Slightly different brake upgrade Q

[Pupp]

For some years mine has been running a '285' (actually 283) mm rotor with 4 pot calipers from a manufacturer who is not especially well regarded round here Seems the rotors are the ubiquitous Cossie RS500 items; these now need replacing.

The ST170 Focus uses 300mm rotors that have a total height of 44.5mm as opposed to the Cossie ones 55mm. Obviously the overall dia is 17mm greater.

So, if (for the sake of filling the wheels some more if for no other reason) I wanted to run the ST170 rotors, the calipers will need to come out from the upright by about 10mm and be spaced further out from the wheel centreline by about 8.5mm

The existing caliper mounts are machined ally billets that are screwed and abut to the usual upright lugs. The calipers are screwed onto the top of the brackets 'radially' (ie the mounting screws are in line with the rotor face.

Six million dollar question is whether new brackets should be made up (more difficult but 'right') or *just* space the brackets out from the upright lugs and the calipers up from the bracket tops - obviously using correspondingly longer high tensile fastners (easier but 'not right').

Assuming everything is clamped up tight and the spacers sufficiently sturdy, are the shear forces on the fasteners actually any more than with one piece brackets?

[spend]

Remove disks & space caliper out + radially to check clearance in wheel, using bolts washers/nuts/packers. Generally if that works out you can get the disks & have new brackets/even adapters machined up. I'd rather have something braced and solid rather than using washers/packers in a critical area like brakes TBH. Nothing wrong with bodging a mock up though ~ 3d visualization can get confusing

[haircutmike]

I run Mk1 Focus RS 330mm discs, might be worth a look?

Fills the wheels.

[Pupp]

haircutmike said:

I run Mk1 Focus RS 330mm discs, might be worth a look?

Fills the wheels.

[/IMG]

I think it is indeed thanks. The height of these seems to be 53mm, which is very close to the cossie ones my set up was specced for (55). Looks like a goer subject to my calipers being able to accept the slightly thicker rotors (28mm as opposed to 24) - last resort is the calipers have centre sections which seem to be interchangeable assuming the manufacturer will supply (I'm hoping there is enough tolerance to cope with 4mm extra in the sandwich). The outward spacing from the wheel centre does not concern me unduly providing I can source appropriately over-length fasteners of the right grade. The bracket and caliper design lends itself to being packed in this direction with plenty of bearing surface available.

Would you happen to know the diameter of the hub boss on these rotors (ie the overall dia of the 'top' of the tophat)? Just want to assess what the appearance is going to be like behind an SP12 front, which has quite a dainty centre...

[haircutmike]

Will look later as I have the wheels off at the mo.

[Pupp]

Many thanks; appreciated

[haircutmike]

6 1/2" across the protuding flat bit the studs are mounted on.

[Pupp]

Thanks for that; learned this afternoon that bridge spacers for the caliper bodies can be sourced at sensible dosh so looks like the job's a good un