Hi,

My son has recently brought an NC23 and we are going over it to make sure everything is working correctly.
The carbs have just been sent to Gary at GF racing for a rebuild as they are in a poor state (all pilot screws are seized) and we are now looking at the brakes as I wasn't impressed with the performance.
We are probably going to get some EBC HH pads and maybe change the front Master cylinder for one off of a CBR600 (any advice as to which one would be welcome).

However, he noticed when riding on a bumpy surface (ie, English roads) that there was a rattle coming from the front of the bike, this turned out to be the calipers which are quite loose on the slides.

I've not had much experience with these sliding calipers and we are going to be stripping them down for a service soon, can anyone tell me if looseness in the calpers is normal or is this a sign of excessive wear?

Thanks

BG

They do move a little and if the pistons are rusted they can stick a little making them looser than they should be. Pistons and seal kits are on eBay pretty cheap

The obvious things to look at apart from what dunkenb mentioned would be sticking pistons, missing spring clips, worn slider pins and even well worn pads with a mix of any of the things mentioned. Best doing a overhaul.

Thanks Guys, should be stripping them down in the next few hours, will let you know what we find

I'd say they're missing the spring retaining clip. Its a thin metal 'U' shape clip at one end of the caliper. They are easily misplaced and would give the pads a few mm and cause that rattle.

Juat a guess of course. So do tell us what the problem was once you figure it out!!!

Sorry, not had time to look at these properly yet. we have stripped one of them down and the spring is there.

I have spoken to Graeme at GFracing and he says that replacing all of the rubber on the callipers is the way to go.
Old seals grip the pistons and pull them back into the callipers which could possibly cause the rattle, also the rubber boots on the slide pins also have the same effect when old. Graeme recons once serviced, the original callipers can't be beat.

New rubber and pads (Carbon Lorraine also as recommended) Have turned up today, Will let you know how it turns out.

BG

If the rubbers on the sliding pins are perished or missing, the caliper will rattle around on the sliding pins. Use of normal mineral grease can cause the seals to swell and eventually perish so use silicon or better still red rubber grease on that part.

While you are there, check the pins and caliper and carrier castings themselves for wear.

OK, so we've replaced all of the rubbers, removed some sludge from the callipers, replaced pads and bled the system and now they are run in I can confirm that they are excellent brakes and the rattle has completely gone.
Thanks for all your help.