buzzword
XS650 Addict
Hi, All -
I'm in the process of gathering all the parts and hardware to swap a 2006 GSXR 750 fork and brakes onto my 1975 XS650, while converting to dual disc and using the stock front wheel. I know that this swap has been done, and re-hashed, and there's a lot of great information and a few good pictures on here to help ding dongs like me figure this kinda stuff out, but I feel like there's a few missing pieces of info that might help others pursuing this same type of foolishness. Luckily the steering stem/triple tree should be a straight swap using the appropriate All Balls bearings top/bottom considering the shorter neck length on my 75. My understanding is that the later frames require some finagling to make it work without shortening the bottom cup of the neck.
So - anyone who has done this, or who can think about this in a functional/mechanical way, please check my work as outlined below.
The math is pretty simple, really - I made a really lame spreadsheet calculator:
All measurements in mm unless otherwise noted...
So - with all that in mind, I calculated the needed rotor spacer width as follows:
(Rotor width) - (Hub shell width) - (Rotor offset x2) = (2x Rotor spacer width) /2 ==> Rotor spacer width
(137 - 86.4 - 30) /2 = 10.3mm
Nothing is together yet, but I am planning to use 10mm rotor spacers, which were available on eBay UK for less than what I could pay a friend to machine them for, and will be arriving sooner than he could knock them out on his CNC mill.
Even though I am using the stock Tokico calipers, and they're radially mounted, will 0.3mm make a mechanically significant difference considering the rotors I am using are full floaters? I'm not familiar enough with modern sportbike stuff to know if that little of a clearance discrepancy will bite me in the ass, or if the combination of full floating rotors and sweet modern brake caliper pots will automatically compensate and be a non issue.
Hopefully someone can just say "GREAT JOB WALTER!!" and I can change the title of this so it's searchable and helpful for others in the future. If not, what should I change?
Thanks!
I'm in the process of gathering all the parts and hardware to swap a 2006 GSXR 750 fork and brakes onto my 1975 XS650, while converting to dual disc and using the stock front wheel. I know that this swap has been done, and re-hashed, and there's a lot of great information and a few good pictures on here to help ding dongs like me figure this kinda stuff out, but I feel like there's a few missing pieces of info that might help others pursuing this same type of foolishness. Luckily the steering stem/triple tree should be a straight swap using the appropriate All Balls bearings top/bottom considering the shorter neck length on my 75. My understanding is that the later frames require some finagling to make it work without shortening the bottom cup of the neck.
So - anyone who has done this, or who can think about this in a functional/mechanical way, please check my work as outlined below.
The math is pretty simple, really - I made a really lame spreadsheet calculator:
All measurements in mm unless otherwise noted...
- Fork spacing - 154 (found here)
- Hub width - 86.4 (rotor mount to rotor mount)
- Rotor spacing - 137 (outside to outside)
- Rotor offset - 15 (using aftermarket Ducati 748/998R rotors)
- Rotor spacer - 10.3
- Caliper spacer - 5 (stock GSXR rotors are 310mm, Ducati is 320)
- Stock bearing spacing - 96.4 (outside to outside, 14mm bearing width)
- New bearing spacing - 92.4 (outside to outside, 12mm bearing width)
- New axle spacer (L) - 30.8
- New axle spacer (R) - 30.8
- New inner bearing spacer - 68.4
So - with all that in mind, I calculated the needed rotor spacer width as follows:
(Rotor width) - (Hub shell width) - (Rotor offset x2) = (2x Rotor spacer width) /2 ==> Rotor spacer width
(137 - 86.4 - 30) /2 = 10.3mm
Nothing is together yet, but I am planning to use 10mm rotor spacers, which were available on eBay UK for less than what I could pay a friend to machine them for, and will be arriving sooner than he could knock them out on his CNC mill.
Even though I am using the stock Tokico calipers, and they're radially mounted, will 0.3mm make a mechanically significant difference considering the rotors I am using are full floaters? I'm not familiar enough with modern sportbike stuff to know if that little of a clearance discrepancy will bite me in the ass, or if the combination of full floating rotors and sweet modern brake caliper pots will automatically compensate and be a non issue.
Hopefully someone can just say "GREAT JOB WALTER!!" and I can change the title of this so it's searchable and helpful for others in the future. If not, what should I change?
Thanks!
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