Front brake pads continously applied

[Guest manx]

Dear all,

I am new to this forum, and also a new, proud owner of a nc700xd bike. I have noticed that on my bike, the front brakes are slightly applied. I have an intention to replace/bleed the brake system (which seems slightly complicated due to the front-rear interactions of the C-ABS system), but is now asking for general advice here.

I think I have a grasp on the general practice on bleeding brake system - but if anyone know - please let me know of the intrinsics of the NC700XD joint brake system (c-abs). 

 

BR, Martin

[poldark 1,509]

If you're doing it on your own then a one-way valve helps a lot, sold as a brake bleeding kit for only a few pounds. Search on fleabay for Item number - 351294401747

 

 

Also it's quicker and easier if you open the master cylinder and suck out the old fluid with a syringe, replace with clean (don't touch the lever while it's empty!) then with the bleed nipple loosened and attached to the kit (with empty water bottle connected) pump away at the lever watching the fluid empty from the master cylinder, add more before it gets to the bottom and repeat until new fluid is coming through into the water bottle.

 

What I don't have any knowledge on is the complication of C-ABS, but someone will shortly advise.

Edited October 24, 2017 by poldark

[trisaki 2,029]

If you  are anywhere near West Sussex  i could do it for  you  

[embee 7,288]

If you're of a mind to do maintenance yourself in future, I'd strongly recommend getting a vac type brake bleeding kit. When you've used one once you'll wonder why you ever tried doing it any other way.

I have a Mityvac kit, others are available but can't vouch for the quality. Mityvac stuff is used in industry and is generally first class stuff. Just as an example, https://www.amazon.co.uk/Mityvac-MV8020-Vacuum-Bottle-BLEEDER/dp/B005O2LQLQ ,you may find cheaper elsewhere with a search. Also note there are several variants with different levels of accessories etc, if you only want to do brakes then the basic kit is fine.

 

The only awkward thing about these vac bleeders is that the bottle will tend to fall over. I made a heavy steel stand for it to slot into, you can make up some sort of stand arrangement to hold it upright with wood etc.

 

On the CABS brakes (only on the 700 note), bleeding is straightforward using a vac bleeder. The rear master cylinder/reservoir does the rear caliper and the middle piston of the front caliper. There are 2 nipples on the front caliper, it's pretty obvious which one does the middle piston. Just bleed this middle one and the rear caliper while topping up the rear reservoir. The front reservoir does only the front caliper outer pistons, the top bleed nipple on the front caliper. The front reservoir/cylinder is not connected in any way to the rear system.

 

If the pads are dragging the most common reason is either the caliper sticky on the sliding pins (use silicone grease) or the pistons sticking in the calipers (clean around them with brake cleaner and then apply some red rubber grease (RRG) around the exposed areas. As long as they clean up OK and aren't rusted/pitted they should work in/out OK with RRG applied, if in any doubt it may need a full strip to make it clean again.

Edited October 25, 2017 by embee

[Trumpet 215]

Welcome to the Forum !  its a great place to pick up peoples practical experiences and knowledge. The linked brakes are pretty basic. The front caliper pivots when applied and presses in a plunger, which then presses on a single piston in the back brake. There will be a slight drag from the front caliper, but not enough for you to notice it wheeling the bike around. Any more than a slight drag needs to be sorted. Its usually just crud around the pistons, pads or the sliders drying out. I tend to strip and clean both front and rear calipers in Spring and Autumn to prevent problems if ridden all year round.

Edited October 25, 2017 by Trumpet

[larryblag 14,236]

I would strongly advise the use of a vacuum or pressure bleeding system. On an older bike, pushing the master cylinder over a full stroke when it's spent most of its life moving only a tiny fraction is likely to damage the rubber piston seal as it passes over the potentially corroded faces.