[DeTomaso] Brake Upgrades & Pads for Stock Brakes

[MikeLDrew at aol.com]

In a message dated 11/26/07 5 26 4, rickrows at hotmail.com writes:


> What are the possible brake upgrades for street use?  Even perfect stock 
> brakes seem to be marginal compared to modern braking systems. 
> 
>>>Have you ever driven a Pantera with 'perfect' stock brakes?

They're terrific.   At least at normal street driving speeds, they are the 
equal of any other car sold in the early 1970s.   The problem is, over time most 
Panteras with stock brakes have suffered varying degrees of degradation due 
to neglect.   I have driven a Pantera that was otherwise in good condition, 
whose stock brakes were absolutely DIRE.   It was later discovered that rust had 
frozen all but a few pistons in the calipers, and it effectively had hardly 
any brakes at all.

But they don't have to be that way.

> What are recommended pads to "optimize"stock brakes?
> 
>>>Well, the first thing to do is to ensure that what you have, is working 
properly.   If you're committed to keeping the stock components (and unless 
you'll be driving the car on a track, there's no reason not to), if you're not 
happy with their performance, you should take the calipers all apart, correct any 
flaws you find (i.e. rusted pistons etc.) and rebuild them.   The Pantera 
vendors sell brake caliper overhaul kits.

(Alternately, you can buy plug-and-play replacement rebuilt stock calipers 
from the vendors, then send your old ones back as cores).

The stock pad material was chosen for effectiveness and long life under 
Autobahn conditions.   They generally don't work very well until they are smoking 
hot.   Therefore, they are virtually immortal--I've seen Panteras with 100,000 
miles on the clock whose original brake pads still look like new.

What good are pads that last forever, but don't stop the car worth a damn?

EBC makes replacement pads for the Pantera, although they fail to equip the 
rear pads with the necessary protrusion to enable the parking brake to work 
properly.   I spoke with the EBC representative about it at the SEMA show, and 
got a complete deer-in-the-headlights look.

Porterfield, on the other hand, totally has their act together.   They stock 
pads for the Pantera on the shelf; if you ASK them, they will make the 
necessary modification to the backing plate to let the parking brake work properly.   
Their R4-S compound is the ideal compromise between pure street use, and 
performance driving.   Although they will work extremely well under racetrack 
conditions, they will literally disappear in a very short time (I know--I've done 
it!), and there will be no indication of it.   They will simply work fantastic 
until you hear metal-on-metal.   So for full-on track use, if you're still 
using stock components at a minimum you should fit their R4 (race) compound.

But I'm assuming that's not an issue for you.   So, you've got functioning 
calipers, and new Porterfield pads.   The next good thing to do is to replace 
the rubber brake hoses with braided stainless steel flex hoses.   These consist 
of teflon tubes wrapped with stainless steel braid.   Unlike rubber hoses, 
they won't expand under pressure, and will give long life and a better pedal 
feel.

For years, people have been advocating removing the stock brake proportioning 
valve in the front, under the impression that this improves braking.   I 
believe this opinion is one of pure ignorance.

I have the original documentation that was used to certify the Pantera for 
sale in the USA.   It's a big fat report, two or three hundred pages thick.   
The DOT has numerous standards, for everything you can think of, from windshield 
wipers to hood latches to seat anchoring, and Ford subcontracted the job of 
compliance testing the Pantera to a company called Ogden Technology 
Laboratories, Inc. in Fullerton, CA.   They were given four very early prototype Panteras 
(VINS 01005, 01006, 01010, and 01011), and among other things, the testers 
dialed in the braking systems on 01006 and 01010.   The proportioning valve was 
in place.

With the original size tires (185/70 and 215/70-15), they noted virtually 
perfect front/rear brake proportioning, in all circumstances.   (They did note 
that on some stops, one rear wheel locked up for the last five feet or so).   

The proportioning valve's function is to reduce braking effort at the front 
end.   That sounds counterintuitive, but the design of the front and rear 
calipers is totally different.   With equal pressure at both ends, the front 
calipers exert far more stopping influence than the rear calipers.   However, in a 
mid-engined car, the greater percentage of the car's weight is on the rear 
wheels, and thus the rear wheels have more braking 'work' to do than they would on 
a front-engined car of the same weight.

Removing the proportioning valve results in a radical increase of 
effectiveness of the front calipers for a given amount of pedal pressure.   To the 
inexperienced, this can be incorrectly perceived as an 'improvement' in braking 
performance.   Around town, it's easier to stop the car than when the brakes are 
working properly.   However, when braking demands become more severe, i.e. 
stopping from high speeds, or making a panic stop from low speeds, the front 
wheels will lock prematurely while the rear brakes are doing hardly anything at 
all, and one can see that this would have a very detrimental effect on stopping 
performance.

(Many Mangustas were set up this way from the factory, which garnered 
tremendous criticism from period magazine road testers, and De Tomaso later 
introduced a proportioning valve to better balance the Mangusta's brakes)

This is educated conjecture on my part, as nobody has ever actually tried to 
compare stopping distances in a scientific way with, and then without the 
proportioning valve in place.   But what scientific data is present, strongly 
supports the need for some sort of proportioning to reduce front pressure to 
optimize overall (as opposed to front-wheel) braking.

Having said that, it's important to ensure that the proportioning valve 
hasn't rusted solid and thus failed.   It's fairly simple to disassemble and clean. 
  Actually, if I was going through the effort to remove it, I would replace 
it with an adjustable valve (like the stock one, plumbed into the front system) 
so I could precisely dial in the front-to-rear proportioning in light of the 
fact that the car almost assuredly is wearing tires whose sizes are very 
different than what it was designed for.

In fact, with the trend towards ever-wider rear tires, the ratio between 
front and rear tire contact patch size has skewed to the point where more front 
brake reduction, not less, is probably needed for balanced braking.

Mike



**************************************
Check out AOL's list of 2007's hottest 
products.

(http://money.aol.com/special/hot-products-2007?NCID=aoltop00030000000001)