Miles Long
Well-Known Member
Hi Buds -
This incident happened last July 2nd. Now that my heart rate has finally returned to normal, I feel comfortable enough to post a question.
In June of last year, I replaced the brake fluid (using NEW DOT 4), in both front and rear brakes, as well as the clutch. I had disconnected the front brake lines because of a handlebar changeout. Consequently, bleeding the fronts took longer than usual - I didn't have a Mityvac at the time - but eventually all the air was purged, and the brakes felt solid. The master cylinder was filled to the proper level.
I also had put on new levers at this time, so I jacked up the front end, spun the wheel, and adjusted the lever screw so that the brakes engaged slightly after pulling the lever, just a little "play". All seemed well, so I thought.
I then put at least 500 kilometers on the bike, mainly short hops, prior to leaving on a tour July 1st.
The next day I found myself on Route 20, the Quebec freeway, tooling along at highway speed, my riding buddy following behind me. It was a hot day, as I recall, not too much traffic, no need to use either brake for some time.
Then it happened - the bike started to hestitate, slowing down quicky - my first thought was that I had dropped a cylinder or two for some reason, I gave it gas, nothing, the bike continued to slow down, really fast, until I was at a complete standstill. 110 kph - 0, in probably less than 10 seconds, using neither front or rear brakes, or gearing down!
Three events occurred that day which confirmed my belief in Guardian Angels.
- I happened to be in the right hand, slower lane.
- When the bike slowed to the complete stop, I was exactly next to a small traffic triangle, formed because of a merging lane. I managed to move the bike slightly to the right, and stopped on this tiny piece of asphalt. I very nearly went over, it was slowing that fast.
- My riding buddy was behind me. This almost never happens.
And oh yeah, the infamous Quebec drivers seemed slightly off their game that afternoon - no speed junkies, no one passing on the right, no one butt-ending my buddy or I in the traffic triangle. Make that four events.
Anyway, both front calipers were seized solid (my buddy saw a cloud of smoke while I was slowing down - he thought the engine had blown),the front discs were too hot to touch - and - the front brake lever was rock solid, no movement in either direction.
After about 10 minutes, the brakes had relaxed just enough so that we could push the bike off the triangle, and onto the side of the highway. After 30 minutes, the brakes were more or less free, as well as the lever. The only change I did during this time was to back off the adjusting screw on the brake lever. We then rode (slowly) to the nearest bike shop, where a mechanic told me "both your front calipers are seized" He wanted to order in the dust seals and o-rings-over $400 worth,- and do the job "within 2-3 days". This diagnosis didn't make sense to me - why would both calipers seize at exactly the same time? The cause had to be because of something common to both sides.
We left the shop and got the nearest campsite. The next morning, I took off both calipers. All pistons were free to move. Other than some glazing on the pads and some wear marks on the rotors,(surprisingly, they did not warp), all was normal.
As for the cause - the only thing I can think of was that the adjusting screw had been too tight, or that the locknut had come loose, causing the screw to go clockwise, therefore eliminating any free play, causing the brakes to drag, causing everything to heat up, eventually boiling the brake fluid until it expanded in the calipers and master cylinder, locking the lever in the fully out position.
In any event, we continued the trip. No further brake problems, 19,000 k. later. I did get in the habit of regularly checking for free play in the lever, while riding, and checking the rotors for excessive heat, after stopping.
My question(finally) - has anyone else ever had a front or rear brake seize like this, while riding? What was the root cause, and the cure???
Thanks in advance, Miles
This incident happened last July 2nd. Now that my heart rate has finally returned to normal, I feel comfortable enough to post a question.
In June of last year, I replaced the brake fluid (using NEW DOT 4), in both front and rear brakes, as well as the clutch. I had disconnected the front brake lines because of a handlebar changeout. Consequently, bleeding the fronts took longer than usual - I didn't have a Mityvac at the time - but eventually all the air was purged, and the brakes felt solid. The master cylinder was filled to the proper level.
I also had put on new levers at this time, so I jacked up the front end, spun the wheel, and adjusted the lever screw so that the brakes engaged slightly after pulling the lever, just a little "play". All seemed well, so I thought.
I then put at least 500 kilometers on the bike, mainly short hops, prior to leaving on a tour July 1st.
The next day I found myself on Route 20, the Quebec freeway, tooling along at highway speed, my riding buddy following behind me. It was a hot day, as I recall, not too much traffic, no need to use either brake for some time.
Then it happened - the bike started to hestitate, slowing down quicky - my first thought was that I had dropped a cylinder or two for some reason, I gave it gas, nothing, the bike continued to slow down, really fast, until I was at a complete standstill. 110 kph - 0, in probably less than 10 seconds, using neither front or rear brakes, or gearing down!
Three events occurred that day which confirmed my belief in Guardian Angels.
- I happened to be in the right hand, slower lane.
- When the bike slowed to the complete stop, I was exactly next to a small traffic triangle, formed because of a merging lane. I managed to move the bike slightly to the right, and stopped on this tiny piece of asphalt. I very nearly went over, it was slowing that fast.
- My riding buddy was behind me. This almost never happens.
And oh yeah, the infamous Quebec drivers seemed slightly off their game that afternoon - no speed junkies, no one passing on the right, no one butt-ending my buddy or I in the traffic triangle. Make that four events.
Anyway, both front calipers were seized solid (my buddy saw a cloud of smoke while I was slowing down - he thought the engine had blown),the front discs were too hot to touch - and - the front brake lever was rock solid, no movement in either direction.
After about 10 minutes, the brakes had relaxed just enough so that we could push the bike off the triangle, and onto the side of the highway. After 30 minutes, the brakes were more or less free, as well as the lever. The only change I did during this time was to back off the adjusting screw on the brake lever. We then rode (slowly) to the nearest bike shop, where a mechanic told me "both your front calipers are seized" He wanted to order in the dust seals and o-rings-over $400 worth,- and do the job "within 2-3 days". This diagnosis didn't make sense to me - why would both calipers seize at exactly the same time? The cause had to be because of something common to both sides.
We left the shop and got the nearest campsite. The next morning, I took off both calipers. All pistons were free to move. Other than some glazing on the pads and some wear marks on the rotors,(surprisingly, they did not warp), all was normal.
As for the cause - the only thing I can think of was that the adjusting screw had been too tight, or that the locknut had come loose, causing the screw to go clockwise, therefore eliminating any free play, causing the brakes to drag, causing everything to heat up, eventually boiling the brake fluid until it expanded in the calipers and master cylinder, locking the lever in the fully out position.
In any event, we continued the trip. No further brake problems, 19,000 k. later. I did get in the habit of regularly checking for free play in the lever, while riding, and checking the rotors for excessive heat, after stopping.
My question(finally) - has anyone else ever had a front or rear brake seize like this, while riding? What was the root cause, and the cure???
Thanks in advance, Miles
