air again. Without any pull/push on the levers/pedal, the compensating port of the master is open to the reservoir and any air bubbles should flow up through that.

Then I commence with normal bleeding procedures, opening up the bleeder screw when the M/C pistons are pushed in, and closing the screw before releasing, as I'm sure your doing. I also tap on the caliper body during bleeding as air can always get trapped between the caliper pistons and body.

Contrary to the Suzuki manual, I bleed the calipers before I do the anti-dive as I'm concerned about introducing air up into the crossover hose between the caliper and anti-dive if any remains in the caliper.

I will also tell you that I've had the braided lines on the bike since '83 and those did reduce the amount of displacement. I have relatively little movement in the brake lever before engagement.

It might help to explain what you have been doing and if the calipers or master was just reworked.

 

[Suzuki mad]

I have great fun with my GS(X)1100e's front brakes with the anti dive unit attached. They can be real bu**ers to get firm.

The GS1000's a doddle, except the rear's when the bled nipple plays up with crud down the inside.

Just don't go there with the Bandit rear caliper. You've got to take the whole unit off the bike to get it to bled.

Onced you can get fluid out of the master cylinder and flowing then its normally easy to sort. One thing that is missed is changing the washers on the pipes when they are unbolted.

What bike are you talking about?

Suzuki mad

 

[Guest]

I've had the same problem but it was bubbles in the master cylinder near the banjo bolt. I take off the brake lever and with the cap off the M/C i push the brake piston in with the old one or a phillips screwdriver and Wallah! Tiny bubbles rise to the surface and a firm lever. The brake lever does not push the piston all the way in so some air can hide behind it.

 

[t3rmin]

I'm an idiot. I've been "bleeding" with several pumps of the lever without closing the valve in between and without the hose submerged. Duh -- no wonder I have a sloppy lever. I'm just expelling air and sucking it right back in. Of course I was closing the valve with the lever depressed, but that's only after I've created a frothy bubbly bunch of fluid in the calipers I'm sure.

 

[salty_monk]

Yep.... I do both, submerge the end of the hose & close the valve on each pump.

Don't re-use the brake fluid you pumped through to top up the master cylinder. Use new stuff from the bottle every time.

Dan

 

[north49]

for those that asked......I've done a complete rebuild on the M/C and calipers. I've done all the things suggested in the many posts re: bleeding. Never knew about air in the banjo bolts , so I loosened all them off as well and let the oil seep out.
The only thing I haven't tried is tapping the calipers and hoses to try and dislodge air bubbles. I'll try that tomorrow

cheers

 

[salty_monk]

You can also try a cable tie around the lever & grip to keep it in the on position & then leave it for a couple of days...

The pressure helps the bubbles rise to the top.

This has worked for me several times with difficult cars (there I used a 2 x 2 cut to length & wedged against the seat frame).

What bars do you have on the bike... with my new euro bars using original hoses it strikes me that I have a loop behind the headlight I'd have to straighten out to help with bleeding if I was to do it now......

Dan

 

[north49]

hey Salty Monk.......yep I even tried the ol' cord around the lever/bar trick over night. Didn't seem to help. The bars are stock Suzuki for North America.

cheers

 

[TooManyToys]

I really would not loosen and tighten the banjo bolts to bleed. The copper washers work hardened as they are crushed. They seal best on the first clamp down.

 

[DimitriT]

The bleeding process should start while the piston is compressed into the caliper. Use a small C-clamp to do this and watch that you don't overflow your master.

Compress the master with a rubber band or your helper's hand.

Then, while holding the caliper, gently tap it with the butt of a screwdriver while slowly rotating it with the nipple pointing up. What you are trying to do is collect all the bubbles up near the nipple so you can expel them.

Attach you hose to the nipple and crack it open. Hopefully one or two bubbles will come out.

Close the nipple and clean up.

Remove the C-clamp and reinstall the caliper.

Once the system is re-pressurised you should have rock hard brakes.

 

[smagnusen]

I just went through this on my gs550. This bike had been sitting and had no pressure in the front brake. Pumping the lever did not build pressure and it would not bleed. Here's what fixed it.

1. Removed caliper
2. Removed cap from master cylinder.
3. Held caliper and tapped it with a rubber hammer, keeping the hose at the highest point so that any air would rise toward it.
4. Compressed the caliper with a c-clamp and watched A LOT of air come up through the MC. (Be careful not to tighten to hard with a c-clamp as it can damage the caliper, or so I've read in my manual)
5. Soaked up all the old fluid in the MC with a rag, cleaned out the gunk, replaced the fluid, and then continued to pump about a half a bottle of brake fluid through the system until it ran absolutely clean and air-free.

 

[bwringer]

A Mityvac is the only way to accomplish this quickly and with a minimum of bad words.

 

[pvtschultz]

A Mityvac is the only way to accomplish this quickly and with a minimum of bad words.

Agreed. It took me almost two hours to bleed my brakes on a GS850G. 20 min for the back, the rest on the front.

 

[TooManyToys]

We've never had great luck in using a vacuum bleeder here in the shop. And the pressurized tanks can become too messy. So we've been using the standard method of pushing the actuator and closing the bleeder with every stroke for years. Unless we have the ABS actuator hardware to do the system bleeds on a particular application.

I really don't see the benefit of compressing the calipers with a c-clamp. Thousands of vehicles have their brake hydraulics serviced every week in this country leaving the caliper pistons in the normal operating position without issue. There is nothing in a motorcycle caliper body that is any different then an automotive caliper.

 

[DimitriT]

I really don't see the benefit of compressing the calipers with a c-clamp. Thousands of vehicles have their brake hydraulics serviced every week in this country leaving the caliper pistons in the normal operating position without issue. There is nothing in a motorcycle caliper body that is any different then an automotive caliper.

Probably correct but I know it works for me. Probably more important to shift the caliper around and get the bubbles moving. When I bleed brakes to replace the fluid I always compress the caliper as I want to replace the fluid in the cylinder too. So this is just part of the process for me.

 

[txironhead]

I helped rebuild the hydraulic clutch on a Nighthawk once and found a neat trick that works for me. I don't have a Mityvac, been meaning to get one but bike parts have been keeping me financially humbled....what I do have is a very large syringe (think elephant tranquilizer) that I picked up at a medical supply store for the purpose of measuring fork oil. No matter how many times we pumped and bled the clutch, it wouldn't pressurize, so I got the bright idea to open the bleed screw and force fluid upwards from the bleed screw with the syringe. Sure enough, bubbles started coming out of the master and soon we had a nice, firm clutch. Did the same trick on the front brakes and he swears he could never get the brakes that firm.

Basically, I attached some clear tubing to the nipple of the syringe and secured it with a clamp. I also clamped the tubing at the bleed screw. You might have to take the plunger out and add more fluid as you go, just make sure to never force air into the lines or you're defeating the purpose. Actually, air bubbles also came out at the bleed screw as I was forcing more fluid in. This is just the way I do it, it works really well for me and I spent less than $5 on the syringe and tubing.

 

[jpaul]

I have a Mity-Vac and still had a hard time gettting the last couple of bubbles out of the MC/banjo-bolt area. What I ended up doing was putting one of the nozzles from the Mity-Vac on and sticking it down into the hole at the bottom of the reservoir, applying a little vacuum, and juggling the brake lever a bit. Worked like a charm.