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Author Topic: Comstars + gsx-r front end  (Read 14078 times)

Offline rs_ss350

  • Posts: 88
Re: Comstars + gsx-r front end
« Reply #30 on: Jun 21, 2017, 16:22:31 »
I read ya. And to be honest, I may do that too, which the OP might want to do. I was doing some quick math just now and with a 32 OD x 25 ID that only leaves 3.5mm wall thickness on the spacer. That might not be strong enough. So there is room for options if that is needed. Thanks for the idea!

SO rather than flange the spacer, making it a consistent thickness would work here?
1979 CB750K - 10th Anniversary Limited Edition
1982 CB750K - Cafe/brat project under construction
1977 CB750K - another project!

Member of Moto Guild SF

Offline rs_ss350

  • Posts: 88
Re: Comstars + gsx-r front end
« Reply #31 on: Jun 21, 2017, 16:23:34 »
I actually have the GSXR drawing too, that might help better. I used Hayabusa rotors with caliper spacers on my cb360, but that has a Harley wheel. You can do this how you want but you will need the measurements Fork Spacing at Wheel Spindle Clamps = 153mm here's the drawing I made up. So really you could put the comstar hub in the gsxr drawing if you want and you should be able to figure out your spacers needed.
Yes, the spacer will be in the seal and up against the bearing.
gsxr: I can't find the actual .dwg for this. It might be on my home computer, I'm at work now. I'll look tonight

THanks, this is great!
1979 CB750K - 10th Anniversary Limited Edition
1982 CB750K - Cafe/brat project under construction
1977 CB750K - another project!

Member of Moto Guild SF

Offline rs_ss350

  • Posts: 88
Re: Comstars + gsx-r front end
« Reply #32 on: Jun 21, 2017, 16:58:23 »
you will need a new internal bushing, keep stock width but make it 25mm ID. Then you'll need custom centering spacers. Then you'll need to measure for rotor adapters. I can made what you need, but with time and material it is going to cost $300-400 for axle spacers and rotor adapters. And I'd need VERY accurate measurements from you, or at least the axle and wheel mailed to me with the replacement bearings and rotors.

Thanks - same width makes sense to me now seeing the above diagram - wasn't sure there was a seat for the bearing.  I found someone to machine up the rotor adapter locally and am currently designing it in cad.  I really appreciate all the tips you guys are giving - I'm just learning.
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 #33 on: Jun 21, 2017, 17:03:15 »
THanks, this is great!
Thanks - same width makes sense to me now seeing the above diagram - wasn't sure there was a seat for the bearing.  I found someone to machine up the rotor adapter locally and am currently designing it in cad.  I really appreciate all the tips you guys are giving - I'm just learning.

Good luck, if you need any measurements just let me know. I remember doing the gsxr swap and even the cbr swap currently it is very helpful to get information from someone who has the parts in front of them. Just let me know
1974 Honda CB360
1979 Honda CX500
2005 Harley Davidson Sportster 883

Offline rs_ss350

  • Posts: 88
Re: Comstars + gsx-r front end
« Reply #34 on: Jun 21, 2017, 17:44:33 »
Good luck, if you need any measurements just let me know. I remember doing the gsxr swap and even the cbr swap currently it is very helpful to get information from someone who has the parts in front of them. Just let me know

I appreciate the offer.  One question I have now is on rotor choice.  I have two sets - a GSX-R set and a Ninja set.  The Ninja set has the holes in the perfect position (slightly wider holes) , making for a simpler adapter.  Those rotors also have an offset which i'm unsure how to measure.  THen the GSXR rotors will require something more like what you designed. Not sure what would be the more solid solution.

What do I need to measure to figure our the adapter width - what surfaces etc?
« Last Edit: Jun 21, 2017, 17:46:14 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 irk miller

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Re: Comstars + gsx-r front end
« Reply #35 on: Jun 21, 2017, 17:52:54 »
When I put VZ800 calipers on my R100/7 Lester rims, I clocked the rotors.  Both the VZ and BMW patterns are 5 bolts but one is 5mm wider than the other.  By clocking it and drilling new holes, it was a super easy solution.  By clocking, I mean rotate the rotors to where the holes for the rim are centered between the existing holes on the rotor.  To figure out the spacer thickness for the rotors, I got everything put together, including calipers.  I ran threaded rod through the wheel holes, bolted it tight on both sides of the wheel, and floated the rotor off the wheel while making sure it was in the caliper nice and neat.  Then I measured with a strip of paper.  You have some leeway with the calipers.  They float back and forth about 10mm. 

Offline erock85

  • Posts: 114
Re: Comstars + gsx-r front end
« Reply #36 on: Jun 21, 2017, 17:59:05 »
I appreciate the offer.  One question I have now is on rotor choice.  I have two sets - a GSX-R set and a Ninja set.  The Ninja set has the holes in the perfect position (slightly wider holes) , making for a simpler adapter.  Those rotors also have an offset which i'm unsure how to measure.  THen the GSXR rotors will require something more like what you designed. Not sure what would be the more solid solution.

What do I need to measure to figure our the adapter width - what surfaces etc?
Make certain you measure the distance between the calipers on the inside. I know the comstar wheel is kinda wide by the hub and tapers down to the rim. You don't want the calipers rubbing on the wheel. I went with 320mm rotors that push out the caliper further where the rim is narrower. The harley rim I used with the GSXR was narrow enough to not have issues. Just something to think about.
1974 Honda CB360
1979 Honda CX500
2005 Harley Davidson Sportster 883

Offline rs_ss350

  • Posts: 88
Re: Comstars + gsx-r front end
« Reply #37 on: Jun 21, 2017, 19:17:15 »
Clocking makes sense! 

Going to the shop tonight to try to measure for the rotor adapters
1979 CB750K - 10th Anniversary Limited Edition
1982 CB750K - Cafe/brat project under construction
1977 CB750K - another project!

Member of Moto Guild SF

Offline rs_ss350

  • Posts: 88
Re: Comstars + gsx-r front end
« Reply #38 on: Jun 22, 2017, 13:29:03 »
Didn't manage to measure for the rotors.  Couldn't get threaded rods.  Will wait for my bearings to rrive tomorrow so I can install on the actual axle.

question about the clocking - the inner diameter of the rotors are slightly off... what's the best method for keeping the pieces together - and centered - while drilling?

one more question - designing the spacer in CAD: what am i measuring on the existing hub or rotor to ensure i place the holes in the right position?
1979 CB750K - 10th Anniversary Limited Edition
1982 CB750K - Cafe/brat project under construction
1977 CB750K - another project!

Member of Moto Guild SF

Offline irk miller

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Re: Comstars + gsx-r front end
« Reply #39 on: Jun 22, 2017, 14:00:39 »
There's more than one way to do this.  I did a GL1000 front end with the stock wheel. I machined the hub to accept a larger OD/ID bearing to match the VZ axle.  I was fortunate to find a modern 300mm rotor to match the GL bolt pattern (95/96 YZF600R).  So all I needed was the spacer.  A used a template from the rotor to plot and drill the spacer.  Because the rotors have a larger ID than the hub face, I machined it with a lip...


Here's the finished product with 99 - 02 SV650 calipers...



The BMW is clocked, and with the same lip as the GL.  A cool thing about the BMWs is they have a metal piece installed on the outside of the rotor that covers the holes, so it looks clean.  I used that same piece to pattern from.  There are online resources for drawing templates, if you don't have the software already...