making progress, brake set up and clutch set up in the car done..terrible work over head..

I want to take the wired proportional valve out and replace it by a simple T distributor, got vented front disks on stock calipers.

Is there ANYTHING else I need to change on the hydraulic??!

A) as in the big distributor there is INTERNALly a black plastic plug (picture) . Should that stay or also out?
B) should I keep the differential switch or just plug it? I might add later a manual proportional vale for fine tuning..




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Original Post
First, I need to clarify I am a "keyboard" mechanic and thus all my comments are opinions without any actual application.

Here is a diagram of the brake fluid paths and purpose of each device.

the "wired tee" is the warning switch that lets you know you have a leak in either the front of rear.
.....If you don't want the switch, it could be removed. (you will need to add a brake light pedal switch)
.....If you want it for looks, the internal seals need to stay working. a "centering tool" can be used to replace the switch piece and keep the spool centered. this would let you keep the pressure activated brake light switch

the Propertional is the other block
....If you don't want if, you will need a tee to provide tubing to left and right
....If you want it for looks, the internal seals could be removed. the exteranal would still be needed


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ok I see how it works, ..not as I thought..(smile).....TX
1) will keep the differential pressure switch and internal mechanics!
- I have a Red light in the maim dash center
I will use for Alarm, i.e pressure loss on sigle side and
brake bads worn out (the latter will never
happen but still)

2) the proportional will go out replaced by a T distributor, will move it a bit inwards so the spot will be empty then as it is sticking out, bad design..

Do a search for "shuttle valve" or "proportioning valve" at the top of the page. There have been quite a few discussions regarding this. I'm sure you'll find the answers to all your quesions.
Tx Husker,
was a bit lazy searching as got still the car dirt on my fingers after full day setting up the Brake Plate with booster and pedals .. and the wild mechanic......

Originally posted by Mat_G:.
2) the proportional will go out replaced by a T distributor, will move it a bit inwards so the spot will be empty then as it is sticking out, bad design..


Just me thinking....
to "clean up" the looks, the tee could be
...on the master cylinder with two tubes going left and right, and the third to the rear
...under the car, with only the front and rear tubing leaving the trunk space
What you pictured is not the proportioning valve, it is the shuttle valve. It acts as a safety device between the front and rear brake systems, if there is loss of fluid on one side (unequalized pressure) the shuttle is pushed over to effectively seal the leak so you do not lose complete braking ability on the other circuit.

You can set the shuttle off when bleeding brakes with a power bleeder, keep the pressure below 5 psi and you should be okay.

Mike Dailey's Pantera Place provides a good breakdown on the proportioning valve and many other good tech tips.


If you are in there now, you should put in the manual valve.

Just my 2 Deutschmarks worth of advice.. or is it pfenigs?

It will save you from another messy job, and then getting all the flaring equipment, cutting the tubing, and rebleeding the brakes (AGAIN!)



Photos (1)
Originally posted by Joules:..if there is loss of fluid on one side (unequalized pressure) the shuttle is pushed over to effectively seal the leak so you do not lose complete braking ability on the other circuit.


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I stand corrected, it looks as though it does not seal the leaking circuit, merely triggers the warning light.

Mattias, why are you doing this? If you have stock brakes and take out proportioning valve, too much power will go to fronts, too little to rears, making your brakes worse. Why do you think the factory put in a proportioning valve if it braked better without it.

And yes, your picture is a valve that has the sole purpose to let you know when one of the brakes circuits are weak, warning light. Why would you get rid of that?
Mikael Hi Hi,
1) I DID change to vented disks for the front
2) current proportional vale is blocked by someone in the past so no balancing anymore, would need to buy a new one WHAT I will not do. If too much pressure in front I will add as Rocky suggested a "reduction valve"..as the best option and affordable as well..

Tx anyways..
Originally posted by Mat_G:
If too much pressure in front I will add as Rocky suggested a "reduction valve"..as the best option and affordable as well....

Isn't the device show a "metering valve", thus its intent is to provide a DELAY in braking. Old school was to allow rear shoes time to expand before the front disc grabbed, preventing nose diving.


the showned "checked meter" can be used to reduce braking chatter normally associated when brakes are applied for long periods, like landing a plane.
Originally posted by Joules:
I stand corrected, it looks as though it does not seal the leaking circuit, merely triggers the warning light.


again, this is just my take looking at illustrations...

But it does look like the front brake circuit DOES restrict the draining of fluid.

I "wonder" is that due to the master cylinder's front circuit piston pushes the rear piston via hydraulic pressure ?
The stock non-adjustable proportioning valve was designed for hard belted-bias 185-70x 15 front tires & 205-70 x 15 rears. If you are not running those tires & sizes, the valve- if it still works- is set wrong and cannot be changed. Replace w/a modern manually adjustable valve to see it you really need one, especially if connected the factory way. Most braking is done with the fronts and the stock prop-valve plumbing limits pressure to the front brakes, unlike every other car on the road that I know of.

