Topic: Brake Rotor Bolt Circle

[Powderman]

Is the bolt circle on the CB750 rotors 78 or 80mm?  I'm thinking it is the same as some Ducati rotors(80mm). I'm looking at a pair that is fairly inexpensive and if they fit I'll jump on them.

[70CB750]

I measured the one I have on the shelf - 80mm - from early K.

[Powderman]

Cool, then it's the same as the Ducati rotors and I can pick up a pair for my build for $50.

[Ravie]

The offset/dish has to be the same as well...You may already know that...just thought I'd say it out loud.

[Powderman]

The offset/dish has to be the same as well...You may already know that...just thought I'd say it out loud.

Not on my application, I'm mounting these rotors on my Kimtabs on a 70 Triumph.
The rotors that came with the Kimtab wheel I bought are warped and needed replacing. I ended up paying $60 for the pair of Ducati rotor. The offset is the same 10mm which is only important for clearing the spokes of the wheel. I have not yet welded the caliper brackets onto the lower legs yet. Will do that after mounting the new rotors.



Will use these Ducati floating rotors. The importance of not welding the brackets was dependent more on what diameter rotor I ended up with. Off set could have been handled by the bearing carriers I'm making.

[grcamna2]

Nice full floating rotors  They should stop your Triumph very well.

[754]

 Yes Ducati rotors fit, and Yamaha too, posted it many times.. off set and diameter usually mean custom work.
 we put a 320 rotor and 6 piston caliper on a Ceriani Roadrace fork..

[RAFster122s]

Would some of the auto wheel rebuilders be able to redo your kimtabs? One place I dont recall name of is in Florida and Columbus Ohio and the redo alloys and balance them up after fixing breaks, warps or other issues. They were a good source but their rates were not obscene and they were actually not much more than a quality strip and refinish job.
They fixed run out and balance to the point they were better than a lot of new alloys , cheap ones at least, out of the box and far better than risking a set from a wrecked car.
They advertized in R&T.

[Powderman]

Yes Ducati rotors fit, and Yamaha too, posted it many times.. off set and diameter usually mean custom work.
 we put a 320 rotor and 6 piston caliper on a Ceriani Roadrace fork..

Some Ducati's and some Yamaha's.  I have 12" rotors on my XR with the Ceriani's. I had to split the 4 piston calipers and make a mounting bracket that sandwiches between the halves. bracket had to be machined for rings and bolts and all. My KawaTon has 395mm rotors (15.5")




I didn't want really large rotors up front, this bike doesn't need that much brake, even though I know they are regulated by the operator. The rear brake I'm putting on this is only around 245mm

[Powderman]

Would some of the auto wheel rebuilders be able to redo your kimtabs? One place I dont recall name of is in Florida and Columbus Ohio and the redo alloys and balance them up after fixing breaks, warps or other issues. They were a good source but their rates were not obscene and they were actually not much more than a quality strip and refinish job.
They fixed run out and balance to the point they were better than a lot of new alloys , cheap ones at least, out of the box and far better than risking a set from a wrecked car.
They advertized in R&T.

What makes you think my Kimtabs need fixing?

[RAFster122s]

Sorry Powderman, i misread the bit about the warp. Must have been speedreading or something...
David

[Powderman]

Sorry Powderman, i misread the bit about the warp. Must have been speedreading or something...
David

yep, rotors not wheels. That's why the Ducati rotor replacement. The Kimtab rotors I got with this wheel are underlined but are Kimtab. Mine on the XR are the same but drilled. They are only 3mm thick and i'm surprised as hard as I used them mine never warped, but it doesn't surprise me that these were. Actually on the rear of my XR the floating caliper froze up at the slide and ended up cupping the rear rotor. I had Coleman Racing Products cut me a new 1/4" rotor for $80

[754]

 if the calipers are not pulling straight on, they can easily warp..

[Stev-o]

Those Duc rotors are beautiful, and at $60, that is a deal.

[70CB750]

Those Duc rotors are beautiful, and at $60, that is a deal.

I say, I may get those for Dorothy.

[70CB750]

Do you have a link to the Ducati rotors or part number, please?

The offset/dish has to be the same as well...You may already know that...just thought I'd say it out loud.

