possible brake problem

[stirlinggaz]

hi,
its nearly that time of year again, when i clean up a couple of the wee strokers, so i have the choice to ride whatever/whenever i want. (& maybe even sell one)

1 bike in particular i have hardly used at all since the last MOT. i'd need to check the milage, but i doubt its done more than 2 or 300 miles in the past year.
however, at last years MOT it got an advisory "rear roller brake test indicates slight fluctuation of brake effort. (3.3Ald)"
anyone any idea what this actually means?

i have been going over the bike, making sure theres a good chance it will pass the MOT (due to previous experiences with testers)
anyway, both brakes were partially seized.

i've stripped the front caliper & freed off the sticky pistons & it seems to be working fine (got both pistons moving eventually)

however, the rear took a fair bit of effort to get the single brake piston freed off. i've used up all the brake fluid i had & will go fetch some in next day or so.
i also noticed the wee pad spring was missing, so i'll need to order a replacement & wont know till its fitted & its all filled up with fluid whether it actually works.
with new pads, new fluid, new spring & everything cleaned up & greased etc im hoping thats the end of it.
i hardly use the rear brake anyway
but, worst case scenario,after all that, the rear brake still doesnt work properly.
how will i know if "the brake effort is fluctuating"?
& after doing all i can at the caliper end, it would mean the fault must be at the master cylinder, rlght?
or maybe the disc is warped?
either of those will involve ordering parts & fitting them & f*ck knows what else.

ideas/suggestions please?

cheers,
GAZ

[monkeybiker]

To me it seems like brake pulsing meaning brakes on/off/on/off. Kind of like ABS kicking in sort of feel.
If you brake hard on the road you may be able to feel it depending on how bad it is.

Could be due to a warped disc or due to sticky piston/caliper slides(depending what caliper you have).

If it's caliper/piston then you need to clean and maybe put in new piston seals. If it's the disc then a new disc is needed.

[Fisty]

You have a warped rear disc.
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[Taught2BCauti...]

If you can get the rear wheel off the ground, try spinning it by hand and checking the distance between the edge of the disc, and a fixed point on the swingarm to see if it is running true.

Also check the disc for excessive wear or signs of damage, and make sure the caliper body moves freely on the slider pins.
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