Pantera Power Brake Booster

Doug,

The Pantera's brake booster check valve is external to the booster. It attaches to the booster inlet.

John

I just have a banjo fitting. The check valve is in the banjo?

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The check valve is in the banjo?

Yes.

John

Thanks John. I haven't looked at this system in years. Wilkinson's site identifies it also. My internal booster diaphram may have died I think? Funny how you can't hear a leak hissing in it though? Not much to complain about since it is the original.

Just goes to prove to me that you don't really need power assist on these brakes at all. Always wondered why they put them in the car at all?

I don't get why it has to be a 5/8" hose either. That doesn't help the idle quality. That's a huge drop in engine vacuum. works best with the stock cam. Not the monster that I'm running.

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Just goes to prove to me that you don't really need power assist on these brakes at all. Always wondered why they put them in the car at all?

I am currently working on a new peddle assembly that will remove the booster completely and move the clutch cylinder to the drivers side of the brake masters. This will clean-up the trunk area a lot!

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Originally posted by ZR1 Pantera:

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Just goes to prove to me that you don't really need power assist on these brakes at all. Always wondered why they put them in the car at all?

I am currently working on a new peddle assembly that will remove the booster completely and move the clutch cylinder to the drivers side of the brake masters. This will clean-up the trunk area a lot!

I'm interested in that pedal system to replace the stock unit. Will your replacement have an adjustable brake bias system with two separate master cylinders (three including the clutch master cylinder) like a race car? Will the pedals be made from aluminium or steel?

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I'm interested in that pedal system to replace the stock unit. Will your replacement have an adjustable brake bias system with two separate master cylinders (three including the clutch master cylinder) like a race car?

Yes

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Will the pedals be made from aluminium or steel?

Aluminium

I'm interested in this as well. When do you expect to have this available?

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I'm interested in this as well. When do you expect to have this available?

I was actually only going to make it for my car but if there is an interest, I will make it available as a new product from SACC.

I should have the design finished and test fit within a week. I have the new peddle box done. The aluminum peddles mounted and the 3 masters mounted. I am working on mounting the drive-by-wire throttle next. I assume others will need mounting for a standard cable type throttle.

Hi
I have modified one pedal assembly like this.

Another shot.

Have only this photo of the assembly installed in the car, I removed it again because the original brakes did not function well with it.
I have now the deluxe 6-piston brake kit from Scott installed, so I think I am going to reinstall.

I'd recommend to change out those plastic master cylinders. I have bad experience from one that had an internal spring wear a groove in the bore creating an internal leak.
Had fun driving from Germany to Finland with clutch that engaged for 1sec at the time. No more plastic for me.

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Originally posted by jannem:
I'd recommend to change out those plastic master cylinders. I have bad experience from one that had an internal spring wear a groove in the bore creating an internal leak.
Had fun driving from Germany to Finland with clutch that engaged for 1sec at the time. No more plastic for me.

This was my first setup, and they are allready replaced. Still have them on the shelf.
May have to change the cylinder bores again for the much larger calipers also.

I ran my Pantera "brake boosterless" for a couple of years but couldn't ever get the pedal pressure to a level I was happy with. I have a CNC dual M/C set-up and tried a few M/C sizes without success. I was running Stop-Tech calipers with 1 3/4" pistons and I was also using the OEM brake pedal assy. I know of one Pantera owner who is happy running no booster but he has Sierra calipers with huge, 2" pistons, which explains his reasonable pedal pressure. I've also driven a factory GT3 Pantera that had no booster and its pedal effort was fine.

Perhaps my problem was the OEM brake pedal. A longer brake pedal (to give more leverage), mounted higher on the pedal box, might have worked.

Let's hope Scott can come-up with a M/C-caliper-pedal combination that gives a comfortable pedal feel. I absolutely know it's possible but I was never able to get there.

Thats why I went back to the stock boster setup.
With the first cylinders I had a pretty hard pedal, and the brake effekt was weak.
When I changed the cylinders to a smaller bore, the pedal was to soft, but the brake prformance was still not good. I concluded that stock brakes just wont work without a boster.
But with the larger brakes both Fwd and Aft, I hope I can find a combination that works.
I have bought the brakes from Scott, so maybe I wait to see his pedal setup for reference.
I think my wilwood pedal has a bit better leverage than the stock pedal, but using the stock pedal box inhibit the use of a longer pedal.

