1100 Evo rear brake

[drheshamali]

The rear brake on my 2011 1100 Evo goes soft if I haven't ridden for a couple of weeks. I had it bled last summer, and it sounds like something that I may not be equipped for at home.

This time it happened after it was sitting idle for 4 weeks over Christmas/New Year's.

Is this a problem anyone else has experienced? What troubleshooting should I go through? What should the cost of bleeding it out again be?

[Luddite]

Is this a problem anyone else has experienced? What troubleshooting should I go through?

The short answer is "yes"! It's a common complaint and not just on the Evo. The problem is that the bleed nipple is at the bottom of the caliper so you'll never remove all the air if the caliper is left in situ. You need to remove and flip it like this...

The rear brake is well known for losing its effectiveness and will benefit from periodic bleeding. That's easier said than done though as you'll have noticed that the bleed nipple is on the bottom of the caliper and so it's very nearly impossible to remove all the air with the caliper in situ. I'd recommend unbolting it and flipping it over so it sits on the top if the disc like this:

https://s19.postimg.cc/mhy61p343/WP_20180204_14_48_12_Pro.jpg (https://postimg.org/image/jnv0o90xr/)

Put some masking tape on the caliper first to protect the paintwork as it will rub against the swinging arm in this position. It won't slide fully onto the disc but it's enough to hold it in the right position to bleed it properly. You can see the bleed nipple is now at the highest point.

Once properly bled, it should be firm enough to lock the rear wheel.

I wouldn't try this until you've got a new caliper bolt though, your slightly rounded one might not stand up to another removal.

http://www.ukmonster.co.uk/monster/showpost.php?p=552311

A dealer will probably charge you an hour's labour to do it, but make sure you tell them to flip the caliper, otherwise you'll be having the same problems again in a couple of months.

[drheshamali]

Thanks for this! The garage did turn it flip it last time which is why I'm a little annoyed its happened again.

Thinking back... I think it was last May so maybe it just needs doing every 8-9 months?

[Mr Gazza]

If it's been bled properly and lever action is restored to firmness, then it shouldn't need bleeding again so soon or often as yours.
There could be a leak somewhere? At any of the joins in the line, or an imperfect seat on the bleed nipple, or tired seals in the master or calliper.
It could also be down to very old fluid in need of a complete change, or inferior, or incorrect fluid.

On my 900 I had problems with the pads not retracting as they should although the brake was very effective. I tried all the usual things but finally cured it by fitting a new master.
The Brembo rear brake masters aren't great and do fail unfortunately.

[alickswud]

I had a pad return issue in my 796 that turned out to be an internal corrosion issue in the master cylinder. I had to replace it to restore the functionality.

[Luddite]

You may still have air in the ABS pump itself. I've heard that activating the ABS a few times helps to clear air from the system (always assuming your back brake is strong enough to trigger the ABS, of course!) The ABS unit can be bled, either by loosening the banjos or fitting a bleed nipple.

As a last resort, it may be corrosion in the master cylinder. See here for more details:

http://www.ukmonster.co.uk/monster/showthread.php?t=55504