Aluminum= air cooled
Copper= cold water.
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Brake bleeding
- Thread starter bosco659
- Start date
Copper= cold water.
Thanks Jim, another tip for the tool box. I’ll mess a bit with different methods of the black coating removal on the copper washers. I have Dremel tool style scuffing pad material that may do the trick.
I sometimes wish I didn’t overthink things. While messing around, waiting for new lines and fittings, I noticed that all banjo fittings and bolts are not created equal. The “good” Russell fittings have a thickness of about 10mm (varies by piece measured), while some other banjo’s I have, are only 8mm thick. Functionally, the 10 vs 8mm shouldn’t make a difference. The “problem” is the banjo bolts and sealing washers also vary in length / thickness. The working shank on some bolts are 18mm and others I have are 22mm. If I try to use thick fitting, with two thicker washers and a short bolt, the threads only stick out about 5-6mm. I don’t think this is a good thing as most fittings are threaded into aluminum. I’m thinking, for the 10mm diameter, the working threads should stick out close to 10mm. The longer bolt seems to be the better length , but I only have 1/5 that are needed. The hunt for longer bolts is on!
I suppose I’ll never die of boredom.
Edit - longest Chinesium bolts found on Amazon - low risk, only $2 each. Not shiny but I can live with it as my wallet is getting skinny buying brake bits. I’m over $360 already in parts
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I thought I read (on here too I think) that copper can be done either way - air cooled or quenched in cold water? And if that's true, is one way better than the other?
One way may be slightly better than the other, but for all practical purposes and for our application, it's prolly a wash.
A few of my students experimented in my sheet metal class and didn't really find a clear winner.
A few of my students experimented in my sheet metal class and didn't really find a clear winner.
But both ways work with copper, right?
Correct.
I like the copper seals better than aluminum. I think they seal better with less torque. However I installed a new rear and front caliper on a KZ im working on and they came with dowdy washers ( steel with rubber middle ) like the one with the bolt Bosco posted and I thought I would try them and they seem to work just fine but will keep my eye on them.
There was one banjo that I couldn’t stop a leak and the solution was using a sealing washer. Ran that for well over 2 seasons without any sign of a leak. On that said connection, I tried copper, aluminum, both thick and thin as well as annealed copper. Must be an irregularity in the sealing surface a couldn’t see and the rubber must have compensated for that. I now have in hand, sealing washers from 3 different sources. They sure aren’t created equal and I’m suspecting the Chinese ones supplied with the banjos won’t be as good. One thing to note is they are also of different diameters.
I was going to mention those Dowdy washers. I've never tried them but they are supposed to work well. Fred swears by them.
They are popular on Brit bikes to make up for CENSORED tolerances. 
Bought a bunch while messing with Norton petcocks/ fuel systems. They seem to do the job there.
Bought a bunch while messing with Norton petcocks/ fuel systems. They seem to do the job there.
The basic design seems to be good. I wad reading up on oring materials and learned the best rubber for DOT3 or DOT4 brake fluid seems to be EPDM or SBR. These washers (Dowty), from Asian sources, will have rubber of unknown type. I’m expecting they would use the cheapest available, but at the same time hope they’d supply the correct material for the application (wishful thinking). In all the spots I’ve used them, they have been leak free so far. I suppose once sandwiched between metal and captured by the steel washer, even if the rubber wasn’t the ideal type, it may retain the fluid?They are popular on Brit bikes to make up for CENSORED tolerances.
Bought a bunch while messing with Norton petcocks/ fuel systems. They seem to do the job there.
One thing @GLJ ran into was banjo bolts that were just a bit too long, the threads bottomed before the washer was tight enough to seal.
It's a common gotcha when sourcing replacement bits n bobs that parts designed to one standard are slightly different that those used by a different country's standard. SAE JIS have some conflicts like that. Add in chinese wil-fit manufacturing "standards" and we're off to the races.
Don't get me started on pipe thread "standards".
It's a common gotcha when sourcing replacement bits n bobs that parts designed to one standard are slightly different that those used by a different country's standard. SAE JIS have some conflicts like that. Add in chinese wil-fit manufacturing "standards" and we're off to the races.
Don't get me started on pipe thread "standards".
Yes, there doesn’t seem to be a standard length. As mentioned in my earlier post, I was having concerns with the bolts being too short. My recenct Chinesium purchase has addressed this, but as per your post, there’s one hole in the splitter manifold that’s a bit shallower than others. If I put the wrong combo of bolt, fitting, washers, the bolt will bottom out.One thing @GLJ ran into was banjo bolts that were just a bit too long, the threads bottomed before the washer was tight enough to seal.
It's a common gotcha when sourcing replacement bits n bobs that parts designed to one standard are slightly different that those used by a different country's standard. SAE JIS have some conflicts like that. Add in chinese wil-fit manufacturing "standards" and we're off to the races.
Don't get me started on pipe thread "standards".
It was round two of “science night” this evening. I tested both new and annealed copper crush washers once again for their bendability, this time measuring the force required with my fingerometer. The difference is quite noticeable. I also noted on my new batch of Chinese crush washers, they aren’t completely flat. They have a bit of an “edge” on the ID and OD, no doubt from the stamping process.
I annealed about a dozen washers (mostly new), then sanded them flat on 240 wet sandpaper. I no longer have finger prints on two fingers to prove it.