Generally speaking the pedal ratio for power brakes is 4:1 and for manual brakes is 6:1 to 7:1. Thats why a manual brake conversion from power brakes (without changing the ratio) results in much higher pedal effort.

Mark

quote:

Originally posted by ehpantera:
Generally speaking the pedal ratio for power brakes is 4:1 and for manual brakes is 6:1 to 7:1. Thats why a manual brake conversion from power brakes (without changing the ratio) results in much higher pedal effort.
Mark

I had to go to my garage to check the pedal ratio. The wilwood pedals I have in my modified setup is 10.5":1.75"= 6:1
VS. original 10.75":2.75"= 4.3:1
The Master cylinders is mounted higher (closer to the hinge) than the original boster/cylinder

I have my check valve off right now and examined it.

Internally it isn't what I expected. There is no check valve mechanism in it that I see of hear.

I see four 1 or 1.5 mm holes drilled into a brass cap.

How does the Panteran brake booster work?

Normally, a brake booster stores vacuum internally when the engine is off to at least boost two or three applications of the brakes?

That works on an internal check valve that is released by the brake pedal to one half of the chamber, there normally being two halves to that chamber.

What should this external check valve do? I presume that it should hold vacuum to be working correctly?

Doug,

The external check valve "seals" the booster's vacuum chambers whenever the engine's vacuum is lower than the chambers' vacuum.

The booster has internal control "valves" that are actuated by brake pedal movement. One valve opens / closes a vacuum port in the passage connecting the front and rear chambers, and the other valve opens / closes an atmospheric port.

With the brake pedal released (no pressure applied to the pedal), the vacuum port is open so that the vacuum is equal on both sides of the diaphragm. Front and rear chambers have equal vacuum. The second valve closes the atmospheric port so that (hopefully) all of the vacuum remains in the two chambers.

When the brake pedal is applied, the vacuum port closes, thus sealing the front chamber from the rear. When the vacuum port is closed, the atmospheric port begins to open, allowing the vacuum in the rear chamber (brake pedal side) to bleed off.

John

I understand that, I suppose the answer is that my external check valve doesn't seal?

Hooked it up to a vacuum pump and it hisses away.

The can held vacuum when I tested it directly so it isn't the booster that is the problem.

Obviously I have never had this issue with any other car since this is a new one for me?

Learn something new all the time. Thanks John.

Here is the Dual Master setup I just finished...

Another pic...

One more...

Last one...

Doug, when our booster went out in 'Vegas 12 years ago, I researched what was available and went with Bob Byars' GM booster/master cylinder assembly. Byars does quite a bit of work on the assembly to make it a true bolt-in for Panteras. His unit is a dual-diaphragm (separate diaphragms for front & for rear brakes), aluminum large bore master (front & rear are different diameters giving built-in proportioning; my totally non-stock brake system still needed a manual proportioning valve), rebuildable, built-in residual pressure valve for front, and it fit perfectly.
At the time, it was $100 cheaper than a stock Benditalia booster (still available in the Ferrari 308 series for $$$$). If one didn't know the car intimately, except for snap-on reservoir lids in place of screw-on lids you couldn't tell it wasn't OEM from the front trunk.

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Originally posted by ZR1 Pantera:
Last one...

Any pics of the back?


Ron

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Any pics of the back?

Hi Ron,

Here are some pictures of the peddle side...

Scott

Picture #2...

Last one...

What does the kit cost? What are the ID's of the cylinders?

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What does the kit cost? What are the ID's of the cylinders?

I haven't decided yet what the cost would be. It depends on how much you want included. For example, The complete kit would include a Peddle Assembly, Foot-well Plate, Stop Light Switch Assembly, Throttle Mount (for drive-by-wire or cable), Balance Bar Adjuster Knob Kit, 2 Master Cylinders, Clutch Cylinder and Combination Proportioning Valve.

The brake master's are 7/8". The clutch is 3/4" mated with a long throw slave...

I drove the car today and I couldn't be any happier with the results!!! It has exceeded my expectations completely.

The brakes are INCREDIBLE! At first I had the balance bar set to favor the front brake cylinder. The fronts would lock very easily. After a couple of panic brake tests, I dialed the knob to give it more bias to the rears. The next test was better. I dialed more into the rears and the car will throw you threw the windshield. The braking performance is better than I hoped, all WITHOUT a booster.

Heading to Willow Springs this weekend. Should have more feedback after some track testing.

Scott