My brake pedal in my 62 Valiant is hard and can stop the car almost adequately. I expected more since I converted to Wilwood discs and 11 inch drums on the rear. The drums were turned with new shoes and hardware, bled and adjusted. I replaced the prop valve with an adjustable, but no improvement. I expected better stopping with such a light car.

My 62 Lancer with 9 inch stopped better.

My only guess is the master cylinder (69 A Body disc)?

Cheers,
Barnaby

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These ones go to eleven...

Well, I'm going to replace the master cylinder with a new unit not re-manufactured. Is there a preferred interchange?

Any other thoughts or advice?

Cheers,
Barnaby

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These ones go to eleven...

All the wheel cylinders and caliper pistons must be free.
Drum brake lining may need to be "arched" to match the drums.
Pressure balancing.
DD

Thanks Doc,
I check out the arc. cylinders are good.

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These ones go to eleven...

Definately have to use judicious force and compare the shoe/pad to the drum surface to make sure you get the most contact with the drum surface.

x2 on the balancing, stock mopar prop blocks tend to lock up the rear before the front by a blink of an eye- use of a secondary prop valve for the rear brakes would help.

I would assume you are running disk brake front and drums in the rear?
Not to ask but why 11" drums in the rear? I converted a C-body with 11" drum all around to manual brakes one year for another project...even with my size 15's I could not get the brakes to actuate worth anything and I used both feet after bleeding (not like stopping mattered for the use of the C-Body anyway...).



-D.Idiot

What does Wilwood reccomend for master cylinder bore size? I don't know how much piston area you calipers have- but brake effect & pedal effort are determined by hydraulic (& pedal mechanical) ratios. Your rear brake setup will have some effect overall but not as much.

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63 Valiant Wagon
225 - 4 bbl

The 11'' inch drums came with the 8.25 rear end conversion. Maybe ex cop car 75 dart?

I have an adjustable prop valve and have never succeeded in locking the drums? I am so puzzled by this? I tend to over do things, and I will check the shoe arc, but with extreme braking I shouldn't the front discs lock up?

Everything is new and or rebuilt except some of the brake line.

Good thought, I should research the Wilwood recommended bore size.

BT

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What master cylinder did you use for your conversion?


-D.Idiot

The master cylinder interchange is 1969 a body disc brake.

Is that the best choice?

Also, I have seen conflicting information about 11 inch brakes being offered on A Bodies. If not from the factory maybe they were dealer installed? I got mine at Wildcat and they said that they occasionally see them in late A Bodies?

BT

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These ones go to eleven...

How does this Wilwood master cylinder compare to my 69? Would there be any benefit to spending the money on this upgrade?
http://www.wilwood.com/MasterCylinders/ ... o=260-6766

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These ones go to eleven...

According to some upgrade articles that one would be acceptable, I don't think it's any better than the late master cylinders.

I've seen 11" drums on a couple of 8 1/4" rears, they were either from 340/360 cars or were extreme duty F/M body cars...the factory manual does not list this as a factory option for V/L series cars.

-D.Idiot

As suggested, it sounds like something wrong other than a hydraulic mis-match so I'd double check the drums/shoes first, but here's food for thought based on nothing being "obviously wrong" with the upgrade (master or system bleeding, etc) and your mention of a hard pedal;

What's the pedal travel like now? Much shorter than before?
I remember dealing with different pedal pivot points that yield different pedal ratios (effort) on C-Body cars, it's been a long while but I'd start thinking about any differences there with regard to manual vs. power and disc vs. drum pedal arms ratios in early A-Body cars (I know nothing about them, sorry). Along those lines are different rear wheel cylinder bore sizes for a given master cyl and vehicle weight, I might start thinking about changing them to get pedal travel and firmness where I want it. Just theory here, but if nothing in the upgrade is "broken", it's where I'd start with a really firm pedal and nothing much happening at the other ends.

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1966 Coronet Deluxe

I noticed that your link to the Wilwood M/C is to a single outlet unit. Are you still using a single pot M/C with the disks and big rear drums? I'm no expert, but some folks here are.
I've gotten the idea that a dual M/C was pretty much required for a disk/drum combo. Maybe (likely?) I'm wrong. T'wouldn't be the first time, or probably the last.

ATB

BC

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'64 Dart GT convertible, 64 Dart 170 2-door post sedan in faded blue and rust (the Az Dart) & a sixty THREE Dart 170 2-door post sedan in faded blue and rust. (future project)
Early Dart Disorder (EDD) is real, and I've got it!

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These ones go to eleven...

I think the tech info you found on their site aligns with my thoughts, but I don't feel comfortable giving a specific recommendation on a change. We're talking about your brakes here and I don't have enough experience juggling brake parts to start tossing out specific bore sizes etc, but if it were my car I'd start with the following;

Verify what bore sizes I have on the master cyl and rear wheel cylinders and with that info I'd start scouring the Mopar Action brake swap articles ("Disco Tech'? and others) for ideas on which way to go. My hunch would be that a rear wheel cylinder (size) change might be the cheapest and most effective way to get a better pedal feel.

Another thing that came to mind was your mention of the aggressive friction material, I think some of the harder materials take a good amount of heat before they start working like a regular 'street' material (like race disc pads vs street pads). Just thinking, maybe that's a small part of it?

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1966 Coronet Deluxe