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Old 11-11-2005, 03:48 PM
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Ford Rear Discs Cobbled Together

Hey gang, I finally got my 78 XR7 going. Currently, I have the following parts.

stock front disc brakes, single piston/rear drums, stock.

I am going to go with an Explorer rear disc setup. I have that all set to go on another housing. Also, I'm planning on using a Lincoln Mark V master cylinder (4 wheel disc) and proportioning valve (4 wheel disc). This all sound ok? Should I use an adjustable in line as well?

Also, I've noticed that the Fox body guys can remove a nutcap and spring from their stock disc/drum proportioning valve, install a Ford Racing nutcap, and run an adjustable valve. Can I just gut a mid 70s Ford proportioning valve? or am I better off using the 4 wheel disc unit I have already?

Looking for advice.

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Old 11-11-2005, 04:09 PM
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Quote:
Originally Posted by Psquare75

I am going to go with an Explorer rear disc setup. I have that all set to go on another housing. Also, I'm planning on using a Lincoln Mark V master cylinder (4 wheel disc) and proportioning valve (4 wheel disc). This all sound ok? Should I use an adjustable in line as well?
First, let me ask you. This MARK V you are using as a donor...does it have discs on the rear? If so, it would probably be easier to exchange the complete asm.

Regarding the proportioning valve, the MARK V valve may or may not give correct bias (it is designed for a heavier car). I would try the installation on a skid pad before the street. An adjustable would give you the correct bias after setup.

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Old 11-11-2005, 04:18 PM
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Had rear discs.. I DETEST the Mark V Ebrake setup, the Explorer is much more user friendly, with an ebrake-in-hat assembly.. I had the Mark V stuff on my Elite a few years ago, and I could never get a pedal adjustment out of it.. just a cable nightmare. Made that disappear thanks to the eBay gods.
I put the drums back. I had the Explorer stuff working in the driveway, but I never got to street test it on the Elite, other than some 15 MPH stops in the yard.

Mark V is around 4700# my Cougar is around 4300#.. And I'm running wider tires, etc etc.

So basically I should be ok with both the mark V valve, and an adjustable in there for fine tuning it? (thus making me spend the least amount of money, lol)
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Old 11-11-2005, 05:20 PM
aka Duke of URL
 
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Quote:
Originally Posted by Psquare75

Had rear discs.. I DETEST the Mark V Ebrake setup, the Explorer is much more user friendly, with an ebrake-in-hat assembly.. I had the Mark V stuff on my Elite a few years ago, and I could never get a pedal adjustment out of it.. just a cable nightmare. Made that disappear thanks to the eBay gods.

I put the drums back. I had the Explorer stuff working in the driveway, but I never got to street test it on the Elite, other than some 15 MPH stops in the yard.

Mark V is around 4700# my Cougar is around 4300#.. And I'm running wider tires, etc etc.

So basically I should be ok with both the mark V valve, and an adjustable in there for fine tuning it? (thus making me spend the least amount of money, lol)
Now I don't care for the drum parking brake setup as to me they always drag and it is just something else to have to fool with. How did you adapt the MARK V brakes to the ELITE? The axle bearing retainers are actually the caliper mounting brackets. And are you saying you had trouble with the hydraulic brake pedal height or the cable foot brake?

Those calipers have an internal ratcheting system to maintain pad clearance. If the pads are replaced incorrectly, the internal adjusters are toast leading to replacement.

I would try the OEM valve first to save money, but wet down a large area and skid the car to see if the rear wants to come around (hmm...the MARK rear asm. may have SURE-TRAC on it) before driving it on the street. If it seems to stop straight, you will not need the adjustable valve.

Regarding the cables, look at a GRANADA/VERSAILLES set-up. They have a short cable coming from the caliper that attaches to the longer cables. That will rid you of the cable problem as the intermediate cables can be cut to size.
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Old 11-11-2005, 06:01 PM
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Here is a -TECH ARTICLE- on the LINC proportioning valve that may help you.
___________________________________________

Am Looking For Factory/Aftermarket Speed Parts For The MEL (MERC-EDSEL-LINC-TBIRD) Engine Family (383-410-430-462) Produced From 1958 To 1968

Also Early FORD Special Service Tools


-Mercury-Edsel-Lincoln-
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Old 11-11-2005, 08:19 PM
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Does no one care about matching calipers front to rear?
The Explorer rears are matched to a front caliper about half the size of that Merc.

Lincoln front/rear caliper balance: ~60/40
Explorer ~65/35
XR7 with stock front, Explorer rear: ~75/25

Do you think you'll need a prop valve to cut rear pressure with a low slung car and a system like that? Just speculating.

I know some people have put comparitively small brakes on the rear and report good results, but I prefer short stopping distances to windshield scraping.
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Old 11-11-2005, 09:34 PM
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Kultulz,

When I did it originally, I basically took the original Mark V brackets off the axles (had the bearings pressed), and realized "wow they have a larger bearing bolt pattern". So.. I unceremoniously C'd the brackets, and drilled new holes in them, and clearanced one side of the bracket for the axle.

I had all the factory cables, etc. But even after adjusting them, I couldn't ever get it right. I also had the same problem on my 85 Toronado, which had the same style parking brake, that NEEDED to be kept in adjustment. Hated it. I like the Explorer setup for its simplicity, and that the Ebrake isn't necessary to adjust the caliper / pedal height. Like you said, they are toast. Auto Zone got a little aggrivated after I went through two sets in a year on the Mark calipers.

