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Discussion Starter · #1 ·
Hello all,

This is another long post that I thought deserved its own thread as it's more searchable and may help someone. This is for my 1968 XL with factory disc brakes. I have previously rebuilt a correct Midland Ross booster for this car and replaced the "whatever" one was cobbled in there. That can be found here 1968 XL - Keeping it Roadworthy Whilst Reparing it. if interested.

It just turns out this braking system was just so bad in so many ways, the incorrect and failed booster was just the tip of the iceberg.

Now even after I rectified the booster problem I did have a decent pedal, but the brakes were really touchy and you could just tell the rears were not doing anything. Then the rears started to work the tiniest bit. Now when we bought the car it master looked recent and so did the rear wheel cylinders so naturally I assumed they just didn't get it bled properly. Well that was probably part of it, a small part of it.

Here's the train wreck, enjoy.





So at first glance the fronts do not look to bad, there's plenty of pad left, but there is a noticeable lip on both sides of the rotor and both rotors look the same.




Other side.

The problem here is that there's little extra meat on the rotor to begin with when they were new. Both front rotors are nearly 0.2" under limit. That's quite a bit! These are junk.






Now I did replace the shoes, springs, adjusters, etc a while back and had the drums machined down. The wheel cylinders look very recent and very clean on the outside.




However there's 2500 miles most town driving on these rear brakes and that's all the dust in them. And probably most of that was because I was a retard :confused: and forgot I had the parking brake on for about 1000 feet. Hence I installed the warning light option for this car.

I just naturally assumed it all would be bad and this car never seems to disappoint when it comes to that. I stripped all the brakes off all 4 wheels.








Let us assess the damage.




Ummmmm, that looks like chunky toxic soup. The brakes lines over the axle were just as packed.




Well at least both sides are equally bad.




The caliper interior is all pitted scaled chunky rusty iron.

Continued in next post.
 

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Discussion Starter · #2 ·
Brake System Continued





The other caliper wasn't as bad, but it's just rusty fluid.




This the flexible over the axle rear line.





Probably just as well the rear brakes never really developed pressure as the line would have went pop anyway. I think this is the original hose, I could snap it like a pretzel. The front lines have a date code of 1995 so those are old and need replacing as well but were in much better condition than this.




This is the 1968 brake valving assembly and those fittings are seized on there. I just cut the lines as I already knew it would be best to make as many new lines as I could from the fluid contamination. Speaking of which, how does that much water get in brake fluid from a car from Arizona where I count on my fingers on how many times its seen rain in its life. :unsure:





This is the rear brake proportioning valve from the assembly. It's just packed with crap.




There's 2 specially moulded seals in the proportioning valve, this is one of them and it's packed.




This is what it should look like.




This is the spring inside.




It's just full of slimy nasty stuff.




I removed the bottom plug off the shuttle valve and it's just full.

It's all bad...... all of it. This is as far as I went with taking apart the original valving, in the rubbish bin it goes, all of it. The whole brake system is contaminated and it needs to pretty much all go.

More to come.

Cheers
 

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Dang, Desert. Do you ever take the short cut?
 

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Great post. Do you plan to replace the steel lines? I went with a stainless kit. That proportioning valve was a nightmare for me. Mine cracked and I got a replacement but from a mercury. The mount was different and I had to improvise. Stainless does not like to bend and getting everything lined up to the valve just right was a real fight.
 

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Discussion Starter · #6 ·
Great post. Do you plan to replace the steel lines? I went with a stainless kit. That proportioning valve was a nightmare for me. Mine cracked and I got a replacement but from a mercury. The mount was different and I had to improvise. Stainless does not like to bend and getting everything lined up to the valve just right was a real fight.
Hello sixtyeightford,

Thank you for the kind comment. I did replace all the lines except the main rearward one. Lifting the body off the chassis to replace that line doesn't interest me at this time. I just flushed that line out copiously. I did make all the lines out of stainless from scratch. That's really nice that they offer a kit for these cars. How did the rest of the lines fit?

Cheers
 

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Discussion Starter · #7 ·
Brake System Continued

I had a complete spare set of these front disc brakes so before I took the XL apart I had all this already prepped.

