Diagnosing front brake with no pressure after caliper and MC rebuild
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6th Gear
Joined: Apr 2022
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From: Georgia
Diagnosing front brake with no pressure after caliper and MC rebuild
Rebuilt front MC and caliper on '97 wide glide as it was suggested to me after brake lever was wobbly and MC was gunked up. Followed the directions to a T, but now I'm trying to bleed the brakes and there's a continuous flow of air from the bleeder. Tried the old fashion way and the brake never built pressure or released fluid from the bleeder. Tried using a vacuum pump and after 2 bottles of fluid there's still mostly air with not much fluid. No pressure at the lever at all..
Any advice appreciated
Any advice appreciated
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From: Honah Lee
Did your rebuild kit include both the master cylinder cylinder insert along with a new piston?
As long as you are keeping fluid in the reservoir, even if it would not pump pressure, all the air would have come out with a vacuum pump.
Obliviously, only way for air in is thru the pushrod end.
However your always going to see a few bubbles leaking past bleeder threads.
If you used old cylinder, it could have had corrosion at bottom and the attempt to bleed with pedal destroyed the new cup seals.
Cap needs to be loose also and that small hole in bottom should make a little wave in fluid when you let off. With brake off, hole should be open to piston cavity. It closes as soon as you push brake pedal.
As long as you are keeping fluid in the reservoir, even if it would not pump pressure, all the air would have come out with a vacuum pump.
Obliviously, only way for air in is thru the pushrod end.
However your always going to see a few bubbles leaking past bleeder threads.
If you used old cylinder, it could have had corrosion at bottom and the attempt to bleed with pedal destroyed the new cup seals.
Cap needs to be loose also and that small hole in bottom should make a little wave in fluid when you let off. With brake off, hole should be open to piston cavity. It closes as soon as you push brake pedal.
Last edited by Jackie Paper; Jun 29, 2023 at 03:49 PM.
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6th Gear
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From: Georgia
It was the OEM kit, had the piston, O rings, spring, rubber dust cap, and whatever else comes in the kit. I used the lubricant that came with the kit, also on the caliper piston I used the right grease and I put fresh crush washers on the banjo fittings.
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From: W. Texas
lube uh always used brake fluid >
How much and how thick is this lube ___ brake grease??
To much might block off port in M/cyl.
WP
Thread Starter
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6th Gear
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From: Georgia
Thread Starter
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6th Gear
Joined: Apr 2022
Posts: 14
Likes: 0
From: Georgia
Some generic one off Amazon. Hard to tell if the vacuum pump loses pressure because of the pump or an air leak at the line/MC. I just pulled the MC again and going to double check it, I'll bench bleed this time. But the volume of air I was getting through the vacuum pump looks like there has to be some kind of leak
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From: Honah Lee