As for using the Mark stuff, I dont have it anymore! only the MC and prop valve. I sold it all.

I did find that link on the Lincoln Prop valve a few hours ago, and that's basically what I did in my Elite when I had the setup in there. Only problem with mine is I broke off the small clip where the Brake light plugs into.

And yesgo, from what I've read, front calipers can be about 2x bigger than rear, others have used Explorer stuff on these cars with good results.

front Xr7 = 3.09"(I think) , rear Explorer (I think) = 44mm = 1.73"... 55% larger in front.
Keep in mind, I'll be hard pressed to lock up the rear tires, as I'm running 275 55 17s and 255 55 17s in front.


Lastly, no comments on dissassembling the disc/drum prop valve and using that plug, or A plug?

I'm eventually (april?) going with dual piston calipers from a 98-02 Crown Vic.. I know then, there'll be no problem, as I'll have recreated the stock braking system from a Crown Vic.
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Old 11-12-2005, 07:25 PM
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Quote:
And yesgo, from what I've read, front calipers can be about 2x bigger than rear, others have used Explorer stuff on these cars with good results.

front Xr7 = 3.09"(I think) , rear Explorer (I think) = 44mm = 1.73"... 55% larger in front.
It's all about square inches, not diameter.
XR7 = 3.09 diameter
=7.5 square inches in area.

Explorer 1.73" diameter
=2.35 square inches in area.
31%, not 55%. Sorry.

2x is a good starting area for many cars, as you say, though most RWDs benefit from using slightly larger rears than half size, and adding a prop valve. With 2x, most cars wont need a prop valve. With more than 3x, you'd be lucky to get much use at all out of the rears with most cars.


EDIT
A 2.125" diameter piston's square inches is about 3.5. That would be a better matched rear for those fronts. 4.9 square inches would be better. That's a 2.5" diameter piston. That's almost as big as the Mark V's rears, which were matched to the same fronts, albeit on a heavier car.
But if you're going to smaller fronts, I guess it's a moot point.

Last edited by yesgo; 11-12-2005 at 07:38 PM.
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Old 11-13-2005, 10:12 AM
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Well... I'm referring to this

http://members.aol.com/MREPRODUCT/ranchero.htm#handling

Others have used the book with successful results on the Torino forums. The Mark parts are out of the question, sorry. Just personal experience with them.

Ultimately I am going to go with dual piston calipers from a 98-02 Crown Vic in front, as I stated in another thread a few weeks ago... so I'll basically have recreated a Crown Vic braking system, on my car, as the Explorer parts are the Crown Vic parts.

Should I just do all this at once then? I really didn't want to have a lot of down time, and I'm a fan of putting something together and using it a few weeks before going onto the next project.

Again... back to the initial question too.. can I gut a mid 70's Ford proportioning valve, like the Fox guys do? My Mark V prop valve is broken (damn brake sensor)
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Old 11-13-2005, 10:32 AM
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Locking up rear tires has a lot more to do with weight transfer/ anti-dive.

Factory valves are not just proportioning valves they are combination valves.

I would run the factory combination valve and an adjustable rear valve in series if necessary.

Look in Street Rodder Magazine and get an aftermarket parking brake.

Last edited by xntrik; 11-13-2005 at 10:38 AM.
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Old 11-13-2005, 10:47 AM
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Never run two proportioning valves in series. If you run an adjustable with a factory combination valve, you must gut the proportioning section inside the factory valve.

Reason:
The way a proportioning valve works is by reducing pressure to the rear brakes in proportion to the front, that is, outlet pressure from valve is reduced in proportion to the inlet pressure. In doing this, there is a certain amount of lag time when releasing the brake pressure. Upon release or modulation of the brake pedal, the outlet pressure will not reduce until the inlet pressure is at or below the outlet pressure. Using two of these valves in series can produce an excessive amount of release lag time (hysteresis), and possibly make it difficult to modulate the braking at only the most inopportune moment.
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Old 11-13-2005, 11:39 AM
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I knew I had to gut the factory unit if I went with an aftermarket adjustable proportioning valve... But if this is the case, can I simply gut the factory disc/drum valve for the Cougar? or should I get a disc/disc unit from a mark?
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Old 11-13-2005, 04:32 PM
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Possibly.
It might also have a metering valve to delay the fronts. It wouldn't really hurt to leave it in, but 4wl disc doesn't need it, and is usually better without it. If you can disable both the front and rear valves inside there, it turns into just a line splitter with a failure warning light, and you can run the adjustable to the rear.

Another option chosen by some is to run with no failure warning.
'T' the fronts directly from the master, and run the adjustable in a line between the master cylinder and rear hose. IMO, this can be done only if a master with a low fluid warning float is used, but if you're the only one ever driving the car....
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Old 11-13-2005, 04:54 PM
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Something about running without the warning light seems wrong. Anyone make a basic distribution block, with a pressure/brake light switch, that has no proportioning function then? I knew I could *T* it, butI wanted to retain the warning light... if I didn't care about the light, I'd use the bad Mark V prop valve I have with the broken plug.
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Old 11-13-2005, 04:58 PM
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I even saw one of these.

http://cgi.ebay.com/GM-STYLE-DISC-DISC-PROPORTIONING-COMBINATION-VALVE_W0QQitemZ8013000082QQcategoryZ33565QQrdZ1QQc mdZViewItem

Crock?
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