How tight for 90 degree brake cylinder elbows?

cnpeters · #1 10-27-2008, 09:20 PM

For AN822-3D 90 degree alum. elbows that attach to my brake pedal cylinders (Bonaco brake lines attach on the nipple ends), how tight have folks tightened these as they rotate them in? Just put fuel lube/EZ turn and tighten 'til fairly tight, or do folks torque these?
Thanks

gasman · #2 10-27-2008, 09:48 PM

Run it in by hand, then on the next turn with a wrench, set it at the direction that you want. It is small........ use a small wrench.

lorne green · #3 10-27-2008, 10:56 PM

Hand tight (snug) then a quater of a turn. I'm told.

Rockyjs · #4 10-28-2008, 06:18 AM

I had a problem with both my lower left master cylinder fittings leaking. It seams that the tap used by Matco left some scoring across the threads. One of them I had to crank in pretty hard and used fuel lube. The other I gave up on and sent back and received a credit from Vans. Do a search there has been discussions here recently.

Mel · #5 10-28-2008, 06:43 AM

After getting a pipe thread hand tight, you will have at least one full turn available for "setting" the direction you want.

robpar · #6 10-28-2008, 10:15 AM

I'm not a pipe fitter but I have done extensive pipe design as well as being a mechanic for 25 years. From this I have had NO good experience with pipe threads. I can not remember an OEM application that used pipe threads on brake components, they leak! The auto manufacturers have been eliminating pipe threads from every component and replacing with gasketed or o-ringed seals. It surprised me that aircraft use pipe threads on brake components.

I have found that installing pipe thread elbows is a bad idea. It is best to install straight male connectors and put the elbow on the hose. If space does not allow than you will have to use the elbow. You will very likely find that where the elbow seals and where it needs to point are never the same. Do not back off a pipe thread fitting to position as it will leak. Over tightening can split the housing. Be very very careful using sealants with brake fittings for fluid compatibility, I would recommend dry fitting I would not recommend using Teflon tape on brake fittings as little pieces of tape can easily get into the system. I would look for components that do not use pipe threads especially on brakes. Pipe threads do not do well in vibrating conditions, they loosen and leak!

I have only found two types of pipe threads; Those that ARE leaking and those that are ABOUT to leak. If any of the components are stainless steel they will always leak.

Sorry for the rant but NPT threads are not suitable in my opinion for anything other than your water taps at home.

Bob Parry

Mel · #7 10-28-2008, 10:27 AM

Everyone's experiences are different, but I have been an auto mechanic for almost 50 years and an aircraft mechanic for 35 years and have never had a problem with pipe threads in any application. I do use a sealer, Permatex Form-A-Gasket.

gasman · #8 10-28-2008, 10:38 AM

Quote:

Originally Posted by Mel

Everyone's experiences are different, but I have been an auto mechanic for almost 50 years and an aircraft mechanic for 35 years and have never had a problem with pipe threads in any application. I do use a sealer, Permatex Form-A-Gasket.

I use HARVEY'S TFE PASTE with teflon. I think that it acts more like a lubricant for the threads so they will seat better.

Inspect the threads on both parts. If they are not GOOD, then it will leak no matter what you put on the threads.

robpar · #9 10-28-2008, 12:28 PM

Quote:

Originally Posted by Mel

I do use a sealer, Permatex Form-A-Gasket.

You use Form-A-Gasket on Brakes??? I stand by my hatred of NPT. With brass and aluminum there is a chance of getting a seal with SS no chance.

Bob Parry

RV10Rob · #10 01-26-2011, 11:01 AM

What else have people had success with? My elbows are still leaking. I have them plenty tight and used fuel lube. On the plus side, I'm getting really good at bleeding brakes.

-Rob