Norton Lockheed Caliper Problem

[snipercwf]

I'm new here - be gentle  

I have just bought a new bleed nipple for my Norton Commando brake caliper - and it isn't making a seal around the threaded hole - no matter how tight it is done up.

I am using a syringe and silicon line method to push air in (caliper is off the bike and empty), and air leaks around the thread of the bleed nipple.

The bleed nipple is the correct replacement - not a modern Jap one.

Unfortunately I don't know if the caliper was holding pressure before - as it is a new aquisition - and the original bleed bolt had rusted away.

Any ideas? I thought about bathroom sealant in the thread - as a sort of built in o-ring.

[L.A.B.]

I'm not sure how long silicone sealant would last considering the amount of pressure there is in the system during heavy braking?

I would have thought it better to try and sort out the reason for the leakage (did somebody drill out the old rusty bleed nipple by any chance? As they would have probably damaged the bleed nipple seating in the caliper) and getting it repaired by a Norton specialist or engineering company could be costly and probably better to find another (good) caliper?
You could give Mick Hemmings a call (01604 638505) and see what he suggests?  

  

  

[snipercwf]

No, I removed the old one with pliers. The thread was fine, but the visible part was rounded off and rusted. I managed to get it out in one piece, without damaging anything.

I might need to get a whole new caliper I guess.......bugger.

[L.A.B.]

I can only suggest you check the seating at the bottom of the bleed hole to see if there appears to be any damage or any dirt that could be causing the problem?

Did the tip of the new bleed nipple have the same angled profile as the old one?

[L.A.B.]

Due to the design of the bleed nipple if  brake fluid is able to escape along the threads then it will also escape from the centre drilling in the nipple, so using sealant on the threads may not work anyway?

[lsdt]

I've probably missed something here, but why are you pumping air into the caliper?
Are you back bleeding, ie forcing fluid through an open bleed nipple? if so leakage past the threads can happen and shouldn't be a problem providing the nipple seals once closed.

[L.A.B.]

(caliper is off the bike and empty),

By what snipercwf said I assume that he is pressurising the caliper at the brake line connection?

[snipercwf]

I am not forcing fluid in. The test was ...... (OFF the bike) bleed nipple done up, pressurising the bleed nipple (backwards) ie, air into the bleed nipple - and air comes out of the thread + pressuring the brake line in - air comes out of the thread again.

When I get a chance - i'm going to rig it up anyway with brake fluid - and see what happens. I might get lucky.

But I think this is a no win - and I'll probably keep my eyes peeled for a new caliper. Any idea of a direct replacement from other makes/aftermarket also? maybe more powerful? it is going on a chopper - so anything with the same spaced mounting holes would be handy.

Many thanks for all your responses :-)

[L.A.B.]

I am not forcing fluid in. The test was ...... (OFF the bike) bleed nipple done up, pressurising the bleed nipple (backwards) ie, air into the bleed nipple - and air comes out of the thread

If you are pressurising the drilling in the bleed nipple I would expect air to escape from the nipple threads! With the nipple tight, as it is the tip of the bleed nipple that seals it to the caliper, the centre drilling and the small side drilling to it that allows fluid to escape when bleeding is above the tip of the nipple.

But pressure should not escape when pressurising from the brake line connection.

[snipercwf]

I will rig it up next week - and post an update.

I work nights so need to find the time!

Maybe i'm just being thick!  

[snipercwf]

Ok - here goes.

I have replaced the caliper now, but I have found the bajo bolt on the old one doesn't fit the new one. The old one has probably been re-tapped to take the jap bolt.

With the new one came a metal attatchment with hollow bolt (caliper side) and thread (bike cylinder side).

Can you get a standard (modern type) banjo bolt that will fit (so I can use standard braided lines)?

Cheers,
Sven

[L.A.B.]

The Norton Lockheed caliper was never designed to take a banjo fitting.

Originally there would have been a short rigid pipe between the hose and the caliper, and it is worth noting that the brake position changed from being on the right side of the bike (1972-74) to the left side on the 1975 model 850 Mk3 Commando so there are two slightly different brake line setups although the caliper is the same unit.

1975 Commando 850 Mk3 = Brake on left side.


I'm not quite sure what you mean by "a metal attachment with a hollow bolt" it sounds like some kind of adaptor possibly, or do you mean the rigid pipe?

The caliper thread would originally have been *3/8 inch UNF* if so then do not try to use a metric banjo bolt.

Until I've got a better idea of what fitting you have it is difficult to suggest anything?

[snipercwf]

Yep, thats what I got. But I know I can get a 3/8 banjo bolt, so that's awesome. Many thanks for your help. I'll shelve the rigid pipe setup and get a 3/8 bolt, so I can use in my braided line system.

Also with my old knackered caliper, I'm gonna plug weld the bleed hole and use a banjo bolt with a built in bleed nipple, to see if I get any joy, then keep as a spare or sell one.

Many thanks to all the replies, and I also appreciate most classic bike owners don't appreciate the likes of me destroying perfectly good bits of old machinary and making deformed creations!  

Cheers all, Sven DGAF MCC

'77 Suzuki Hardtail Chop

[L.A.B.]

Ok then, one thing to look out for if you intend to use a banjo fitting is that the area around the caliper hole is generally left un-machined, so it may not make a very good sealing surface and the face is not always square to the hole so you *could* end up with leakage problems?

[snipercwf]

Just an update on the caliper saga. Finally got it sorted - woo hoo!!  

Went and got a 3/8" UNF banjo bolt from Hel Performance - whoose HQ/factory is only a couple of miles down the road from me! and it now works with my goodridge braided line and Honda master cylinder - success!!

Also does anyone know of a cheap direct replacement brake disc - rather than the cast iron one?