So i dug deep into my spares box and found my old XT-M755 disc brakes (4 pot callipers). They have been sitting in my spares box for at least 6 years or so but they have fairly new looking pads. I used some fine wet and dry on the disc to remove any rust spots and fit the front brake and they feel fine with all pistons moving and returning as normal but there is no bite. Will this just be a case of riding them and bering them in again or do they need to be restored somehow?

Bleed them and new pads – Hope M4/Mono M4 pads will fit, too.

Even though the pads look new?

Try bedding them in.

Doubt many have relevant experience.

May aswell, could be no bite because they’re contaminated?

How does the lever feel? Firm? If the lever is firm then if try new pads or try and bed them in.

If there is excess lever travel try a bleed.

The lever feels firm so it probably isn’t a bleeding issue.

Would sanding down the rotors and pads help?

It could, you should be able to see if they might have a bit of a glaze on them, by all means give it a try

I’ll give it a go. It’s only a cheap commuter so reluctant to spend much money on it. Maybe some 2nd hand brakes if sanding doesn’t work.

New pads would be cheaper than another set of brakes!

True. But these are a pain to set up with washers being the only way to centre them and pad clearance is tiny. So I’d rather spend the £20 2 sets of pads would cost towards new brakes. But I’ll try restoring them first.

Put the pads in a 200 degree C oven for 10 minutes, then sand them back a bit. It can bring them back to life. TBH though, you’ll find some cheap aftermarket pads for far less than £20 for 2 sets.

Sanding should help as it will reface the pads and remove certain imperfections giving you a new surface to bed to the discs. However this will not solve the problem if the pads are contaminated with brake fluid.

If you need new pads try Uberbike Components. Great selection of pads at excellent prices.

http://www.uberbikecomponents.com/

I~ have a set of Clarks Organics for M4’s you can have for £5 posted. Unused, too!