Carl,
I can't speak for all TR4's, but the front rotors on the TR6 start at .510
thickness. 10 mm is a little under .250 inches - those rotors are pretty
thin. I want to point out that replacement rotors are relatively cheap, I
recently saw prices in the $25 per rotor somewhere - there it is: TRF part
number 209327 list price around $35... and the TR4 brake rotor is the same
part as the TR6.
For the rear drums, there should be a number cast in the drum for max
overall diameter. I do know that all big Triumphs use 9 inch drums (except
TR2's and early TR3's, so I looked through a pile of them in my garage.
Save the wisecracks, but the only number I did find on a drum was on an
Al-Fin drum and it listed 9.055 max. inside diameter (230.0 mm for you
folks in the "civilized" world.) I don't see the cast iron stock drums
really supporting a whole lot more of an oversize.
This part is more problematic for you, as they list for about $100 ea., but
you can usually turn them a few times before you have to toss them. FWIW,
the rear brakes do a lot less work than the fronts, so the regular drums
should last a good long time - mine have over 100k miles on them and
they're still okay. I only turned them once.
If you have a pulse in your brake pedal, measure the runout on the front
rotors. But again, with rotors as thins as you listed - you probably need
to replace those puppies.
Get new bolts and lockwashers for the rotor to drum mounting. You might as
well re-grease the front bearings while you have things apart, so get some
new grease seals while you're ordering stuff.
Hmmm, this is starting to add up.
But don't cheap-out on your brakes. Please.
regards,
rml
=====================================================================
Bob Lang | TR 6 Guy | Editor: New England Triumphs
Phone: | 617-253-7438 (days)| 781-438-2568 (eves)
Occupation: | ComputerZ | TR fixer-Upper
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