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Author Topic: Comstars + gsx-r front end  (Read 14263 times)

Offline rs_ss350

  • Posts: 88
Re: Comstars + gsx-r front end
« Reply #50 on: Jun 22, 2017, 22:37:58 »
Any other rotor suggestions are welcome :). What's another pair of rotors for the sake of getting it right?
1979 CB750K - 10th Anniversary Limited Edition
1982 CB750K - Cafe/brat project under construction
1977 CB750K - another project!

Member of Moto Guild SF

Online irk miller

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Re: Comstars + gsx-r front end
« Reply #51 on: Jun 22, 2017, 23:03:08 »
Hmm, something is off on the gsxr rotors I bought then... these have 5 holes... https://www.ebay.com/itm?itemId=322469292439
That they are. My bad.

Offline rs_ss350

  • Posts: 88
Re: Comstars + gsx-r front end
« Reply #52 on: Jun 22, 2017, 23:08:35 »
That they are. My bad.

Nonetheless, still a more complicated spacer situation.
1979 CB750K - 10th Anniversary Limited Edition
1982 CB750K - Cafe/brat project under construction
1977 CB750K - another project!

Member of Moto Guild SF

Offline erock85

  • Posts: 114
Re: Comstars + gsx-r front end
« Reply #53 on: Jun 23, 2017, 09:35:23 »
Here's what I would do:
It appears the rotor center spacing is 132mm. The hub is 70mm on Comstar, from rotor mounting surface to rotor mounting surface. Your rotor spacer has to be 28.5mm on each side to correctly space the rotors in the center of the calipers. Next get some Hayabusa rotors, specs on those are PCD: 91mm; (5)10mm mounting holes; OD: 320mm; ID: 69mm; Thickness: 5mm
Clock the rotor spacing to the Comstar hub spacing on your 28.5mm spacer  ;D EDIT: you'll want to countersink the mounting holes from spacer to hub
Then you will need 5mm caliper spacers, cheap to buy or I have a drawing to get them made. I had mine made.

1974 Honda CB360
1979 Honda CX500
2005 Harley Davidson Sportster 883

Offline rs_ss350

  • Posts: 88
Re: Comstars + gsx-r front end
« Reply #54 on: Jun 23, 2017, 13:29:59 »
Here's what I would do:
It appears the rotor center spacing is 132mm. The hub is 70mm on Comstar, from rotor mounting surface to rotor mounting surface. Your rotor spacer has to be 28.5mm on each side to correctly space the rotors in the center of the calipers. Next get some Hayabusa rotors, specs on those are PCD: 91mm; (5)10mm mounting holes; OD: 320mm; ID: 69mm; Thickness: 5mm
Clock the rotor spacing to the Comstar hub spacing on your 28.5mm spacer  ;D EDIT: you'll want to countersink the mounting holes from spacer to hub
Then you will need 5mm caliper spacers, cheap to buy or I have a drawing to get them made. I had mine made.

Thanks! that's all super helpful.  Questions...

Are these the rotors you're referring to? http://www.ebay.com/itm/99-07-SUZUKI-HAYABUSA-GSX1300R-ROTORS-FRONT-BRAKE-DISC-WHEEL-OEM-STRAIGHT-/252966078859?hash=item3ae5f4098b

for the spacer, I understand countersinking the holes for mounting to the hub (what diameter would that be?).  If the hub mounting surface is flat against the hub, how do the rotors get mounted?
1979 CB750K - 10th Anniversary Limited Edition
1982 CB750K - Cafe/brat project under construction
1977 CB750K - another project!

Member of Moto Guild SF

Offline erock85

  • Posts: 114
Re: Comstars + gsx-r front end
« Reply #55 on: Jun 23, 2017, 14:04:00 »
Thanks! that's all super helpful.  Questions...

