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3/05/2016 7:25 PM  #1

Need brake parts advice

Ok guys, I’m looking to buy more brake parts and need some help. All on a 67 Coupe with a 390 and the tall Cobra Lemans valve covers. I have the 05-14 Mustang GT Brakes for the front already and will be buying the kit for the back. I decided against the Explorer brakes.

I need a power brake booster and was looking at MujstangSteve’s PB-6770 unit. Will it clear the valve cover?? Looking at what O’reilly’s has online, the unit I need should be around 7 ½” in diameter. Sound about right? Does the booster come with the rod to attach to the brake pedal?

I will also need the master cylinder. The brake lines need to come off of the driver side. Is the Ford Ranger unit the best choice? Was it from a 92 model? Are the reservoir port dimensions, diameter and distance apart, the same across most master cylinders? It would make it easier to find a unit that is not on an angle like the Ranger. Is there a better choice?

I have the old distribution block that was on the car. It doesn’t look that great. Can the seals inside be replaced??

Looks like I will need a proportioning valve too, what is going to be the best bet? From a recent post by MustangSteve, it appears that an adjustable is needed.
Thanks John

John  -- 67 Mustang Coupe 390 5 speed

3/06/2016 6:30 PM  #2

Re: Need brake parts advice

When gong from disc/drum or drum/drum to disc/disc there are couple of considerations.  First, discs operate at much higher pressures than drums.  Typically a drum or disc/drum master cylinder will not work right in a disc/disc setup.  It depends on what the master is doing, some set line pressure, others don't.  If it doesn't then this isn't a concern. 

Second, discs and drums use different volumes of fluid.  Using a disc/drum master on a disc/disc setup can cause the rear calipers to suck the master dry and allow air into the system under the right circumstances.  Again, its going to depend on the specific master, which is why I would just use whatever MS recommends. 

Bottom line, get a dedicated disc/disc master cylinder.

Third, as for the proportioning valve, any time you go to a non stock configuration its advisable to install an adjustable proportioning valve so you can tune the brake bias front to rear.  Disc brakes in the rear means you can now ask more of the rear brakes.  With drum rear brakes the bias is heavily towards the front to prevent the rears from locking up prematurely and sending the car into a skid.  Discs don't have this problem, though the backs will still likely lock up before the fronts due to the weight bias being on the front.  However, a tire width difference front to rear can also affect this.  So, this is why an adjustable valve is desirable, and once you get the system working you can tune the bias to where its right, which is typically rear lockup just before front lockup. 

I'm pretty sure there is a reseal kit for the distribution block. 

On the booster, not sure, but be sure that whatever booster you run is what MS recommends because there have been a lot of posts where there were braking problems caused by using an inadequate booster.


3/06/2016 8:45 PM  #3

Re: Need brake parts advice

The bendix booster will fit with the LeMans valve covers. 92 Ranger disc/drum mc can be fitted with 2000 Mustang v6 tank to get rid of the sloped tank. I have been using that mc on my 4 wheel cobra discs for years.  I think the 2000 Mustang v6 mc is better but has ports on engine side.

Money you enjoy wasting is NOT wasted money... unless your wife finds out.

3/07/2016 10:00 AM  #4

Re: Need brake parts advice

 I got a proportioning valve from MS. I think it was something like a reproduction 1970 combo valve. I have only driven my car a little bit, less than 20 miles, but it appears to work well. It is not adjustable.
 One thing to watch out for on the brake booster is getting a booster from a rebuilder like Cardone. They use crossover parts, meaning you probably wont get the booster for the application you thought. I ordered my booster form rock auto and it was not the Mustang booster I ordered. The 2000 Mustang master cylinder resivoir hit the booster. I called Rock auto and we figured out it was a crossover part and actually a booster from a Ranger. I went to Oreily and every booster they had was different with a different indentation where the master cylinder bolts up. I think MS told me or I read a post where he has an "in" with his supplier to get only the the boosters that used a core that is correct for the application. If I had it to do over I would have got the booster from him too. I ended up heating the end of the resevoir to deform, make a flat spot so it would clear.
 I also used MS pedal pin relocation kit and the firewall plate that you modify your existing bracket. Both worked out good.


3/08/2016 9:37 AM  #5

Re: Need brake parts advice

Thanks for the feedback guys. It helps a lot. 