Some took considerable effort to remove imperfections and the black coating from annealing. One thing I did learn was if you drop the hot washer in water, about 50% or more of the black coating falls off, making sanding faster.Another interesting point (which I suppose should be obvious), is that not all copper washer materials are equal. The new crush washers supplied with my Alls Balls caliper rebuild kit are actually quite soft right out of the package, plus the OD and ID lack the sharp edges seen on my Amazon assortment. They actually seem to have a bit of a radius.
Conclusion - going forward, on anything I expect to hold pressure, I will anneal and flatten washers. On things like oil drain plugs I may not care as much, but perhaps it would be best to heat them up but I may not bother with sanding them. Thanks to @bazz for putting me onto this.
More interesting info….
I kept thinking about the annealing thing so I did another experiment. I took a 1/2” ID copper washer and squeezed it between a 1/2” nut and bolt at 35.0 ft lbs. Then I did the same with an annealed washer from the same batch. Here’s the results:
- washer thickness before test: .0325”
- washer thickness after 35.0 ft lbs applied: .0310” or .0015” compression
- annealed washer thickness after 35.0 ft lbs applied: .0275” or .0050” compression
Quite a bit of difference in compressibility. If the numbers were real close I’d say it could have been measurement error but I think this might prove it’s worthwhile annealing the new stuff.
Note: the “experiment” was performed @ 35.0 ft lbs, perhaps I should have used an M8 nut and bolt at 12ft lbs. this may have been more relevant to this discussion on banjo bolts. Maybe later this winter I’ll drill and tap a plate and use an actual banjo bolt for the test. Stay tuned.
Interesting info re: banjo torque. This is for an aluminum caliper. Seems torque specs are all over the place. I saw one for 41 ft lbs! - a GM spec on a cast iron caliper.
I kept thinking about the annealing thing so I did another experiment. I took a 1/2” ID copper washer and squeezed it between a 1/2” nut and bolt at 35.0 ft lbs. Then I did the same with an annealed washer from the same batch. Here’s the results:
- washer thickness before test: .0325”
- washer thickness after 35.0 ft lbs applied: .0310” or .0015” compression
- annealed washer thickness after 35.0 ft lbs applied: .0275” or .0050” compression
Quite a bit of difference in compressibility. If the numbers were real close I’d say it could have been measurement error but I think this might prove it’s worthwhile annealing the new stuff.
Note: the “experiment” was performed @ 35.0 ft lbs, perhaps I should have used an M8 nut and bolt at 12ft lbs. this may have been more relevant to this discussion on banjo bolts. Maybe later this winter I’ll drill and tap a plate and use an actual banjo bolt for the test. Stay tuned.
Interesting info re: banjo torque. This is for an aluminum caliper. Seems torque specs are all over the place. I saw one for 41 ft lbs! - a GM spec on a cast iron caliper.
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Fantastic, well done. I love it when folks go that extra length and share their findings 
I feel justified now that I know that I've not wasted my time annealing new washers over the years, although I kick myself for not trying that trick myself at some point. But then again I thought that annealing (even if new) was just the "done thing" LOL
I feel justified now that I know that I've not wasted my time annealing new washers over the years, although I kick myself for not trying that trick myself at some point. But then again I thought that annealing (even if new) was just the "done thing" LOL
bazz
XS650 Enthusiast
The other thing to add is when you anneal your new or used copper washers
Do it just before you plan to use them
Not days or weeks before hand
I don't know for sure if this makes a difference but some say it does
And it can't hurt
Do it just before you plan to use them
Not days or weeks before hand
I don't know for sure if this makes a difference but some say it does
And it can't hurt
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Doing an old virago for the neighbor. It barely made it to the garage, the front brake was sticking so bad.
It's getting SS lines. MIGHT anneal the old washers, but to be honest usually don't.
I removed calipers and pads with brake lines intact and forced out the pistons a ways with the master cylinder FIRST. THEN removed the lines etc. Took both hands on the lever to get all 4 moving, a flat bar in the caliper stopped one piston at the limit so the second would (reluctantly) pump outward.
Only one piston really fought me on the way out but cleaning, lubing with brake fluid, and pushing back in twice freed it up enough that air pressure popped it out. A bit of patience helps, the piston was moving VERY slowly with 80PSI applied but moving. I used a magic marker to gauge progress.
Note: I had a tapered drift blocking the rear port and a rubber head on the air gun nozzle to apply pressure. The passages are drilled at an angle into divots in the casting.
It's getting SS lines. MIGHT anneal the old washers, but to be honest usually don't.
I removed calipers and pads with brake lines intact and forced out the pistons a ways with the master cylinder FIRST. THEN removed the lines etc. Took both hands on the lever to get all 4 moving, a flat bar in the caliper stopped one piston at the limit so the second would (reluctantly) pump outward.
Only one piston really fought me on the way out but cleaning, lubing with brake fluid, and pushing back in twice freed it up enough that air pressure popped it out. A bit of patience helps, the piston was moving VERY slowly with 80PSI applied but moving. I used a magic marker to gauge progress.
Note: I had a tapered drift blocking the rear port and a rubber head on the air gun nozzle to apply pressure. The passages are drilled at an angle into divots in the casting.
For those of you who dont want to go through the annealing, this is where I get my copper washers from. I normally buy 50 or so of a few sizes to have on hand. I buy a Lot of the 6mm washers where weeping at a case bolt may be an issue
https://belmetric.com/washers/solid-copper-gaskets/
While you at it you can also pick up some gaskets for the oil and sump drain bolts
https://belmetric.com/washers/hollow-crush-gaskets/
https://belmetric.com/washers/solid-copper-gaskets/
While you at it you can also pick up some gaskets for the oil and sump drain bolts
https://belmetric.com/washers/hollow-crush-gaskets/
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