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I'm a newbie '76 Shovelhead owner and finding my way bit by bolt. I had to remove the front caliper to replace the bushing, which was causing the caliper to rattle like a trash can, and that fixed the problem. I thought I had reassembled the caliper correctly, though I may have had an extra washer left over. It seemed fine though on the few short rides I took before winter set in. This spring after a couple rides which seemed OK, I thought I smelled brake shoes from the car in front of me, and then noticed the brake lever got hard. And when I rolled the shovelhead into the bike barn it was hard to push. So it wasn't the car in front of me. It seems the front brake was grabbing and wouldn't let go. Returning to the bike after it cooled down, the lever was easy again and the bike rolled fine. This happened again on the next ride. So I am going to disassemble the caliper again and just thought I'd put it out there to see if anyone could share thoughts theories so I know what I'm looking for. Thanks.
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Rodfun,
A) What you are experiencing is typically caused by the fluid level in the master cylinder on the handle bars being to "Full".
Please verify the fluid level is not overfilled. It requires a proper air gap above the fluid to allow it to expand when the fluid warms up from braking friction.
B) Your master cylinder piston may not be fully returning to its home seated position determined by the return spring and snap ring. If the case, the fluid can not retract properly when the hand brake lever is released, causing drag.
C) There is a pressure bypass and an equalization port in the master cylinder. They will become restricted and plugged due to lack of Brake fluid service work. If they are not open, your brake will hang up.
D) The piston in the brake caliper maybe be hanging up and not "retracting" as designed when the hand lever is released. This can be caused by a piston that needs cleaning, caliper seal grooves that need proper cleaning or aftermarket caliper seal kits that measure dimensionally larger than OEM.
Hope this helps,
Duke Kleman
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Exactly what Duke said.
Short version, check the vent hole in the master cylinder cap.
I goofed one time and painted mine shut and had the same issue.Comment
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If it started immediately after working on the caliper, I would suspect the caliper first or overfilled cylinder like Duke suggested.Comment
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I just checked and the master cylinder well is about a quarter inch from the top and the vent seemed clear when easily I ran a wire through it. I believe it was working fine before that, but I hadn't ridden it much at all as winter came on fast here. When I disassembled the caliper I did not disconnect the brake line or open the master cylinder or bleed it. Didn't seem necessary. After I replaced the bushing I just re-assembled it. So I assumed I did something wrong on re-assembly.
It was gone through and set up by my experienced mechanic, and I quote: "Front brake caliper and master cylinder leaking and generally in poor condition. Rebuilt caliper, replaced puck. Installed new pads. Cleaned out M/C, dressed surface installed new gasket." I'm going to take it back to him for some other work but he's 200 miles away and I was hoping to ride it up there. So maybe I need to just disassemble and see if anything jumps out at me.
Thanks everyone,
RodComment
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Rod,
If you elevate the front tire, does it spin freely before you ride it?
Or
Does it have a drag ...light drag or heavy drag?
I have a few other suggestions based on your findings.
Duke KlemanComment
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It has a fairly heavy drag. Spins less than 1/4 turn.Last edited by RodFun; Yesterday, 02:48 PM.Comment
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A couple of things to check for:
A) The thickness of after market brakes can be an issue if they are thicker than OEM, which isn't uncommon.
B) The replaced puck you mentioned could be out of dimension and not allow enough space when fully retracted.
C) The new bushing you installed may not have enough clearance to were it doesn't " Float " on the pin causing drag.
D) The new bushing may not be pressed into the bore parallel causing a issue with parallelism and float.
Hope this helps,
Duke Kleman
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