21 replies to this topic

[Jez]

Hi all,

Need some advice on rear disc. The old girl failed her MOT on the rear disc recently, twas almost see-through in places. Being the tight-wad that I am I bought an EBC one.

The EBC one is solid, ie stamped from one piece, whereas the original one comprises one disc inside the other with things like buttons joining the two. Bear with me here.....

The point is this: The EBC one feels warped. I know it is flat 'cos I have taken it off and tested it. Therefore it is not sitting flat when bolted to the wheel. I have taken it off and cleaned the mountings.

My question is: Does the fact that the Yammy disc is three peice mean that it is more tolerant of being not fitted straight? Is it floating or summat like that?

The lass has passed her MOT now but I need this sorted. I will procure a Yammy disc if necessary.

Ta for any help.

BTW this is my 100th post, woohoo!!!

[Jez]

Thanks for the tip Graham. I think I see where you are going. If I clock the disc and locate a 'high' spot I could then remove the disc and address any raised area on the wheel. As I said I clocked the disc and it is flat when not attached to the wheel.

Sounds ok. The disc I took off was prolly original so the mounts were indeed furry. I did clean them but I am worried about filing too much and wrecking the wheel.

I agree about OEM quality. I bought the disc from M&P after hearing good things about EBC.

I am tempted to try an orig disc before wrecking the wheel. It is a case of my tight-fistedness battling with my laziness. What a dilema.

[Pict]

Need some advice on rear disc. The old girl failed her MOT on the rear disc recently, twas almost see-through in places.

Jez, How long did this disc last? My original chewed up quickly (within the latter part of 8000 miles), showing rings of deep wear, and a mate's is looking the same. Had mine replaced under warranty.

[JBX]

Don't forget the rear brake pedal servicing : grease the axis frequently as it's exposed to dirt & water.
If the pedal does not rotate well, it may keep the pads on the rear disk and wear it out quickly.

[Pict]

Don't forget the rear brake pedal servicing : grease the axis frequently as it's exposed to dirt & water.
If the pedal does not rotate well, it may keep the pads on the rear disk and wear it out quickly.

Thanks JBX - a good reminder. I've been surprised at the crudeness of the rear brake assembly - the whole thing depends on the tightness, yet lubrication, of the spindle going through the mounting plate, held on by the pedal, with no bearing, or bush, or any other support. It doesn't look built to last. Do you know how much travel there should be at the rear cylinder on a 900, as there does seem to be relatively little in my case? It has always worried me.

[JBX]

Thanks JBX - a good reminder. I've been surprised at the crudeness of the rear brake assembly - the whole thing depends on the tightness, yet lubrication, of the spindle going through the mounting plate, held on by the pedal, with no bearing, or bush, or any other support. It doesn't look built to last. Do you know how much travel there should be at the rear cylinder on a 900, as there does seem to be relatively little in my case? It has always worried me.

Piston travel is not really an issue, as hydraulic brakes self-compensate for free-play.
The piston travel is actually very small but it should allow the pads to "fly over" the disk without contact.
This is possible only if :
1 the brake pedal rotate freely & does not keep the fluid under pressure when not in use.
2 the piston is clean and not covered with dirt which would not allow a good travel inside the calliper & the seals.

Brake pad lining thickness should be 0.8mm min.
Same apply to the front callipers.

BTW what is the correct word : axis or axle ?

[Pict]

WHAT - do you ride with your foot on the rear brake or something.
I've got nearly 74K on my bike and its still on the original rear disc.

Nope - I ride with the ball of the foot on the peg, which is why this was such a weird issue. I'm glad to hear your experience, which gives me hope it was just a one-off for me, whatever the reason. Am keeping a closer eye on the pedal lubrication now.

Piston travel is not really an issue, as hydraulic brakes self-compensate for free-play.
The piston travel is actually very small but it should allow the pads to "fly over" the disk without contact.
This is possible only if :
1 the brake pedal rotate freely & does not keep the fluid under pressure when not in use.
2 the piston is clean and not covered with dirt which would not allow a good travel inside the calliper & the seals.

