front brake dragging on 84 CR250

n8MX

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Joined
Mar 27, 2001
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#1
Hello,

I am having problems with my 1984 CR250. I first noticed the problem when wheeling it around... it was harder to move than any other bike I have been around. I thought it was just because of the weight (I am fairly new to riding the bigger bike), but it seemed pretty bad.

Last week I was working on it, and had it up on a stand, so I thought I would see if the front wheel rotated OK (since I thought it might be the cause of the problem). I picked the front wheel up off the ground and tried to rotate it - it would hardly move! I would say it took about 10 pounds of force on the tire to move it - definitely the problem. I never expected that it would be so severe. My dad wanted to leave (we usually keep our bikes at our friends house since it is almost the only place we ride), so I decided to work on it later...

I went back on Saturday to work on the bike some more, and I worked on the brake with the help of a friend who has tons of experience working on mx bikes. After cleaning the disk/pads as best I could with brake cleaner (which didn't help at all) we took off the front wheel and the caliper, because he suspected a frozen piston that was binding against the disk. Everything seemed OK, the pistons came out and pushed the pads together, so we cleaned it more and put it back together.

The wheel spun freely while it was up in the air. When the front brake lever was pulled, it stopped the wheel fine - or so it seemed. When I took the bike off the stand it rolled fine at first, but after stopping it about three times with the brake lever, the system seemed to 'pump up' to the previous condition. The front brake is usable when riding, so it is working soemwhat. It seems like the pistons aren't pulling in quite far enough when the brake is released, and instead staying pressed against the disk more than they should.

Does anyone know what the problem could be? Maybe suggestions on stuff to look for or what steps to take next?

Thanks,
Andy
 
Joined
Jan 25, 2001
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#2
Option 1 my favourite: take the brake lever off & see if it gets better. Some pattern or incorrect levers won’t allow the piston back far enough in the master cylinder to open the return hole. Take the cap off the mc & ensure the internal rubber cover is still there & the breather hole in the cap isn’t blocked.

Still not better? pump the calliper piston out & flush, there may be sludge behind it stopping it return.

Master cylinder might need a rebuild.