Comstars + gsx-r front end

Now i'm really itching to get to the shop! Might have to leave work early...

Another question - your spacer is 110mm OD. The mounting surface of the rotor off the Comstar I have here is 100mm. is the extra width to match up with the rotor? Reason i ask is when I test fit the Ninja rotors, the ends of the studs that hold the rim together protrude out the right side enough to get in the way of mounting that rotor. I wonder if the extra 10mm might get in the way... but i'll measure that up too.

Then on the OEM rotor bolts, looks like the holes need to be coutnersunk as well?
s-l1600.jpg
 
OK, I put all your measurements into the CAD, no countersinking yet. For the hub holes, looks like I'll need to drill into the flange for countersinking?
spacer2.jpg
 
What's going on with those holes next to the flange? Doesn't look like room for a cap head. You gonna have cutouts on that flange for the caps? Or am I missing something here?
 
rs_ss350 said:
OK, I put all your measurements into the CAD, no countersinking yet. For the hub holes, looks like I'll need to drill into the flange for countersinking?
spacer2.jpg
Yea, you'll need cutouts for the bolts in the flange. however you countersink them should take care of that. As far as the oem hardware, I think the portion without threads is the thickness of the rotor itself
The 110mm diameter was just a guess really. That can be altered to whatever you need, but leave enough meat around the threads
 
Your guess of 110 was pretty good as it leaves adequate meat for the thread. However it definitely hits those studs. and in the same position as the rotor holes. See my measurement below. How much space from the hole to the edge do you think I'll need for the thread? I can reduce it to I will need to figure something out or this setup won't work. I may be able to make a small cutout for it in the back, but not deep enough that it interferes with the rotor holes? I think that might be the answer. I'll design it up and post it here.

hub1.JPG


As for the hub question - I confirmed that it is using a long bolt and a nut to fasten the rotor to the wheel. There are no threads in the hub. I also confirmed this on my other bike, my daily rider 79 (see photo below). I suppose I can put heli-coils in there or something? Otherwise it may be difficult to find a bolt that long.

hub2.JPG

hub3.jpg
 
irk miller said:
What's going on with those holes next to the flange? Doesn't look like room for a cap head. You gonna have cutouts on that flange for the caps? Or am I missing something here?

Yes I hadn't done the cutouts yet, just sussing out the specs and trying to see what's next. I think I know what to do next. Will check back in when I have a plan of attack
 
rs_ss350 said:
Your guess of 110 was pretty good as it leaves adequate meat for the thread. However it definitely hits those studs. and in the same position as the rotor holes. See my measurement below. How much space from the hole to the edge do you think I'll need for the thread? I can reduce it to I will need to figure something out or this setup won't work. I may be able to make a small cutout for it in the back, but not deep enough that it interferes with the rotor holes? I think that might be the answer. I'll design it up and post it here.



As for the hub question - I confirmed that it is using a long bolt and a nut to fasten the rotor to the wheel. There are no threads in the hub. I also confirmed this on my other bike, my daily rider 79 (see photo below). I suppose I can put heli-coils in there or something? Otherwise it may be difficult to find a bolt that long.
Well the way you can get around those other bolts interfering with the spacer is to not have the whole piece 28.5mm thick. I made a cut away on the back side.
Also on a side note, those comstars appear to be slightly different than mine. Make sure you check all the measurements I gave you against what you physically have. Stuff changes throughout the years. I wouldn't want to steer you wrong with a bad measurement.
 

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http://cx500forum.com/forum/build-threads/8320-cafe-bike-buildup-80-cx500-19.html

This build is a good read
 
erock85 said:
Well the way you can get around those other bolts interfering with the spacer is to not have the whole piece 28.5mm thick. I made a cut away on the back side.
Also on a side note, those comstars appear to be slightly different than mine. Make sure you check all the measurements I gave you against what you physically have. Stuff changes throughout the years. I wouldn't want to steer you wrong with a bad measurement.

Ah, that makes sense.

