Dan Masters wrote:
>All of the above notwithstanding, I have made major improvements to my brakes.
>In the rear, I have changed the 9 inch drums with 1 3/4 inch shoes to 11 inch
>drums with 2 inch shoes. In front, I have replaced the two-pot calipers with
>four-pot calipers, and I will use high performance brake pads. The fronts
>still won't have the stopping power of the rears, so I am adding a
>proportioning valve to equalize the brakes, front to rear. (without the
>proportioning valve, the rear brakes will lock up while the front brakes have
>yet to reach their maximum braking force) Very shortly after the car's initial
>completion, a major update to the front brakes will be added, bringing their
>performance up to the level of the rear, so I can do away with the
>proportioning valve. (with more powerful front brakes, they will lock up
>before the rears do, eliminating the nasty business of having the rear end
>swap places with the front - very disconcerning in a panic stop!) The only
>reason I don't do it now is money. If it were a critical safety item, I would
>just delay completion till I could afford the upgrade, but it's not.
Back when I was young and dumb I used to drive the TR6 QUITE hard on
certain favorite twisty roads around Medford, Oregon. On TWO occasions I
used the brakes hard enough in rapid succession to produce pad fade... hard
pedal, but no stop! Neither event resulted in any kind of accident, but
certainly either COULD have. In general, I've always been impressed with
the TR6 brakes, particularly with semi-metallic pads. I noticed that to
get them working at their best, you need to warm them up a little. But,
even though I'm not likely to ever be quite so hard on the brakes (and the
rest of the car) again, I've always wanted to make some improvement to
eliminate/reduce that pad fade.
I always thought that having the rotors grooved would have a substantial
positive impact on this. I've seen a pretty simple groove "pattern" on
stock-class race cars that consisted of two grooves on each rotor face.
Each groove would make a "chord" across the rotor, passing the rotor's
center "unmachined" portion next to the hub. On one side of the rotor, the
two grooves would be parallel. Turn the rotor over and there would be
another set of grooves, also parallel to each other, but at a 90 deg angle
to the grooves on the opposite face.
Seems like a simple machining process, much simpler than the typical
radiating/angled grooves that I've also seen and are popular for street
bike's brakes. I've had it in my mind that whenever I end up putting new
rotors on the TR6, I'd maybe have this done to them.
Any thoughts? Anyone know how deep and wide those grooves would need to be
to get the maximum effect without damaging the integrity of the rotors?
Again, we're talking about avoiding PAD FADE here, not FLUID FADE.
And Dan... Where d'you get the 4-pot calipers? You speak as though they
were a direct bolt-on to the standard TR6 stuff.
Pete Chadwell
1973 TR6
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