Here is a couple more questions. Do the newer cars have a factory proportioning valve or is that handled through the ABS system? I went googling last night, but didn't find a decent answer. MS, which proportioning valve is on your car?

John  -- 67 Mustang Coupe 390 5 speed
     Thread Starter

3/08/2016 10:26 AM  #6

Re: Need brake parts advice

My proportioning valve was an original from a 77 Lincoln Versailles with four wheel discs.  Next time I make any brake changes I am going adjustable. The Versailles valve works well as far as I can tell but is nearly 40 years old.

The 65-66 pedal pin relocation kit is not applicable to a 67, so that is not a consideration. I will only provide parts that are correct for your car.

Money you enjoy wasting is NOT wasted money... unless your wife finds out.

3/08/2016 10:54 AM  #7

Re: Need brake parts advice

A lot of newer cars are totally different animals.  Once ABS reached a couple of generations it got pretty sophisticated, and you have cars with things like split diagonal ABS, which improves braking and keeps the car more stable if you stupidly slam on the brakes mid corner because you're going too fast.  But, this also means that the ABS system controls braking to a level never before imagined with simple mechanical valves.  In newer vehicles the ABS is also incorporated into the traction control, adding another level of complexity.  So, the answer is no, they don't use proportioning valves, but what they use serves the same function with on the fly adjustability handled by a computer. 


3/08/2016 11:02 AM  #8

Re: Need brake parts advice

Thanks again guys.

John  -- 67 Mustang Coupe 390 5 speed
     Thread Starter

3/09/2016 8:21 PM  #9

Re: Need brake parts advice

A tandem Ford MC with a constant bore diameter throughout (same size bore on the secondary side as the primary side) will produce a given amount of output pressure for a given amount of input pressure applied on the brake pedal. This will be true whether it's a drum/drum, disc/drum or disc/disc MC. In simple terms, the MC is just a manually-actuated hydraulic pump.

While pressure and flow are related, they are still independent of each other. There's a primary and secondary seal on each of the primary and secondary MC pistons. The distance between the seals on each piston determines the amount of volume the pistons will displace when the brakes are applied, for a given amount of pedal stroke.

Some examples in the differences in the distance between the MC piston seals seen here ('84-'90 1-1/8" Mk VII/SVO MC on the left,  1-3/16" primary piston and 13/16" secondary piston on '87-'93 5.0L Mustang GT/LX MC at top right and a '99-'04 V6 Mustang 1.00" bore MC at bottom right).

Typically, a 'conventional' cast iron Ford disc/drum MC will have a larger primary reservoir than the secondary reservoir. A typical, 'conventional' cast iron drum/drum MC will have equal sized reservoirs. Brakes are the most important system of any vehicle and requires a good deal of knowledge in how the various components work, if you're changing things up.

It is possible to use a disc/drum or a disc/disc MC on a drum/drum or disc/drum vehicle but, it's never a good idea to use a drum/drum MC on a disc/drum or disc/disc equipped vehicle. The reason is in the size of the primary brake reservoir of the drum/drum MC. A drum/drum MC will not have enough fluid reserve to support the front brakes, once the pads and the rotor friction surfaces wear down. As these items wear, the pistons have to move outward to compensate for this wear.

This means the front pistons will pull more fluid volume from the primary MC reservoir to fill the void that would be left in the calipers and is why the primary reservoir on the disc/drum or disc/disc MC is larger than the drum/drum MC.

Typical, 'conventional' Ford cast iron drum/drum MC.

The standard hard brake line diameter in these vehicles is 3/16" (outside dimension). The passages of the MC, brake valve, calipers/wheel cylinders and the flexible hoses are all designed to flow accordingly to this dimension.  In a drum/drum application from '67-onward, the brake valve used was a Pressure Differential Valve. It sensed for an imbalance in pressures between the primary (front) and secondary (rear) brake circuits. If there was a brake component, hard line or flexible brake line failure, where there was a loss of brake fluid --and thus a loss in brake pressure in one of the circuits, the valve spool inside the PDV would shift, close the contacts of a switch mounted in the valve body and illuminate a brake warning light on the dash.

Inner workings of a pressure differential valve (this valve [upper half of photo] is for a '67-'72 Ford truck. It's configured and works just the same as a drum/drum PDV on a '67-up Mustang).