Good point on the measurements... question is, how do I go about getting those measurements you have in this drawing, like the hub mounting surface to mounting surface, and the space from the bearing seat, etc to make sure I make the right size axle spacers?

m24hEPX.png
 
erock85 said:
http://cx500forum.com/forum/build-threads/8320-cafe-bike-buildup-80-cx500-19.html

This build is a good read

Ah, countersunk on one side, nd threaded on the other, using through bolts. This should work for me too...
 
rs_ss350 said:
Ah, countersunk on one side, nd threaded on the other, using through bolts. This should work for me too...
Yea, when I saw that I thought it was perfect for your application
rs_ss350 said:
Ah, that makes sense.

Good point on the measurements... question is, how do I go about getting those measurements you have in this drawing, like the hub mounting surface to mounting surface, and the space from the bearing seat, etc to make sure I make the right size axle spacers?
I just used a cheapo digital caliper from Harbor Freight to get all my measurements. The opposite end of the measuring tool can be used to measure depth, i.e. your bearing cup depths
The hub measurements should all be the same as mine, however, I did not have the same mounting hardware on my wheel as you do in the pictures. So when I noticed the discrepancy, I figured I would point out to double check your wheel against my measurements.
 
AH, that's what that thing is for on my digital caliper :D i'll check the measurements today when I pull the old bearings. Thanks again!

The one disadvantage of machining two different spacers (the side with the threads needs 8mm threaded holes i assume) is that it will seem to double my cost... at least if I go through emachine. I'll need to shop around a bit more I think.

Here's my latest adapter design based on our discussion...
rotor-adapter1-front.jpg

rotor-adapter1-back.jpg
 
rs_ss350 said:
AH, that's what that thing is for on my digital caliper :D i'll check the measurements today when I pull the old bearings. Thanks again!

The one disadvantage of machining two different spacers (the side with the threads needs 8mm threaded holes i assume) is that it will seem to double my cost... at least if I go through emachine. I'll need to shop around a bit more I think.

Here's my latest adapter design based on our discussion...
Looks like it should work well, the rotor holes do not need to go through the whole part, but it won't hurt anything. Looks good
 
This is of great interest to me, I have a front end from an RZ350 that I would like to use on my RD350 (1mm larger tubes and much better brakes, especially with the EBC rotors I have for them) but I want to use the RD hubs with alloy rims and stainless steel spokes. I'm not sure if this is doable.
 
Update - pulled my old bearing to get some measurements and it looks like there were some significant differences. The hub from mounting surface to mounting surface is 80mm. The collar/spacer inside the hub was 64.5mm. The ID of the axle bore is something larger than 32... it's not evenly bored out (gets narrower in the center) and there were three protrusions around the inside radius that held the old collar in place.

For the fork width, I'm getting 153.5, and on the left side of the axle there is a built in spacer that's 14mm. given these numbers, how do I calculate the centering spacers? 153.5, -64.5 collar, -18 for the two bearings? Cut the remainder in 2, then subtract 14mm from the left spacer? Giving me 35.5 for the right side and 21.5 for the left?

Plus, my caliper spacers would each need to be 5mm more narrow, correct?
 
Actually... the rims are too wide for the calipers... what can be done about this? One of the early posts in this thread shows a comstar with these calipers. Can i swap the forks to pull the calipers out a little? Or anything else can be done?

Thanks!
 
rs_ss350 said:
Actually... the rims are too wide for the calipers... what can be done about this?
Which calipers do you have? Are you trying to run 4 pot with pistons on both sides?
 
when i fit the calipers i had to sand a bit off the back of the caliper

cosmetic really and only along one edge

then i also touched a spot on the comstar spoke plate returns you cant tell but it gave me a extra bit of clearance and its all

been working well for that last few years
 
irk miller said:
Which calipers do you have? Are you trying to run 4 pot with pistons on both sides?
yes 4 pot calipers on both sides... is there another option?

in the photos, i rotated the wheel so that the calipers would actually mount between the "spokes". no way the wheel was turning. how much metal did you grind off the inside of the caliper?

rotor1.jpg

rotor2.jpg

rotor3.jpg
 
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