Front brake problems

[Andy666]

Hi all, apologies for the wall of text.

Just been on a quick test ride, and my front right brake disc is getting far hotter than the left. Those pistons aren't moving either way as far as the others, but when stripped down they moved freely. The disc is uniformly discoloured, so it isn't warped.

As a bit of back story, a while back I bought a second-hand brake lever (with adjuster) and some braided lines. I fitted them, and first time out the front brake locked up at 60 and down I went. The calipers were seized (RH in particular) and the brake lever solid. On inspection, the top bolt was completely wrong for the braided lines (holes didn't line up with the banjos), which I'm guessing is the main reason for the off; fluid having enough force to go down, but not return to the M/S.

Sod the braided lines, I've decided to go back OE, as I'd rather have standard brakes than brakes so sharp I can't move the bloody thing off the driveway. :D

After a hell of a lot of trouble, I get them bled using a syringe. The bike has been stood for a month since, while I sorted the other bits that it needed, and I come back to it to find that the lever has again gone rock solid. Thought it could possibly be the lever's reach adjuster keeping the plunger ever so slightly pushed in, and gravity has pulled enough fluid down to lock the brakes, so I've filed a little off the adjuster just in case. (As a side note, when comparing the new adjuster on my 94 NC30 to the one on my brothers 89 NC30, they are pretty different. Could one be VFR the other RVF, or have I got one off something else altogether?).

Anyway, what could be causing the pads in one caliper to bind to the disc?
Any suggestions appreciated, cos this has got us well and truly stumped, and I have to watch bikes speed past mocking me

[Sligeach]

so have you recently rebuilt the calipers then? new seals red grease,etc?

when you say when stripped down they move freely, is that will the pads out and just pushing the pistions back into the caliper?

[Cammo]

On inspection, the top bolt was completely wrong for the braided lines (holes didn't line up with the banjos), which I'm guessing is the main reason for the off; fluid having enough force to go down, but not return to the M/S.

It doesn't matter where the hole ends up, there is a recess in the banjo bolt to allow for this.

I'm guessing your off was caused by the brake pads not returning due to the pistons being stuck!Steel or standard brake lines won't make any difference to this.

You can usually rebuild them with new seals, proper assembly, etc, but it sounds as though it would be easier (and cheaper!) for you to just get a set of second hand calipers in good working condition, you can pick them up cheap.

The rvf and vfr levers are the same.


Fix it before you have another off!

[superlite]

Banjo bolts have different hole spacings depending on the width of the banjo fittings you use. If they're only a little off, you can space it with another copper washer or two. I've never had any problems doing it.

[Andy666]

so have you recently rebuilt the calipers then? new seals red grease,etc?

when you say when stripped down they move freely, is that will the pads out and just pushing the pistions back into the caliper?

Yep, the calipers were stripped and rebuilt properly by a qualified mechanic, all seals are in perfect condition. When pushing the pistons back they are all moving as they should be.

The rvf and vfr levers are the same.

Hmm, wonder what mine's off then? Brother's 89 NC30 at the top, my second hand NC30 one at the bottom. Not so much the lever I'm interested in (both have been bent about), as the reach adjuster.



And yes superlite, you're correct, it was the position of the holes down the length of the bolt. My fault for not making sure they line up, but it never occurred to me that banjos came in different widths.

Cheers for the help people.

[Malc]

One's after-market while one's OE? Shape unimportant, check the working parts (pivot position, piston actuator, etc.) and they should be identical.