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1961 - 1966 F-100 & Larger F-Series Trucks Discuss the Slick Sixties Ford Truck

66 Master cylinder question

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Old Jul 27, 2020 | 04:45 PM
  #1  
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66 Master cylinder question

Had a quick question about the brakes on my 66 2wd. Trying to diagnose why the brakes turn to **** after she sits for a while and finally noticed a bit of fluid around the master cylinder/brake line connection. Started tightening everything and the piece in the middle developed a nice crack. I'm guess the cracked piece is a bit of "engineering" by the previous owner? I don't see it in parts search.

 
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Old Jul 27, 2020 | 05:16 PM
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That is a factory part. Adapter, Straight, Pipe to Tube.

Don't quote me - it's been a while - I think it is 1/8" NPT male to 3/8"-24 female inverted flare. This should be it. Double check the size.

Amazon Amazon
 
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Old Jul 27, 2020 | 05:43 PM
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Oh awesome thanks. With the 'fixes' I have found on the truck I wasn't going to be surprised if it was an added piece. Just seemed weird that I couldn't find it on the parts sites so I figured it wasn't legit.
 
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Old Jul 27, 2020 | 06:54 PM
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You can get it at Ace Hardware.
 
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Old Jul 28, 2020 | 07:17 AM
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Originally Posted by freekwonder
Had a quick question about the brakes on my 66 2wd. Trying to diagnose why the brakes turn to **** after she sits for a while and finally noticed a bit of fluid around the master cylinder/brake line connection. Started tightening everything and the piece in the middle developed a nice crack. I'm guess the cracked piece is a bit of "engineering" by the previous owner? I don't see it in parts search.
I just finished a complete brake job on my signature truck, including a master cylinder. All went well but I have a minor leak around the same fitting shown in your post. I have tightening it to a point where I'm afraid that one more crank might put it in the same category as yours. I may try to find a new fitting to see if it will terminate the leak. Any ideas from the crowd are appreciated.
 
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Old Jul 28, 2020 | 10:06 AM
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Use a couple of wraps of teflon tape around the threads - it will help get a good seal without having to tighten it to the moon.
 
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Old Jul 28, 2020 | 10:17 AM
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From: Elizabeth
Originally Posted by TA455HO
Use a couple of wraps of teflon tape around the threads - it will help get a good seal without having to tighten it to the moon.
That's between the fitting and the master cylinder...

If it's leaking on the line side, the flare is bad or the seat in the fitting is bad.
 
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Old Jul 28, 2020 | 10:21 AM
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Originally Posted by 62SY4
That's between the fitting and the master cylinder...

If it's leaking on the line side, the flare is bad or the seat in the fitting is bad.
Good point - thanks for chiming in. Some of these will be due for a new hard line with new flare I'd suspect.
 
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Old Jul 28, 2020 | 10:39 AM
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Not a fan of brass adapters/fittings, engine vibration tends to cause a weakness in dissimilar metals, if replacing the fitting suggest either go with metal, or change the thread count on the brake line fitting and connect directly to the MC?
 
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Old Jul 28, 2020 | 11:03 AM
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Thanks for the help. I've only owned the truck for a bit over a year now. The previous owner was the 2nd, but he owned her for 30+ years and I really don't know what kind of maintenance was done or when parts replaced. She could probably use some new lines front to back, already went through and replaced drums and other brake parts. Probably end up buying one of those pre-bent kits like I did for my Datsun.

I'll have to hit up ace today and see if I can get my hands on one of these flares.
 
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Old Jul 28, 2020 | 11:12 AM
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Originally Posted by daveengelson
Not a fan of brass adapters/fittings, engine vibration tends to cause a weakness in dissimilar metals, if replacing the fitting suggest either go with metal, or change the thread count on the brake line fitting and connect directly to the MC?
That's a new one on me. Ford has been screwing brass adapters into cast iron engines for years without any difficulties that I've heard of. Let me give you a few examples. The 4th picture is a NOS 427 side-oiler with screw in brass plugs that were unique to the 427 high performance engines. Same plugs used in 1966 when Ford won LeMans. The brake system is 'once removed' from engine vibration.









 
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Old Jul 28, 2020 | 11:28 AM
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From: Elizabeth
Originally Posted by freekwonder
I'll have to hit up ace today and see if I can get my hands on one of these flares.
If not Ace your FLAPs (friendly local auto parts) will have it. Pretty common fitting. Even the national chains o'reileys, advance, NAPA, etc. will have them. They won't be able to look it up you have to go to the bins in the back. Probably will be in a Plews-Edelmann or Weatherhead assortment.
 
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Old Jul 28, 2020 | 11:35 AM
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From: Elizabeth
Originally Posted by daveengelson
Not a fan of brass adapters/fittings, engine vibration tends to cause a weakness in dissimilar metals, if replacing the fitting suggest either go with metal, or change the thread count on the brake line fitting and connect directly to the MC?
The OE master cylinder has 1/8" national taper pipe threads, so some adapter is needed to get to brake fittings anyhow...
If by metal you mean of the ferrous type, that fitting is available but expensive for little gain. I'm more apprehensive about the working pressure than the potential for work hardening and fatigue, that steel line is likely brazed tube anyhow. The fact is the fitting has served it purpose for 50+ years without issue, no reason to do anything different.
 
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Old Jul 28, 2020 | 12:05 PM
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Originally Posted by TA455HO
Use a couple of wraps of teflon tape around the threads - it will help get a good seal without having to tighten it to the moon.
Thanks, TA455HO. I was leery of teflon tape and brake fluid. I'll try it.
 
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Old Jul 28, 2020 | 12:25 PM
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Perhaps I should have noted I am not an authority and I am not a fan of brass fittings, perhaps due to the application, imagine one can find a number of brass fittings on an engine block just seems to me a ridged brass fitting with a fuel, oil, or brake line has the potential of cracking or leaking, both of my 65's there is either a loop, or flex line to allow for vibration? Anyhow, not as issue with me, as noted IMO, may save one the need for Road Service??
 
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