oops. cracker.

[Lumpy]

Reason for that crack is simple looking at the corrosion on the discs and fork legs.
The rivets/bobbins which allow the disc to float have seized from the buildup of corrosion.When they seize the disc cannot move as it should when it expands/contracts and its only option to allow its movent is to crack at the weakest point, which it has.
The pictures also show the disc bolts have been replaced with standard bolts and washers.
When you replace the 2 discs, replace the bolts with the proper ones and overhall the calipers at the same time. With that level of corrosion it is possile the capipers are close to seizing point.

thanks. Despite appearances the calipers are free as a free thing and the pistons push back with finger pressure. The crack started at the outer edge too. There is no proper screw to use only usual. The hex bolts are absolutely fine. What reasoning do you have to think otherwise pleasethe fork legs look like that due to recent salted roads. And like I said, despite appearances all of the important things are tip top and no expense spared

[unfazed]

I use my Fazer which I bought new in 2003 all year round (73500miles) and to prevent corrosion on the lower fork legs I wipe them with a cloth soaked in WD40. Kept away from the disc obviously. The only way I have managed to prevented the corrosion on the rivets/bobins was to rinse them down with water after using the bike on salt laden roads, which could be every evening. I changed my discs at 69000 miles as they were worn and used EBC ones, they make a funny whirring sound which took some time to get used to.
Good to hear the calipers are ok.
This is the type of bolt which should be used when replacing disc with a bit of blue loctite to prevent them loosing.

[Lumpy]

[quote author=unfazed link=topic=5646.msg50500#msg50500 date=1357381622]
This is the type of bolt which should be used when replacing disc with a bit of blue loctite to prevent them loosing.
[/quoteplease would you tell me why I should be using this type of SCREW please? These are more regular and better on the left side to clear the soeedo drive but hrx bolts are perfectly acceptable.  More important to torque them up than use 243.

[unfazed]

The head of the bolt is wider than normal and therefore spreads the load better. Generally a bolt without a washer retains its torque better than a bolt with a washer. This is why many automative bolts are flanged and are used without flat washers.
I was not advocating stainless steel, it just happened to be the best picture I had to show the correct bolts.

[Lumpy]

Gotta be careful with stainless. I use titanium on my other bike. Hex screws are pretty much the same area but the force is in shear so the head area is irrelevant effectively. I will be changing them but 6 of the originals got mangled. The hex HDS have been used for 25 000 miles thus far. Stainless is fine as long as the correct type is used

[unfazed]

Yes, I agrees with you on the stainless issue. Best of luck

[Lumpy]

Yes, I agrees with you on the stainless issue. Best of luck

cheers. Can never have too much of that out there. Every day is an adventure