'67-'69 Mustangs with factory front discs and drums on the rear got a PDV along with an external proportioning valve. These two brake functions weren't integrated into a common brake valve assembly until 1970.

'68/'69 Mustang disc/drum brake valve (PDV with external proportioning valve).

1970-later factory disc/drum equipped Mustangs would have had an integrated PDV/proportioning valve like this. The proportioning pressure is preset and non-adjustable with this valve.

A proportioning valve isn't active everytime you step on the brakes. --during normal braking, it doesn't do anything. It only becomes active when the pressure rise inside the brake system becomes sufficient enough to act on the annular ends of the proportioning poppet valve to force it to overcome the tension of the spring and then to move the poppet valve over to begin reducing the rate of pressure rise to the rear brakes, relative to the pressure acting on the front brakes. Proportioning valves don't limit the amount of pressure to the rear brakes. They only slow down the rate of pressure rise to the rear brakes, proportional to the pressure acting on the front brakes.

Manually-adjustable proportioning valves get installed on a lot of vehicles but, I suspect very few are actually set with the use of brake pressure gauges.  Turning the knob and making some stops, repeating the process, equates to nothing more than a WAG at what the M-A proportioning valve is actually being set to, without the use of pressure guages. If you do have a set of pressure guages, you first have to know what the minimum, preliminary pressure setting and percentage of reduction is that you're trying to set the M-A proportioning valve to. --for an early Mustang, that would be 300 PSI @ 50% reduction in the rate of pressure rise of the rear brakes, in proportion to the fronts. Without a set of guages, you would most likely overshoot or undershoot this mark. M-A proportioning valves are also not DOT approved for highway use.


3/11/2016 2:14 PM  #10

Re: Need brake parts advice

Thanks for the explanation Ultrastang, I work well with pictures.

I do have more questions, though. I have spent all of a couple of hour’s researching and now have enough knowledge on the subject to be dangerous!  I went googling on how to set the adjustable proportioning valve using a pressure gauge. All I found was pictures of gauges & fittings and the explanation of drive it, hit the brakes, twist the knob, and repeat if necessary. One article did measure the pressure front and back for comparison, but that was it. Can you explain how it should be done, please?

Also, you mentioned the “300 PSI @ 50% reduction”. I saw it in the chart in the tech page you posted too. I make the assumption that if you hit the brakes hard enough, like a panic stop, the valve will react to the quick pulse of pressure when it achieves 300 psi for the momentary reduction in time before it makes it to the back tires. Is that a correct assumption?  A normal stop would react differently and may not activate the valve at all?? I want to know that I am understand the process correctly.

I’ll make another assumption that Ford’s research and testing came up with “300 PSI @ 50% reduction” from a Mustang with factory sized brakes and the skinny biased ply tires of the day. Now that I will be changing the equation by adding wider tires and bigger brakes, is that still a good value?  
Just trying to understand.

I agree that a disc/disc master cylinder would be the better choice, but there is not much extra real-estate under the hood on an FE powered Mustang.  I did find some master cylinder banjo bolts by Pure Choice Motorsports that would let a hose leave the master cylinder at a 90* angle. Has anyone ever used one of these? It might allow for enough room to run the 2000 V-6 master cylinder.

John  -- 67 Mustang Coupe 390 5 speed
     Thread Starter

3/11/2016 6:00 PM  #11

Re: Need brake parts advice

Disregarding that the gauges are connected to an OEM type brake valve assembly, you would connect a brake pressure gauge to the inlet side of the M-A proportioning valve and one to the oulet. You'll be able to read the differential in what pressure is being applied to the valve vs. what's actually coming out of it.

Set the M-A proportional valve to this initial pressure setting and then test the brakes. You can fine tune from there, if needed. From the gauge readings, you'll know exactly what your pressure setting to the rear brakes will end up being, rather than it being a complete unkown.


3/11/2016 7:36 PM  #12

Re: Need brake parts advice

ultrastang wrote:

Disregarding that the gauges are connected to an OEM type brake valve assembly, you would connect a brake pressure gauge to the inlet side of the M-A proportioning valve and one to the oulet. You'll be able to read the differential in what pressure is being applied to the valve vs. what's actually coming out of it.

