Hello everyone,

I recently purchased a Silver 1987 Hurricane 1000F with 24K miles.
I have recently come across an issue with the front brakes that has me stumped. Whenever it is setting out in the sun or on a hot day the front brakes will compress on the rotors. As you can imagine that can be pretty inconvenient when trying to actually move the bike.

So far I have: Rebuilt the Master cylinder which didn't solve the issue so I installed stainless steel braided brake lines. (double banjo bolt at the master into two separate lines) and now it is still doing it but not as bad.

When it happens I can pop open the bleeder on one side and a bit of fluid jets out then and the pads release the rotors. So I don't think that the calipers are sticking.

Any ideas other than carrying around a wrench to release the pressure?

Thanks for any help!

 

Firstly welcome to the CBR Forum Tim.

Now to the brakes. Have to brakes been bled correctly - no air AT ALL in the lines? The brake fluid DOT 3 or 4 will not expand with heat but air will. Have you tried reverse bleeding to ensure all air is out of the lines?

Apart from that I'd be looking at the calliper seals and rubbers.

Cheers, SB

 

Hi Tim

You say you have rebuilt the master cylinder. If on reassembly something is preventing the piston from returning completely (a slightly tight lever or something else) this does not allow the pressurised fluid in the lines to exhaust back into the res erviour then pressure will be retained in the system.
You will need to check that the front pressure seal on the piston comes back far enough to clear the port in the bottom of the reserviour.
Ask me how I know this .....I had the same problem with the brakes on a CX550 sport that I owned a few years ago.Careful checking of the piston travel and lever position showed this to be the cause.

 

Thanks for the welcome.

I am fairly certain that there is no air in the lines, but I will double check that.
I have new pads arriving this week so I will check the calliper when I go to put those on. Thanks for the suggestions.

 

I will definitely check that out. Thanks!

 

Re-bled the brakes and didn't see any air. Tomorrow is supposed to be nice and sunny so I should know if it helped by the afternoon.

 

I've cleaned and put new seals on the calipers and new brake pads. First ride to test the new brakes and I hit a patch of wet grass in the driveway while braking and went down. I don't think I damaged anything but plastics... Got the bike back right side up and did a small test ride. The front end shakes under heavy breaking worse than it did before, I think I warped the rotors when the brakes were clamping down before and it did that before changing brakes and laying it down. So New rotors, fork seals and tires are on the way and with any luck will be on the bike by the end of next week.

Hopefully cleaning the calipers and new seals has taken care of the original issue but I think by the time the bike is back on the road the hot weather will be done and I may not be able to verify that the issue has been taken care of until next summer...

 

Tim, have you checked the pin hole for releasing the fluid back into the master cylinder after the brakes are let go is not blocked? My '87 suffered that problem. I rebuilt the callipers but the brakes would lock up after a couple of heavy applications. I found corrosion in the hole, punched a needle through it when I scrubbed the master cylinder clean and no problems since.

Cheers, SB

 

Yup that is nice and clean. Once I cleaned up the callipers and replaced the seals and was in the process of bleeding the lines I did notice that the pads appear to be moving better now. When I take it to the shop to have the fork seals, tires and rotors done I'll ask them to give the brakes a once over to double check my work.

I appreciate all the help so far, you guys are great!

 

Apparently I didn't get the pinhole cleaned out all the way... Took another stab at it this weekend, since the weather decided to clear up enough so I could go outside and work on the bike, and double checked the pin hole. Now I am able to get fluid back into the master cylinder. I talked to a mechanic at the local "old bike" shop and they are going to open that hole up a little bit more so that it doesn't get clogged as easy. So that solves the puzzle! Thanks to everyone!

The bike goes into the shop this week for tires, front rotors, fork seals, sprockets and a new chain. So I should be back up and in good shape for the end of the season.