Not on my application, I'm mounting these rotors on my Kimtabs on a 70 Triumph.
The rotors that came with the Kimtab wheel I bought are warped and needed replacing. I ended up paying $60 for the pair of Ducati rotor. The offset is the same 10mm which is only important for clearing the spokes of the wheel. I have not yet welded the caliper brackets onto the lower legs yet. Will do that after mounting the new rotors.



Will use these Ducati floating rotors. The importance of not welding the brackets was dependent more on what diameter rotor I ended up with. Off set could have been handled by the bearing carriers I'm making.

[Powderman]

Do you have a link to the Ducati rotors or part number, please?

I give up, I've searched all the parts fiches and can't seem to find this rotor or part#. I see lots of them on EBay but no part number and when I check out specific models this rotor came on I see about 10 different rotor carriers but none like this, though those will work also. They are 80mm bolt circle with a 10mm offset.
This set came off a 916 (unknown year) , but also fit 748 916 998 998 Monster 900 ST2 ST4 according to the listing. I believe they were used from the early 90's right up to the early 20's.
Check out this link and you will see 4 others of this same rotor for sale there at the top under "more chances to get what you want:
http://www.ebay.com/itm/351667277194?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT



Here's another:http://www.ebay.com/itm/DUCATI-OEM-EARLY-monster-SS-FRONT-ROTOR-3-851-888-748-916-750-900-FITS-MANY/371554026584?_trksid=p2047675.c100011.m1850&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D35852%26meid%3Dc28810e2d90945b28f5dc20f91fe492d%26pid%3D100011%26rk%3D1%26rkt%3D10%26sd%3D351667277194


Looks like I got the pair for the price of a single rotor due to the condition of the chrome which I will blast off and powder coat the carrier and replace the buttons with removable ones.

[70CB750]

Sorry, did not mean to frustrate you:)

Thank you for the ebay links, that will do.

[70CB750]

What is the out diameter of the Ducati rotor?  I am thinking up this combination of VFR fork and brakes and CB750 wheel - Ducati discs would crown it all 

[Powderman]

Sorry, did not mean to frustrate you:)

Thank you for the ebay links, that will do.

I was frustrating myself as I wanted the info also, couldn't find jack.  I believe the Ducati rotor is 320mm.

[754]

One thing needs to be mentioned, the center hole on other rotors is usually bigger, if you make a spacer, it should have a snout to center the disc.
 Here is a pic of the Duc 320mm on the Ceriani..the big challenge was the 6 pot caliper clearing the spokes, and finding a way to mount caliper..
The F forks and GL. Forks make this part much easier to build mounts.

[Powderman]

One thing needs to be mentioned, the center hole on other rotors is usually bigger, if you make a spacer, it should have a snout to center the disc.
 Here is a pic of the Duc 320mm on the Ceriani..the big challenge was the 6 pot caliper clearing the spokes, and finding a way to mount caliper..
The F forks and GL. Forks make this part much easier to build mounts.

i bought a set of those calipers and they would to clear the spokes, so I had to use a 2 piston floater instead. How did you mount them to the Ceriani's? The center hole bigger shouldn't be an issue if your 6 rotor bolts and holes are snug. I'm a bit concerned because I read in one post where the bolt holes in the Ducati rotor was 10mm and I think mine are only 8mm in the wheel. I'll drill the wheel to accept 10mm studs instead if that's the case.

[754]

Just make adaptor washers if bolt holes are bigger than your bolts.. The main part is to get the rotor centered.
 Will add a pic of the caliper mount. Took about three shoehorns to get that to fit..

[70CB750]

Good to know, Frank, thank you.

[Powderman]

Just make adaptor washers if bolt holes are bigger than your bolts.. The main part is to get the rotor centered.
 Will add a pic of the caliper mount. Took about three shoehorns to get that to fit..

I'm mounting the rotors, bolting the caliper bracket to the caliper, locating the caliper on the rotor,
putting air pressure to the caliper to grab the rotor and then welding the bracket to the leg at that point.

[754]

Run a battery overflow tube, hesvy wire or cord, along outer edge of rotor to give the caliper pins clearance from the disc..