Locating a rotor/centering on the wheel

[TAftonomos]

A "combo" of stuff I ended up with is beginning to be particularly difficult.

The rotor is from Galfer, standard wave rotor, but zero offset.  The rotor bolt holes to bolt the thing to the wheel are 10.55mm in diameter.

The wheel is from carrozzeria. 

M8 threads

Problem is the shoulder bolts that I can find all have 10mm shoulder diameters, and the center hub of the wheel is small that the rotor's center hub....so the rotor can walk around in a circle about 1.5mm in any direction when not bolted down snugly.  How do I get this sucker centered properly?

Custom shoulder bolts?

Machine some sort of hubcenteric ring and the carrier of the rotor?

I had thought of finding a piece of shim stock the thickness I needed, cutting out a 5mm wide long strip, and shimming the hub of the rotor to the wheel.  What do you think?

[Raux]

turn a piece of AL that can acts as a centering hub. put the axle through it and then slide the brakes on, bolt them down, take the centering piece out, then mount the wheel?

just a thought

[BK_856er]

Good question.  I took a look at some of my wheels.  My OE rotor bolts have 13.99mm diameter heads and fill the Brembo rotor holes nicely, and the rotors also center/fit well on both the OE Brembo wheels and the aftemarket OZ wheels.  Is it safe to have a rotor that is not physically centered by the wheel hub?  Seems to me the wheel/hub should be carrying the braking forces and not the rotor bolts....

BK

[DarkStaR]

Hub-centric is ideal, but not totally necessary.  There are rotor set-ups that are not hub-centric that work just fine. (e.g. MTS, BMW, Buell, etc.) With a round hub, regardless the set up, the shear force is going to be transferred to the bolts.

With that said, it being hub-centric would make life a lot easier.

Is the rotor carrier countersunk for the bolt heads?

[Raux]

yeah totally agree on the hub being the load carrying of the brake rotor and not the bolts

the master mechanic that helped me with my bike said the same. wouldn't make me spacers for the offset difference.

I had to find 15mm offset 6 bolt rotors to match my wheel/fork combo

[TAftonomos]

Hmm...All ducati hubs are round, so the sheer force is going to be on the bolts then?  Got another question about the monster setup I just posted...at the bottom of this post.


First off, the 2vsbk project.  Carrozzeria (sp?) wheels, with their "brake kit".  The rotor has 10.55mm holes for the rotor bolts.
The hub of the wheel is countersunk to allow the shouldered portion of the bolt to seat.  Still, I don't know how to hold the rotor centered up as I can move it around.  I called them today, but spoke to someone who didn't have the answer....told to call back on Mon.  Pretty sure this is the setup they sell, so I'm curious as to what they might say.

NOW...


Now, my monster with those rotors/spacers.  The shoulder on the bolts isn't long enough to engauge the spacer, but is the correct diameter to center the rotor.  The spacers is centered because of the hub on the wheel, the rotor is centered because of the shoulder bolts and it's all clamped down tight.... I wonder if I should get bolts with a longer shoulder that engage the spacer....

I did not need to center the rotor to the spacer on this application, because the shouldered bolts fit tightly on the rotor, and it centers itself.

[Raux]

the longer the bolt that is out of the threaded part of the wheel the more stress on it.

so. in this case, I imagine your spacer is about 5mm, at the 4-5mm thick of the rotor mount and you have about 10mm protruding from the wheel. (if I'm right about your fork offset, more if it has the 15mm offset)

whereas a stock situation would have only 5mm protruding.

so you have only 5 longer bolts holding the rotors on and lack of assistance from the hubcenter.

I think I heard you need to grab about 7-8 threads as well on the bolts.

[DarkStaR]

...
Now, my monster with those rotors/spacers.  The shoulder on the bolts isn't long enough to engauge the spacer, but is the correct diameter to center the rotor.  The spacers is centered because of the hub on the wheel, the rotor is centered because of the shoulder bolts and it's all clamped down tight.... I wonder if I should get bolts with a longer shoulder that engage the spacer....

I did not need to center the rotor to the spacer on this application, because the shouldered bolts fit tightly on the rotor, and it centers itself.

Shouldn't matter too much, as you got everything aligned on that set-up.

FYI, This is the same deal with the OZ wheels for the sport classics.  The wheels come with spacers for the rotors if the stock 2 pot calipers are going to be used, but still use the OEM hardware to bolt it up.  We didn't use the spacers, since the calipers were upgraded to 4 pots.  The spacers were nice cnc anodized black pieces. The axel spacers were of the same quality also.

As for the not-aligning set-up,

The bolt holes being too large would bother me more than it not being hub-centric.  How about turning down some inserts to get the holes to the proper diameter, and pressing them into the rotor carrier?

[DarkStaR]

the longer the bolt that is out of the threaded part of the wheel the more stress on it.

so. in this case, I imagine your spacer is about 5mm, at the 4-5mm thick of the rotor mount and you have about 10mm protruding from the wheel. (if I'm right about your fork offset, more if it has the 15mm offset)

whereas a stock situation would have only 5mm protruding.

so you have only 5 longer bolts holding the rotors on and lack of assistance from the hubcenter.

I think I heard you need to grab about 7-8 threads as well on the bolts.

I agree.  With the spacer, there will be more stress on the bolts.  Is it enough to cause failure...idk.

[Speeddog]

~~~SNIP~~~
Machine some sort of hubcentric ring
~~~SNIP~~~

Yes.

[TAftonomos]

Monster:

When I took the rotors off a previous wheel from a bike I parted, they were using 5mm spacers behind the rotor, and the bolts didn't center ANYTHING.  The hub of the wheel protruded enough that it centered the rotor, but if the rotor was loose it could rotate a bit before hitting the bolts (which were smaller than the bolt holes).

My setup is different because the hub won't center the rotor (only 5mm deep).  I could have some deeper shoulder'd bolts made up to capture the spacer with the rotor, not sure if that will be any better or not.  

I know there are a few monsters running around with 5mm spacers and longer bolts on them, anything different about those setups?  Any failures?




For the 2v bike, I suppose that can be done, just not sure how to go about it.  My other idea would be to machine the wheel down further, and then press on an aluminum ring/sleeve to center the current rotor.  That way if I bend a rotor and need to replace I could just buy one, as opposed to having to machine the carrier all over again.