Hi all,

I have done my community service and introduced myself in the new member section (although it's more of a reunion as I was on here a while back and have fallen off after a couple of years). Now I'm hoping to get some feedback from you smarties on an issue that our NC35 has had for almost 4 years now.

Basically, the rear brake seizes in a consistently random pattern - meaning it will seize on almost every ride we take it on, but it may be after 5 minutes or 55 minutes, hot or cold weather, if you use it or don't use it. It seizes completely on its own and locks up both the brake lever as well as the caliper. We have to pull over and crack the bleeder on the caliper to relieve the pressure and this fixes it.

We have replaced the rear rotor, then rebuilt the rear master cylinder and still no luck. The brake line is steel braided and in California (sea level) there was no problem but after we moved out to Colorado (about 1 mile in altitude) this problem arose. We thought it might be heat related given how close the line is to the exhaust so we re-ran the line on the other side of the shock but this didn't fix it either. We are thinking of re-running the line on top of the swingarm next (it is currently run through the swingarm which was fine in California) and replacing/rebuilding the rear caliper.

So....questions are: does this sound like it could be heat related? Has anyone heard of a brake building pressure on its own? Anything else to try for a fix? It seems like throwing money at it isn't working so we're trying to do more research before we buy more parts.

Thanks for your help!!!

What do you mean by 'locks up the rear lever and caliper'?

Are you saying when you push on the lever it does not return? Presumably you are still running the standard footpegs with return spring?

Pull the caliper off the disc and press the brake lever. Watch what the pistons do, they should expand (press the pads together) and retract. If they do not expand or retract freely, you need to rebuild the caliper.

Chances are your caliper pistons is dirty, scratched or damaged in some way preventing it from moving properly. Brake caliper seals are cheap and it's an easy job, especially if you have already done the master cylinder. While it is all apart I would check the line doesn't have a blockage too.

So a little more detail on the issue - if the bike is off the brake works just fine (you press the lever and the brake engages and disengages). At some point during our ride the brake will engage on its own. For instance, we will come up to a stop sign using front brake only and the bike will feel sluggish. Sure enough when you try to push the bike (without the engine engaging) it won't move. You hop off the bike and the brake lever is pushed all the way down and you can't move it up or down. Tee caliper is completely engaged until we crack open the bleeder.

We do have WR rearsets on the bike (hopefully those haven't been the source of any issues for other folks) but those were on for a few years before this started happening. When we looked at the bike last night we think maybe the brake line had too many bends in it by having it run through the swingarm and having the rearsets so we are going to replace the brake line and run it on top of the swingarm now which might help it out too.

I also think we cleaned out the caliper a few years back (right when this first started happening), but agree that it couldn't hurt to check it again.