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Offline LongTimeFordMan

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73 wagon uneven braking
« on: November 22, 2017, 01:29:29 PM »
First off happy thanksgiving to everyone.

Well my lil red wagon is running well and the new engine project is progressing but Ive been thinking about an ongoing annoyance Ive been having.

During hard braking one or both rear wheels tends to lock up.

When I got the car 2 years ago the previous owner said he had had the brakes redone, replaced master cylinder, shoes and pads. But from the first time i drove the car the problem has persisted. Since i got the car ive driven it probably 8000 miles..

Most of the time on dry pavement there is no problem but in a panic stop from 50 mph both rear wheels lock and the car will go sideways on drynpavement. On wet pavement I really need to use care.

Its a stock 73 wagon, 2.0, front disks. It seems like that in order to get enough pressure to the front breaks, it applies too much to the rear.

I have inspected the rear braks and everything looks new, however I am not sure if the master cylinder is correct, it has a round end pointing forward and the replacement ones i have seen seem to have the round end pointing rearward.

I checked with a couple of part stores and brake places and only organic pads are available for 73 pintos. However carid sells c-tec semi metalic pads for "pinto wagons" and I was wondering if the wagons might have had semi metallic pads.

Any tthoughts?
Red 1973 pinto wagon DD, SoCal desert car, Factory 4 speed, 3.40 gears, Stock engine, 14" rims and tires, 60 K original miles

Offline Pintosopher

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Re: 73 wagon uneven braking
« Reply #1 on: November 22, 2017, 07:05:05 PM »
Plugged up Brake proportioning valve might be sticking , there's another member Under the Bleeding Brakes thread rebuilding one .
Yes, it is possible to study and become a master of Pintosophy.. Not a religion , nothing less than a life quest for non conformity and rational thought. What Horse did you ride in on?

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Offline 65ShelbyClone

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Re: 73 wagon uneven braking
« Reply #2 on: November 22, 2017, 10:47:21 PM »
The MC in my '72 has the large (front brake) reservoir facing the firewall. I wonder if yours is plumbed backwards?
'72 Runabout - 2.3T, T5, MegaSquirt-II, 8", 5-lugs, big brakes.
'68 Mustang - Built roller 302, Toploader, 9", etc.

Offline Wittsend

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Re: 73 wagon uneven braking
« Reply #3 on: November 23, 2017, 11:13:14 AM »
My 73 wagon behaves similarly.  If you do rebuild the proportioning valve and it changes things for the better PLEASE let us know. My experience with older cars is they nose dive more than a modern car. Two people in the front seats, a near empty tank of gas and heavy braking can take a lot of weight off the rear end and make brake lock up more likely.

Offline LongTimeFordMan

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Re: 73 wagon uneven braking
« Reply #4 on: November 23, 2017, 02:24:26 PM »
Update on brake issues..

I inspected the brake linings/pads and see that replacement is in order... approx  .035 left on rears, .040 on front.

Some minor leakage on left rear wheel cylinxer, backing plate moist but pads dry.

My plan is to replace linings on front and rear and wheel cylinders on rear.

After some conversations with a local well respected old school mechanic/ hot rod builder here, he suggested adding an aftermarket adjustable proportioning valve to the rear lines.

I have seen several offered online for less than $30, will get a recommendation from him and have him install it.. will report about results.

Has anyone had experience with semi metallic pads on front disks?

I have used them on mgbs and they work well but are hard on the rotors. I may start with the organics and see how they work.
Red 1973 pinto wagon DD, SoCal desert car, Factory 4 speed, 3.40 gears, Stock engine, 14" rims and tires, 60 K original miles

Offline 65ShelbyClone

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Re: 73 wagon uneven braking
« Reply #5 on: November 24, 2017, 03:19:49 PM »
You shouldn't need an adjustable prop valve with a stock setup. I think there's a problem with the setup.

Organic pads are what I would get for a street car. In fact, I wish they more widely available. They're usually cheaper and nicer to the rotors, which is a big consideration given the cost of early Pinto rotors nowadays.

"Lifetime" ceramic and metallic pads are pretty mainstream, but are a false economy. I might be $20 for pads that are guaranteed forever, but they eat the rotors instead so the manufacturers don't have to replace them.
'72 Runabout - 2.3T, T5, MegaSquirt-II, 8", 5-lugs, big brakes.
'68 Mustang - Built roller 302, Toploader, 9", etc.

Offline dick1172762

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Re: 73 wagon uneven braking
« Reply #6 on: November 25, 2017, 05:16:52 PM »
It is very common for people to put the brake shoe backwards on the backing plate. I always leave one side alone till I finish one side just so I get every thing right. If you reverse the brake shoes on one side it will cause the brakes to lock up before the other side.
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Offline Wittsend

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Re: 73 wagon uneven braking
« Reply #7 on: November 26, 2017, 05:01:19 PM »
Should there be any difference between the set up (proportioning valve) for my 73 Pinto (wagon) and the 78 Mustang II I sourced my drum to drum 8" from?

Offline Pintosopher

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Re: 73 wagon uneven braking
« Reply #8 on: November 26, 2017, 07:39:22 PM »
Should there be any difference between the set up (proportioning valve) for my 73 Pinto (wagon) and the 78 Mustang II I sourced my drum to drum 8" from?
My 72 Hatch worked just fine when I switched to 8" MII rear axle assy  No changes in brake bias for the subsequent years of usage. Didn't set the Pinion angle with shims though :P My 3:40 gear went in in a fairgrounds Parking lot during a Memorial Day  Autocross event as seen below...
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Offline dick1172762

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Re: 73 wagon uneven braking
« Reply #9 on: November 27, 2017, 09:40:25 AM »
I road raced my 72 Pinto with both 6 3/4" and 8" rear ends with no changes at all. Pinion angle was right on with no mods. Brake bias was the same. Got the 8" rear end out of a Mustang II and it fit perfect.
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Offline hotrodln

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Re: 73 wagon uneven braking
« Reply #10 on: December 20, 2017, 10:01:21 PM »
My 74 was completely stock and it too would lock the rears before the fronts. I think it was just a design flaw. I learned all about the topic when i put bigger front rotors on my 87 Camaro. the rears started locking up under hard braking- that's how you crash! The manufacturer of the front brakes ( Baer) said I need to cut into the line going to the rear brakes and install an adjustable proportioning valve. After I installed it I kept testing different settings until the fronts locked up BEFORE the rears.   So when i did the granada rotor swap on my 74 recently I bought another bias adjuster and installed it. I also removed the factory one ( which was leaking) and just used a tee on the front brake lines.  with the salt on the road I haven't been out to do much testing with it, but I will be adjusting it as weather allows.