Author Topic: brake bleeder screw question  (Read 1534 times)

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Offline MikeJW

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brake bleeder screw question
« on: July 15, 2010, 12:59:42 PM »
Been fixing things on my '72 CB750 since I got it eight months ago. Next on the list was front brakes which stopped me OK but I knew they were dragging a little. So, ordered the parts, disassembled the caliber and cleaned it carefully and installed new pads & seal. Put it back on the bike and started to bleed air from the system. I had read the FAQs...even printed some of them and studied at night. So, several hours later, I am still sucking air bubbles out and apparently, making no forward progress. I felt like I had sucked enough air to inflate the Hindenburg. I decided something was amiss. I removed the air bleeder screw and wrapped the threads with some Teflon tape & replaced it. Twenty minutes later, I had 99% of the air out and my brake lever was firm and my brakes worked.
So, the question is: Was the Teflon tape an incorrect solution? Is there some major reason not to have used it. I was really getting hot & frustrated. For those of you not familiar with this area, it is 98 degrees with about 120% humidity. Still about 90 at 9:00 at night.
Mike in Memphis
1972 CB750K2

Offline eideteker

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Re: brake bleeder screw question
« Reply #1 on: July 15, 2010, 01:31:24 PM »
I've been to Memphis in the summer - *oof*  :D
"Spit on the tip of your finger, lube the inside of the hole, and then wiggle it around and twist a bit back and forth as you apply pressure." - mystic_1

1973 CB500K - not bad for a first bike
2009 SFV650 - torquey, reliable 90° V-twin

Offline kenolds

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Re: brake bleeder screw question
« Reply #2 on: July 15, 2010, 01:39:24 PM »
The threads of the air bleeder do not do any sealing except when it is actually open and being bled.  The pointed tip of the bleeder is what seals the bleed hole when it is tightened.  I don't think the teflon should have done any good, but it shouldn't hurt either.  It may help keep it from getting stuck in the future.

Kenolds
Parts, Parts, Everywhere - But Not A Bike To Ride.

Offline MikeJW

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Re: brake bleeder screw question
« Reply #3 on: July 15, 2010, 02:04:12 PM »
Well, I know it's not supposed to, but no matter how little I cracked the bleeder screw open, when I applied suction, I think it was pulling in outside air around its threads. When I put the tape on, it apparently made that impossible and I got it done.
1972 CB750K2

Offline markb

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Re: brake bleeder screw question
« Reply #4 on: July 15, 2010, 02:15:16 PM »
I think it was pulling in outside air around its threads.
I think that's correct and that's been my solution more than once.
Mark
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Offline nancy

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Re: brake bleeder screw question
« Reply #5 on: July 15, 2010, 02:56:56 PM »
Fit a new bleeder screw - cheap. Threads will be rooted.

Offline kenolds

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Re: brake bleeder screw question
« Reply #6 on: July 15, 2010, 04:09:20 PM »
OOOHHHHH!  Now i get it. I had no idea you were using suction to bleed the brakes.  I have always just pumped it through the system with the master cylinder into a bottle.  Makes more sense to me now, but It doesn't change my opinion that the Teflon tape is OK.

Kenolds
Parts, Parts, Everywhere - But Not A Bike To Ride.