Front Brake lock up!!!
Club Member
Joined: Feb 2007
Posts: 16,320
Likes: 306
From: Boynton Beach, FloriDuh
Jumping on this thread as I'm having this exact issue with my '06 Fat Boy. Same symptoms - drag started a mile from home at ~20mph, which stopped me in my tracks. Bled the front brake to release pressure, and was able to get it back to my garage.
I found a lot of crud in the master cylinder reservoir, and discovered that the brake fluid would not transfer down into the line when bleeding with a MityVac. This pointed towards the master cylinder being clogged, so I purchased the rebuild kit, cleaned everything out well and re-assembled. Brake fluid now freely transfers.
After bleeding to remove air, I went for a short test ride. Within a block of where it happened last time, the front brake locked up again. So, I'm now at a loss - thinking the caliper needs to either be thoroughly cleaned or replaced.
I found a lot of crud in the master cylinder reservoir, and discovered that the brake fluid would not transfer down into the line when bleeding with a MityVac. This pointed towards the master cylinder being clogged, so I purchased the rebuild kit, cleaned everything out well and re-assembled. Brake fluid now freely transfers.
After bleeding to remove air, I went for a short test ride. Within a block of where it happened last time, the front brake locked up again. So, I'm now at a loss - thinking the caliper needs to either be thoroughly cleaned or replaced.
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Elite HDF Member
Joined: Nov 2006
Posts: 4,525
Likes: 8
From: Wheeling, WV
+1 on what cHarley said. The crud probably worked its way down into the caliper now. I haven't torn into mine yet, but I'm figuring both the master cylinder and caliper will need cleaned/rebuilt.
Road Master
Joined: May 2007
Posts: 899
Likes: 10
In general no matter what DOT fluid it says to use on the master cylinder cap or the manual if you start with a clean flushed out system you can use any DOT fluid. However, once someone makes the mistake of mixing DOT 4 and DOT 5, and it's in there long enough to jell, you're kind of screwed. You can flush out the calibers with denatured alcohol when you aren't sure what DOT fluid is in them, like when you buy a used caliber for a build, but getting already jelled fluid out is very hard. And it only takes a small bit to break loose and cause problems down the line.
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