Yes the metering valve is from the drum brakes.. So I need an adjustable proportioning valve? Previous owner put in disc brake mc and booster. I did not replace mc so I did not re bleed it. I have not bled the brakes since starting the car back up with the power boost. Don't know if that makes a difference but a good place to start and if that doesn't work then the proportioning valve?
Fuselage front suspension rebuild
- Thread starter pmschmitt
- Start date
SF-66TC
Well-Known Member
I'm a little confused here. You did a disc brake conversion, but you said the previous owner already had a disc brake master and power booster with the drum brake system? If that's so then all you did was pull the front drum setup and swap in the disc brake setup? Since you had to change the rubber brake hose, you did need to bleed the entire system. If you didn't that's most likely the reason why your brakes feel the way that they do.
RE: PROP VALVE - I did a lot of research before doing my disc brake conversion and spoke at length with Wayne Brown aka Mopar Brake Expert "theramman". He mentioned that Ma-Mopar did NOT use pressure reducing or proportioning valves on C-bodies disc brake cars (see 11:33)
Also, if you look at the components of a factory "C-body" with disc brakes you will see that what Wayne said was indeed true.
I later read Rich Ehrenberg's "Disc-O-Tech" write up for disc brake conversions and he states the following in that write-up shown below.
"Next, you'll need a rear brake proportioning valve. The valve may be of the stock non-adjustable variety (which, in some years, was built into the brake tee assembly.) Ideally, though, for ease of installation and, more importantly, optimization of front/rear braking balance, the Mopar Performance/Wilwood "add-on" adjustable valve, Mopar #P5249088 (or similar) is highly recommended, and, therefore, was used in our swap. The standard, nonadjustable valve was, of necessity, a compromise. The same valve was used on wagons and 2-door coupes, slant sixes and Hemicars, meaning that most cars rolled out of the assembly plant with less-than-ideal proportioning, characterized by a tendency toward early rear-wheel lockup.
There are other ways to alter front/rear balance. One way, which reduces rear lockup, is to use a 7/8-inch rear wheel cylinder in place of the standard 15/16-inch unit. Try Raybestos part number WC37236 for this. (Original application: late ‘70-early ‘80s light-duty Dodge trucks w/10-in. rear drums)."
The full write-up can be found here - Mopar Action On-line - Tech Archives
When I did my conversion I was only going to use the distribution block that came with my drum brake system (no prop valve), but it so happened that I came across an OEM Mopar Performance/Wilwood Prop Valve #P5249088 that Rich Ehrenberg mentioned in his write-up so I added it in line with my rear brakes just for the heck of it. If you decide to add a prop valve just go to Amazon and just key in "proportioning valve" and you'll come up with a bunch; Wilwood, JEGS, Allstar etc... any one of these would be sufficient.
I'd say, If you're going to be driving this car with those two beautiful babies you show pictured with you, it'll be best to add a prop valve... Better to be safe than sorry...
saylor
Senior Member
I can only speak for my own car 68 fury III but I used the stock metering / combo block and did not add any regulator or prop valves.
im with sf-66tc on this - the story isn't making sense with a disc MC already installed, but still drum brakes.
im wondering if it is the correct MC. the piston size and rod length on the MC plunger matters.
also- trace the brake lines and make sure the front and rear are not crisscrossed - I mean make sure they are connected to the MC in the correct positions.
try not to die -
- saylor
im with sf-66tc on this - the story isn't making sense with a disc MC already installed, but still drum brakes.
im wondering if it is the correct MC. the piston size and rod length on the MC plunger matters.
also- trace the brake lines and make sure the front and rear are not crisscrossed - I mean make sure they are connected to the MC in the correct positions.
try not to die -
- saylor
SF-66TC
Well-Known Member
I'm with saylor. If you can't confirm that the master is DEFINITELY for a disc brake car (receipt stating or identifying it as for a disc brake car), I would replace it. I can't say for certain, but maybe the person you purchased the car from installed a dual master for a drum brake car....
The Raybestos MC36307 is a dual master for a '73 front disc, rear drum New Yorker - unfortunately Rock Auto is out of stock, but Amazon has it for $46.49 shipping. 18 x 10.2 x 10.1 inches
Amazon product ASIN B000C6ZY8U
The Raybestos MC36283 is a dual master for a '69 front disc, rear drum New Yorker and is available from Rock Auto for $45.89 plus shipping OR $54.19 from Amazon Prime with 1-day Free Shipping. It's sold and shipped by Amazon which is the best part and if you were to get this one I'd get it from Amazon. 11.6 x 7.8 x 5.4 inches
Amazon product ASIN B000C75NZ8
There is a big difference in dimension between the two units. The MC36307 looks more like the style you presently have. Bore size makes a difference in pedal feel. Larger bore size, harder pedal and visa versa. Not enough information about your booster, push rod length, bore size etc... you'll have to research. I'm using the MC36307 master with my factory drum power booster and it works fine.
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Ok so to clarify.... Yes, the previous owner installed a disc master cylinder and booster as well as a power disc brake pedal but the car was running power drums when I bought it. I am not 100% sure it is a disc MC or booster but I think it is as the pedal even states power disc on the footplate. so I assume it is all from one car ( yes I know what it means to assume) . Why there would be these things with a drum set up... I have no idea it always perplexed me myself.
What I did.... Replace from spindles out with 73 disc brake set up, also replaced the hydraulic hoses to the front and had to replace a brake line to the front drivers side. I bled the brakes ( front only) did not bleed the back after the swap. Pedal feels hard .. Not spongy but car is slow to stop does not have any real stop power of I mash the brakes.
PLAN:
I plan to re bleed ALL brakes first.
