If we were talking about modern slotted rotors with cooling fan vanes
between the friction surfaces. Many brake rotors are cast iron, which by
definition IS cast. There is the possibility of core shift during
casting. They ARE turned or more commonly ground to final dimensions &
could be subject to some off center machining. The better rotors ARE
balanced by removing metal on the periphery between the friction
surfaces or adding weights to the center vanes. Certainly builders of
high performance cars such as Porsche & Corvette balance the rotors.
Back to the subject;
On the antique Healey thin rotor design, which still starts as a
casting, without slotted center cooling fans, which give them much
less mass, an out of balance rotor is less likely to cause problems than
a drum. Not sure how you would balance the flimsy Healey rotors in the
first place. I suppose you could remove metal from the outer periphery
to balance without seriously affecting the swept area or friction radius
too much since it is at the center of the rotor & not on the periphery.
I doubt if there is much to be gained on these relatively low speed
cars. Running at Bonneville would be a whole different story but the
rotors are likely to be of more modern construction in the first place.
A combination of three 10" diameter X .275" thick rotors can stop a 400
pound motorcycle fairly well but four of the same would get hot pretty
quickly on a 2400 pound car. The old Healey disc brake designs are
marginal at best.
Just my opinion, bit I think that the BN2 drum brakes actually have more
brute stopping power than the drums, although once hot, they don't cool
as quickly.
Probably not worth the trouble to balance rotors.
Dave Russell
BN2
davidwjones wrote:
> "If they're built to the same exacting standards
> (sic) as the drums they may contribute to the shakes, rattles and
> rolls.
> Anybody balanced their rotors and, if so, was it worthwhile?"
>
>
> Since rotors are turned on a lathe already, in their manufacture, rather than
> cast, like the drums, and have less overall mass to start with, I would assume
> that they are by design better balanced...
> Also, if found to be out of balance, what would you do to correct them, since
> the calipers wipe the entire outboard surfaces? Try turning them on the lathe
> again? Potential gain seems miniscule...
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