Banjo Bolt & Copper Washer Headaches

Conundrum number 581... I installed the brakes on my project months ago. Finally got the pedals installed and was preparing to bleed the system, so I filled the master cylinder (after bench bleeding). Came out the next day and there was a large puddle under the driver tire and a smaller puddle under the passenger tire. The leak is coming from around the copper washers where the banjo bolt mounts the brake caliper.

I checked the mounting surfaces on the hose end and calipers for burrs or uneven spots and everything looks good. My narrow track D30 axle is from a 78 CJ-5 so I used the OEM calipers/rotors/pads (the two-bolt calipers mounted on the trailing side of the axle). I double-checked the part numbers for calipers, rotors, copper washers, and banjo bolts. Everything checks out.

My hypothesis: the OEM brake hose ends have a flat surface into which the circles are machined for the copper washers, leaving a small raised area around the perimeter. The copper washers have an outer diameter that is slightly larger than the outside diameter of machined circle. I think this is preventing the copper washer from seating evenly/fully and causing the leak. I've tried finding copper washers locally with a smaller OD that will still fit the banjo bolt with no luck - the local parts shops have a very limited selection. I know not to reuse the copper washers, so I ordered new washers and even new banjo bolts just to be sure. I believe this is the culprit because each used washer has a small section (~20%) that is lacking the grooves from the machined area (see attached pics). If I'm not crazy, the two options are 1) file/grind down the washer outer diameter to fit within the machined area, or 2) grind down the raised edge on the hose ends.

Anyone else encounter this goofiness? I'm open to suggestions.

https://1drv.ms/u/s!AidRSUR_eJT9gbtOPjGYlzL2ZrMzZw?e=UZFfAF

 

I have the same brakes. Haven’t had this problem and I have reused the washers.

 

A wild thought... try annealing the copper to soften it. (Heat it and plunge into cool water.)

 

The copper washers are probably too hard to properly deform and make a seal. annealing them like peteL said should help or you could try aluminum crush washers. I have had good luck with copper washers from earls and allstar performance

 

Maybe try visiting a motorcycle shop for the washers, the shop I frequent has a large assortment of those copper washers in stock.

 

I was in Harbor Freight the other day and noticed they had a copper washer assortment pack.

 

Well, if there's some obscure, bizarre problem that can occur it'll find its way to me! Thanks, all. I'm gonna try annealing the washers before installing and see if that resolves it. I'll post a response once I brave the cold pole barn.

 

I guess we’ll know in May.

 

You can heat them with a torch and let them cool slowly, that anneals them and they will be soft again. We did that with BSA motorcycle head gaskets to reuse them. Good luck

 

Interesting. I grew up in the school that says use a rapid quench.

But researching the interweb, I see that there is much debate on this, and perhaps the true answer is that either fast or slow cooling works, the important factor is the prior heating to dull red. Possibly the water quench removes scaling.

But either way the consensus is that annealing is very important.

 

Ayuh,..... Copper is quite unique in the world of metals,.....
Unlike steel, it matters not how ya cool it, so long as ya get to the dull red color when heatin',......
I've done it both ways, quenched, or slow cooled,..... either way softens it,.....
Did a length of hard copper tubin' the other day, heated to the dull red, like it cool, 'n bent it after it cooled,.....

Also agree with flat sandin' the washers after the annealin',....
A bit of sandpaper, 'n a flat surface,....

 

I am not sure about annealing copper, which is pretty soft to begin with, but I do know that some copper plumbing pipe is harder than the coiled copper.

I am very experienced with working brass which is an alloy containing copper. I use brass to make various parts for the banjos I build. It is annealed (softened) by heating and a rapid quench, and it is hardened by heating and a slow cool down, the slower it cools the harder it gets.