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Brake fluid leak - banjo bolts

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BobS76

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I was just finishing up my brake rebuild (yes, I know has been quite a while, but until I pick up my leaf springs, schedule is a moot point) when I found that both banjo bolts (left / right front calipers) had small leaks.

I had cleaned (but not sanded) the caliper mating surface and the surfaces of the banjo bolt. I used all new copper washers. I further tightened the banjo bolt after noticing the leaks - I am now at 40 ft-lbs torque on one, and am afraid to go further. Does anyone know what the torque dpec should be?

At this point, does anyone have anything to suggest? I hesitate tearing it all back down as the brakes have been bled.

The car is a 1976 1500 Midget.

Thanks,
Bob Shaw
 
Are you sure you used the correct size washers. There are two different sizes on each bolt.
 
And... are you sure you didn't leave an old one on the bolt?
 
I still have the old ones on my work bench. The new ones came from a local parts store and were very close in size - the inside diameters, even if a bit larger, still effected a good seal to the mating surfaces. The new washer next to the caliper surface (inner) was the same thickness as the other (outer) new washer: both 0.060. The original washers were 0.030 and 0.060 for the inner and outer washers respectively. At best, I might have lost 1/2 of a thread on the bolt. Is it likely there could be a difference in the hardness of the copper?

Bob
 
I dunno. I've never had a problem with them leaking before. Before you over torque them, I think I would remove them and clean and install new washers. It shouldn't require much bleeding if you seal the brake MC tight before doing the job.
 
im not sure if i know what im talkin about, but....
i changed my brakes last summer and the copper washers
are pretty soft and help seal thing when compressed ...z
 
That is what I expected to happen.

But there must be a torque spec; does anyone know what that is?

Bob
 
Snug.

Remove the leaker and inspect for a contact pattern.

If the contact pattern on the washers looks good try tightening and loosening 2 or 3 times then snugging down.

Snug might be about 15 ft/lbs.

And yes it could be from a country of undetermined origin and work hardened copper. Carlson is the name to look for in brake hardware. Take a small [censored] punch and push into the copper . it should indent easily.
 
Make sure the surfaces are completely clean.

Copper washers have the disturbing quality that, after they are tightened down, they "deformation harden". Meaning that they are not as soft as when you bought them and will not seal as easily.

The FAA approved method is to heat them up until glowing red and allow air cooling. This normalizes them making them soft again, at which time they can be reused.
 
i remember now...
i had the same problem...
went to oreillys and got a
pack of brake washers of random
sizes, matched the best i could,
and no problems since .......zimmmy
 
And 40 ft/lb can stress crack those banjo bolts. Give 'em a REALLY good visual inspect for cracks running in the threads. 20~25 ft/lb should seal. If you lap the washers with #600 "wet-or-dry" then normalize them as Donn has outlined they ~should~ seal. I'd be for getting another set and lapping those, though. And it goes without saying: "hospital cleanliness" for assembly. A light film of brake fluid can actually help "lubricate" the copper as you tighten it, too. If it's a bit too "hard" it can gall as the bolt is tightened if completely dry. Just wipe any residual away after you're done.
 
I am going to disagree with Donn about softening the copper washers.
I have heard that with steel you heat it to glowing and air-cool to soften but with copper it is the opposite, you heat to glowing and water-quench to soften it. I think that this is correct.
Bill
 
Yep it is, water-quench copper.
 
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