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New bearings and races.

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Brand new rotors. These are the 1968 year only rotor deal and as you can see a two piece design. My biggest fear on these is they are becoming hard to find. In fact I cleaned Rock Auto out. Since we have two cars now with these 1968 front disc brakes on them. A couple years ago Rock Auto had two brands of these in stock. What's interesting is when I bought the Raybestos out (they only had 2 left) I noticed the AC Delco brand they used to sell wasn't even listed. I thought that odd. I looked up the AC Delco part number then did a part number search in Rock Auto on that AC Delco and sure enough they showed 4 in stock at a really low price, but someone at Rock Auto didn't have the part number linked to an application anymore, so they were sitting in limbo. I took a chance and bought all 4 and sure enough they showed up. Sometimes it pays to think out of the box.

With the economy, such that it is currently, I just bought a lifetime supply of disc brakes for these cars; rotors, calipers, caliper parts, hoses, hardware and pads.

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New wheel studs

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It presses together very similar to a 4 wheel drive pickup rotor. It's just a smaller version of the 1 ton brakes on our old Dodge Power Wagon.

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That's both rotors done.

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The calipers I cleaned and powder coated and they just received all new internals. These calipers didn't have the amount of rust in them as the golden XL did. These brakes are off my other '68 XL. I use the Red Rubber Grease as you do not want to use petroleum based lube on the seals. This grease is vegetable based and will not cause the seals to expand.

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The old pistons were still pitted though and needed to go.

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For the brake line bolt, these were the closest I could find.

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These are a wee bit too long as you can see the original one on the right compared to the old one in the middle. I just shortened them a smidge.

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Both calipers put together.

continued in next post.
 

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Discussion Starter · #8 ·
Brake System Continued

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I bought new wheel cylinders but took them apart to inspect and I powder coated the housings since I was doing the calipers.

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New brake pads.

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New hoses. These were from Brake Hoses Unlimited and they make the rear hose for the Ford 9" equipped '68's (FE optioned cars), otherwise the '68's came with the WER Salisbury axle with a Windsor engine.

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A new master cylinder. Now this is an interesting topic, I previously bought two brand new 1968 Disc brake masters and neither of them had the RPV (Residual Pressure Valve) inside them as they are supposed to. However this new one did. This is why you have to check everything now-a-days and I do mean everything. I decided to take a chance on yet another new master to see if it would come with it, otherwise I would have to had added an external RPV. In this case it was going to be that pinkish deal.

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This is the RPV in the master for the rear drum brakes.

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To remove the flare seat and gain access to the RPV I threaded it carefully with a 4-40 stainless bolt and used a small slide hammer to tap it out. Easy peasy.

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This is the part number that had the RPV in it.

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This is a comparison of one of the previous masters I bought and neither has the RPV in them. I guess they just forgot. I'll just toss the other two as they are substandard parts.

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And yet again, the XL gets another substantial infusion of new and refurbished parts.

Continued in next post.
 

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Discussion Starter · #9 ·
Brake System Continued

Time to start putting this car back together.

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Starting from a bare backing plate. Now for those that find drum brakes frustrating to assemble, here's my easy steps to put this back together without frustration.

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New wheel cylinder with hardware and I use anti-seize on everything.

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Installed, no biggy there.

Wheel Tire Automotive tire Motor vehicle Tread



Take the secondary shoe and attach the parking brake cable to it and let it dangle.

Automotive tire Motor vehicle Vehicle brake Alloy wheel Tread



Insert the push rods in the wheel cylinder and insert the shoe retaining pin for the rear secondary shoe through the plate and stage the retaining spring and cups atop and put the pliers in your rear pocket and then install that rearward shoe onto the plate and everything is within easy reach now to assemble.

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Automotive tire Vehicle brake Motor vehicle Alloy wheel Disc brake



Again stage the parts for the primary shoe. This one is a little more cumbersome with the parking brake equalizer bar to contend with.

Wheel Tire Automotive tire Locking hubs Tread



Pretty straightforward so far. The rest is really easy now.

