Topic: How much brake fluid?

[Nortstudio]

1976 CB550K:

I am draining and redoing my front brakes today.  Have the manual and the TT post about it.  I can't seem to find the total amount of fluid needed in the manual or searching the board.

My question is: Since I am going to be draining the fluid completely, can I use that fluid to place the bleeder hose in when I later do the bleeding?  Or do I need fresh fluid for the hose to sit in?  Also, approximately how much fluid does it take to refill, and then to waste a little while doing the bleeding process?

I bought a 12oz bottle, will that be enough? 

Thanks so much.

Scott

[Skunk Stripe]

I guess I never worried about the ounces of fluid, I just used what I needed. I would use clean fluid though as your are using the fluid to prevent air from getting in the line. So would you want clean or dirty fluid in there? I will say a 12 oz bottle should be plenty though. If you use all of that, wow.

[Nortstudio]

Thanks.  I was just looking to make sure I had enough on hand before I started. 

I figured the clean would be better, just didn't want to run out.  If 12oz seems like it should be enough, then I shouldn't have any issues.

Appreciate the help.

[ekpent]

Agreed and as you probably already know cover your tank and keep that stuff off painted surfaces.

[Alan F.]

One small bottle of new brake fluid is always enough, often it's enough to do 2 bikes.

[Nortstudio]

Perfect!

Actually, I did know about the paint stripping problem, but since I wanted to strip the paint anyway, I thought about possibly being a little sloppy  

Actually, will wait to do that with the proper materials

[ekpent]

One other thing,if you are replacing the pads,check their fitment first to make sure there are no binding issues etc in the caliper. Sometimes they need a little dressing up as the material can be a little oversize in the manufacturing,at least on the 750's.  Have fun 

[Kong]

To answer your original question about using the old fluid in a capture vessel fed by a hose from your bleeder (a lot of guys don't know about that trick, but its a very good one) I would say don't do it.  You only need a little to cover the end of the hose, an inch in the bottom of a water glass is enough, so its not like a lot of fluid will be wasted.  So even though there is virtually no chance of used fluid being reintroduced back into the system.

For those who haven't tried it, you get a short section (two or three feet) of clear plastic tubing, usually quarter inch, and push one end over the already loosened bleeder and put the other end in a glass bottle (quart bottles work well) that has a bit of brake fluid in the bottom it makes the bleeding process nearly foolproof. You will be able to see the air bubbles leave the system in the tubing and because the other end is submerged in the bottle that has a bit already in the bottom no air can be sucked back into the system as you bleed.  So you just pump the lever until no more air comes out (being sure to keep the MC near full) and tighten up the adjuster.  It really works well, a lot better than trying it without.

[Gordon]

As has been said, it's not really a big issue because the volume isn't much, but using old brake fluid instead of new at the end of the outlet tube is fine.  It would have to be an extremely short tube to risk sucking the old fluid back in, and if all you're doing is sucking fluid backward through the system then you're doing something very wrong.  Or think about it this way:  the instant the old fluid from inside the caliper starts pumping into the catch jar, the entire contents become contaminated and it's now old fluid anyway.   

[Duanob]

Nortstudio, these little kits work great:
http://www.harborfreight.com/one-man-brake-bleeder-kit-37201.html
You can find them at just about any auto parts store.

And DON'T fill you master to full, the diaphram on the cap will push fluid all over the place when you go to tighten it. I only fill mine about 2/3 at the most. And when you bleed set the cap on top of the master reservoir to keep fluid from squirting out all over the place evry time you pump the brakes. Have you taken the brake system apart? If not then make sure you pump all the old fluid out with new fluid before bleeding.

[Nortstudio]

One other thing,if you are replacing the pads,check their fitment first to make sure there are no binding issues etc in the caliper. Sometimes they need a little dressing up as the material can be a little oversize in the manufacturing,at least on the 750's.  Have fun 

Where would it need "dressing?". I have read about making sure they fit ok, and about sandi g them to size. But nobody ever desribes where they may be mis-sized. Is this like grinding down the lead edge, or something totally different?

My main concern is rerunning the brake line because of these new drag bars, so I figure a fresh install of clean fluid would be good. But I want to do Te pads too if I can get them to fit correctly.

Thanks for all the responses.

[Nortstudio]

Nortstudio, these little kits work great:
http://www.harborfreight.com/one-man-brake-bleeder-kit-37201.html
You can find them at just about any auto parts store.

And DON'T fill you master to full, the diaphram on the cap will push fluid all over the place when you go to tighten it. I only fill mine about 2/3 at the most. And when you bleed set the cap on top of the master reservoir to keep fluid from squirting out all over the place evry time you pump the brakes. Have you taken the brake system apart? If not then make sure you pump all the old fluid out with new fluid before bleeding.

