Banjo sealing issues

[Dave Bilyk]

I have slight leakage from HiSpec rear caliper banjo tightened as much as I dare, but no torque figure supplied or used.
Does anyone have a torque figure for a 10mm a 1 banjo in alloy caliper?

Also, I have tried two washers, the first, as supplied, was a solid washer.
The second was a used washer with smaller OD (= higher tightening pressure) which sealed better but still a small leak.
I then tried annealing the second washer, now only one leaks a tiny bit.
This second washer, has a groove in the outside edge, which makes me think it may not be a simple solid washer. If so, maybe I need to use new not used to get a seal.
I also saw a USA site offering something similar to a Dowty washer, (a rubber seal with a metallic reinforcing / retaining ring.
Anyone have any comments on these three washer types?

Note I am desperate not to overtighten and lose the caliper thread esp since the bolts as supplied were too long and I had to shorten them 3 threads. Makes me nervous.

Any help gratefully received.

Dave

 

[MReid]

Dave,

When I have had problems with banjo's leaking it is usually the washer or a tiny particle of metal under the washer. I prefer the copper flat washers. Nothing fancy, but they work well. I had to shorten the three banjo bolts that attach hoses to my brake and clutch master cylinders. I was also worried about protecting the thread, but so far no leaks.

I've always tightened them until they don't leak or until they feel like they are going to strip. Sorry I can't give you a more accurate torque setting.

 

[Jim Cowden]

Dave

If I have had problems of this nature I have found alloy washers are good.
They are softer and tend to crush easier.

As Mark has said thier is usually an inperfection on the surface.

Best of luck.
Jim

 

[Steve C]

Dave,

As others have said insure all surfaces free of burrs AND use a new crush washer every time.

Steve

 

[Randy V]

How are you annealing the copper washers?

I hang them on a length of wire, heat them with a propane torch for a bit (30 seconds or so) and then quench them in a cold can of icewater..

I also put just a thing smear of anti-seize on the threads of the banjo before I tighten them. Not torque spec but just using a regular hand wrench I get them reasonably tight.

 

[Dave Bilyk]

Thanks guys,
I will double check for burrs, particles, but have already been careful.

Jim, you said alloy, so that is another option, were the alloy ones you used with or without rubber inserts?

Randy, I annealed with a similar method, I put the washers on to a piece of thin steel plate and heated until the washers were dull red then dunked them. I think the anti sieze is a good idea, I will use that as it will help increase the crush for the same torque, and probably give a better feel when tightening.

One point is that the tapped hole and the sealing face need to be really square, the higher the tolerance or actual error, the more crush is needed to seal, also it is something that is very difficult to check in manufacture, so it probably isn't.

I'll try new annealed washers and anti seize next.

 

[Frank Catt]

Dave, I have had a lot of problems sealing Hi Spec brake calipers, I tend to use Dowty seals if I cannot resolve it with soft annealed aluminium washers, but at the end of it the quality of the component is the real problem !!

 

[Paul W]

Dave, you could try the crush type copper washer that has a 'u' type cross-section or the more modern alloy washer with a rubber seal molded in the middle of it. I got all of my fittings off.....
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