If that doesn't improve the feel then time to swap out the MC
Would you all agree with that plan?
What I did.... Replace from spindles out with 73 disc brake set up, also replaced the hydraulic hoses to the front and had to replace a brake line to the front drivers side. I bled the brakes ( front only) did not bleed the back after the swap. Pedal feels hard .. Not spongy but car is slow to stop does not have any real stop power of I mash the brakes.
PLAN:
I plan to re bleed ALL brakes first.
If that doesn't improve the feel then time to swap out the MC
Would you all agree with that plan?
commando1
Old Man with a Hat
Wow. Too much bs.
Just look at the effen master cylinder.
Is the resevoir nearest the firewall bigger than the other one?
Just look at the effen master cylinder.
Is the resevoir nearest the firewall bigger than the other one?
commando1
Old Man with a Hat
OK. Your M/C is fine.
Now we distribute it.
Lines from resevoir nearest the firewall goes to where?
Now we distribute it.
Lines from resevoir nearest the firewall goes to where?
commando1
Old Man with a Hat
Trash that sucker. It's a Rube Goldberg contraption that gave up years ago.
commando1
Old Man with a Hat
Yes. Going on the assumption the m/c is recent. That prop. valve looks original.
i didn't see mention of the proportioning valve being replaced with the conversion.
are you sure that is a proportioning valve and not just a distribution block?
70-80% of your braking is done with the front brakes. the front calipers also require more volume (larger m/c chamber) and pressure. if your proportioning valve is not balanced correctly ( the orifices inside are metered for the appropriate system) it will cause a problem like you described.
are you sure that is a proportioning valve and not just a distribution block?
70-80% of your braking is done with the front brakes. the front calipers also require more volume (larger m/c chamber) and pressure. if your proportioning valve is not balanced correctly ( the orifices inside are metered for the appropriate system) it will cause a problem like you described.
commando1
Old Man with a Hat
That is a proportioning disruption valve.
65sporty
Old Man with a Hat
I would find a 73 model proportioning valve and change out the metering block that is there now. If you need further fine tuning on the rear then add a adjustable unit.
SF-66TC
Well-Known Member
The brake lines to that pressure reducing valve/distribution block ARE CORRECT.
CORRECTION: That valve does nothing more than distribute fluid and operate the idiot light switch in the middle. If pressure is lost one either side (front/rear brakes) the sliding internal piston will ground the switch and turn on the idiot light. THAT'S ALL IT DOES - IT DOES NOT BLOCK OFF THE LOW PRESSURE SIDE.
the valve senses a reduction in pressure from either the front or rear lines it simply activates the idiot light. BTW, by the time the light comes on it's already too late lol!
Commando is correct, it appears you do have a front disc master - this is a photo of mine. The small black rubber piece shown is to use ONLY if you have manual brakes.
The photo below is the dual drum master I was going to install prior to acquiring the disc conversion
- Just for safety plum in a prop valve in between the brake line that goes to the rear brakes.
- Remove the FRONT reservoir line at the master and at the INLET of the pressure reducing valve #3 and install a plug there.
- Remove the rear brake line from the pressure reducing valve #5 and install a plug there.
- Decide where you want to mount the prop valve then plumb a new line from the FRONT reservoir to the INLET side of the prop valve.
- Connect the rear brake line (removed from step 3) to the OUTLET side of the prop valve.
- Bleed all 4 wheels
- IMPORTANT: Adjust the rear brake self adjusters. Whichever side you adjust make sure you remove the wheel for the opposite side for ease of spinning the wheel and adjust for drag. When adjusted put the wheel back on and remove the opposite side wheel and repeat.
I installed my prop valve on the side of the inner fender.
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Brake Technical Information
http://www.airheart-brakes.com/pdfs/MasterCylinder_Selection.pdf
Master Cylinder Bore Size Affects Pedal Travel Distance And Effort | Master Power Brakes
Master Cylinder ID Guide - Powered by PageTurnPro.com
Now go read...
This should explain all you need that hasn't already been said...
Nobody is going to be able to fully diagnose this without their hands on the car or very exact part information. You should be able to figure out if your stuff is correct from this... BTW the disc brake pedal pad doesn't actually mean anything but that pad was disc brake... you should find and write down every p/n you can. Research what cars stuff came from if you have that info... but mix and match brakes are not just about if it bolts on.
http://www.airheart-brakes.com/pdfs/MasterCylinder_Selection.pdf
Master Cylinder Bore Size Affects Pedal Travel Distance And Effort | Master Power Brakes
Master Cylinder ID Guide - Powered by PageTurnPro.com
Now go read...
This should explain all you need that hasn't already been said...
Nobody is going to be able to fully diagnose this without their hands on the car or very exact part information. You should be able to figure out if your stuff is correct from this... BTW the disc brake pedal pad doesn't actually mean anything but that pad was disc brake... you should find and write down every p/n you can. Research what cars stuff came from if you have that info... but mix and match brakes are not just about if it bolts on.
65sporty
Old Man with a Hat
That's some good info there
commando1
Old Man with a Hat
For YEARS I have wondered why they always included that little thing.
Now I know. lol
saylor
Senior Member
i question the disc brake pedal and related linkage TO the booster/mc.
is the throw different from a drum pedal and a disc pedal? and/or the related linkage?
or is the piston bore different? rod length?
etc.
when I swapped, I used drum pedal/linkage/blah/blah everything stayed the same I did not change pedal or any of that.
- saylor
is the throw different from a drum pedal and a disc pedal? and/or the related linkage?
or is the piston bore different? rod length?
etc.
when I swapped, I used drum pedal/linkage/blah/blah everything stayed the same I did not change pedal or any of that.
- saylor
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