Brake pad lining thickness should be 0.8mm min.
Same apply to the front callipers.

BTW what is the correct word : axis or axle ?

Thanks JBX. Of the 2 "axle" is the better one, but in this case "spindle" would be more appropriate - axles are for wheels. "Axis" is simply a geometric term for a centre line of rotation.

Edited by Pict, 01 October 2006 - 04:00 pm.

[tdm850rider]

BTW what is the correct word : axis or axle ?

Axle if you are referring to the metal rod that your wheel spins on.

As for 'axis' well, look here:

'Rotation is the movement of an object in a circular motion. A two-dimensional object rotates around a center (or point) of rotation. A three-dimensional object rotates around a line called an axis. If the axis of rotation is within the body, the body is said to rotate upon itself, or spin— which implies relative speed and perhaps free-movement with angular momentum.'

So an imaginary line going thru the center of your axle is the axis of the wheel.
I would go with axle, it's simpler.

[JBX]

Thanks mates !

[Nig]

Christ that was complicated

[tdm850rider]

Christ that was complicated

Tis no fun if I can't make it complicated!

[Jez]

you're very unlikely to be able to get a warped disc running true, by removing metal from the mounting face on the wheel, as when you tightne it up it'll just pulled in around the mounting hole, and not on the brake pad swept area, plus you're wrecking a wheel

How have you checked the disc with it not mounted on the wheel
The only way to do it like this is set it up in a lathe, clock the mounting surface and get it running true, then clock the brake swept area.

If you have a DTI, clock the the disc whlist mounted to the wheel , whilst it is on the bike. You could always then 'adjust' the runout with a dead blow hammer or copper faced hammer (I've done that before now).

If you're struggling to find a disc, I have a good spare. PM me and we can come to a deal

Thanks Graham for your continued input. I am indeed very reluctant to remove metal from the wheel face. Therefore I have come to the conclusion that it would be worth trying an orignal Yam disc. I have located several discs on ebay but have not committed to buy yet. I will pm you this evening. I would be happier to deal with a Carpedian than take pot luck with a breaker.

I checked the disc by laying it on a tool maker's marble stone flat thingy at work and clocked it (well I didn't clock it personally I got a proffessional to do it). I am surprised that they can be 'adjusted' with a hammer.

Jez, How long did this disc last? My original chewed up quickly (within the latter part of 8000 miles), showing rings of deep wear, and a mate's is looking the same. Had mine replaced under warranty.

I presume the disc was the original factory fitted one, judging by the ally fur and the thread locking compound on the bolts. I binned it at 33000miles because it was extremely grooved.

[dandywarhol]

You can adjust anything with a hammer!!!

[ROB1]

Pict-the way i addressed the pedal lubrication on my 850 was to drill & tap the pedal spindle & put a grease nipple on.i did the same with the gear shift pivot cos the heat of the enjun dries the grease out.

[Pict]

Pict-the way i addressed the pedal lubrication on my 850 was to drill & tap the pedal spindle & put a grease nipple on.i did the same with the gear shift pivot cos the heat of the enjun dries the grease out.

Thanks Rob. I'll psych myself up, down a couple of malts and dig out the Black and Decker. I take it you just drilled down the centre of each spindle for the nipple, then a second at right-angles mid-way for delivery? Better invest in a decent tap set, though, rather than my street market one.

[Jez]

Thanks to all for your sage advice.

Thanks especially to GuyGraham for help above and beyond the forum. Yammy disc received today, fitted this morning and test rode to work this aternoon. Warpage problem instantly cured.

Thanks a bunch, mate.

[Minty Hippo]

Thanks to all for your sage advice.

Thanks especially to GuyGraham for help above and beyond the forum. Yammy disc received today, fitted this morning and test rode to work this aternoon. Warpage problem instantly cured.

Thanks a bunch, mate.

For future reference - am I right in thinking the EBC disc was warped from new?

I wouldn't touch EBC pads with a bargepole but this is a step up in shoddiness! Did you get a refund? Or have I misread this thread?