Simple Question: Do all of these bikes have some brake drag?

Al st1100 said:
that's in mm not inches which is less than .001 in inches.
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No it is not.
The specifications from the Honda ST1300 service manual are;
Front brake disc warpage- 0.20 mm, 0.008".
Rear brake disc warpage- 0.30 mm, 0.012".

See the attached page from the Honda ST1300 service manual.

Al st1100 said:
lateral run out and thickness variation is critical to smooth brake operation. M/C spec are tighter that I thought.
Click to expand...
Actually, in this case at least, motorcycle specifications are much looser than most car specifications that I am familiar with.
Lateral run out becomes critical if it is beyond the allowable specification. Up to the allowable specification the design of the floating caliper brake system is such that the ability of the caliper to move with the rotor is supposed to be able to absorb the run out. If it can't there is something else wrong or the specification is wrong. I do find this specification to be very liberal compared to most cars which are, as you mentioned, in the 0.003" range.

Most cars also have a tight tolerance for rotor thickness variation as well. It is less critical on a motorcycle rotor. It would seem that Honda doesn't consider rotor thickness variation to be very critical at all on the ST1300 as they didn't bother to provide a tolerance for it- or I haven't found it in the manual.
 

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Al st1100 said:
that's in mm not inches which is less than .001 in inches. lateral run out and thickness variation is critical to smooth brake operation. M/C spec are tighter that I thought.
Click to expand...

Less than a thou runout is not a reasonable value for this application. All my rotors run around .006, including my badly worn and once cooked rear rotor. .010/.012" or less would be functionally acceptable, providing the rest of the caliper is in good working order,, imho,,, Cat'
 
Andrew Shadow said:
No it is not.
The specifications from the Honda ST1300 service manual are;
Front brake disc warpage- 0.20 mm, 0.008".
Rear brake disc warpage- 0.30 mm, 0.012".

See the attached page from the Honda ST1300 service manual.


Actually, in this case at least, motorcycle specifications are much looser than most car specifications that I am familiar with.
Lateral run out becomes critical if it is beyond the allowable specification. Up to the allowable specification the design of the floating caliper brake system is such that the ability of the caliper to move with the rotor is supposed to be able to absorb the run out. If it can't there is something else wrong or the specification is wrong. I do find this specification to be very liberal compared to most cars which are, as you mentioned, in the 0.003" range.

Most cars also have a tight tolerance for rotor thickness variation as well. It is less critical on a motorcycle rotor. It would seem that Honda doesn't consider rotor thickness variation to be very critical at all on the ST1300 as they didn't bother to provide a tolerance for it- or I haven't found it in the manual.
Click to expand...
Wow .. I can't believe it but your right,
 
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