<< Didn't Ramon have this problem last year?? >>
Yes, Bob was right, it was a year ago this month when we broke a brake rotor
at an autocross.
It was a clean, round break, completely around the circumference of the plane
where the rotor mounts onto the hub. As a result, the rotor itself stayed in
place. Although the noise it made was real scary, it didn’t do any other
damage except chip a little paint off the inside of the dust shield. And,
since the rotor remained captive there on the hub, the pads didn’t pop out and
I didn’t loose any braking effort at the other three corners.
The funny part was that it was a brand new rotor, that hadn’t been on the car
for much more than six or seven months . . .
My brake rotor story actually begins in December, 1990. I was ordering some
stuff from Vicky-Brit., and I noticed that they had brake rotors listed in the
catalog. <YA-YA, I know . . . But this was 1990 . . . we didn’t have no
Tiger-list back then . . . And how was I to know they were THE Vicky-Brit.?>
Anyway, even though I didn’t need ’em right then, I knew I would someday, so I
ordered a pair. <$99.50 each, in 1990.> They went on the shelf in the shed,
and remained there until sometime in the spring of ’97.
Then in April of 1995, I was ordering some other stuff from Rick, and I
noticed that he had brake rotors listed in the catalog. Even though I didn’t
need ’em right then, I knew I would someday--two Tigers are surely going to
need two pairs of brake rotors someday, right?--so I ordered a pair <$67.00
each, in 1995 . . . get the message here boys ’n’ girls?> They too went on
the shelf in the shed.
Then, in the spring of ’97, I started fooling around with the brakes on the
autocrosser. Bought some of those high-tech carbon-kevlar pads from Dale, and
decided that now was the time to swap in a pair of new rotors. The old ones
weren’t all that bad, and could have been turned, but hey, I had new ones on
the shelf. So I grabbed a pair off the shelf and went about trying to learn
how to drive with the much-improved brakes.
Shortly after that, in preparing the street car for a trip somewhere, I
determined it was time to repack the front wheel bearings . . . might as well
swap in some new rotors, no? So on went the second pair.
(This is sort of related, because at this point, I didn’t know which pair had
come from where. I had a pair of new rotors on the autocrosser, and a pair of
new rotors on the street car. One pair had come from Rick, the other from
Vicky-Brit. But I didn’t know which was which.)
The first indication that something wasn’t quit “right” with the situation was
the response I got when I called Rick’s place to order another rotor for the
autocrosser. “We don’t carry new brake rotors any more,” she said. “We have
some good used ones . . .”
“Well, hrumph!!! I already have a shed full of good used ones; I need another
new one! . . . And why doesn’t Rick have ’em any more? Curt has ’em. Yucky-
Brit. has ’em. And somebody told me the club in England has ’em? What’s
wrong with Rick???”
Now it just so happened that last summer I was in the middle of a complete
rebuild of the front crossmember for the Series II soon-to-be pointy-fin-
racer. I needed new rotors for it, but nobody listed rotors for the Series I
& II Alpines. I was just beginning to think about the possibility of taking a
pair of later Alpine/Tiger rotors and turning them down to fit the Series II.
If that would work, I might as well get three from Curt--a replacement for the
busted one and a pair to modify for the Series II. <That, it turned out,
would not work, but that’s yet another story.>
So, before ordering three rotors from Curt, I decided to call Dan Walters and
see what he had to say about the possibility of using the later rotors on the
early car. I opened the conversation with something like “Hey Dan! We broke
a brake rotor at Devore last week and I was thinking about . . .”
As soon as he heard about the broken rotor, he wanted to know ALL about it.
Was it old/new? Where did I get it? How did it break? You know how Dan is;
he’s not like the rest of us--you and me. I see a busted rotor, and I think
“Wow! I need another rotor!” Dan sees a busted rotor, and he thinks “Why did
that rotor break?”
And the reasons for Dan’s concern:
1. According to Dan, about a year before that, Dale had discovered a cracked
brake rotor on Jeff Queen’s vintage race Tiger. It hadn’t broken, but it was
cracked . . .
2. Then, maybe five or six months before that, according to Dan, Tom Sakaii
had broken a rotor while engaged in a vintage race.
Under “investigation,” Dan discovered that the rotor on Tom’s car had been
machined improperly. The surface on the inside of the “hat” where the bolts
go through to mount the rotor onto the hub had been machined out too far.
This made the little funnel-shaped surface that joins the disk part of the
rotor with the mounting surface too thin. This is most noticeable, Dan said,
when you install the things on the hub. On an original/OEM rotor, you have a
tough time putting a socket over the bolt because there is hardly enough room
between the bolt head and the inside surface of the “hat.” This too was a new
rotor, and after checking a number of others, Dan determined that all such new
rotors were improperly machined in this area.
Per Dan, I compared my busted rotor with some used/OEM rotors from the shed,
and the bad news is that the diameter of the inside portion of the “hat” where
the disk joins the mounting surface is approximately:
o 4.180 inches on a used/OEM brake rotor
o 4.320 inches on a new brake rotor
The difference, nearly an eighth of an inch, substantially reduces the
thickness of the material that joins the disk to the mounting surface of the
rotor.
According to Dan, it was when he called Rick and explained the situation that
Rick stopped selling the things.
I called Rick to verify the story, and he did. According to Rick, all of the
new brake rotors that have been available for a very substantial period of
time came from the same supplier. He also said that the supplier claims to
have manufactured the rotors EXACTLY to match a brand-new Girling rotor . . .
???
When I checked the new rotors on the street car, they were identical to the
broken rotor on the autocrosser, which means that these things have been on
the market since as early as December of 1990, as near as I can tell, and
quite possibly earlier, though my records do show that the ones I bought from
Vicky-Brit. were back-ordered for a couple of months and didn’t actually ship
until February of 1991.
So, should we go into a “panic” mode if we have these new rotors on our cars?
I don’t know. All of the failures I’ve heard of have been in competitive
driving situations--haven’t heard of one breaking on a street car. I replaced
’em on the autocrosser with resurfaced originals, but I still have ’em on the
street car . . . Yes we still drive the street car--drove it to Pleasanton to
have a peek at Bo’s really neat-o garage a couple of weeks ago--but do have a
funny feeling about aggressively Tigerin’ down a twisty mountain road with ’em
. . .
The new rotors bear casting numbers of “BDC48C” and “R1” (or perhaps "RI") 180
degrees apart on the inside “hat” surface.
The End
Ramon
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