help needed with sticking calipers

[rigsby]

I have an nc23 race bike which has lately been suffering from draging front brakes. I cleaned pistons and greased everything up which helped a little but were still dragging enough to be a pain pushing it around in the paddock. I then borrowed some nc29 calipers and tried these and no improvement, so i then borrowed a master cylinder, fitted that and still no better. i then decided to buy some new lines as i have had this problem with cars and sometimes the lines can fur up but still no use in fact i can no longer spin the wheel its locked solid. So now i have newer nc29 callipers in good condition and a secondhand master cylinder with new lines bolted to the bike and its worse than the old set up.
So either i have 2 pairs of callipers that both happen to be suffering from sticking pistons or 2 master cylinders both of which arent releasing enough pressure when the lever is out or im missing something. i dont want to strip callipers if i can help it and would probably fit new master cylinder seal kit first but has any body had this issue before or could possibly explain this fustrating problem.

Cheers rigsby

[RICKNC31]

Have you checked you have a litle clearance between the brake lever and the master cylinder piston as if you do not the brakes will drag hope it is as simple as this all the best rick

[Cammo]

It's more likely to be stuffed master cylinder seals in my opinion. Personally I would only buy genuine m/c seal kits but it's your choice.

I've owned at least half a dozen stuffed m/c's in the past. I gave up on trying to sort them (I suspect some had scratched bores etc) and splashed out on brand new Nissin units from Japan.

Rick makes a good point, many aftermarket brake levers can cause issues.

[Davez29]

I have had the aftermarket lever problem that made my front brake drag and luckily i still had the small original piece that sits next to the master cylinder, this solved the problem. another option would be to file a small amount from the flat section, or buy oem levers. one other thing worth looking at is if you have worn slider pins.

[The Novice]

Sure the discs arent warped?

[rigsby]

Hi thanks for replys.

Very interesting about the after market levers as this is what i use, i get through alot of front levers.
I decided to disconnect the lines from the master cylinder thinking if the m/c is problematic then when i disconnect lines the brakes will relax and allow the wheel to spin but its made no difference. I now have just the callipers on the bike the lines and m/c disconnected and the wheel is still locked so its got to be the pistons sticking. i know the calliper hangers and discs are ok as i was racing it last season with the other dragging callipers.
Im begining to think i have 2 pairs of callipers both which have sticking pistons its just that the newer nc29 ones are sticking worse than the original callipers they replaced.

Does everyone agree with the m/c disconnected it must be callipers?

Cheers rigsby

[Adrian89]

I expect you are anyway, but make sure you use 'red rubber grease' and not copper slip or bearing grease or anything like that to lube the sliders.

I made the mistake of using copper slip a few years ago lol, my calipers soon gummed up and stopped 'floating/sliding' all together, the pistons were fine, just the slidey bit was pretty much seized/very very stiff.

Adrian