Set the M-A proportional valve to this initial pressure setting and then test the brakes. You can fine tune from there, if needed. From the gauge readings, you'll know exactly what your pressure setting to the rear brakes will end up being, rather than it being a complete unkown.

Cool. Thank you

John  -- 67 Mustang Coupe 390 5 speed
     Thread Starter

3/12/2016 2:13 AM  #13

Re: Need brake parts advice

This is an SN95 (Cobra) Mustang MC shown with banjo fittings on the ports.

There's also the option to use a '90-'94 Ranger disc/drum MC (1.00" bore with ports on the left). Its reservoir just doesn't sit level. It slopes like the Cobra MC pictured above.

Or, if you have the factory Bendix dual diaphragm '67/'68 Mustang brake booster, running a 1-1/16" bore '95 Explorer disc/disc MC should be no problem for the dual diaphragm unit. The Explorer MC's ports exit on the left, the reservoir is level and it's the same 7-1/2" long just like the SN95 V6 Mustang MC.

Explorer MC shown in my '69 F100 with a factory Bendix dual diaphragm booster from a '75 F350.

Explorer MC in my '68 Mustang.

Explorer MC a '65 Mustang (Fox 5.0L dual diaphragm booster).


3/12/2016 7:34 AM  #14

Re: Need brake parts advice

Wow, thanks for all the pics ultrastang!  5,000 words worth of information without all the typing! 


3/12/2016 3:32 PM  #15

Re: Need brake parts advice

TKOPerformance wrote:

Wow, thanks for all the pics ultrastang!  5,000 words worth of information without all the typing! 

You're welcome. I'm glad if you (or anyone) got something useful or informative from my previous post/photos.

In 2003/2004, Glen Buzek and I were working on a conversion bracket setup to put '94-'04 Mustang V6/GT rear disc brake assemblies onto the 8 or 9-inch rear ends under early Mustangs and related Fords. I got our prototype brackets and began installing them on a '65 fastback with an 8-inch rear end in the fall of '04.

During the course of this development time, I was extensively searching the internet for a suitable 4-wheel disc MC to use with this setup. The two primary MCs people were using then ('03/'04), that would pop up, were the Corvette cast iron MC and a Mopar MC with an aluminum body and a black plastic reservoir. I didn't want to use either one of those. I wanted something that was a Ford product in a 'modern' design 4-wheel disc brake MC but, there just wasn't any information or photos of anything suitable about this on the internet then.

It finally dawned on me (then) that the logical solution was to try and use the 'modern' MC from an SN95  Mustang. I got a brand new Bendix SN95 V6 Mustang MC from the local Ford dealership and mounted it to the booster in the '65 Mustang, got it plumbed up and then tested out the new rear disc brake conversion. It was a great success.

After everything had been installed and tested, I had posted several photos of the installation on this and several other Mustang forums. Up until this time (2004), nobody was talking about or had any photos or information of this MC being used in an early Mustang or related Ford vehicle. Today, 12 years later, it's a completely different situation and there's a LOT of talk and/or photos referencing using this style MC in an early Mustang, as a result of mine and Glen's efforts back then.

These are some of the photos I had posted here and elsewhere, back in 2004, that started the trend of people using this MC for this application.  --back then, I didn't have the direct-connection ISO metric bubble flare connectors to plumb the lines directly to the MC ports and I had to use adapters on this installation.


The lines are not as close to the engine as they appear to be in this photo.

A similar trend is occurring in the old Ford trucks since I posted photos of the '95 Explorer MC I installed in my '69 F100, last year, when I converted my truck to front discs and posted photos of its installation on the old Ford truck forums. I can currently think of at least 9 people who've either already installed this type MC or, who've told me they plan to install this MC on their truck, as a result of seeing the work I did on installing one on my F100.

There's a sense of satisfaction that comes from doing something nobody else is doing and then the trend becomes that people are emulating what they see you doing for their own use. It's a good feeling and even flattering when you know something you were involved in or, have done, advances and makes a positive impact in your particular automotive hobby. 


