A few weeks ago I replaced my faulty brake light switch(activated by brake fluid pressure) on my '75. It seems to seep slightly even though I have tighted it in increments since the installation. I don't want to over-torque it or hurt the banjo bolt. Is it OK to use something like Permatex sealer on the threads, or will that cause problems? Other suggestions? Thanks!

 

Does it use a copper crush washer to seal against the banjo bolt? I don't have that switch (I have a mechanical one on the pedal box) so I can't refer to mine but all brake parts that I've dealt with that have a banjo bolt have crush washers on both sides of the banjo fitting. They're there to deform to seal the fitting and prevent a leak.

My guess is that's the problem, but perhaps someone here can confirm it. If you did use crush washers, did you reuse the old ones? If so, any deformation may lead to your leak.

 

Thanks for the thought about crush washers, but the switch involved does not use them. It's a pipe thread that's supposed to seal without a crush washer. Guess I'll keep thinking...

 

Did you wrap the thread with plumbers PTFE tape before doing it up......

 

mk1leg- No, I didn't use anything, but after a discussion with an experienced local parts guy, I'm in the middle of a test right now. The PFTE tape has been soaking in some brake fluid since Friday and so far seems to be holding up well. Have you used tape in contact with brake fluid successfully? I'd feel more confident before going ahead if I had some positive feedback from another classic owner. If you used it, how many turns of tape did the trick? Thanks for any advice you can offer!

 

in my experience

classic or other wise

Teflon tape is not required or advisable in a brake line. Never used it in a brake line . . .