Thanks for the link. I got a plain brake bleeder hose at auto store, but it's not nearly this fancy. It's just the hose with a doohicky at the end. I'm gonna do TTs procedure, which seems to take longer but can be done one man I think.

I'm planning on empty fluid, move brake line (hopefully can get banjo out of MC) and then refill and bleed. Somewhere in there, I'm going to replace pads when it's empty.

Sound like a plan?

[Duanob]

Check the pad depth if there is plenty left just run some sand paper over them and you will good to go there. Make sure they and the cylinder piston slide in and out of the caliper easily. If not then get a new caliper seal they are cheap insurance and clean the cylinder piston really good and make sure there are no big pits in it. I had minor pitting on mine but it was at the outside of the seal so I cleaned it and put a new seal in. Cleaned up the pads and everything works great with new fluid. Of course I completely rebuilt my system with MC kit and new upper line. But having good brakes is most important.

[Nortstudio]

I do have the new caliper seal and pads. So maybe I will just go for it.

[Duanob]

If you have the seal then definitely check the caliper piston. When you unbolt the caliper or take off your front wheel squeeze the brake lever to push the piston out of the caliper. Use a small bucket or rags underneath cause it will gush fluid.

[Nortstudio]

Planning on doing the whole shebang. Thanks for the reminder about the mess I'm abo to make on the curb!

[ekpent]

As for "dressing them" it is usually a matter of sanding down the brake material around the outside edge to match the size of the steel backer plate. They can be a little oversize.A beveled edge around the top edge is what the stock pads,again on the 750's anyways,had originally also.

[Nortstudio]

Houston. We have a problem.

I made the mistake of draining the fluid before I got the piston out. I put the metal hose back on and now can't seem to charge the system enough to pop the piston out.

The fluid come reviling out the tube with blessed open, but can't tell of that is the old stuff

The new fluid I put in the MC doesn't seem to be really going down much. 

Any help would be appreciated. I need to figure out how to get fluid flowing through te system again.

Thanks

[Nortstudio]

Disaster averted. Stand by....

[Nortstudio]

OK folks.  Thanks goes out to all of you who helped me thru this mess

I completed getting the front brake system bled, moved the line to a more appropriate place for now, cleaned out the MC and cleaned off the entire innards of the caliper.  Replaced piston seal, sanded down the pitting on the piston, and stuck her all back together.  Put new fluid in, got it running out the bleeder, and then got all the air bubbles out. 

Of course then, on the high from completing that, I decided to mess with the clutch adjustment, and not sure if i got that worse!!!  That's for another post...

What a long, strange trip.

Any thoughts on how best to test the new set-up?  Obviously, I will take her someplace abandoned (not likely in NYC!) and test the brakes at very slow speed.  But anything else?  Any special tricks???

Thanks again!

Scott   

[Nortstudio]

Quick question:  how hard should these front brakes be locking down?  I just did a test ride, and they didn't lock up. That's a start. But they don't seem to be braking as hard as I thought they would.

I aligned the stationary brake about as close as I could with the feeler I have, bit maybe it should be closer?  Would that make it brake a little soft. I just bled them and the handle seems stiff like i think it should, but its not rock hard.  With the both the front and rear brake I'm good, but I feel it should be a bit better.

Any advice is appreciated.

[seaweb11]

It's old.

[Nortstudio]

Thanks Sea. I was looking for a little more detail.

[TwoTired]

How old are the rubber lines?  (Rubber fatigues with flexure cycles. )

How many fingers are you using to squeeze the lever?
Does the lever make contact with the grip when applied?

New pads or old?  If the old ones were EVER contaminated with ANY fluid, they're trashed.
New pads need some time to fully seat.
Rotor must be clean and dry.

With ss lines and using all my fingers, I can squall the front tire in a panic stop.

I do not WANT to lock the front tire, as it will invariably force the front tire sideways, and then add side bits of the bike for added stopping power. 

[Nortstudio]

The pads, fluid and piston seal are brand new. I followed your directions to the Letter, TT (thanks for the FAQ). The only thing I changed was a bit of the manual method to get the fluid flowing since I drained it completely. The hoses are from PO, but they really do look brand new. I will be ordering the SS cables soon.

I used my full right hand to pull on it, but it never seemed to be right on the brink of locking. I know I would never want this to happen, but I was testif it on a side road alone. Not going too fast. The lever definitely does NOT come back to the bars. It feels pretty stiff to me.

Also, I was only able to use a .012 feeler.  Should I try to get the static pad closer to the disc?

Maybe it's the needing to seat. the rotor is cleaned and dried. But I would ultimately get a new one. It looks a little shot.