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Need a recommendation for thread sealant for hydraulic brake lines. My calipers use pipe threads on the AN line adapter and I need a sealant that's impervious to brake fluid. TIA, John
 

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Discussion Starter #3

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Is there a difference between 54540 and Permatex 59235? Amazon carries both sealants
My smart azz answer is 4,695... :)

From Permatex's site it appears the 59235 is more general, but does say it is okay for automotive brakes.
 

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You don't need sealant for any of our brake line fittings... I would strongly advise against it. If it gets into the system it can cause a blockage.

What are you trying to seal?
 

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Discussion Starter #6
You don't need sealant for any of our brake line fittings... I would strongly advise against it. If it gets into the system it can cause a blockage.

What are you trying to seal?
The AN to NPT thread adapters that screw into the calipers.
 

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Discussion Starter #9
Don't need it, just tighten the fitting into the caliper.
OK, will do. I guess I was channeling my old days as a plumber's apprentice where they put sealant on all npt joints.
 

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OK, will do. I guess I was channeling my old days as a plumber's apprentice where they put sealant on all npt joints.
I always add some sort of sealant, from decades of working in Industry. Never had a problem so far, just keep the tape/dope away from the first 2 threads. I've noticed some brake fittings come with a red sealant of some sort pre-applied. No harm installing them dry, if it leaks you can always go back and address it.
 

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I always add some sort of sealant, from decades of working in Industry. Never had a problem so far, just keep the tape/dope away from the first 2 threads. I've noticed some brake fittings come with a red sealant of some sort pre-applied. No harm installing them dry, if it leaks you can always go back and address it.



NO SEALANT! Period! End of story! Nada! If you want to give advice, try giving good advice.
 

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NO SEALANT! Period! End of story! Nada! If you want to give advice, try giving good advice.
Just giving my personal experience, and if you'll note, my final comment was to try installing them dry. If sealant was NEVER required, suppliers would not ship fittings with it already applied. It can also avoid over-tightening a fitting that's dripping, which can strip out or crack fittings. I'm glad you're so superior, but I have Decades of experience in Industrial pneumatics and hydraulics.
 

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I've seen that red stuff on threads of various new lines. I've yet to see a consensus of whether it is a sealer, threadlock, or combination of both. I don't know either but I can definitely say manufacturers definitely put something on brake line threads quite often. I don't recall ever using or needing sealer on brake lines but I often use sealer or teflon tape on other types of hydraulic line threads. Since brake systems are basically just hydraulics with a different type of fluid (not oil) I don't have a problem with the judicious use of sealer.
 

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I think that red stuff is made to be a threadlocker but it seems to double as a sealer.......
I use it for both. It’s kinda rubbery/plastic feeling. Not sure what the OE’s use but this is what I use

https://www.vibra-tite.com/threadlockers/removable-reusable-threadlockers/vibra-tite-vc-3-threadmate/

Yes I know a pipe thread should need nothing, but the fit of that stuff these days is less than ideal. I put Wilwood brakes on the front of my Mustang and used that so the caliper fitting was pointed where I wanted it without having to really crank it tight and risk cracking the caliper housing, maybe there was a better solution but that worked for me without any issue. Hasn’t moved or leaked.
 

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Need a recommendation for thread sealant for hydraulic brake lines. My calipers use pipe threads on the AN line adapter and I need a sealant that's impervious to brake fluid. TIA, John
Ask the manufacturer of the caliper.

Sent from my SM-G950U using Tapatalk
 

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I've never used a sealer in applications a lot more demanding than a classic or resto-mod Mustang. If you get crappy fittings, a burr in the part or wonky flares it could be an issue. If you get the fittings from someone like Pegasus you should be good to go. Where I've had the biggest issues are the crush washers on the banjos. When we could we'd fab lines that didn't require adapter fittings but sometimes that wasn't possible. For example when you convert a a 70s-80s GM metric caliper to a system with a race master cylinder you'd have lines that had metric on one end and SAE on the other.

There are compatible sealers but good fittings, good flares and good adapters it should be good to go with no sealant.
 

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I've never used a sealer in applications a lot more demanding than a classic or resto-mod Mustang. If you get crappy fittings, a burr in the part or wonky flares it could be an issue. If you get the fittings from someone like Pegasus you should be good to go. Where I've had the biggest issues are the crush washers on the banjos. When we could we'd fab lines that didn't require adapter fittings but sometimes that wasn't possible. For example when you convert a a 70s-80s GM metric caliper to a system with a race master cylinder you'd have lines that had metric on one end and SAE on the other.

There are compatible sealers but good fittings, good flares and good adapters it should be good to go with no sealant.
You are obviously getting higher quality parts than the run-of-the-mill Industry/Automotive product ! :) I've had plenty of NPT fittings that won't seal with 100 PSI, let alone brake system pressure.
 

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Note: All my comments are strictly referring to NPT threads. Also note that the material matters, Brass/Aluminum connections usually seal up pretty easily, Steel/Stainless steel, not so much.
Side note: You always want to use something on SS to SS connections, unless you want them to gall and become a permanent assembly!

Crap, keep missing my Edit window
 

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You are obviously getting higher quality parts than the run-of-the-mill Industry/Automotive product ! :) I've had plenty of NPT fittings that won't seal with 100 PSI, let alone brake system pressure.
Automotive brake plumbing uses the flare as a seal. The thread is the fastening means to apply the force to the seal. On a properly fabricated joint the hydraulic fluid shouldn't make it past the flare to the thread. If it leaks there is an issue with the seal and not the thread (assuming it's the proper mating thread). It's different from something like a fluid or gas conveyance pipe where the taper of the thread is used as the primary sealing means. In that case we need tape or pipe dope.

Use a proper sealer for this application if you like. There are several out there. I'm not going to go on some anti sealer rant but claiming it's required for a proper connection in this application isn't the case.
 
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