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Install the upper shoe guide at the top, loop in the adjuster cable and install the primary shoe spring.

Automotive tire Vehicle brake Alloy wheel Crankset Disc brake



Install the adjuster cable guide and the secondary shoe return spring. This is the tool I use and it makes life easy with these springs. It's really old and has seen many drum brake repairs, but works a treat. I do believe it may be an old Lisle tool. I would encourage anyone doing drum brakes to buy one.

Continued in next post.
 

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Discussion Starter · #10 ·
Brake System Continued

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Install the star wheel adjuster, the adjusting lever and stage the lower spring.


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After the spring is installed you can pry up on the adjusting lever and loop in the cable.


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Easy and no frustrations. Just adjust the star wheel so the shoes barely touch the drum when installed and call it done.


Tire Wheel Automotive tire Locking hubs Tread




Light Automotive tire Gas Auto part Wood



New over the axle brake hose.
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For now this is where I'll leave the rear brakes, time to assemble the front brakes. Both rear brake drum assemblies are done, it just needs new brake lines from this hose to each wheel cylinder.

Wheel Tire Automotive tire Automotive lighting Motor vehicle



Starting with a cleaned spindle.

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Caliper brackets go on first.

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Ford used safety wire on these bolts which took me by surprise. Now Ford just took some bailing wire and twisted it on these bolts like a garbage bag tie. I took the time to make it a little neater. I had to learn how to do this on our airplane.

Continued in next post.
 

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Discussion Starter · #11 ·
Brake System Continued

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This the stainless safety wire and special pliers I use to do the twist.


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I powder coated the dust shields.


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I used a little RTV between the spindle and the splash shield since I don't have the gaskets and didn't feel like making any.


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For the seals, Rock Auto had a clearance on these CR seals. I think they were 50 cents each and I bought a Timken to compare.

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Turns out the sealing lips on the CR seals are more defined and in my opinion a better seal than the flashy Timken ones.

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Interesting.
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Here's the final round of parts going on the rotor assembly.

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The inboard pad goes in first then the boots slide in.

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A little grease on the boots helps them slide right in.

Continued in next post.
 

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Discussion Starter · #12 ·
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The myriad of anti-rattled clips that go on these brakes.

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Automotive tire Vehicle Automotive fuel system Motor vehicle Automotive design



This is a rather overly complicated and cumbersome disc brake arrangement.

Gas Paint Font Electrical wiring Machine



New front hoses.

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Those hose bolts are a bit of a pain to get to.

I've assembled both disc brakes and now it's time to make some hard brake lines.

Automotive tire Wood Motor vehicle Gas Bumper



I'll do the easy ones first, the rear axle lines. I start with a section of 304 stainless line, stainless guard spring and an assortment of 304 tube nuts and go to town.


Automotive tire Wood Automotive design Floor Flooring



I've covered how I make these lines in other threads, so I'll just show the results. Trust me it's tedious.

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The other side of the rear axle line.

Continued in next post.
 

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Discussion Starter · #13 ·
Brake System Continued

Vehicle Tire Motor vehicle Automotive tire Hood


Tire Automotive tire Automotive lighting Hood Motor vehicle


Rear axle done.

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Now for this nightmare. In no way am I using this. In fact this one was leaking fluid out the rear proportioning valve. Now I do have used one that I put together and whilst it's functional, there are special moulded seals in this and they are old, even in a functioning one. Unless you have a show car, it makes no sense to use a specialized part you can not get parts for. So I decided on using a very common reproduced GM combination valve in lieu of this unique Ford valving.

Wood Gas Tool Machine Electrical wiring


Here's my spare I redid a while back, but in retrospect it makes no sense to use it. So I stripped everything off the bracket of the one off the XL on the right.

Gas Wood Machine Auto part Household hardware


This is the idea. This is a GM Disc/Disc combination valve. They do make a Disc/Drum reproduction as well, but you actually want to use the Disc/Disc in this case. The reason is that the GM Disc/Drum combination valve has a hold off valve for the front brakes to allow the rear drums to apply first. This is how GM handles the mismatch of disc and drum brakes. Ford uses an RPV to keep 10 or so PSI on the rear brakes at all times to sync apply off the disc and drum. With the RPV in the Ford master you do need nor want the hold off function in the GM valve. Therefore the Disc/Disc combination valve is the way to go.

