DeTomaso Mailing List: April 2000, Message #333

Hi guys,

I spent this weekend thrashing my Shelby GT-350 replica at Thunderhill 
raceway.  Check out:

http://members.aol.com/mikeldrew/Thunderhill.jpg

I had installed Porterfield pads about a year ago, and have been very pleased 
with their performance.  Thunderhill is an especially power- and 
brake-intensive track (or it can be anyway) and I pushed the car harder than 
I ever have before.  I started to detect substantial brake system degradation 
near the end of my run sessions on Saturday.  

After the last run, I managed to get some unsolicited help and the next thing 
I knew, the car was in the air and all four brakes were being bled.  The 
rears looked nice and fresh, but the front brake fluid looked awful.  I'd had 
a new master cylinder installed by a reputable Mustang shop, but they must 
have used very non-fresh brake fluid 'cause it looked like crap.  

(BTW, a reminder--any bottle of brake fluid in your garage that has been 
opened already is GARBAGE.  Brake fluid is like some vaccines--once you 
uncork the bottle, you use it or throw it away, since it can easily gather 
moisture and render it relatively ineffective at higher temps, even if the 
bottle was kept securely tightened.)

Anyway, the following day I noted great improvement.  On the last session I 
decided to experiment and went out of my way to absolutely punish the brakes, 
running from about 100 mph down to 30 mph with absolutely max braking, 
several times a lap.  After about five laps, I began to smell the stink of 
brakes and the performance started to slip.  I then ran a moderate lap to let 
'em cool, and found the performance was right back up where it had been.

There was light to moderate brake pad dusting on the front wheels at the end 
of the weekend (eight 25-minute sessions), nothing serious or worth 
mentioning.  Also FWIW the rear pads are standard issue (I have a Lincoln 
Versailles rear end with discs) so it's quite possible that the Porterfields 
were still hanging in there but the rear brakes had checked out.

I'm told that cooling is the key to brake longevity, and I've got all the 
hardware necessary to install super-trick brake cooling ducts to the front.  
The only problem is a lack of TIME to do so before I drive the car in Vegas.

Anyway, the R4-S compound seems like the best overall solution for a car that 
is primarily driven on the street but sees occasional track use.  If I 
started my braking slightly earlier for each corner and didn't abuse them, 
they would last forever without fading (or so it seemed.)  It took a 
concerted effort on my part to induce brake fade.  I haven't yet pulled a 
wheel to see how pad life is looking, but this is my fifth open-track day on 
these pads and I noticed no significant wear after the first four days.

Regarding oil pans:  I'm currently running a borrowed original 1966 Shelby 
T-pan, a 7.5 quart pan that supposedly has baffles.  I own a reproduction 
T-pan which developed a crack, and although it's fixed I haven't had the 
opportunity to swap it back in.

Although I never experienced (or at least never noticed) any problems with my 
reproduction pan, with this pan I noted that while my oil pressure stayed 
right at 60 psi down the straights and in all RH turns, during extended LH 
turns the pressure would suddenly drop down to 20 psi, sometimes less, even 
running ordinary Z-rated street tires.  Yow!  I suppose it didn't keep 
dropping only because the turn ended.  I also noted pressure drops during my 
especially abusive straight-line brake testing.  Thus I had to modify my 
driving style (read:  slow down) in all LH turns to keep the engine alive.  
That's no fun when you're chasing somebody and you think you might be faster! 
:>)

So anyway, although it's been mentioned on this list many times in the past, 
I thought it was worth mentioning again that although the standard Ford oil 
pan issued with the Pantera 351C is fine for street duty (there's virtually 
no way you will be able to generate the sustained cornering/braking loads on 
the street to overcome the rather elementary design), the stock pan can 
quickly become a limitation on a roadrace track if the car is driven "con 
brio."  

FWIW I didn't develop any problems until late in the first day, as I was 
gradually working up my speed from one run to the next.  When driven at 
8/10ths, there was no problem whatsoever.  So if you're entered in the 
slowest run group and don't see yourself going like hell, but instead just 
want to drive considerably faster than you could on the street, you will 
probably be okay with the stock oil pan (but check your gauge to be sure.)  
But if you've got super-sticky tires, a heavy right foot and a yearn to turn 
and burn, realize that the resultant oil pressure drop could be followed 
shortly by the sound of connecting rods making a valient bid for freedom from 
the confines of your engine block! :>)

Mike