How Much Brake Fluid from dry?

[Sam 78 GS750]

How much brake fluid should I have on hand to fill and bleed a dry system? Front and rear on a 78 GS750.

Manual doesn't seem to list capacity, and even so, capacity wouldn't tell me how much extra to have on hand for bleeding...

Worst case scenario with tons of air in the lines... How much would I need to not have to run to the store in the middle of the job?

 

[Nessism]

Recycle. Of course this assumes you cleaned the system properly by taking apart the calipers/masters and cleaning them, and replaced the brake lines. Assuming yes, recycling is fine. All you need is a small bottle of new fluid. Or get a large bottle and don't recycle. And if you didn't take the system apart and didn't replace the lines...get busy.

 

[Sam 78 GS750]

Yup, brand new lines with parts from Earl's, and completely rebuilt master and calipers front and rear... You could eat off my brake system right now.

 

[Guest]

For what brake fluid costs I would buy a larger bottle (~1 quart) and then not worry about running out when bleeding in case you have a problem getting everything really solid. Keep the unused fluid in the bottle with the lid on tight for doing a quick pre-season bleeding every spring.


Mark

 

[bobgroger]

For what brake fluid costs I would buy a larger bottle (~1 quart) and then not worry about running out when bleeding in case you have a problem getting everything really solid. Keep the unused fluid in the bottle with the lid on tight for doing a quick pre-season bleeding every spring.


Mark

Brake fluid does not store well. I would start with the smaller bottles, buy 2. If you don't open the second bottle it should last a year or 2. http://www.epicbleedsolutions.com/resources/faq/shelf-life-of-dot-mineral-oil-brake-fluid/

 

[Sam 78 GS750]

Thanks guys. So basically a couple small bottles or 1 large bottle would be enough to fill and bleed from dry. Judging by that article, I should be ok using the bottle I got to use in reassembly for coating the seals and pistons, right? It's only been open for a week or two...

 

[Guest]

Thanks guys. So basically a couple small bottles or 1 large bottle would be enough to fill and bleed from dry. Judging by that article, I should be ok using the bottle I got to use in reassembly for coating the seals and pistons, right? It's only been open for a week or two...

That will be no problem. People get all excited about brake fluid not storing well, but it keeps pretty much the same in the bottle (assuming it is tightly capped) as it does in the master cylinder and no says you have to flush and change fluid in your lines and MC every few months. Of course, I also live in a low humidity semi-desert area. Those living in very humid locations may not have the same luck. As I said before, brake fluid is not very expensive. If you ever question a bottle sitting on the shelf, replace it with a new one and avoid worrying. The absorbed water initially lowers the boiling point of the fluid, which isn't much of an issue for anyone riding on the street (at least any street I have seen). Eventually enough water will accumulate that it will start to corrode the steels in the brake system, which is a major problem. I change fluid every second year in all my bikes and have never noticed any issues with that interval.


Mark

 

[Sam 78 GS750]

OK, I have the front pretty solid. Took waayyyyyy less than I was thinking. Have a bungee cord on the lever right now to get out any lingering bubbles. All said and done, it was pretty painless.

 

[Sam 78 GS750]

I torqued everything to the high end of the spec range listed in the Suzuki manual during assembly. Left overnight with a bungee cord on the lever. Went to check on them this morning, and there's a drip of fluid on a couple of the banjo bolts...

Should I give them a bit of an extra crank, or is that little drip after a bungee overnight not gonna be a factor during normal braking?

I'm thinking where fluid can come out, air can go in...

 

[Guest]

I torqued everything to the high end of the spec range listed in the Suzuki manual during assembly. Left overnight with a bungee cord on the lever. Went to check on them this morning, and there's a drip of fluid on a couple of the banjo bolts...

Did you use new copper washers? I wouldn't over tighten them, I would figure out why it leaked when torqued properly. Yes, I understand that doing so is a PITA.


Mark

 

[Nessism]

I'd give the leaking banjos a little extra torque. Nothing crazy of course though.

 

[Sam 78 GS750]

New bolts, new washers. The washers don't look copper, they're silver colored...but they're the OEM parts listed on the fiche.

Gonna try an extra nudge with a ratchet and leave the bungee on a bit longer. See if that does the trick...

 

[leftlostcommonsense]

Little trick an old man told me about brake fluid is when you open a bottle don't pull the tab just poke a small hole in the foil that way when you tighten the lid back down there's the little extra seal still around edge of the lid and only a small hole for moisture or anything else to enter the bottle. Keep it closed up tight and open as little amount of time as possible and the bottle should be good to go for quite a bit longer than if you open it all the way.

 

[bwringer]

The torque specs are useless -- what you need is the appropriate amount of "squish" for the aluminum sealing washers.

Over time, you develop a feel for the appropriate level of squish.

Or I guess you could use a light torque to take up slack, then another half turn or so to squish the washers just enough.

 

[Nessism]

I think the OEM crush washers are nickel plated copper. I've seen raw copper and raw aluminum crush washers too, from the aftermarket. All work.

 

[bwringer]

I think the OEM crush washers are nickel plated copper. I've seen raw copper and raw aluminum crush washers too, from the aftermarket. All work.

Ya know, I've always wondered why the OEM washers are shiny. Hm.

I once went through an embarrassing number of aluminum washers from a local shoppe at $1.50 a pop. Couldn't get them to seal, never could get that "squish". Turns out they were some harder alloy of aluminum, totally unsuited to sealing duty. In a fit of rage I ordered 100 proper aluminum washers from Spiegler for 25 cents each, which worked perfectly the first time, every time. I don't like using copper; they tend to turn dark or green and look weird.

Back to the original question, I just cleaned, rebuilt, and bled a system tonight using less than half a small bottle of brake fluid. But you can't count on that. Always pays to have at least two of the small bottles around, unopened.

Only squirted brake fluid in my eye once, too. Maybe one day I'll get the hang of this.

 

[Sam 78 GS750]

Back to the original question, I just cleaned, rebuilt, and bled a system tonight using less than half a small bottle of brake fluid. But you can't count on that. Always pays to have at least two of the small bottles around, unopened.

Yup, seems the large bottle I bought was way too much for the job, and will likely go to waste. Oh well, live and learn.

 

[Sam 78 GS750]

The torque specs are useless -- what you need is the appropriate amount of "squish" for the aluminum sealing washers.

I think you're right about that. I've never bothered with a torque wrench for brake lines, and never had any issues with leaking. On this build, I've been torquing everything to spec.

Seems manual spec didn't give the appropriate amount of "squish" on the washers. Cranked down to "2 finger tight" with an extra nudge for good measure, and the crush washers were adequately crushed. No leaks after a few more hours with the bungee cord on the brake lever.

 

[Guest]

The torque specs are useless -- what you need is the appropriate amount of "squish" for the aluminum sealing washers.

As a mechanical engineer I will disagree with that. If someone went to the trouble to provide a torque spec there is a reason for it. If the manual provides a torque number I ALWAYS use it. I have assembled my share of brake systems with a torque wrench and never had a leak at a properly torqued banjo bolt.

I just cleaned, rebuilt, and bled a system tonight using less than half a small bottle of brake fluid. But you can't count on that. Always pays to have at least two of the small bottles around, unopened.

Indeed. Sometimes they go really easily and sometimes it is a fight the whole way. Last summer I was flushing fluid on my wife's ZX6R and was just about done when a moment's inattention resulted in sucking the MC reservoir dry. It took me half a bottle of fluid to get the air back out of that line after that screw up...:stupid:


Mark