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Them's the brakes

To: fot@autox.team.net
Subject: Them's the brakes
From: Mark J Bradakis <mjb@autox.team.net>
Date: Tue, 21 May 2002 01:31:24 -0600 (MDT)
Well, the second IVR race weekend of 2002 is over now, I'm safely back home
in Salt Lake.  Driving back yesterday was neat, whiteout conditions on a
clear summer day.  At times one could see blue sky above, but ahead, behind
and to the sides was nothing but white, blowing, van rocking white as a
wicked wind did its best to relocate the salt flats to Idaho.  Unusual
conditions.

For the race I sort of prepared a '65 Mark 2 Spit, sporting a Mark 3 1296
motor.  Same car I ran in the IVR enduro last year, where I took the green
flag running great, and managed to be running at the checker.  If only there
hadn't been 45 minutes of pit time between the two flags.  Drat.

For this year, we decided to try a two hour enduro.  The fellow who was the
main proponent of the double length race afterwards said something like "If
anybody requests a two hour enduro again, just shoot them!"  With the extra
race time, I suggested to Bob Allred [*]  that it might be fun to have a driver
change and we could both run the Spitfire.  So we made our plans, and
got some work done on the car.  This work included new front brake pads.
I would have liked to use the same pads that Killer has, but the red racer
has the early Spit calipers which take a slightly different size pad.  Some
time spent with a file and bench grinder got new pads of unknown origin and
composition to fit.  Fitting is one thing, working is another.

Anyway, enduro day comes, and off we go.  I take the first stint at the
wheel, and watch the water temp climb slowly towards the boiling point.  It
never really gets there, though, but close.  After half an hour and roughly
25 laps of the 1.06 mile course, I head for the pits.  The temp needle is
moving too high, I park a slight distance from our spot as I have this
feeling the radiator is going to start spewing coolant when I stop.  It does,
but not on our stuff.  I gotta get some shrouds around that radiator!

We finally get it cooled a bit, top up the water level, and get Bob into the
car.  I tell him the brakes are feeling really soft, and seem to be getting
worse.  Off he goes.  About a dozen laps later, the red Spit comes roaring down
the main straight and zips into the east sweeper.  And from my vantage point
the car behaves oddly for a moment, then it heads for the broken concrete south
of the course, spinning up a huge cloud of dust.  Bob and the car appear out
of the cloud, both seemingly intact, and he motors to the pits.  He comes
in and shuts the car off.  The cockpit is full of gravel, but the immediate
concern is the black smoke coming from the driver's side rear wheel area.
We get the fire put out, no problem.

According to his report, the soft brakes suddenly got a lot firmer for a lap
or two.  He was a bit worried, as problems that crop up rarely fix themselves.
And as was heading into the sweeper, most likely at the highest speed the
car attains on that course, he went for the brakes and the pedal just slapped
the floor.  Luckily he kept his cool and spun it into the least damaging area.
And no other drivers were in the immediate vicinity, which was good.

Anyway, it may be that the bogus pads on the front were not doing their job,
so the rear brakes were working harder than they normally would.  So they
got pretty hot.  Hot enough to weaken the hose, which may have swollen or
started breaking up, giving the suddenly firmer pedal.  Then the hose burst,
spraying brake fluid on the overheated drum.  Yikes.

A while later when we got the wheel and drum off, it wasn't pretty.  The shoe
lining was not really worn but more like shattered.  Take a look at
http://www.team.net/mjb/spit_brake.jpg if interested.  You can see the ragged
end of the brake hose against the powder covered upright, and down by the
lower shock mount the rough edge where the shoe lining was falling apart.

I've been thinking for some time I'd like to get GT6 brakes on all the corners,
and a dual circuit master cylinder, if not a dual master Tilton setup or some
such like that.  This may be a good time to look into that.

mjb.

ps: We finished fourth overall, though, not bad!  I won't mention how many
    cars were in the grid, but we did beat at least one other car.

 *:  http://www.team.net/mjb/allred.jpg

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