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dwilson

Well Known Member
I don't undersdand how to tighten/seal the brass elbows for the brake master cylinders. I bought bakerseal as suggested by some on this list. (Thanks Dan) I painted the threads of the brass elbows. I threaded the elbows into the master cylinders.

I cannot make them "tight" and properly positioned to attach to the tubing. If I loosen it a little so that the proper orientation can be made then to fitting is too loose and sort of flops around when the pedals are moved.

What am I missing here????

Thanks,
Duane
 
NPT fittings

I cannot make them "tight" and properly positioned to attach to the tubing.
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When I first started messing with these things I thought the same thing. My buddy with 100 years of experience taught me that you can almost always get another turn on an NPT. I haven't stripped one out yet.
 
With a wrench?

Should I use an adjustable wrench? An open end? or my fingers???

Thanks,
Duane
 
NPT Fittings

I used an open end wrench. One of them will fit - I think it was a 7/16", but it was a couple of weeks ago. Try your metric wrenches too - one might fit better.
 
Adjustable wrench on the cylinder

I used an adjustable wrench on the flat sides of the cylinder, and an open-end wrench on the fitting. I felt like I was torquing the hell out of it, but I got it tight, pointing in the right direction, and didn't strip or break anything.

Of course, I have not leak tested it yet...
 
Mindful of Darwin's advice when I was assembling the fuel pump, I chose not to go crazy on the fittings on the master cylinders either. I tightened it by hand and that usually got me to about the 3 or 4 O'clock position. But I needed it to be at 12 (and in one case, 1), so I just used a wrench to tighten it to the proper clock positioon and no more.

Could I have gone around one more turn? Boy, I bet if I tried real hard I could. But from what I understand, I don't have to.

We'll see.
 
You never want to back the threads up on NPT fittings to make things line up. You are asking for leaks. If you look closely, the threads are tapered toward the starting end.

Derrell
7A
Alpharetta, GA
 
Right, and that's what I did. I never backed off. When I was sitting ther ethinking, "should I go for another turn," it occured to me that if I did and if I found tough sledding halfway around, I would be pretty much screwed. So I stayed where I was, relatively confident that things wouldn't be leaking. If they do, well, I guess I'll consider it an experiment and learn from it. ;)
 
Bob Collins said:
I tightened it by hand and that usually got me to about the 3 or 4 O'clock position. But I needed it to be at 12 (and in one case, 1), so I just used a wrench to tighten it to the proper clock position and no more.

Could I have gone around one more turn? Boy, I bet if I tried real hard I could. But from what I understand, I don't have to.

We'll see.
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Bob... one thing you could try is to take the fitting out, clean off the the fuel lube or whatever compound you use, put fresh compound on, and try again.

Each time you do this, you clean out some of the galled aluminum/brass, and the fitting will make it in an extra 1/4 turn or using the same torque.

Try it, it works.... and it is possible to destroy the part you are screwing into with excess torque... :(

gil in Tucson
 
Gil, I'm not following you on the advice, I'm afraid. I don't see the need to remove the fitting and try again because I think it came out fine. My point was that I didn't see a need to apply excess torque and so, I didn't. It's basically a half turn beyond finger tight at the moment. Are saying that I've already applied to much torque and that it should be only finger tight in the proper clock position?
 
I did it and it worked!

Thanks folks,
All the advice was great. I tightened each fitting finger tight and then used an open end to continue tightening on around until I got to the proper orintation.

I love this forum!!!!

Duane Wilson
 
Clarification.....

Bob Collins said:
Gil, I'm not following you on the advice, I'm afraid. I don't see the need to remove the fitting and try again because I think it came out fine. My point was that I didn't see a need to apply excess torque and so, I didn't. It's basically a half turn beyond finger tight at the moment. Are saying that I've already applied to much torque and that it should be only finger tight in the proper clock position?
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Bob.... sorry if I didn't put it clearly... my fault....

I also think I quoted the wrong poster.... :mad:

What I was trying to say... if you tighten to a certain torque, and get a particular orientation of an angled fitting...
Then, if you remove the fitting, clean it and the hole, put new fuel lube on it, and then re-do the assembly to the same torque.... you will have moved the angle forward a 1/4 turn or so. Repeat as needed to get the postition you want.

Always turn "forward", backing up can loosen the joint and may cause a leak under pressure....

If you got it to the correct postion without excess torque (but with a reasonable torque.... :) ), and don't back it up... you should be OK....

The tapered fit actually does work by galling the surfaces between the two parts to get a leak proof fit.

gil in Tucson
 
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Bakerseal pipe sealant alternative?

For reference, does anyone know whether Bakerseal has any "magical" properties that make it appropriate for aircraft? I found some pipe sealant with teflon at Home Depot that appears to have identical specs:
- pipe sealant with teflon
- safe for use on all metals
- good in high pressure applications up to 500 F
- pliable (does not harden)
- etc.

It come in a small tube, and appears to be identical. The price and availability are obviously right too.

Any reason why this can't be used on non-fuel NPT threads? I use EZ turn on the fuel system, but I am needing somehting for brakes and other NPT applications.

THanks,
Scott
7A Finishing
 
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