Are these the rotors you're referring to? http://www.ebay.com/itm/99-07-SUZUKI-HAYABUSA-GSX1300R-ROTORS-FRONT-BRAKE-DISC-WHEEL-OEM-STRAIGHT-/252966078859?hash=item3ae5f4098b

for the spacer, I understand countersinking the holes for mounting to the hub (what diameter would that be?).  If the hub mounting surface is flat against the hub, how do the rotors get mounted?
Yes, those are the year rotors you want 99-07
The diameter would depend on the mounting hardware you are using. If you go with allen head bolts, which i recommend, you would need to make them the diameter of the head of the bolt. You can find those specs online - McMaster Carr
The rotor mounting holes would then have to be a threaded hole and you can use the stock bolts that Suzuki would have used. part #http://www.partzilla.com/parts/detail/suzuki/SP-09106-08148.html
I think they are M8x1.00 Edit: They are M8x1.25
« Last Edit: Jun 23, 2017, 14:06:38 by erock85 »
1974 Honda CB360
1979 Honda CX500
2005 Harley Davidson Sportster 883

Offline rs_ss350

  • Posts: 88
Re: Comstars + gsx-r front end
« Reply #56 on: Jun 23, 2017, 14:09:28 »
Fantastic - thank you!  Would Aluminum 6061 be the proper material to use, for the adapters and the axle spacers?

Just thought of something... even if using allen head bolts, I'd still need hex nuts for the other side?  and then enough clearance to get a socket in there?
« Last Edit: Jun 23, 2017, 14:16:53 by rs_ss350 »
1979 CB750K - 10th Anniversary Limited Edition
1982 CB750K - Cafe/brat project under construction
1977 CB750K - another project!

Member of Moto Guild SF

Offline erock85

  • Posts: 114
Re: Comstars + gsx-r front end
« Reply #57 on: Jun 23, 2017, 14:21:44 »
Fantastic - thank you!  Would Aluminum 6061 be the proper material to use, for the adapters and the axle spacers?

Just thought of something... even if using allen head bolts, I'd still need hex nuts for the other side?  and then enough clearance to get a socket in there?
To mount the spacer you will be using the old rotor mounting points on the comstars, which is a threaded hole through the hub. An allen bolt would suffice to mount the spacer to the hub. Then use the rotor mounting hardware to mount the rotor to the spacer using the threaded holes created in the spacer. No nut is needed
6061 is perfect for this application, strong enough and easy enough to machine.
1974 Honda CB360
1979 Honda CX500
2005 Harley Davidson Sportster 883

Offline rs_ss350

  • Posts: 88
Re: Comstars + gsx-r front end
« Reply #58 on: Jun 23, 2017, 15:20:17 »
Hmm, when I took the existing rotor off my Comstar it was fastened by a long bolt that went straight through the hub with nuts on the end.  I'll investigate more this afternoon. could be the PO did something funky there....  Also this wheel was originally fitted with only a single rotor.  I wonder if that makes a difference with the hub?  Seems like two rotors would mount fine.
« Last Edit: Jun 23, 2017, 15:28:38 by rs_ss350 »
1979 CB750K - 10th Anniversary Limited Edition
1982 CB750K - Cafe/brat project under construction
1977 CB750K - another project!

Member of Moto Guild SF

Offline erock85

  • Posts: 114
Re: Comstars + gsx-r front end
« Reply #59 on: Jun 23, 2017, 16:14:49 »
Hmm, when I took the existing rotor off my Comstar it was fastened by a long bolt that went straight through the hub with nuts on the end.  I'll investigate more this afternoon. could be the PO did something funky there....  Also this wheel was originally fitted with only a single rotor.  I wonder if that makes a difference with the hub?  Seems like two rotors would mount fine.
Interesting..mine too was a single rotor with a cap on the other side without a rotor. I used the old rotor mounting point and the cap mounting holes for my application
1974 Honda CB360
1979 Honda CX500
2005 Harley Davidson Sportster 883