NTV650 rear brake pad marks

[Bru]

OK, so the title is not great. I have just fitted new pads to my rear caliper, replaced the piston and seals, and replaced the rear disc (could have bought a new bike with that.. ). Similarly the front. Anyway, took it for a test ride, and noticed that while the front pads are marking the disc uniformly, on either side, the case is different with the rear.

The pads are marking the nearside of the new disc fully, but only the outer edge of the offside. I also noticed radial lines on the disc, almost as if the assembly is skipping/vibrating.

OK, so I could strip the entire thing and begin again. But, as the rear is slightly different to the front in design (separates and rotates upwards for pad replacement), does anyone here know for sure if there are specific rules for lubrication of these calipers? I covered the rubber-shrouded shafts with copperslip, and bolted (and thread-locked) the caliper to the Haynes torque settings.

I am guessing that something is either loose or stuck part-open. What do you think? For a rear disc brake, it sure is poor right now.

[finpos]

For a rear brake, I'm guessing it only has a piston on one side of the caliper, if that's the case: it's usually a sign that the pins that the two halves of the caliper slide on (rubber shrouded shafts?) are either worn, or corroded, or both . You might have to remove and split the caliper to get a good look at them. Should just be a case of pulling the caliper apart.

If it's got pistons on both sides, then I guess one of the pistons is sticking.

finpos.

[Bru]

It is a single piston caliper.

From wikipedia.org: "A floating caliper (also called a "sliding caliper") moves with respect to the disc; a piston on one side of the disc pushes the inner brake pad until it makes contact with the braking surface, then pulls the caliper body with the outer brake pad so pressure is applied to both sides of the disc."

That is the arrangement. The shafts were not rusty. Just not sure if it needs to 'bed in', but it seems unlikely. I guess it will have to come apart, but what a pain in the butt, as I do not know what exactly to look for. There is some play in the arrangement when the brake is off. Just how much should there be? Should I be able to wobble it?

[finpos]

No - any wobble is bad and usually means the pins are worn. You are relying on those pins to keep the pads on the non-piston side exactly parallel with the pads on the piston side, and from what you describe that's not happening.

If you remove the pads and push the piston back in, what you should be able to do is to grap the two parts of the caliper with you hands and really easily slide them into each other (and pull them apart again). They should not wobble against each other. If they are very worn, they tend to grab (i.e. not slide at all) so that's even worse.

You can sometimes buy just replacement pins. The other option is just to let the wonky pad wear in (so it's not even any more), it might be ok, unless it's grabbing.

finpos.

[Bru]

Thanks. Guess that's it, really. This really is becoming a pain, but I cannot risk my new disc. Will try to find pins or a (lottery gamble) replacement caliper.

[Bru]

Hey, talking of replacement parts - are all rear calipers the same, from Revere 600 onwards? What about Bros? My Haynes only states the difference in disc thickness, between the Revere and the later 650. Thank you.

[Itchy]

crap mine does this too , , now its gone all sticky, getting replacements done soonish
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[finpos]

If it's just sticky, then stripping and cleaning them will sometimes fix it. Usual cause is that water/grot has been getting at the pins, if that's the case you can buy a hideously overpriced set of new rubber bits to prevent it happening again. It's only when there's ridges worn in the pins that they start flopping around and grabbing.

Bru - I reckon it's worth your while taking the caliper apart, confirming this wobble, inspecting the pins and re-seating your pads. None of this bad stuff usually happens unless the caliper pins actually look in a bad state, and it's more common that they seize than wear. You never know.

finpos.

[Bru]

An update: I stripped the rear caliper, and discovered that the fixed sliding pin is indeed worn. It is plain that the caliper was skewed for some time, which suggests why there is play when unpressured. I will be looking for a replacement rear caliper as a happy gamble.

As an aside, I recently received my HEL SS hoses from Online Offroad, a dealer on eBay. I gave positive feedback, and then commented that although the fit was OK, the front hose could have been a bit longer (for relief, as it was slightly shorter than the original). The guy asked me for the original measurements, and sent me a new hose to that spec., without charge. That's good service. Now if only they dealt in calipers..

[Itchy]

I stripped the rear caliper cleaned 'er up then the front caliper seized up so I did that one too, maybe they were right about dominators and their enclosed disc brakes surely less crud 'll get into them.
____________________
Spain 2008France 2007Big one 2009 We all die. The goal isn't to live forever, the goal is to create something that will. In the end, your life will flash before your eyes. Make sure it is worth watching.

[Bru]

As an update to the rear caliper business, I have (kind of) sorted it. First came the eBay calipers, which were rusted and useless (surprise). Then the lightbulb went on, and I phoned my local Honda dealers. Yes, caliper slider pins exist, and could be had for £7 and change. Spent half an hour using heat, WD40 and a plumbers wrench before resorting to a file and adjustable spanner (file your own nut - marvelous). Pin screwed out. Inspected new one, to realise that 'hollow' end was formed to take a hexagonal drive (Allen key). Hit head against spanner as punishment.

Lesson to be learned: phone the professionals first, as they know the score (after you guys, of course). Clean item prior to dismantling - it's amazing what you might find.

Outcome: still some wobble, because the cast alloy hole in the piston block is softer than the worn forged steel pin. Nnn..

Guess that's it, tied up. No excuses now, but to ride the damn thing.