So the details pertinent to adaptor bracket design not mentioned above are:
- Stock ute upright mounting hole thickness: 15mm steel
- FD3S RZ/RS caliper mounting hole thickness: 17mm alloy
- FD3S RZ/RS caliper distance to rotor slot: 17mm air :-p
Not sure what the legal minimum thickness of steel or alloy is for the adaptor, but I can have a look now. What I do know is that it's going to be <= 17mm. There's also a 0.25mm stainless shim clipped on there right now.
ASCII art time:
Assuming bolt head = upright thickness = both caliper thicknesses, then...
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Key:
- Bolt
- Caliper
- Adaptor
- Upright
Looks like large metric fine taps aren't too hard to come by, which is good. I guess I have no option but to use steel given that I will be tapping it, I wouldn't trust alloy threads to hold that much torque and force. Didn't find anything concrete, but it seems 12mm steel is likely. I'd be happy with that.
Stock rotor is 256x20
New rotor will be 314x32 +/- 24mm dia
So if I don't angle it around, the centre to centre distance from the caliper holes in the plate to the upright holes in the plate will be...
FD 65.0 from holes to centre of pad, 19.0 from centre of pad to edge of disk
Ute 55.5 from holes to centre of pad, 24.0 from centre of pad to edge of disk
Ute 256 rotor, 128 centre to edge, minus 79.5 edge of rotor to centre of mounting holes = 48.5mm
FD 314 rotor, 157 centre to edge, minus 84.0 edge of rotor to centre of mounting holes = 73.0mm
Difference is just 24.5mm for 314mm rotors
Or 17.5mm for 300mm rotors
Or 32.5mm for 330mm rotors
New measurements required...
Centre of hole to edge of upright, 15mm
Centre of hole to edge of caliper, 17mm
Sum of 32mm. Hmmm, I hope 330mm rotors fit under my 16" wheels! :-D However with the caliper correctly rotated down so as to be vertical the tabs will not line up, and some overlap would be OK. I'll need to get something designed and mocked up in wood before I know it can work, but I'm 99% sure it could work with a smaller rotor when rotated.
Now, what's the angle we need to rotate? Let me see...
12.5 degrees from the vertical. I also measured a horizontal offset of the two holes of 28-29mm. Which would make the long side of the right angle triangle 140mm, what was the memory trick? SOHCAHTOA? So 28-29/140 should equal the sin of 12.5 degrees. Well, 12.5 degrees gives 30.3mm offset, and 12.5 degrees was fairly imprecise, too. Doing it backward from 28.5 we get 11.75 degrees. So, around 12 degrees and 29mm match up. I'll have to draw it in CAD to see if it helps in using a smaller rotor. I'll also have to get hold of an FD 16x8" again and see what'll work.
A bit of good pad monologue here:
http://www.fd3s.net/brakes.html#TRS
R4E Porterfield sounds quite attractive after reading that. Pad info:
http://porterfield-brakes.com/images/po ... _41_04.pdf
He also talks about performance friction pads, which are listed here, the one he mentions is now obsolete, replaced with '97'.
http://www.performancefriction.com/moto ... tions.aspx
I originally wanted to buy a set of Ferodo DS3000s or similar. Not sure how pricey those are, though.
The calipers have pads in them... so that is what it'll be running for a start, possibly. Unless I decide I don't want to corrupt brand new disks with unknown pads. We'll see.
Need to pull a pad out of the rear axle setup and see what shape they are. Handbrake and caliper are separate there, so I could swap to basically any caliper I could design an adaptor bracket for that has good off the shelf pad selection.
EDIT: I did:
https://twitter.com/FredCookeNZ/status/ ... 5563509761
Probably not available in a performance compound to match the fronts so likely to be changed to something that does have those compounds available, and is preferably lighter, possibly 2 or 4 pot.
Subaru 2 pot, but the pads look tiny :-/ correct thickness for my van rotors, though.
Fred.