Brake fluid?

If you had to pump like hell, that is what it will take to get your front brakes to work.
Sounds like you have some sort of blockage / restriction.
How are your front brakes plumbed?

Thanks all for the brainstorming. In the end I think PanteraDoug was probably spot on about air in the Master and my vacuum pump not able to pull it through. I couldn't get the wife to sit in the car and pump the pedal, so I tried it myself. Last problem bleed was the passenger front. So I opened the passenger front bleeder very slightly, went to the drivers seat and pushed the brake pedal down as far as I could with about a 2 foot long piece of scrap wood and lodged the other end of wood against a long plank wedged against the bottom of the seat (protecting everything with a lot of towels of course). While pressure was still on the brake with the wood, I went to the passenger bleeder to open it a bit more and fluid/bubbles came through, and then I tightened the bleeder again. Then I did the same process with the wood bleeding three more times and pure fluid finally came through the bleeder on the second try. Third push was just for good measure. Just test drove the car and all is fine now. I assume the pressure bleeder may have worked too, and may pick up one of those anyway. I never knew retirement would keep me this busy.

I was just trying to save you needless work.

In Panteras, there are 2 other considerations when trying to bleed air from the brakes under vacuum. First, use a couple of turns of teflon pipe-tape on each bleeder screw as you open it, to keep from sucking air in around the bleed screw that's loosened, then right back out. This can drive you nutzo because it may only happen under fairly high vacuum. Brand new bleed screws (or Speed-Bleeders) are coated with something that's supposed to prevent this but it only lasts a few open/close cycles.

Second- especially if the car is stock, the brake warning-light shuttle valve under the booster can get stuck at one end of its travel, mostly but not 100% isolating both fronts OR both rear brakes from the rest of the system. Any air trapped inside tends to stay inside. Unlike almost every other car that uses such a valve, in Panteras there are no return springs inside, so manually returning the shuttle to center is the only option, and its sloppy at best. This is one large reason I discard the assembly entirely.

quote:

Unlike almost every other car that uses such a valve, in Panteras there are no return springs inside, so manually returning the shuttle to center is the only option

A return spring would defeat the full purpose of that warning system.

When the brakes are applied and one brake circuit won't hold pressure, the shuttle valve moves to the low pressure side and completes the electrical circuit for the dash warning light.

If the shuttle valve had a return spring, then, when the brake pressure return to zero (foot off of the brake pedal), the shuttle valve returns to a centered position and the dash warning light would cease to be illuminated, giving the driver a false sense that the braking system is OK.

As I recall, that shuttle valve assemble is from a Ford Torino.

John

quote:

Originally posted by Bosswrench:...
Second- especially if the car is stock, the brake warning-light shuttle valve under the booster can get stuck at one end of its travel, mostly but not 100% isolating both fronts OR both rear brakes from the rest of the system. Any air trapped inside tends to stay inside. Unlike almost every other car that uses such a valve, in Panteras there are no return springs inside, so manually returning the shuttle to center is the only option, and its sloppy at best. This is one large reason I discard the assembly entirely.

More than likely most are lucky and the spool is stuck in the safe position

In Bosswrench's post about eliminating shuttle valve, do you use a coupling for one side and a tee for the other to incorporate the tail light switch? My shuttle valve had a broken plastic lamp switch and was leaking fluid so I made a plunger that fit into a cap plug and into the body of the shuttle valve after centering it so it would not move side to side. I am having problems getting good pedal, feels like air. New master that was bench bled, rebuilt front calipers and bled three times. Still feels mushy. I think I may still have air in the shuttle. Does that make sense? Also, can you remove the shuttle AND the proportioning valve both and have reliable braking?

Removing the shuttle valve means as you described- hooking the front brakes together, on one line from the master and the rears together on a second line so your car still has a dual-circuit master cylinder is for safety. I added the stop-light switch to the front brakes for convenience- the electrical lines wouldn't reach to a rear setup. Be sure you know which master cylinder port is for the fronts! Some owners use a mechanical switch attached to the brake pedal so no electro-hydraulic brake switch is needed. Our Pantera has been without the shuttle valve and stock proportioning valve for 31 of the 36 yrs we've owned it.

Anyone upgrading their brakes should ash-can the stock proportioning valve and its plumbing. Whether you can run without ANY proportioning valve depends on how your Pantera's running gear is set up & what's there. True- the stock non-adjustable valve is worthless if you've changed tire or brake sizes, and brake action is transformed (to the good) when 100% pressure is available to the big stock fronts instead of to the small stock rears. But once re-plumbed, you may still need a manual valve spliced into the rears at the master cylinder to reduce rear pressure and prevent premature REAR lockup.

Try it without any valve and have a couple of friends (one on each side of the car) watch you do a panic stop to see which end locks up first. If it's the fronts, you'll be fine without a valve. Premature REAR lockup is highly unstable & leads to snap-spins.

