Bleeding my brakes--weird problem

[Anonymous]

I am bleeding the brakes on my 1979 GS850G and it started off well. Fluid coming out and everything. Then the new, clear stuff started coming. All of a sudden, nothing's coming out. I'm squeezing the brake, closing the bleed screw, letting the brake out, opening the screw, squeezing and getting absolutely nothing.

Also, should there be a bleed screw on both sides of my front tire? Right now there's only one on the left side. We disconnected that cable to try and isolate the right side, and when we squeeze the brake lever the tire spins freely. So the right side of the front tire brake isn't working. Should it?

Do I have the same problem as DonN?

 

[snowbeard]

sorry to ask, but you were continuing to fill the res? otherwise I'm worthless to ya... :wink:

 

[Hoomgar]

You may have let it drain in the master cylinder reservoir and sucked air in. You have to get that burped through now if that is what happened. Loosen the banjo at the master cylinder and get it bled through there first. Be sure to put a good absorbent rag under it

After you get it there then try to resume sending it down to your brake caliper. Make sure you do not let the reservoir go empty!

You front caliper is a single piston unit so yes only one bleeder on it is right.

 

[Anonymous]

sorry to ask, but you were continuing to fill the res? otherwise I'm worthless to ya... :wink:

Yes, the reservoir was never empty

 

[Hoomgar]

Sometimes they get picky like this. Try opening up the bleeder and just pump slowly, not fast and see if you can get it flowing again. No need to close and open the bleeder right now. Simply pumping the fluid through will be good enough until you get it to start down again.

Again, you may need to start at the master cylinder first. I have had what your describing happen to me many times and doing what I am suggesting here has never failed to work for me.

Give it a try and let me know how you make out.

 

[Jethro]

In this case, I would do the following:

Pull the lines right off the calipers and position them over a bucket or basin. Put a strap or something around your brake lever, holding it at the compressed position, and fill the resevoir with fluid. Take a needle and gently poke into the smaller of the two holes in the bottom of the master cyl. Wait a while and see if the fluid is draining through. If it isn't, I'd say a master cyl rebuild is in order for sure.

If it drains right through, put the lines back on the calipers real loose. Have a friend keep filling the master cyl with fluid while you reattach the lines quickly. The try again to bleed the brakes like normal.

I'm squeezing the brake, closing the bleed screw, letting the brake out,

This kind of confused me a little, but maybe it's just a clairification thing. It's important that you don't let the lever bottom out before closing the bleeder valve. You should be pumping the lever 5 or 6 times (or 20) with the valve closed first, then squeezing the lever (hopefully you feel resistance), then opening the bleeder valve a tiny bit, and before the lever hits the bar you should close the valve. Course, you should have fluid coming out, so maybe we aren't at this stage just yet.[/quote]

 

[Anonymous]

We definitely weren't doing that. Every time we squeezed the brake we were opening the bleeder valve. However, we were getting fluid for a while. I'll remember that next time.

 

[Anonymous]

Your front caliper is a single piston unit so yes only one bleeder on it is right.

Question: does that mean only one bleeder on the whole front tire assembly or one bleeder per caliper? My friend who's helping me says there are two front calipers and each should have a bleeder.

 

[Hoomgar]

Your front caliper is a single piston unit so yes only one bleeder on it is right.

Question: does that mean only one bleeder on the whole front tire assembly or one bleeder per caliper? My friend who's helping me says there are two front calipers and each should have a bleeder.

He is right. You should have one bleeder nipple on each caliper. If one is broken off you should be able to see where it is by looking at the other one. I hope that isn't the case but it does happen when they are not maintained correctly. If so, soak it with a good penatrant spray for a while and use an easy out to remove it.

 

[Anonymous]

Well, I look at the caliper on the left of the tire and it has a bleeder screw on top. The caliper on the right just has a normal hex head screw. Does this mean I need to replace it with a bleeder screw?

 

[Hoomgar]

Well, I look at the caliper on the left of the tire and it has a bleeder screw on top. The caliper on the right just has a normal hex head screw. Does this mean I need to replace it with a bleeder screw?

Yes. Someone must have broken that off and put that in there to plug the hole. They are a common item and you can get one at the dealer or I would think an auto parts store? Although on the later I am not sure about the thread size? Anyone else know?