I've used this Disc/Disc valve in our old Dodge Power Wagon and added an external RPV for the rear drum brake line. The reason I did this is the GM Disc/Drum combination valve has that hold off valve that protrudes through the valve in the front and to facilitate bleeding you are to pull and hold that valve out. On the Dodge that combo valve is located in a near impossible place to get a tool on it to help bleeding so I opted for the Ford approach of the RPV approach rather than the hold off function of the GM.

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I've also used the GM Disc/Disc valve on this 1966 chassis. Now this 1966 chassis uses 1968 front disc brakes (same as the XL) and has rear Ford Explorer disc brakes.

Wood Cylinder Gas Tool Metal


First step is to cut out a plate for the GM valve. Since this valve is heavy and will vibrate I want to use 4130 because it resists cracking due to vibration.

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You can see from the stamping then vibration the original bracket has cracked. I have 4130 TIG rod I can bolster this with.


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Something along these lines for a mounting bracket.

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Done.

More to come.

Cheers
 

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Nice write up. I have a question on the combination valve. Is it also a metering valve? I know next to nothing about brakes. Can you just use a common one for all applications or is it chosen based on front to rear weight. Just asking because I don't know. Did Ford eliminate the inline valve to the rear when they adopted the single piston calipers in 68?
 

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Discussion Starter · #15 ·
Nice write up. I have a question on the combination valve. Is it also a metering valve? I know next to nothing about brakes. Can you just use a common one for all applications or is it chosen based on front to rear weight. Just asking because I don't know. Did Ford eliminate the inline valve to the rear when they adopted the single piston calipers in 68?
Hello 5851a,

You've asked a good question, let me try to answer it as best as I can as it is a general question covering a bit. This GM valve is commonly called a combination valve because it does more than one thing that's integrated into it. For the Disc/Disc GM valve it does just two things. First is the shuttle valve that senses a pressure differential to either the front or back and if so will trigger your brake warning lamp. The second thing it does is provide a proportioning valve in case of emergency/panic stops. During a fast hard brake, a proportioning valve will reduce pressure to the rear brakes (doesn't matter if it's disc or drum) to alleviate the tendency of the rear wheels to lock up as the weight transfers to the front of the car (nose dips down).

And this by chance is exactly with the 1968 Ford factory valve assembly does. It's just not technically a combination valve because it's one assembly for the shuttle valve (does the brake warning lamp) and another separate assembly for the rear proportioning valve.

Now to cover the front to back brake balancing. That's governed solely on the physical brake assemblies at each wheel. For simplicity sake, lets assume it's a non mixed system (either all drum or all disc brakes). In the case of all disc brakes since the rear brakes for all vehicles do less braking effort than the fronts the rear calipers will have a smaller piston and smaller pad area than the fronts. The same pressure is present at all four wheels so a smaller piston and smaller pad area will put less clamping force on the rear rotors compared to the fronts.

In the case of all drum brakes the rear brakes have a small diameter wheel cylinder and less pressure is developed. Also the rear drums aren't usually as deep as the fronts so there is less brake shoe area also.

In the case of disc and drum, it's harder to draw a comparison because you need to know the clamping force of that particular disc brake and that particular drum vs brake line pressure.

Another tidbit you need to keep in mind, is that disc brakes apply the clamping force with regard to brake line pressure in a linear fashion. Whereas drum brakes are 'self energizing' and the clamping force with respect to brake line pressure is closer to the square law. That's why it is easier to lock up drum brakes in a panic stop than disc brakes (no ABS obviously).

Another tidbit is disc brakes when released still allow the pad to lightly rub the rotor. The result is there's little physical travel needed to apply the brakes since the piston is against the pad and the pad lightly dragging on the rotor. Drums on the other hand when released have more mechanical bits that move and have more lash/movement when released. In other words the shoes have to travel further before they start making hard contact with the drum surface compared to disc. This can lend to the front discs engaging first and the rears hardly doing anything at all.

