Rear disc fitting

[Dan505]

Need to fit a new rear disc as somehow i've managed to score the old one nearly all the way thru :o any tips on fitting? I.e grease placement, tips for ease of stripping it down?

Thanks

[Rabb]

1. New bolts to hold them on.
2. Ensure you have cleaned the facing surfaces so that they are completely flat to the new disc.
If it's not you will have problems.

That's about it - easy to do and you shouldnt have any problems.

[Gooz]

Make sure you clean and regrease the rear wheel spindle too whilst your at it Dan, its an ideal time to clean those hard to reach parts. check your chain and sprocket too whilst the wheel is out.

[Mitch9128]

Threadlock the bolts..

[Snowy]

You will need new Brake pads as well.

[Crosbie]

You will need new Brake pads as well.
I would hazard a guess he needs new pads anyway.

Dan would i be correct in assuming your current pads have worn down to the extreme that the fixing surface has scored the disc? ;)

If you have copper grease put a teeny tiny amount on the rear of the pads - this will help stop any squealing moments unless thats your thing. :D

Oh and do the job with a pair of cheap cloth gloves on - saves having to scrub the skin off your hands later/walking around the office/house with mucky hands for the next week.

[Scotty]

Check both sides of the new disc to see if the bolt boles are counter-bored (recessed) on one side - if they are, this in the side that the bolt head sits in so it faces away from the wheel. This might sound obvious but ten years ago I bought a ZX-9R from a muppet who worked at MCN and he'd refitted the rear disc the wrong way so the bolt heads were proud and they fouled the calliper bracket badly. It would have been impossible to rotate the wheel or push the bike anywhere as the foul condition was that bad so what had he done? Simply ridden it like it and the bolt heads had chewed themselves some clearance into the bracket. I couldn't believe what I was seeing when I discovered it. Anthony Orfeo, hang your head in shame...

Another important point; use a good hex drive bit on a socket to remove the disc bolts and ensure that it's fully engaged before trying to turn it. Chewed-up bolt heads are never easy to remove, especially when thread-locked in. It isn't necessary to replace the bolts, up to you if you want to but if they're undamaged they can be re-used (with thread-lock)

[Jon_W]

As with scotty.

You don't need to replace the bolts if they are in good condition. Just make sure you clean off the old thread lock and degrease the bolts and holes befre applying the new threadlocker.

[Dan505]

Cheers for advice guys, yeah have new pads as well. Whats best way to remove threadlock? Bolts only 3 yrs old so will re-use them. C&S is brand new so no dramas there, have no torque wrench so guessing just over hand tight should be enough for the disc bolts?

[Scotty]

The best way to remove threadlock residue from threads is with a wire brush.
A decent torque wrench is a good investment, I'd recommend either buying or borrowing one for this. Most M8 disc bolts will need around 20Nm of torque (or just over) which is a bit more than just over hand tight. These are important fasteners so it's worth doing the job properly. 8-)

[Dan505]

Agreed they're essential but have no budget for wrench, may fut them then see if a garage will check them for me :-/

[Jon_W]

Only use medium or low strength thread lock. If you go for High you may never get the bolts out again without heating...

[Dan505]

Noted ;) thanks

[wiltshire builders]

Most importantly, gradually tighten the bolts one after the other
e.g. Bolt 1 5 turns, bolt 2 5 turns etc until you get back to bolt 1 again. Repeat until they are all tight.
This prevents damaging the new disc.

[Dan505]

ah ok, same as rocker cover bolts on a car, thanks

[Snowy]

If it was me I would tighten the bolts up in a diagonal sequence i.e do the opposite bolt each time. That will spread the tightening torque over the whole circumference of the disk and help prevent warping. Only do a bit at a time on each bolt.

[njl]

shoot me a pm if you want to borrow a torque wrench tonight - both over and under tightened have bad outcomes

[Dan505]

have fitted this all now and was very simple and straight forward...until he allen key snapped and stabbed me through the finger, ouch, am now getting 'black' transfer from my pads onto my disc, any ideas why? They are CC EBC pads

[Swanny]

Brake dust? Some pads are messier than others.
The green stuff I used to have fitted to my car were dirty little buggers

[Dan505]

seems abit dark for pad transfer

[Gooz]

new pads bedding in mate they will do it for a couple of weeks, clean your wheels off then put some wax on them afterwards, stops it sticking quite so bad.

[Dan505]

Ok ta, hope you mean wax the rims not the discs! :-?

[Gooz]

erm yes :-/ :-/ :-/

[Dan505]

:D joke, used wrong smiley :P