I have a question specifically for Kelvin, but I thought it might be of
interest to other B owners...
I recently received a Moss flyer advertising Greenstuff brake pads. It noted
that the MGB-V8 pads could be used in an MGB for an "increase in swept
area". This sounded good, until I thought about it for a bit, and realized I
didn't actually know precisely what it meant.
To illustrate what I am talking about, let's say we assume the V8 pad is
larger than the regular B pad; that is, it has a greater surface area of
friction material. So far, so good. But what occurred to me is, this does
not necessarily result in an "increase in swept area". For instance, if the
V8 pad is only larger in one dimension, and that dimension is the direction
of rotation of the disc (the circumference), then that does not actually
increase the swept area (the swept area is determined by calculating the
area of the circle defined by the radius of the furthest point of the
friction surface from the hub center, minus the area of the circle defined
by the radius of the closest point of the friction surface to the hub
center).
OK, fine -- then it must be larger in the other direction (the radial
dimension -- this would indeed increase swept area. But this brings up
another question: on most discs in actual service, there is going to be a
ridge at the inner and outer edges of the original swept area. If you
suddenly install a set of pads with a larger radial dimension, they are
going to be riding on this ridge, probably resulting in severely decreased
braking power (and a lot of squealing) until they wear corresponding
grooves. So, you would definitely want to have the discs turned in this
situation.
So I thought I'd ask -- is this a correct assumption?
--
Max Heim
'66 MGB GHN3L76149
If you're near Mountain View, CA,
it's the primer red one with chrome wires
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