Thanks Bosswrench, my brakes are original setup with only slightly bigger tires,205/60 front and 275/60 rear. I already removed the proportioning valve when I has the calipers rebuilt and replaced with a puck style tee. That is why I asked if removing both shuttle and prop. valve was viable. I am not sure if the shuttle is plumbed right. Looking at the drawing JFB#0577 posted, my lines run as such. Going clockwise from top left, top left to rear brakes, center to warning light(capped now), top right to puck tee, far right at end to master cylinder first port (close to driver), bottom right to stop light switch, and bottom left to front master port (toward radiator). From the tee there is the inlet from top right of shuttle and one to each front brakes. I do not see what the proportioning valve did if this was plumbed right. Maybe harder pedal as valve restricted front fluid flow? All I know is I believe there is air in the shuttle after taking apart to fix the switch leak. I will bleed one more time the is out with the shuttle. Thanks for this forum and all you guys in "The Know"

Ha ha, so much for my initial naive thought of just turning 4 bleeder screws, sucking fluid through, filling with correct fluid and then having lunch. Although I ended up struggling with my situation a little bit, I am glad I didn't end up with some of this business above.

Brake line routing at the pressure differential block.

John

Thank you all for the great info. Glad "Does 200" got his situation resolved. Now I'm on the quest of ridding my system of the elusive air.

quote:

Originally posted by DOES 200:
Ha ha, so much for my initial naive thought of just turning 4 bleeder screws, sucking fluid through, filling with correct fluid and then having lunch. Although I ended up struggling with my situation a little bit, I am glad I didn't end up with some of this business above.

Actually all of this re-plumbing in the front trunk is on the easy side and if you do anything to the brakes that is not completely stock should be considered as required.

In my opinion that includes even just changing from the stock brake compounds to something like the Porterfield's.

What is tough is making the plumbing look artistic and presentable?



The entrance spots through the floor and the way the inner fender curves in make it tough to do a nice loop-d'-loop on the metal lines.

The real criteria for needing a real proportioning valve is how much rear braking your modifications create.

If you are going to do any work on the lines, take the stock proportioning valve out, plumb the fronts together and install a Wilwood proportioning valve into the rears.

Just leave the dial stock, i.e., as it is delivered out of the package and try the car.



You need to remember though that to begin with the stock Pantera has VERY "decent" brakes stock.

Putting wider wheels, wider and better compound tires AND changing the shocks and springs (changes the weight transfer and therefore the tire loading) and ALL are messing with that balance.

You are increasing the braking on the car significantly and putting in race capable, i.e., race car like brakes. Brakes on the order of "Factory GT Racing" (where the car manufacturers compete,i.e., "the Big Boys".)

This stock balancing is probably ok for street driving and the imbalance, where you lock up the rear first and the rear wants to come around (like the stunt drivers do in the movies) is going to happen MOST LIKELY at double and triple the legal street speeds.

Some of these Panteras now have much better brakes in them than the late 60's and 70's race cars did and are closer to the old Can-Am cars than you think.

One last remark on this subject though, the stock pads for purely stock/street driving are probably the best you can use for just jumping into the car and zooming off.

They take the least amount of heating up to work and work the best stone cold. They FEEL the most like "anyone" would expect brakes to feel like and therefore are probably the safeset set up for a novice.

The Porterfied 4s, "s" for street compound, are not so good stone cold, those things need to get hot to work, THEN they cut 30 feet off of you stopping distance.

Stone cold the brake pedal is going to feel like concrete and will until the brakes get HOT. Hot as in, "why are your rotors glowing?"

If you let your "teenager" even just drive the car around the block with them good chance he/she is going to hit a tree? About three laps and they should be hot enough to stop the car at that point. You have to survive the three laps though.


My neighborhood resembles a LeMans start in the morning. It's pretty bad. They would hit a herd of elephants BEFORE they actually looked in their mirrors.

I have to wait until they all clear out before I go anywhere. Even the dog won't go for her walk with me until then. Smart dog.

Oh, and she's a Greyhound. Too tall to fit in the Pantera. She likes a convertible with the top down. She's tall enough to just roll up in the passenger seat and put her head on top of the door and "veg out".

...a fast convertible at that, saves her all the wear and tear of running, she's retired now.

Jan, I have one more little mod to your front brakes: run the connecting line from the left front to the right front UNDER the front-trunk floor. I usually find the connecting line badly corroded since as stock it runs above the trunk floor, behind & under the battery, protected only by a piece of unshrunk shrink-tubing. Always scares me when I find solid-red-rusted hard lines...

quote:

Originally posted by Bosswrench:
Jan, I have one more little mod to your front brakes: run the connecting line from the left front to the right front UNDER the front-trunk floor. I usually find the connecting line badly corroded since as stock it runs above the trunk floor, behind & under the battery, protected only by a piece of unshrunk shrink-tubing. Always scares me when I find solid-red-rusted hard lines...

Thanks for the tip. I think I will leave the Group 4 alone since the brakes are working good now. I am not sure how the lines are routed underneath but everything was replaced new on that car in dry Arizona, so there shouldn't be any rust. Still not sure why I had problems pulling fluid through on the front brake bleed though with my vacuum pump. I would think that as long as I didn't let the resivour level go down too much to let air in, that I could just suck old and new fluid through. Maybe I accidentally let it run low, as I was paying too much attention to my Drambuie level than brake fluid level.

I gotta visit your shop!! I love Flying Tigers! I assume there's an automatic Drambuie dispenser?

Damn, you learn all kinds of stuff on this forum. Looked up Flying Tiger, and that recipe looks right up my alley for my next Pantera brake fluid challenge. Thanks for info sharing. Time for Autozone and Bevmo for supplies.

Just looking at an old Chasing Classic Cars where Carini finds the Miura and states the car used mineral oil brake fluid. Google it and found this interesting site on brake fluids.


http://www.epicbleedsolutions....luid-vs-mineral-oil/