There's two common approaches to this problem. The first is when you step on the brake pedal, the front disc brakes are held from applying for a short pedal travel and this gives the rear drums a chance to make contact around the same time the front discs can engage. You get a little more brake pedal travel but the front and rear brakes apply more evenly.

The second approach is to constantly keep around 10 PSI on the rear drums at all times, even with the brake pedal released. This small residual pressure keeps the shoes and all the mechanical looseness from all the bits from totally relaxing and the shoes are held much closer to the drum surface, in the same way the front discs are. Now when you press on the brake pedal both the front and rear apply more evenly.


In regards to your question of can you use one setup for all applications. Yes and no. I know that doesn't help right. So you can use the Disc/Disc GM combination valve on a Disc/Drum system only if your master has an Residual Pressure Valve or you add an inline one.

Now if your master cylinder has an RPV and you convert the rear drums to rear discs (all wheel disc) then you have to remove that RPV as that constant 10 psi will keep the new rear disc brakes constantly lightly applied and you'll cook them.

You need to know exactly what the system has before you pick parts out, so one setup cannot rule them all :)

I tried to condense a broad topic into a few key points and I hope this helps.

Cheers
 

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Discussion Starter · #16 · (Edited)
Brakes Continued


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Now to deal with the cut off rear brake line. This line runs between the body and chassis and I'm not removing the body off the chassis to change this line. It will stay for now, just be flushed out.


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The goofy line comes up then wraps down and around the frame and comes up the other side. Added to this odd routing, it's double sheathed and I couldn't get the outer sheath off.

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I had to cut it back and double flare it there with a tube nut. I'll have to add a small extension. What a pain to get up there and flare it in that tight space. After I did this I flushed out the line and good grief it was full of nasty stuff.

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Once flushed out I reattached the rear line.

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The new GM valve installed on the frame rail.

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This is the short extension brake line to connect up to the short rear brake line.

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It is what it is :) Now to make new front lines.

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This is the passenger side front line. I can't believe it snaked out without bending it. That was truly stunning.

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Continued in next post
 

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Discussion Starter · #17 ·
Brakes Continued





It still amazes me that whole line snaked into place.





This is the drivers side front.





So far so good.




This is checking the push rod spacing. Now the service manual calls for a gauge you put on the booster. But that's assuming the master is made exactly to print, which I wouldn't put much faith in that. So I loosely ball up some food aluminum foil and put a wad in there and press the master onto the booster.




Carefully extract the foil.




Then measure the crush. This is fine. You do not want the push rod resting on the master cylinder piston.







Master to combo valve lines.







I took some artistic license in making these.

Continued in next post.
 

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Discussion Starter · #18 ·
Brakes Continued





The Ford master has the disc brake reservoir in the rear and the GM valve needs that line in the front. So the lines have to cross. I tried to make this look as appealing as I could.





I think it looks better than Fords original spaghetti monster.





I have to lop off the Ford warning lamp plug and use the GM plug.




I want to be sure the wiring is intact between here and the bulb so I shorted the connector to ground and I should have a brake warning lamp.




and there it is. Cool beans this works for the first time in probably a long long long long..... long time.




They do sell a little tool that screws in place of the switch on the combo valve that's supposed to help keep the shuttle valve centre'd whilst bleeding.




Like so, but I've had mixed results using it. It may be more of a gimmick.




The fronts passed their drug test :p

Wow clean fluid... and not the murky swamp fluid that came out of it originally.




The backs passed too.




For the astute that noticed the steering gear was out, well here it is installed and the P.S. hoses clear the new combo valve and all my custom made lines.

The brakes work really well now. The rear brakes are definitely working and on gravel I can lock all 4 up. I do feel the brakes are a bit over-boosted, but they are many many times better than when we bought the old girl.

I hope you enjoyed and maybe this helps someone one out.

The end :)
 

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Desert, I went with a proportioning valve for my front disc conversion. Right now the knob is halfway but IDK if that is the best place for it. What is your advice?

 
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