Brake light staying on
Thread Starter
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6th Gear
Joined: Mar 2010
Posts: 10
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Brake light staying on
I am after some help with the brakes on my '89 Sportster.
First some background - The front master cylinder, and front brake cylinder, were rebuilt about 18 months ago. At the same time, the front brake switch was replaced, and new brake and clutch lever fitted.
Now the problem, which started about 9 months ago - The front brake light stays on continually.
The first thing I checked was the brake switch itself. This is secure, and is working fine.
I then reassembled everything, and still had the same problem when the front brake was applied. The brake light stayed on.
On closer inspection it looked as though the pushrod in the master cylinder wasn't being pushed out far enough, by the main spring behind the piston, to activate the switch. To solve this, I added a small spring between the pushrod and the master cylinder housing. Now I had a working brake light. Unfortunately this only helped for a couple of months, and I was back with a brake light that stayed on after the front brake lever was released.
I then found a Youtube video, showing a similar problem, and used Red Rubber Grease to lubricate the dust cap and pushrod. This made a difference, and the brake light switched off. This worked for a couple of weeks, and then the problem returned.
Yesterday, I stripped, cleaned, and rebuilt the entire Master cylinder with a rebuild kit. The brakes were bled, and out I went for a test ride. An hour later, when I got home, I still have the same problem, but with a small twist. Now, when I release the front brake lever, the brake light goes out after about a minute.
I just can't get the brake light to go off when the front brake lever is released.
Short of buying a new master cylinder, how can I fix this and get the brake light to work the way it should?
First some background - The front master cylinder, and front brake cylinder, were rebuilt about 18 months ago. At the same time, the front brake switch was replaced, and new brake and clutch lever fitted.
Now the problem, which started about 9 months ago - The front brake light stays on continually.
The first thing I checked was the brake switch itself. This is secure, and is working fine.
I then reassembled everything, and still had the same problem when the front brake was applied. The brake light stayed on.
On closer inspection it looked as though the pushrod in the master cylinder wasn't being pushed out far enough, by the main spring behind the piston, to activate the switch. To solve this, I added a small spring between the pushrod and the master cylinder housing. Now I had a working brake light. Unfortunately this only helped for a couple of months, and I was back with a brake light that stayed on after the front brake lever was released.
I then found a Youtube video, showing a similar problem, and used Red Rubber Grease to lubricate the dust cap and pushrod. This made a difference, and the brake light switched off. This worked for a couple of weeks, and then the problem returned.
Yesterday, I stripped, cleaned, and rebuilt the entire Master cylinder with a rebuild kit. The brakes were bled, and out I went for a test ride. An hour later, when I got home, I still have the same problem, but with a small twist. Now, when I release the front brake lever, the brake light goes out after about a minute.
I just can't get the brake light to go off when the front brake lever is released.
Short of buying a new master cylinder, how can I fix this and get the brake light to work the way it should?
Seasoned HDF Member
Joined: Feb 2013
Posts: 25,075
Likes: 19,467
From: New York
I had a similar situation. It turn out the front brake leveler was not returning fully due to the way I had it position on the bars. I rotate the the master cylinder assembly and no more problems.
Thread Starter
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6th Gear
Joined: Mar 2010
Posts: 10
Likes: 0
The master cylinder fits into the switch housing. This is correctly fitted, and tight. I know this can have an effect on the brake light if not fitted properly.
I have posted pics to show how the setup is mounted. My bikes live on motorcycle dollyies and stand straight up, rather than at an angle on their jiffy stands.
What I don't understand is that this worked for ages before suddenly not working.
Tourer
Joined: Oct 2014
Posts: 378
Likes: 134
From: South Dakota
So, why not share what you found so that others can have the benefit of your experience?
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