Customs OK, I give up. DeSoto wagon brake issue.

"As an aside, my usual build has involved using ALL the components from whatever donor car I got the engine and trans from, I'd use the rear end, the MC and booster, prop valve and all, so stuff always has worked fine".

That's how I've done it in the past .... master, booster, pedal ***embly, combo valve, all from one vehicle, and therefore designed to work together.

 

I am today pleasantly surprised to discover new combinations of things that are not supposed to go together, but actually work!

 

I would like to find that combination of stuff!

 

Thats why I try and match specs from my Wagner brake bible. The only issue is that my "late model" version only goes up to 02 I think?

 

I just machined 0.009" off of the stem on a set of new Suzuki forks, and then put them on a vintage BMW.

There is always a combination that will work. It is all a manner of finding stuff that is close enough to be nudged the rest of the way.

 

Is this is your set up Do you have the brake warning light hooked up? If so is it on? If it is on open a front bleeder and have someone slowly push down on the brake pedal until the light goes off and stop then close the front bleeder . If the light blinks you pushed the valve to far and have to repeat opening a back bleeder. Some valves are spring loaded and the warning light will only be on when the brakes are applied. but most once the plunger is pushed it will only move back with line pressure the other way once the valve is off center it will shut off fluid to the end that it thinks failed. This can happen when using the pump the brake method of bleeding. I guess the first question should have been do you get any fluid at the rear bleeders?

 

I this is your set up Do you have the brake warning light hooked up? If so is it on? If it is on open a front bleeder and have someone slowly push down on the brake pedal until the light goes off and stop then close the front bleeder . If the light blinks you pushed the valve to far and have to repeat opening a back bleeder. Some valves are spring loaded and the warning light will only be on when the brakes are applied. but most once the plunger is pushed it will only move back with line pressure the other way once the valve is off center it will shut off fluid to the end that it thinks failed. This can happen when using the pump the brake method of bleeding. I guess the first question should have been when you pressure bleed do you get any fluid?

 

One of these tools can save a lot of headaches when bleeding brakes that have that type proportioning block ***embly.

 

Yep! but he has a Front/ Rear bias issue that is caused by too big front caliper [piston]
And also bleeding and pedal travel issues [which could mean low-drag calipers]

The explorer rear discs are reasonably large diameter to accommodate the park brake drums inside.
So to get a decent Fr/Rr bias they reduced the co-efficient of friction [with smaller pads]

The OP needs a 1" diameter M/C to increase clamping pressures and match those 1-7/8" bore Explorer calipers [ a 22% reduction in M/C bore area]

But this then creates another issue.[Too much pedal travel AND too much Fr Brake bias]
So the front caliper piston size needs to be reduced to 2-9/16" this compensates for higher line pressures and smaller volume also reduces pedal travel.

A 63.4mm bore [82-95] 3rd or 4th gen Camaro caliper would be close enough and should bolt on.

A 95 Crown Vic also has the same M/C and Fr/ Rr caliper bore sizes as an Explorer.

 

I hav

I already have metric GM style front calipers, and 1" bore MC. And, if by pedal travel you mean too little, that seems to be an issue, as opposed to too much, which goes along with the wrong pedal ratio, which I think the guy at Speedway helped me find. So, there's a lot wrong, or was, much of it based on me not realizing the rear axle was from a Sport-Trac, which uses completely different brake parts than the Explorer 4x4 I thought it was. Partly based on my listening to a counter person who said, "They're all the same."

 

According to what you 1st wrote, you have a Corvette M/C which is 1-1/8" diameter [22% larger swept area]

This was taken from your 1st post

Pull it off and measure it!
And what size "metric" calipers do you have? They can go up to 3"

And if they are low drag calipers, you will need a stepped M/C or you will be bleeding it forever and still get too much initial pedal travel.

 

A while back I put a set of 1977 Suzuki GT750 (water buffalo) trees and front end on a 1975 Guzzi 850T. I wanted dual front discs, and sourcing a T3 front end with twin Brembos was rare and expensive.

 

If they happen to be low drag calipers, regular ones can be had, for not much coin.

 

LOL, good advice. It's been a year (almost) since I got the parts, so my "Old Timers" may be partly responsible. I believe Speedways catalogue calls them "Corvette style...".

 

I had no idea that could happen. I've bled dual system brakes before, well, admittedly about once every 5 years, and hadn't had a problem. I suppose that could be it, but would that not prevent fluid being pushed to the rear lines?

 

Reading this makes me glad I went with the F-150 11” drums on 8.8 I installed. When I went to buy the front discs the companies I contacted all asked to tell me the brake pedal ratio in the car before recommendations for booster/non booster and MC piston diameter. I’m sure you will figure this out...

 

They’re all Corvette style, just like every swap meet SBC is a Corvette engine.



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I usually think of the Corvette style master as having two wire clips to attach the lid. Not to be confused with the Ford style with one wire clip to hold the cap.

 

That is what he has.

 

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I call them Pot Belly myself.

 

OK. My rear brake line pressure is 400 PSI. This should, I would think be roughly half what it should be. I moved the push rod mount up the brake pedal 1", which is all I can reasonable get with that, and, visually, the rear wheels ALMOST stop with very hard pedal pressure. The next step is to find out why the pressure is too low. I checked the brake trouble light fitting on the distribution block, it does not light a light, so I believe that is open, which means the little valve inside isn't bad. I have 20 inches of vacuum at idle at the booster. I can lengthen the pedal a couple inches, which would actually be better for positioning, which would give a better than the roughly 4.5:1 I have now with the new pushrod location, but still nowhere close to 6:1 that seems to be recommended for power brakes, but I think a new pedal ***embly that isn't recycled would be neater and not cutting up the pedal. Again. So, that's my plan. Any other suggestions?

 

Maybe the rod length between the PB and the MC.

 

I'm throwing in the towel, and throwing money at it. Giving up the salvaged, evidently never-going-to-work junkyard Dodge hanger and too-long pedal, what turns out to be, checking with my order history, a too large bore MC at 1 1/8", and a maybe too small booster, even though it's a dual, to an 8", all I can get on the firewall, and even that will require t******* a hood hinge bracket. There's nothing money won't fix, my father in law used to say. That's my "fix".

 

A 7/8” bore M/C is usually for non booster brakes which I have and the work fine. There is the theory that a 3/4” would be better.
With that said 1” or 1-1/8” is for boosted or ***isted brakes. Same for the pedal ratio: 5-1 or 6-1 for non power and less for ***isted so you won’t throw yourself through the windshield.
Even though you may not buy their products I would call Wilwood and ask they are professionals They and a place in South Carolina were both very helpful when I was wanting to change brakes. Both wanted to know ratios first before anything else.
Also by moving the push rod it is now on an angle (not a straight push) and can make contact with its closest object. For me it would be the M/C itself and could cause a bind. Once again good luck...

 

Lossen the line that goes to the rear brakes at the proportioning valve to see if the valve has shutoff the fluid to the rear brakes.

 

Reading with interest b/c I'm doing much the same on a 50 Desoto. I'm using a 1-1/8 disc-disc MC with a 7" dual booster. Explorer rear. MC will be under floor with original pedal in a custom bracket though. I won't know how my setup works for some time so I really want to see how this gets resolved.

One quick thought, make sure the brake line junction on the rear is not clogged. Same for the hard lines if they are not new.

Also if you're using a residual valve temporarily remove it for test purposes.

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Everything is new. We'll revisit this after I get another truckload of new parts.

 

There's 400 PSI at the rear calipers, no need to loosen the fitting at the prop valve. Lot's of fluid. Not nearly enough pressure.