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much has been said regarding this topic but I need to hear it again. To achieve an honest improvement in braking what is your recommendation. I have 17" front wheels and 18" rear, and don't race the car. So is the improvement worth the money? are there any other tricks to improving the brakes? I have always had Webers on the car and use a vacuum pump rather than pulling vacuum off the motor. can the strength of the vacuum be changed?

Thank youIMG_6517


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  • IMG_6517: power brake vacuum pump
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I compare it with the brakes on a C7 corvette that I recently drove rather hard. The difference is quite noticeable. Maybe I don't need that much stopping power, but the difference was considerable. Not that I need to do this, but I doubt I can come close to locking the tires up. I've owned this car for 42 years and am used to its idiosyncrasies, but you know how we like to tinker, and you probably know how good/bad stock brakes are.


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  • IMG_6078: all stock except Alden shocks

Husker is correct- Porterfield R-4S pads work well on lightly modified Panteras. Wholesale brake changes are recommended only if you truly know what you're doing and I don't mean that in a negative way. Many decades ago, Pantera owners could buy complete Pantera brake master cylinders mounted on stock power boosters from several sources

Then someone exceeded his skill-set in changing one himself, and shortly thereafter ran his car under a semi-trailer when it failed. His heirs sued Bendix-Italia who promptly stopped selling such parts. What's available today is a very similar assembly for 308-series Ferraris which is why the price is quite high. 

I will add that I have the Porterfield pads on two cars.

The pads don't necessarily add friction to the system to give you harder stops.

What they do is give you less brake fade at hard use like in hard autocrossing.

In order to get more braking you need a larger brake system. Bigger pads. Calipers with more clamping. Larger diameter rotors for greater braking leverage.

In a Pantera, although it isn't particularly difficult to improve the brakes, it is a little touchy.

Mid engine cars are quite a bit different then front engine cars are as far as weight transfer in braking. Any big changes are going to require rebalancing the system front to rear and you just can't do that on the street normally. You need to do high speed panic stops and that really needs to be done on a closed course.

The largest danger is putting too much braking in the rear.

Look at how small the original rear pads and calipers are. Those are a little overkill but that was done so that the rear of the car won't come around on you in a panic stop.

Any improvements in the rear are necessitating an in line adjustable proportioning valve.

To show you how delicate that can be, some race cars have that adjustable valve in the cockpit within reach of the driver so it can be adjusted in real time.

As far as the strength of the vacuum goes, the Pantera brake booster adds around 150psi to the brake pressure going to the calipers.

It SEEMS to be designed for 22 inches of vacuum. You will only get close to that with a stock cam and CJ engine. If you have for instance, 15 inches at idle, you are getting less boost to the brakes.

When you go to a full manual master cylinder you need to increase the size of the master cylinders bore to increase the pressure. There you will feel it in the brake pedal effort.

The stock Pantera master bore is 24mm. That is about 15/16" or the size of a stock Mustang master with power brakes. To go to manual brakes with about the same braking pressure, you are 1-1/16" to 1-1/8" bore. That's like stepping on concrete on a street car but probably to be expected on a race car since very little brake pedal movement would be necessary, pressuming your leg is strong enough to move it.

I've got a Compcams vacuum pump in the car. The thing is noisy but with the noise of my solid lifter engine, 180° headers and Webers, it gets lost in the engine racket and it is all behind you killing innocent bystanders while you play with the tweeters on your stereo system in the cabin.

With the pump, my brakes are getting 22 inches of boost. That's maximum.

Most brake boosters I've worked with won't even provide any boost below about 12 inches of vacuum at idle. The brakes feel like manual brakes at that point because that is what they become.

Last edited by panteradoug

Thank you all for the useful information. I think I may not make changes to my stock system after all and just continue to drive with care and within the limitations of this setup. The cool factor of having showy aftermarket brakes may be outweighed by more harm than good if not installed properly.

The question arose because I had won a day at a track and decided not to take my Pantera. I drove a rented  C7 Corvette instead and had a ball, but it didn’t  have the seat of the pants heart pounding exuberance of a Pantera. The Vette was quiet, handled very well, had traction control and brakes that were as strong as the motor. What’s not to like, unless you own a Pantera.

@panteradoug posted:

I will add that I have the Porterfield pads on two cars.

The pads don't necessarily add friction to the system to give you harder stops.

What they do is give you less brake fade at hard use like in hard autocrossing.

As a matter of fact, the Porterfield pads DO provide more friction than the stock Pantera brake pads, especially when cold.  The stock Pantera brake pads will wear out your rotors before the pads themselves wear out - maybe a bit of an exaggeration...  But they will not stop the car quickly in a panic stop when cold. Ask me how I know!  The stock pad must be warmed up to work effectively, and even then they're not great!

The Porterfield pads on the other hand will stop a Pantera quite well, even when cold!

I will agree that the stock Pantera pads need to heat up but what I see is one or two touches of the pedal and they are ready.

I have the Porterfields on both my GT350 and Pantera. The Shelby was first. The first thing that I noticed was the hardness of the Porterfield with the first touch. It was like the pads were wet.

Two touches and there was a response. The first touch was one of those "come to God moments" where your entire life flashes before you in an instant and the beads of sweat are instanly there on your forehead.

In what I am seeing, that is VERY similar to how the stock Pantera pads work.

I apparently was taught that you get underway gradually in any vehicle and the first thing that you do then is test the brakes. Truckers do this religiously.

Scientifically I'd need to do a controlled experiment of measuring the stopping distances with one v the other and that is simply not worth the effort unless I am the manufacturer and want to emphasize the positives.

Where the Porterfields shine is when the brakes are smoking hot.

...and they do smoke when hot.

Incidentally, the point of using the 1.25" wide vented rotors v the .710 either vented or solid, is that the cooling vents are more significant and they cool faster under extreme conditions. The solid rotors of course have no cooling vents at all.

Originally the Comp Cobras and the GT40's all used solid rotors which I always found interesting since ultimately one of the difficulties in them was early brake failure under competition conditions.

This became such an issue that eventually the Mk.IV's had wheels designed for them with fan blades as part of the wheel spokes. Each wheel location had a unique wheel for it which blew air out of the wheel well. The intake was supplied by 4" ducting from the nose of the car.

Solid rotors are something very consistent with European originated cars. I'm not sure Girling approved at all of vented rotors?

Last edited by panteradoug

Tom, as was said, vented rotors are of two sizes. Stock thickness of 0.810" x 11.3" OD and the wide-body 1.25" thick x 11.5" OD. The thicker ones are similar to what the Gr-4/GT-4 factory cars used with some success at LeMans. Pro racing heat loads are such that brakes need more thermal mass to stabilize at a temperature below that which will cook pds and boil fluid inside the calipers. Which, by the way must also be replaced when using thick rotors.

The thinner ones (with stock calipers) are for street use and light competition- like autocross or a few laps of amateur open track days. Any prolonged use of thinner rotors will overheat them, just like the stock solid ones. But the thin vented ones do reduce sprung weight and thus aids day-to-day handling.

Bottom line: if you can lock up your brakes now, you don't need bigger brakes, you need more tire. All bigger brakes will do is make it easier to lock them up.

If you cannot lock your brakes, then your car will benefit from better brakes- perhaps even aftermarket assemblies.

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