 

[Anonymous]

Question: What is the rubber diaphragm inside the brake fluid container there for? We filled it up thinking it was the reservoir and I think we ended up pumping a lot of air through the brakes. What is it for?

 

[Big T]

Brad,

It sounds like you have worked your way into a hole here, so it's time to stop digging.

So,

1. Unscrew the good brake bleeder and take it to a parts store and get another one (or two) just like it. Get a spray can of Brakecleen or similiar product.
2. Install one bleeder screw in each caliper and gently tighten
3. Remove the black expansion diaphragm from the master cylinder and place it with the master cylinder cap on a couple of paper towels to keep them safe and clean
4. Now look in the master cylinder reservoir. Is there brake fluid in there? :?

If yes, the fluid level should be between the lines (low/high). Add it until almost at the high mark and gently and slowly the brake lever, looking in the reservoir. There should be a small hole that either squirts some fluid or lets out some bubbles. If it squirts, keep gently pumping until the lever firms up. Then bleed fluid from the caliper bleeder screw as noted above.

If there are bubbles, continue to pump 20 or 30 times to see if they stop. Do it gently to keep brake fluid from squirting out onto your bike. If they stop, proceed to bleed both calipers

If the fluid level is below the low mark, then you need to hook up a hose to an open bleeder screw and put the other end of the hose in a container. A small glass jar works great as you can see the fluid and bubbles. Pour brake fluid into the reservior and slowly pump the lever. Check what comes out of the house. It will probably be frothy at first, then become all liquid. Close the bleeder and repeat on the other caliper (this one should go faster)
Keep the level in the reservoir above the low mark at all times. Check the hole in the reservoir and see if it is squirting fluid or bubbling. Pump slowly until the lever firms up. Immediately spray Brakecleen on any surface brake fluid spills on during this process. 8)

Reinstall the black expander diaphragm and the cap. Spin the tire and test. If good, roll the bike and test. If good, slowly ride down the street and test several times. Ride north into the Kettle Moraine on back roads for a full test.

Report back to this forum.
:wink:

 

[Anonymous]

It's too cold to ride into the Kettle Moraine today. Good suggestion, though.

Well, the problem was that we felt like we bled the brakes perfectly, they just didn't have any resistance. So, I did what someone suggested in a different thread and tied the brake closed to the throttle overnight. Woke up this morning and tested it and it works great and feels solid.. I think I'm all right. I may try it again later just to make sure, but for now I'll leave well enough alone.

 

[Detman101]

It's too cold to ride into the Kettle Moraine today. Good suggestion, though.

Well, the problem was that we felt like we bled the brakes perfectly, they just didn't have any resistance. So, I did what someone suggested in a different thread and tied the brake closed to the throttle overnight. Woke up this morning and tested it and it works great and feels solid.. I think I'm all right. I may try it again later just to make sure, but for now I'll leave well enough alone.

That's weird, I tried that and when I came out to the bike on saturday morning the lever wouldn't come up at all! It was like it was stuck!
Then when I jiggled it a little it came about halfway out and wouldn't come any further. Now there is about 1/2 an inch of play in the lever and I can't get a full squeeze on the brake lever?
What did that?


Dm of mD

 

[Detman101]

Slow pressure buildup on front brakes

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There was a bit of a thread on this on the mail list. My experience was that my front brakes would slowly build pressure (over one to three days) even though I had avoided using them, except when absolutely necessary. I had cleaned the calipers, changed the pads, bled the system well and (I thought) cleaned the master cylinder well.

The problem lies in the master cylinder. With the top off the master cylinder (as well as the rubber diaphragm inside) you can see two holes in the bottom of the master cylinder. You can see the holes best if you remove the plastic reservoir that is held in place by an O-ring. To remove the plastic reservoir just twist and pull and, if necessary, pry gently with a broad, flat screwdriver, being careful not to damage the plastic.

The holes must be clean. The larger of the two, located closest to the mirror, is relatively easy to clean and to see. The other hole, farthest from the mirror, is within a small, scallop-shaped depression in the surface of the master cylinder. The first time I cleaned the master cylinder I missed it and the problem persisted. The second time, I managed to open the hole by reaming it with a 0.008" wire (a piano wire). This started the hole and I completed the cleaning with a 0.014" piano wire that seemed to just fit perfectly. I re-washed the entire unit in solvent and reassembled. It primed and bled easier and the slow pressure buildup no longer occurred.