Sureal goings on at the rear!

[Mr Gazza]

[QUOTE=slob;570923]It’s normal to have more wear at the leading edge of a pad. /QUOTE]

Maybe so. But I think that wedge shaped pads have something to do with the wheel locking going backwards phenomenon?

Looking again at the calliper picture, and zooming right in to the damaged area, I can see what might be marks from an engineering vice or metalwork vice, but as mentioned these could only be made when the calliper halves are split.
If you look below the red ringed area, to where the body halves meet, you may notice an abrasion which looks consistent with contact with the edge of the disc. It appears to be on the same plane as the ringed damage.
If these marks are caused by contact with the disc, surely they must have been made, either with no pad present or with extremely worn pads, as the pad pictured appears to be higher than the damaged area whilst being hard against the back of the calliper body? So the pad is preventing the disc from touching the damaged area.

Howsoever caused, if it is the disc that has contacted the calliper to make these marks then something is seriously amiss. I suggest that maybe the wheel has been turned with no pads and the calliper bolts only very loosely in position, or with the wheel spindle not tightened up... Hopefully it was not ridden in this (presumed) condition!

[rbt1548]

Thanks guys for all your input.

I am not so concerned now about the small lateral play in the mounting bracket as it has been explained there should indeed be some movement and on mine there is a bit less than the 2mm mentioned.

Both pads are flat with no wedge shaped wear on either, there is a chance that it was dirt that was causing the reluctance to move, as after I had cleaned it it is moving freely in both directions, but I will keep an eye on it as suggested.

The damage to the bodies could have been caused by putting the calliper half in a vice at some point previous to me getting the bike. What I did notice when I had it apart was the calliper to mount Allen screw had been cut short for some reason, was 15mm should be 20mm with, no washers fitted, I will replace that with the proper size. Maybe something did happen with the rear brake before I got it and I have just noticed it during cleaning, maybe a good clean more often may help?

The brake seems to function fine now after cleaning and bleeding, and if anything I have less pedal travel, the only way to tell for sure is on the road which will not be for a week or two due to stuff going on... now if I only could get my foot to touch the pedal with out contorting it that would be a bonus!!!!

The disc itself shows no sign of wear or having been in contact with another metal surface and with a thickness of 4.1mm seems hardly worn.

Anyway thank you all very much for your help and advice , it's much appreciated!

[Capo]

Full floater

Thank you all for your contributions to this thread, the remarks are worth it.

[rbt1548]

Ok, guys an update, and it's not too good for me!

With the mounting bracket on the bench I decided to give it a good clean, only to discover that one of the calliper mounting holes, the rear one that does not hold the torque arm, has been helicoiled and not very well done at that!, so for some reason, something definitely has been messed about with in the past.

I have helicoil kits in the garage but because it's the mounting for the rear brake calliper I am reluctant to redo it. I have looked for the bracket online and they are not cheap but it looks a though I may need to bite the bullet and get one.

"C'est la vie" as they say or in my case "Bollocks, don't need this just now!"

[slob]

Personally I wouldn’t worry about helicoiling or timeserting it. The end result will be a stronger thread than the original. We used to ‘pre-helicoil’ the brackets on DD bikes, to reduce the chances of stripping the thread during frequent tyre/wheel changes at the track, where engineering is more difficult than the workshop.

[Mr Gazza]

Well there you go. It might explain how the calliper drifted onto the disc at some point if the bolt let go.
I had to get a replacement bracket for mine when the powder coaters lost my original!

If I recall, it was about £60-£70 from Moto Rapido with 10% UKMOC discount. Note that you have to buy the bush in the bracket separately and press it in yourself.

Luckily for me the powder coaters footed the bill, but they probably wouldn't buy you one?

As Slob says, nothing wrong with a properly done helicoil. So long as the calliper is still pulling down flush to the bracket and not being held out of line in any way.
2V cam belt tensioner bolt thread holes are helicoiled from new btw.

[rbt1548]

Great guys, thanks for the info and reassurance. I will take out crap helicoil , clean it all and see if I can re insert a new one, hopefully it will take a new one.

If necessary I will keep an eye out and see if I can get an undamaged bracket, I'm sure they'll come up from time to time.

Cheers

[Mr Gazza]

Do check Moto Rapido's price for the bracket and bush, as my memory does play tricks on me.

Also worth noting, apparently there is a Wurth insert available that is over size from Helicoil and can be used sometimes if the 'ole is too big to helicoil successfully.. I have been told.

[slob]

the wurth one is called a timesert, it’s a steel threaded sleeve that expands into the oversize hole.

[rbt1548]

I'll try the helicoil first as I have an M8 kit amongst others, if it doesn't feel right I'll look at the Wurth Timesert.

Cheers