The shuttle valve often builds up varnish in the areas at each end of the shuttle's bore. Then when brakes are bled or something else happens to drive the shuttle into the unused areas, it sticks and has no return springs (like other cars) to push it back to center after the problem is fixed. A shuttle stuck at one end of its travel stops about 90% of fluid flow to the two brakes on that end of the car- a VERY dangerous thing!

Sometimes the shuttle can be blown back to the center with air pressure (very sloppy!) but most often it takes complete removal from the car and disassembly to re-center the shuttle. It's function of lighting a red warning light on the dash is compromised by 'other' functions- if the e-brake handle is slightly pulled, the same light lights, as it also does if you have brake pads with grounding wires attached to the chassis and the pads get thin. So when that red light lights, you must search among the 3 possibilities to find the real reason. Not worth the effort IMHO- a good owner will inspect pad thicknesses & brake fluid levels periodically, and not drive if the e-brake is partly on. I dumped the OEM shuttle and prop valve from our '72 in the last century and have not missed either.
more complex than I thought..Tx for diskussion!

back to my spec:
1) front; vented rotors, stock calipers
2) rear: stock rotors, stock caliper
3) front: 225 x15" (BFs today) or 235 x 15" (Pirelli or NEW Michelin), need approval for high speed
4) rear: 305 x 15" (BFs today ), but will go for modern high speed Michelin 295 x 15" (ok for 150 mph)
5) Street use, no Race, NO Rain, no Sandstorm, only dry street use (smile)
6) want to stay as much stock as possible as need to pass German TÜV/Mot, they are sensitive on changes on brake system
(changes to Willwood brake system etc ..would NOT get approval easy) so no change on brake system if ever possible

SO NO Balancer REST all Stock?
....fine with me, do not want to do too many experiments!


I write letters every year on behalf of folks seeking approval from their Department/Ministry of transportation. With no factory to provide information, the integrity of an INTERNATIONAL owner club established in 1973 has a bit of clout with your MOT.

Please never admit to any modification. Only provide the information requested by your MOT. We are happy to write letters which alleviate their concerns.

In regards to the brakes, if you remove the proportioning valve using the least amount of new tubing or parts it shall be difficult if not impossible for the MOT to detect your changes. I applaud installation of ventilated front disks to compensate for the additional heat generated by the front disk brakes after removal of the proportioning valve. The MOT shall not realize that ventilated front disks are not OEM.

You shall find the tires and/or wheels are by far a more difficult obstacle for the MOT.

Debbie and I are here to help.
In my understanding the reason for the OE proportioning valve is:

The Pantera OE rear Calipers are weak (compared to the "potential" braking on the rear due to the Pantera having 59% of its weight on the rear axle)

Therefore DeTomaso in their design limits the braking force of the front to "balance" the braking and to prevent the front wheels to "lock up" prematurely.

BTW the Brakes does not stop the Car, The Tires do!!

Willwood makes an excellent set of calipers for the rear and combined with their adjustable proportioning valve (then to limit rear braking force) they can be balanced to obtain maximum advantage of the powerful OE 4x38mm piston front calipers.

well after all day work it looks now like this..
.. poportional vale vout and fully new tubing...



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Matthias, test your brakes in a safe area when road is wet, you risk locking front wheels easier and thereby have a significantly longer braking distance. Hope not, but be safe.

BTW, yes beautiful install

The photo above that you recently posted introduced something new to this discussion that hasn't been previously noted.

Are you aware that the brake master cylinder in your photograph, on your car, is not the original master cylinder but an aftermarket replacement?

You previously stated changes to the brake system, such as Wilwood upgrades, are very difficult to get approved. I fear your nonstock master cylinder whether it is Wilwood or not will prove to be a large problem, based on what you have previously said.

Tx did not know that the master cylinder is not original! I still lack detailed skill severely.
What is the apprearence of the original, is it the one with the two plastic containers on top? Would prefer that version as much nicer as this NON original with the open containers, hard to fill and work with (my Corvette 1967 C2 has a similar set up).
Well hope this Cylinder will do the technical job!!?? .. for the moment..

I am positive this cylinder will make it through the German MOT/TÜV, as it looks pretty much original (smile)! Brake components with Willwood sticker on it are more of a problem. ..we will see as TÜV is HOPEFULLY going to happen in Beginning July.
Tx anyways..
Matthias -

That looks like the same/similar master I have on mine (#5357).

I was told it's from a small Ford pickup truck (maybe a Ranger?)

Let me know if you cross-reference the part number. Thanks

Your's has the booster adapter/convertor, the small aluminum spacer between the booster and the MC.

Last edited by rocky
Rocky, Team Tx
I will try the German MOT/TÜV with it as is!
(No more invest as tooo much spent already..)

Honestly I DO NOT understand the function of the BOOSTER adapter (Ok understand this is the Aluminium spacer of app. 1/2 inch).
Love to go for the brake cylinder with 2 plastic containers IF this is the ORIGINAL set up, as much nicer to work with.

comment? Original? With or without booster..then?
...happy to open a new THREAD on this..as still learning...on detail..as typical for an retired engineer...(smile)

The adapter just converts the boosters bolt pattern from the 4 bolt on the booster to the two bolt Master Cylinder.

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