Brake Bleeding Question.

[stoc445]

Up front, I followed the bleeding articles posted on this site and utilized a hand pump Mity-Vac. Problem is I'm having flow issues during the bleed. 4 of the 7 ports have great flow with no problems filling the clear hose with fluid. 3 of the ports will only produce dribbles. I've barely cracked the port to half turns. I've ran a dozen reservoirs of fluid through each with no improvement. I've done this across two sessions with several hours in between. Specifically, the ports in question are both right front caliper and the middle on left front caliper.

Is this normal? Anyone else experience this sort of thing?

Peddle-lever wise, rear peddle is strong, front, not so much. Long travel before decent resistance, bit spongy.

 

[forgitaboutut]

try doing it manually?...have someone hold the brake tight, and open the bleeder....close and releast lever SLOWLEY...about 10 times....

 

[dduelin]

No, I have not experienced these problems so it would not be normal for me.

Did you wrap the bleeders with teflon tape prior to starting the bleed procedure?

Bleed RF outer bleeder, then LF bleeder, then test front lever for firmness at this point? At this point the front lever is no longer used in the procedure, as you know, and the lever should be hard before going on to the rear reservoir circuits.

Did you remove and the hang the LF caliper at the 15 degree above horizontal line after bleeding both front outer bleeders?

Do you use the brake pedal to aid the vacuum pump when bleeding the center bleeders on the front calipers as wheel as the proportioning valve and rear caliper? This greatly aids flow from the rear reservoir.

 

[stoc445]

try doing it manually?...have someone hold the brake tight, and open the bleeder....close and releast lever SLOWLEY...about 10 times....

Rich,
I had this thought as well. I'll try it tonight.

Thanks

 

[stoc445]

Dave,
Yes, this is the process I followed.

 

[RCS]

Make sure you have a good vacuum tight seal on the nipple AND on the reservior attached to the pump.

Make sure that the hose is on the nipple securely so that you get a vacuum seal. I have the Mity pump with a pressure gauge on it so I can confirm a good seal before I open the bleed screw. Sometimes I don't get a good seal because the hose is bent a certain way or the opening of the hose is stretched too much so I cut off a half inch of hose and try it again. Once I get a good seal I need only pump the Mity vacuum to build up a vacuum. Then I wait for the fluid to flow. I may need to pump again a few times after a minute or two. If you have to consistently keep pumping the Mity vacuum there is a good chance that you don't have a good seal either at the nipple or the reservior attached to the pump.

I've found that patience and time are the two best traits needed to perform the ST1300 brake bleed correctly. I go through 3.5 bottles of fluid for the brakes and a full bottle for the clutch. Takes me about 4-5 hours to do the brake and clutch bleeds correctly per the Service Manual with the Mity hand pump.

 

[st1300r]

How many psi do you get on the mityvac gage when you start the bleed?

 

[RCS]

How many psi do you get on the mityvac gage when you start the bleed?

I don't pay attention to the psi, but rather the fact that I have created a stable vacuum. The needle goes about 3/4 of the gauge and stays at 3/4 for a few minutes during the bleeding process without having to add additional pumps to the unit.

 

[dduelin]

I pump 20-25 lbs of vacuum on my Mityvac to start.

After doing it so many times I now use only about 2.5 or 3 small 12 oz. bottles for clutch and brakes. There is no need to pump more than 1.5 or 2 full reservoirs through even the longest circuits from the rear master cylinder. Keeping an eye on the graduated collection container alerts how much has drained out of the reservoir to keep from pulling air.

 

[RCS]

After doing it so many times I now use only about 2.5 or 3 small 12 oz. bottles for clutch and brakes.

Do you follow the Service Manual instructions and drain all the lines before filling them with new fluid?

 

[Scooter]

3 of the ports will only produce dribbles

What do you mean by dribbles? Low fluid flow or bubbles in the line or ??? You should not need to run 12 reservoirs worth of fluid to bleed the front brake lines.

I have noticed that the relative hardness feel of the brake lever is affected by which number you have the lever adjustment set to.

 

[dduelin]

Do you follow the Service Manual instructions and drain all the lines before filling them with new fluid?

No. That would make no difference in the volume of new fluid from topped off reservoir to bleeder valve anyway. Depending on the circuit less than 2 reservoirs runs new fluid throughout each circuit. After removing the master cylinder cover I syringe out the old fluid out of the reservoir and then top off with new Dot 4. By pulling new fluid down the lines it flushes out the old and replaces with new. Done without excess it's barely more than 24 oz for everything.

