Brakes with a mind of its own !!
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Novice
Joined: Apr 2013
Posts: 15
Likes: 4
From: Hopewell Jct
I was riding my 2006 FLHXI the other day just a few miles from home, I stopped for a traffic light proceeded down the road after the light changed , never touching the FRONT BRAKE LEVER AGAIN !...and all of a sudden the brakes applied by themselves and locked my front wheel up...Down I went !..As myself and bystanders who helped me right the bike said lets push it off to the side , bike wouldn't move an inch , couldn't move front brake lever at all , banged on the Master Cylinder on the handlebars and sure enough it released..Has anyone ever heard of this happening before ??....PS~ ordered a new Master Cylinder !
Road Master
Joined: Mar 2013
Posts: 1,151
Likes: 14
From: Seattle
When buying a used bike (even from a dealer) it's probably a good practice to replace ALL fluids when you get it home including flushing the brakes. You never know how well the bike has been maintained.
Glad you didn't get hurt and have it handled.
Glad you didn't get hurt and have it handled.
Stage II
Joined: Jan 2018
Posts: 2
Likes: 0
From: North Carolina
Front brakes with a mind of their own
Same thing happened to me last week. Came to stop and front brake lever wouldn't move (but brakes weren't engaged) Started off and at around 30mph I felt front brakes engaging on their own. Before I could stop, they locked up, sending me headfirst to the asphalt. Had the bike almost a year and flushing brake fluid was first thing I did after I saw how bad the oil looked (16000mi and don't think it had ever been changed) The brake fluid I flushed was cloudy with lots of debris, but never were any braking issues. After regaining consciousness and returning home from ER, found my front brakes to be working fine. No one I've talked to has ever heard of this happening. Luckily I was pulling over as they locked up and only going around 20mph or could've been much worse. Hindsight-should've checked everything when lever wouldn't move, but I guess that's why it's 20/20
Grand HDF Member
Joined: Jan 2012
Posts: 4,453
Likes: 2,839
From: Oklahoma
Obviously, it happens. If you were on more forums you would see that this is somewhat common. There is an equalization port in the master cylinder. It does 2 things, it lets in new fluid to the brake line as the pads wear and allows fluid to escape the brake lines if heating causes expansion. It is intentionally blocked when activating the brakes so that fluid pressure can be maintained, and it should open again when the lever is released. It can be blocked either by dirt or a master cylinder piston not fully retracting after use. On our machines the port is very small so not much dirt is needed to block it. Brake fluid attracts water and water causes corrosion. We see the results of corrosion as the dirt in the bottom of the reservoir. The "dirt" can also bind the piston so that it doesn't fully retract after use and that blocks the port. With my brake lever there is no free "flop" in its movement. The spring in the master cylinder and the piston travel push the lever against the stop. If that spring tension disappears, the piston is not fully returning to the normal position and the lever will have a tiny amount of slop before contacting the plunger.. This is the only hint you will get that trouble is ahead. Taking the top off the reservoir and checking for "dirt" should be done periodically, based more on TIME than on number of miles.
Stage II
Joined: Jan 2018
Posts: 2
Likes: 0
From: North Carolina
Sounds right,except that brakes never engaged upon stopping at stop sign,lever wouldn't move, but brakes weren't engaged at all.Stopped using rear brake,had geared down so was nearly stopped when I tried either. But I do think heating as I was starting back was what was engaging them.
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Grand HDF Member
Joined: Jan 2012
Posts: 4,453
Likes: 2,839
From: Oklahoma
In a NON ABS bike, the fluid was already trapped and your fate was sealed. In an ABS bike, the most frequent cause is the ABS controller has a corroded, stuck valve and the fluid pressure from the lever won't even get to the caliper. No brake, rather than a locked brake.
Seasoned HDF Member
Joined: Oct 2012
Posts: 11,210
Likes: 3,040
From: St.Louis Mo.
had that happen on my 79 lowrider back in about 82. pulled into a gas station and when i hit the smooth pavement down i went. ended up at the feet of a very good looking young gal getting gas. it was hard to look cool with my knee hurting. broke the bleeders loose and made it home. rebuildt master cylinder and all was well. took me awhile to trust it again.
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