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How To Test The Combined Braking System?


WalkThisWhey

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My bike has had several owners, and I am pretty sure it had some track day use prior to me (although I am track day-ing it now :) )

This is my first sport style bike, I had a cruiser before - In performance situations, I am not sure what a CBS system is supposed to feel like compared to a standard system.

I'd like to test to see if a previous owner disabled the CBS system. How can I test to make sure the brake system is working as a CBS system, or what should I look for?

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When approaching a stop sign or in an open parking lot where you practice your emergency stops that you have already and are certain is clean of debris that could result in a drop try to slow the bike by just applying the rear brake.

You should feel the bike slow much more quickly than a bike that does not have linked brakes.

You can also test by having a friend spin the rear wheel while it is on the center stand. When the rear is spinning manually compress the secondary master on the left front fork lower that links to the rear brake and verify that the rear brake is stopping the spinning rear wheel.

Your bike has very good brakes with the second generation LBS (or CBS for other markets) and the ABS. Because the system does not rely on electronics (apart from the ABS) there really is not much to go wrong as long as you have firm pedal and lever they are working correctly.

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  • 2 weeks later...

When approaching a stop sign or in an open parking lot where you practice your emergency stops that you have already and are certain is clean of debris that could result in a drop try to slow the bike by just applying the rear brake.

You should feel the bike slow much more quickly than a bike that does not have linked brakes.

You can also test by having a friend spin the rear wheel while it is on the center stand. When the rear is spinning manually compress the secondary master on the left front fork lower that links to the rear brake and verify that the rear brake is stopping the spinning rear wheel.

Your bike has very good brakes with the second generation LBS (or CBS for other markets) and the ABS. Because the system does not rely on electronics (apart from the ABS) there really is not much to go wrong as long as you have firm pedal and lever they are working correctly.

The friend spinning the real wheel seems interesting, I will try it!

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The CBS system connects the front and rear brakes to enhance braking stability. When you apply just the back brake it apples pressure to 2 of the 3 rear pistons, and through a delay valve, 2 of the front pistons. When you apply just the front brake, the left caliper rotates slightly and moves a secondary master cylinder, and this applies pressure to a single piston in the back brake. If you've got lots of plumbing going to the front calipers, then the CBS is in place.

Because of the design, just spinning the back wheel with the bike on the stand and grabbing the front brake does nothing, the front wheel needs to be turning so the secondary master cylinder is activated.

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It'll be quite obvious out on the road, the bike stops very well simply by just applying the rear brake. The front squats down like you are applying the front (because you are!) :)

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Because of the design, just spinning the back wheel with the bike on the stand and grabbing the front brake does nothing, the front wheel needs to be turning so the secondary master cylinder is activated.

That's actually what cornercarver said to do... To actuate the secondary master by hand... Not the front brake lever.

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  • 1 year later...

So if my back brake is clamping on, it would be to do with the front? could this be an electrical fault, how would be best to fiddle and check?

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The secondary master cylinder attached to the fork leg drives the centre piston in the back caliper; when you apply the front brake, the caliper rotates a little with the disc and generates pressure using the secondary master cylinder. It is not uncommon to get some crud in the SMC that stops the pressure being released from the centre rear circuit. You can confirm which hydraulic circuit is the culprit by cracking one bleed nipple at a time at the rear caliper and seeing which one releases the brake. A good brake bleed session might flush the debris through if you get lucky. You need to follow the exact procedure/sequence in the service manual. 

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