How do you drain the lines per SM? Pull the old down the lines until the reservoir is empty?

 

[stoc445]

Hey guys,
The dribbles I mentioned was just that. The fluid flow would just dribble out, like half the tube was being utilized. I have 3 different kind of vacuum pumps but did the old school thing tonight and managed get the last little bit of air out. I'm thinking since I had so much air in the lines, the slow process did a better job of purging the last bit of air bubbles. Both are very firm now. Love it!

Thanks all!

 

[RCS]

How do you drain the lines per SM? Pull the old down the lines until the reservoir is empty?

Yes, exactly. Getting all of the old fluid out of the system first is very important for two reasons: 1. improves braking power, and 2. helps prevent damaging of the seals in the system over time.

I try to drain the reserviors prior to draining the lines because the old fluid has absorbed air over time, air rises, and I don't want to drag more old fluild than I need to through the lines while draining them. Not draining the lines first, per the Service Manual, risks not getting all of the old fluid out of the system. Old fluid has air in it and air will diminish braking power when heated and also increase the possibility of damaging the seals in the braking system over time - think secondary master cylinder and the rubber brake lines.

The reason that the service interval on the brake system is based on mileage AND time is because brake fluid absorbs air over time while in the brake system. This happens naturally over a period of time. You may think the system is sealed, but air does enter the system and is absorbed into the brake fluid.

Google brake fluid and service intervals for more info, if needed.

 

[dduelin]

You don't get any more old fluid out by draining it than by pushing it out with new. If you use the collection container with the MityYac it is very apparent when new fluid is coming out of the bleeders due to the color change. It takes 1.5 to 2 reservoirs of new to displace the old fluid completely with new fluid.

What do you do with the air that comes in when draining the lines? Maybe that is why you have to use so much extra fluid if you are pulling lots of air all the way down from the reservoir.

We are actually doing the same thing BTW - replacing all of the old fluid we can with new to obtain the benefits it brings - hard lever & pedal, no pedal drop when releasing the hand brake while still pushing the brake pedal, restoring the best braking power the system has to offer, keeping seals supple, etc.. Note I said that I use a syringe to remove the old fluid then refill with new. Then the act of pushing this new fluid down and out replaces the small amount of old fluid in the lines, proportioning valve, SMC, and calipers. There is no need to repeat this 10 times per circuit unless you just want to do it.

 

[st1300r]

ftfy "moisture" from the air. also there's sometimes crud in the bottom of the reservoir, good idea to wipe it out.

 

[RCS]

We are actually doing the same thing BTW

Not true. Someone once told me that you'll never be wrong if you follow the Service Manual. Of course, not the typos in the Service Manual.

Using the syringe to drain the cylinders is great, but skipping the draining procedure risks not getting all of the old fluid out especially in this linked braking system.

Let me put it another way. The old fluid has air in it. Think very teenie tiny air bubbles. New fluid has much less air in it. When one tries to push new fluid into old fluid the more dense fluid - new fluid - mixes with the less dense fluid - old fluid. The process is called Osmosis. As a result, one gets fluid with air in it. Now, the mixed fluid may look clean to the naked eye.

Further, old fluid may get trapped in some of the pockets of this very long linked braking system like the secondary master cylinder. If this happens, there may be a higher concentration of air in the fluid in this cylinder. Not good.

 

[bkra13]

Way overkill. Unless you're taking the calipers off, removing the pistons and sponging up ALL the fluid that's in there, you're going to end up with exactly as much old fluid in the lines as someone that flushes with new fluid. Not to mention that by using fluid to flush, you remove the issue of adding air to the system and having a devil of a time getting it all back out. Where exactly did you hear that air in the system damages lines/seals? If that were the case, then about 99.9% of all cars on the road (and probably 90% of all motorcycles) would be leaking brake fluid from all orifices. Just doesn't happen.

 

[Igofar]

Throw the mityvac away and use a simple motion pro bleeder check valve. Vac's draw too harshly and create micro bubbles and foam.
Use the motion pro tool ($15) and 2 small bottles of brake fluid for the brakes and 1 bottle for clutch. Follow service manual routine.
After bleeding, take nylon tie and clamp down brake lever over night to let any air missed out.
Check out some of my brake bleeding threads. I can do the entire brake system in the ST or the GL1800 in about 30 minutes and end up
with a firm lever and no air.
Good luck.

 

[RCS]

I can appreciate others points of view on the ST1300 brake bleeding topic.

In my opinion, you either follow the Service Manual procedure or take your chances....