I agree with the 2nd part of your message Bill. And, I wouldn't use any
abrasives, either, for the reasons you cite, plus if you really worked
at it I suppose you could rub the rotor out of true.
Light surface rust (no pitting) is not a concern, will wipe right off
the first time you step on the brakes.
Jeff, if you have any doubt, turn them, even lightly, mostly to be sure
they are true. I've even had brand new rotors turned, when the runout
gauge shows a bit more than I like (.003" is a good rule of thumb).
Turning will only cost $15 - $30/pair. They may be warped, which would
be corrected, or could already be undersize and should be replaced. Many
auto supply stores have the equipment to do the turning and can often
do the work while you wait, finding all kinds of other goodies you can't
live without (Fuzzy Dice, Pine Tree Air Fresheners, "No Fear" stickers &
Cupholders). They'll measure them & inspect them for you.
The min. thickness is usually cast right into the rotor when they are
manufactured. Look for something like .38 or .44, usually on hub area,
although I am not sure the actual dimension for your car and these are
just examples. These examples would indicate min. thickness of .38" or
.44" respectively. The shop is prohibited by law from turning beyond
that point.
If you need to replace, my most recent Spit catalog (Vicky Brit, '98)
shows $30 each for new rotors. The ones I got from that vendor for my
TR4 were about that price & are Brembo disks... a good brand, IMHO. I
consider this cheap for the peace of mind of good brakes. NFI, of
course.
Fyi, you can use a moderately grooved rotor, if there is no runout, they
are an adequate thickness and don't have a heavy ridge around the
outside rim. When reusing without turning, though, expect new pads to
take much longer to seat and the brakes to be less than fully effective
for a couple hundred miles. If also reinstalling your used, but adequate
pads on used, but adequate rotors, be sure to keep them matched up as
they came off the car to minimize wear in, maximize effectiveness.
*None* or this is true of drum brakes. If there is much grooving, turn
em & install new shoes. Period.
Incidently, my '97 Land Rover's rotors are $130 each/front & $110
each/rear OEM, or $360 for a set of four aftermarket brand, and they
cannot be turned at all. Soooo, I love turning or replacing them on my
TR!
No matter the cost, don't settle for anything less than good brakes. If
your crankshaft breaks, you can't go. If your ignition fails, you can't
go. If your carbs get gummed up, you can't go. But, if your brakes fail,
you can't *stop*!!!
Alan Myers
San Jose, Calif.
'62 TR4 CT17602L
Bill Kelly wrote:
>
> Jeff,
>
> No sandpaper, nor steel wool. You might try removing any scaling with a
> medium stiffness wire brush, though. The idea is, you don't want any
> abrasives between pads and rotor. They'll eat the rotor when you apply
> the brakes! Sandpaper sand, steel wool dust, and rust scale are all
> abrasive.
>
> That said, it's hard to tell from the photo just how rusted they are.
> Best thing to do would be to take them off and have them resurfaced
> ("turned"). There are legal limits on the minimum thickness after
> turning. I don't have the figure, but any decent brake shop should be
> able to look it up. Based on that they can tell you whether or not they
> can do yours. Shouldn't cost much, definitely a lot less than a new pair
> of rotors.
>
> Bill Kelly
--
MZ
|