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There is a thread on the chemical composition of PTFE tape (Teflon tape) here: Master cylinder leak but my question is, will PTFE tape stand up to the heat generated by front disc brakes? Or, will the heat generated melt it and just make a messy goop that no longer really seals?

EDIT: Applying a little Google-foo to the problem turned up this:

[PTFE is a white solid at room temperature, with a density of about 2.2 g/cm³. According to DuPont its melting point is 327 °C (620.6 °F), but its properties degrade above 260 °C (500 °F).

So the question can be refined to is that high enough to avoid problems with front disc brakes? Since the tire begins to soften to the point of not working well at roughly 160 to 170 deg C (320 to 338 deg F) it should be fine.

Does this match what folks have seen or tested in the real world? Is there a downside to using PTFE tape on brake bleeders, like bits of the tape getting into the brake line?

(The quote comes from here: https://answers.yahoo.com/question/index?qid=20070824070354AAUaCbi )

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    TBH I've never seen teflon tape on brake bleeder screws or any brake line fittings. It seems kind of stupid to try especially in a professional environment where you're open to litigation and possibly criminal charges if the tape fails and someone dies.
    – Ben
    May 18 '16 at 23:26
  • The good news is that PTFE is very heat-resistant - it's also known as Teflon, AKA the stuff put on frying pans. The bad news is all the stuff in the answers below. TL;DR - it won't melt, but it might dissolve. Apr 4 '18 at 22:44
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TBH I've never seen teflon tape on brake bleeder screws or any brake line fittings.

It seems kind of stupid to try especially in a professional environment where you're open to litigation and possibly criminal charges if the tape fails and someone dies.

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  • It can be useful is bleeding to make sure air isn't being sucked around the threads. When the bleeder is closed, it should be able to seal without the tape. It if can't, replace the bleeder or caliper.
    – rpmerf
    May 19 '16 at 11:33
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    I saw that in the other thread on this, and I couldn't understand how air would get past the threads since the only time lts loose is when the pedal is depressed. And when the pedal is depressed there's flow out of the bleeder. With flow out, how would air get in?
    – cdunn
    May 19 '16 at 12:06
  • @cdunn I've never had this problem either. having someone pump, using a vacuum or pressure bleeding.
    – Ben
    May 19 '16 at 12:56
  • I'd be very concerned in this application that shreds of the tape could work their way into the brake system. That's an experiment I wouldn't want to do…
    – dlu
    Jul 30 '16 at 19:40
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Two points;

  1. Teflon tape is not a sealant. It lubricates the threads, so that you can insert the threaded part deeper, and as a side-effect it fills small gaps - but it was never designed as a sealant.

  2. Brake fluid dissolves/degrades PTFE. Try Permatex instead, if you want to go this route.

  3. If you think you need a seal, you should fix the problem rather than putting a band-aid on it.

If you still want to use PTFE still, then buy the good stuff (it's usually grey in color), rather than the 50c white stuff at the big box hardware store - a tip for plumbing as well as car repairs!

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    "Teflon tape is not a sealant." actually it is, ask any plumber, just not in this case.
    – Moab
    May 18 '16 at 20:03
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    And there is no "real problem". The question came up because I found other threads that talk about using it in this application and I had never heard of ding that. It seemed like a bad idea so I thought I would ask the question. Especially since so many of the folks in here are pro's, and while I may not do it for a living, its the level of work I aspire to. So when I find something that seems off, I ask.
    – cdunn
    May 19 '16 at 2:40
  • And according to the original listed post, virtually nothing degrades the tape chrmically. It's one of that materials key properties..
    – cdunn
    May 19 '16 at 2:42
  • The title of the article I'm linking here is: Thread Seal Tape en.wikipedia.org/wiki/Thread_seal_tape It's all about PTFE tape. A Google search for (What is the purpose of PTFE tape) produces 168,000 hits, the first page of which is all about how PTFE tape is used to seal threads. It's not good for this application, but that was the point of the question, since other threads here suggest that it be used. Hence the curiosity about it.
    – cdunn
    May 20 '16 at 17:14

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