This may be a (very) silly question but I have two front wheels for my ST, both of which have a warped left disc. Can I use a right hand disc on the left side? and make one good wheel from the two). I know they are different but as far as I can see the bolt holes would line up and the only difference would be that the teardrop shaped cutouts underneath the bearing surface would be the other way round. Is there something I'm missing?
Front discs interchangeable?
- Thread starter Lockkeeper
- Start date
Compare part numbers from one of the on-line part sites like www.ronayers.com or partzilla.com. It they are the same, they are interchangeable.
I've never tried swapping them around, but I think the only difference is as you said, the cosmetic appearance of the swirls between the braking surface and the mounting area. Also, there are differences in the diameter of the rotors between the ABS and non-ABS versions, those can't be interchanged, but you probably already know that.
wjbertrand
Ventura Highway
They are specific right to left. I think besides the swirl direction the drilling patten is different. Having said that, I can't see why they wouldn't work on either side.
-Jeff
-Jeff
I measured the bolt pitch on each side and they seem to be the same, and the OP says the bolt patterns appear to line up the same on either side. I always wondered why Honda didn't just make the swirl pattern non-directional and have one rotor part number instead of two.
edit: the bolt attachment points are symmetrical across the hub. The location of the bolt hole on the left side is directly opposite the bolt attachment point on the right side.
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Kevin_56
Site Supporter
There are Rotation directional arrows on both the right and the left rotor. At least the ones on my '03. Just be very careful when installing new tires that you have the correct wheel rotation noted. Should you use two rights the rotation arrows will be contradicting each other.
they must have added that on the 1300, on the 1100 there are no such markings, at least not on mine.
Thanks for all the replies. I'll swap one over and procede cautiously! I'll post an update when its done.
ST1100Y
Site Supporter
uhoh... I have to object here!
Those spokes (or swirls) are definitely designed/arranged to ensure equal load distribution while braking...
Installed correctly the torque will cause "contraction", thus centre/align the braking surface with the hub (like in a spoked rim).
Installed incorrectly the torque could cause "expansion", thus force the rotor to warp out of alignment, thus risk of cracks...
All the OEM ST1100 front rotors I'd seen/held have [L] & [R] markings embossed; do not mix up their orientation.
Take extra care on those paper-washers between hub and mounting-ring, replace (preferable a full set for that side/rotor) if one has ripped during removal; they compensate thermal expansion of rotor base.
Also see that all fixing bolts get a drop of thread-lock (medium) and are installed with proper torque as listed in workshop-manual.
I have no evidence either way, but I'd be surprised if the swirl orientation makes any difference at all. The swirl part is only styling AFAIK, I don't think it has any functionality, but I could be wrong. I guess we will wait and see what the OP finds.
edit: I agree with your comment about the swirl orientation being such that the braking forces being applied to the swirls would tend to compress the swirl part towards the hub, and with the swirls in the opposite orientation those forces would tend to pull on the swirls. But since there's still one rotor in the correct orientation those forces will continue to be applied as designed on that side, there's only one side that will be reversed. I'd suspect that the entire system is designed with plenty of margin for the applied forces, and that the direction of the swirls isn't really a critical design parameter. Given that he would otherwise have to buy a new left rotor anyway, seems like its worth a try.
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I'd be cautious about swapping sides with the rotors as well. Spokes for lack of a better description of the rotor are set up to resist tension or pull under braking. If mounted on the opposite side they would be subjected to compression under braking. I'm not confident that under sever load or heavy braking that they would behave the same as when placed on the proper side.
Think of it like spokes on a bicycle wheel but remove one set of spokes so they all go the same direction like that of the rotor. In the correct orientation you could pull the tire and the spokes would pull the hub in the same direction without issue. However, if you reversed the wheel direction the spokes would want to flex and bend under pressure instead of pulling the hub. I hope this makes sense.
Think of it like spokes on a bicycle wheel but remove one set of spokes so they all go the same direction like that of the rotor. In the correct orientation you could pull the tire and the spokes would pull the hub in the same direction without issue. However, if you reversed the wheel direction the spokes would want to flex and bend under pressure instead of pulling the hub. I hope this makes sense.
yep, that's the big question at this point, whether those 'spokes' are active or passive.
My guess is they are passive, they don't deform enough for the direction of force to matter. My logic for thinking this way is why would anyone purposely design a brake rotor that flexes under load, its bad engineering design. If the metal deformed every time you hit the brakes, the rotor spokes could eventually experience metal fatigue from repeated deformation cycles, that wouldn't be good. It would make more sense to over design them such that the rotational load was negligible compared to the strength of the spokes.
But, its just a guess, I could be wrong, and we all know the consequences of rotor failure could be pretty severe.
edit: after a bit more thought, I'm joining the "NO" camp. If it were my bike, I'd be concerned enough about it that I'd be constantly checking for early signs of fatigue/failure. That alone wouldn't make it worth the cost savings of buying the proper side replacement rotor.
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FWIW, I talked to one of the reps at Galfer and his opinion was similar. He said the spoke orientation is probably a combination of style and function, and since you can't be 100% sure that it has nothing to do with function its better to not take any chances.
ST1100Y
Site Supporter
Might be as simple as ventilation... they are arranged like turbine blades...
I think it's mainly about style. So proper symmetry/aesthetics would be the only issue. Ventilation or somehow reducing drag might be a consideration.
I'd compare the design to other models of Hondas and years of Hondas. Not much changed on the ST1300s but maybe the GoldWing rotors changed over the years.
If there were some structural advantage in the design of the ST's rotor I'd expect to see similar styles with little variation on all Hondas. And making the rotors "stronger" in one function over another doesn't make any sense.
Unless money was really tight and making "one good wheel" was temporary? I'd consider getting the proper rotor if only to avoid the "Hey you got one on backwards" people. Unless you want to tell 'em "Yeah it makes me faster in left turns!"
I'd compare the design to other models of Hondas and years of Hondas. Not much changed on the ST1300s but maybe the GoldWing rotors changed over the years.
If there were some structural advantage in the design of the ST's rotor I'd expect to see similar styles with little variation on all Hondas. And making the rotors "stronger" in one function over another doesn't make any sense.
Unless money was really tight and making "one good wheel" was temporary? I'd consider getting the proper rotor if only to avoid the "Hey you got one on backwards" people. Unless you want to tell 'em "Yeah it makes me faster in left turns!"
**UPDATE** Thanks for all the replies. I have (temporarily) put the spare R/H disc on the left side. I can confirm it fits and rides normally. I will however be getting a replacement L/H disc ASAP!
yeah, unfortunately for you this is the one area where you don't want to take ANY chances. The fact that the cost of the proper part isn't trivial makes it even harder to give in to using excess caution, but I think that's the right way to go in the end.
I wouldn't worry a bit about "unequal loading ".
There are plenty of bikes that have only ONE front disk. That's about as unequal as you can get. And there is no problem with these one front disk bikes.
Save you money and run whatever disk on whatever side you want !!
There are plenty of bikes that have only ONE front disk. That's about as unequal as you can get. And there is no problem with these one front disk bikes.
Save you money and run whatever disk on whatever side you want !!
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