3/12/2016 9:06 PM  #16

Re: Need brake parts advice

Due to the pedal ratio of only 3.5:1 on the 67-69 Mustang power brake pedal, my testing has shown that anything larger than 1.0" bore will result in insufficient line pressure to properly activate typical disc brakes.
The original disc brake master cylinder was 1.0" and no matter what brakes you have you still need sufficient pressure, about 1,000 psi is good number to shoot for.  Simple physics lrts you calculate the pressure you can get out of the system. A bigger mc bore reduces the line pressure.

Ultra, I am sure you found out the V6 mustang mc from early 2000's works great, but stating you discovered it first is a bit of a stretch.  My daughter's 2000 Mustang had one from the factory and I also started using them around 2002 in my kits as well.  My first Cobra kit came out in 1999.

As for adjusting a proportioning valve, I don't see how adding a gauge helps adjust it. Trial and error under real world conditions and ultimate performance of the brakes is really all that matters, isn't it?

Money you enjoy wasting is NOT wasted money... unless your wife finds out.

3/12/2016 11:27 PM  #17

Re: Need brake parts advice

Hi Guys, thanks for the information and all the pictures as always.

I was able to read some of the new post earlier today, but not all of it. I like the idea of a disc disc master with ports to the left. Again, I'll clarify that I know enough to be dangerous and I ask questions to get a better understanding. I want to know the science behind the decisions.

I've read or been told that the 1 1/16 bore was too big also. With a power pedal at 3.5/1 ratio, what is the manual pedal ratio? If it's higher, would that work with the factory Bendix booster and the 1 1/16 bore master? I ordered the booster from Steve the other day.

When you go looking for a master, what are the driving factors? Bore of master cylinder, port location, size of port fittings, or the internal pistons?

On a side note, Ultra, I remember your bump side. It's a nice looking truck. I read somewhere that Ford used the same brake pedal for manual or power brakes. Not sure that I can verify that, just something I read.

The "while your at it" bug shows up and I'm thinking how hard would it be to adapt ABS onto one of these cars!!! Should add a whole bunch more issues. 

John  -- 67 Mustang Coupe 390 5 speed
     Thread Starter

3/13/2016 12:46 AM  #18

Re: Need brake parts advice

Manual pedal ratio is about 6.25:1.  I misstated the power brake pedal at 3.5:1.  It is actually only 3.0:1.  The manual pedal would make a dangerously overboosted condition and will not even connect to the booster due to different geometry.  Well, it WILL connect if you like your brake pedal right on the floor to start with.

Unlike the 65/66 cars that did not ever come with factory power disc brakes, the 67 and later Mustangs DID, so why not use a factory proven design?  The bendix booster and power brake pedal work well together.  The master cylinder only knows what piston size it has and can only push as much fluid as that piston will allow.  I have tried larger bore master cylinders on my cars in the past.  I always come back to the 1" to get enough line pressure so the car actually feels like it will stop correctly.

Money you enjoy wasting is NOT wasted money... unless your wife finds out.

3/13/2016 2:12 PM  #19

Re: Need brake parts advice

MS wrote:

Ultra, I am sure you found out the V6 mustang mc from early 2000's works great, but stating you discovered it first is a bit of a stretch.  My daughter's 2000 Mustang had one from the factory and I also started using them around 2002 in my kits as well.  My first Cobra kit came out in 1999.

I don't know that I 'discovered' the use/installation of an SN95 V6 MC in an early Mustang, since it's quite possible that someone could have done it and just didn't post any information or photos of it to the internet at that time.

I do know that in 2004, I spent hours each day for several weeks looking for any information or photos of a 'modern' MC that I felt would meet the requirements of what I was looking for, to install a 'modern' MC in an early Mustang. At that time, information/photos specifically of an SN95 V6 Mustang MC in an early Ford application was non-existent. There was no mention on the internet of this MC's use, in this kind of application, until after my postings of it in late 2004.

I recall a conversation you and I had (via email) in 2007 where you were looking to offer a 'modern' MC and you had asked me if I had ever used an early '90s Ranger MC. I said, "no," but, that I had used the SN95 Mustang V6 MC and that (at that time --'07) I was looking into the possibilities of an Explorer MC.


3/13/2016 9:18 PM  #20

Re: Need brake parts advice

Having the 2000 Mustang in the garage made it easy to find a master cylinder.  Doesn't matter how it came to be, but it does work well.  I wish the ports were on the driver side.

Money you enjoy wasting is NOT wasted money... unless your wife finds out.

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