Inliners International Forums General Discussion MOPAR Power brakes for '47 Plymouth

any one know of a source for power assist 'kit' for braking a 1947 Plymouth?

Frump

Really need a little more info as to what you have in mind. Are you going to a dual master or staying with original one holer?

PlyDo offers a remote power booster, also you can get complete pedal assemblies with powered dual master cylinder. Butch's Rod Shop, Master Power Brakes and maybe Andy Bernbaum could get you these parts also. Several hundred dollars either way, and they are not "2 hour install by a novice" type parts.

The car has sat for 30 years so I assume all the brake stuf is junk - that's my worst case for budget planning. This is to be a 'sounds cool, runs safely' kind of a car. A resto-rod if you will. Given those parameters, what do you guys think the solution should be? Frump

I have the MAster Power pedal and booster in my '48. I know a few guys who have done this one.

Do you plan on upgrading to disc brakes or staying with drums? Is power assist really necessary, or just a wish list item?

Gearhead - my intent was/is to stay with a freshened up drum brake system with a booster for extra braking power and heightned feeling of security. The booster deal is a bit of rationalization, but it seems like the right thing to do?!

Frump

Ok, I was just wondering.

Is the master cylinder one of those that holds the pedal assembly as well, or is it independent?

Frump,
The double leading shoe drum brakes on your Ply. really don't need a power booster.
Jim R

Gearhead - I m not where the car is so I can't tell yoou about the mounting of the master cylinder. Why do you ask the question? fyi - I'll be with the car about mid-April.

I assume that the master cylinder will not be rebuildable after 30+ years. If that is true, what would bee the optimum choice for a replacement?

Frump

The master cylinder on the 47 Plymouth does mount the brake pedal. Some of the 12 Port News advertisers sleeve the master cylinders. This makes an acceptable reconditioned master cylinder. I am still running the double leading shoe drum brakes on my 48 Plymouth coupe, but will update to discs and a dual master cylinder some day. If you haven't driven a vehicle with drum brakes for a few years you tend to forget just how poorly they operate compared to a disc set up.
Jim R

Forgot to add: the brakes don't require a lot of effort to operate.
JIm R

Gearhead/Jim at the expense of beating a dead horse, is there value in implementing a dual master cylinder with otherwise stock brakes? Frump

Just a couple of pennies thought on that, if you don't mind: The intent of dual circuit systems is two-fold.

One, you get a safety redundancy if a wheel cylinder or caliper decides to puke fluid all over the place and empty the master cylinder. I've had several cars come in over the years that have been run so long on the front pads that the disc has ground away and allowed the caliper piston to pop out, dumping the fluid. Granted, I hope that no Inliner would do that, but Detroit operates under some different liability rules than we do.

Two, after installing a dual master, the package should also include fitting a proportioning valve. Kits sometimes have adjustable units since the supplier doesn't know your particular vehicle weight distribution. The valve allows the fluid pressure to operate the front and back brakes at an optimum level so the vehicle stops without using too much front or too much back brakes. To put it differently, since the load on the front and back brakes is not equal, the amount of braking should reflect that difference.

I posted this elsewhere on the B-board in a reply to a question on torsion bar suspension:

"I have a friend here at work who is updating a '65, and I gave him a dual-diaphragm booster and master cylinder that I had alreay customized from an S-10. He is keeping his original manual steering, so didn't have any interference problems like I had between that particular booster and the trans shift arm from the column. He wasn't interested in changing to disc, and is very happy with the all-drum power system (with no proportioning). He just ran one master outlet to the front and one to the back and split the pipes like I did."

I don't recommend a valve-less system. But you get the point about using modern master and booster systems on an otherwise stock lower end.

Give a holler if I can help out any more. BTW, I guess that was a little more than 2 pennies worth, huh



------------------
David

Frump,
The reason I asked about the mounting of the master and pedals is that the master cylinder housing has a pair of ears on the front of it that the shaft for the brake and I think clutch pedals run through. If you try to replace the stocker, you will need to find a way to re-mount the pedals or replace everything. there are several ways to do this, but first I would ask if you are going to use an automatic or keep the stick?

As for re-sleaving, there are several places that do this, some use stainless steel and some use brass. the brass is about half the cost. Look in Hemmings Motor News under the services section.

The cheap and dirty way would be to pull the guts out of the old master and cut open the rear and mount your new master behind the old one and run a longer pushrod right thru the old master. Make sure the rod doesn't bind on anything.

Another way would be to fabricate a replacement bracket for the stock master and mount your new master in basically the stock location.

If you go with an automatic, The aftermarket pedal assemblies work good. I am not aware of an aftermarket assembly for manual tranny, but there might be something out there, or possibly adapting an assembly form another make/year could be made to work.

There is also the option of a remote fill reservoir setup that Master Power Brakes sells, if you don't want to fill it by going through the floor.

You could also convert it to swing pedals with the master mounted on the firewall, but it would likely end up costing you more in time and money, also in my opinion it looks like crap.

Get a copy of MP Brakes catalog www.mpbrakes.com They have alot of info on how to set up the system and what parts to use in which combination. Disc/drum and all drum setups require different sizes of masters and the metering/proportioning setups are different. If you intend to go with discs up front, go with that the first time around or you will need to monkey with the other parts also (why do it twice?). I look at what the discs are coming from and use a master with a bore the same size as the donor car, same for the proportioning/metering valve. Once you think you have figured out what you want to run, talk to a tech rep at some of these places and see if they agree.

No reason you cant run power assist with either set of brakes. It's only more money. The bore of a powered master is usually larger than non-powered also.

Good luck.

What an out pouring of knowledge and experience based information. I need to sit back and digest now. Thanks to all until you are better paid....Frump

I have a 50 Ply Woodie, so it is big & heavy. Did a Power booster & dual master (with the stock drums) from Butch's some years back. Installation was anything but "Bolt-in" as the x-member needed to be notched and things didn't sit just right out of the box. Even now the pedal sits too close to the accellerator, just not close enough to bother fixing it. Anyway, the end result was very satisfactory at 60mph, whereas before any offramp with a down slope was scary.

The dual system is a good idea- I had a hose fail on a 46 DeSoto, and a line fail on a 41 Chrysler, and luckily nothing happened.
It could have been a lot worse-I live in the mountains.
BUT That's what real old cars were/are like.
Safety?
I use my PT.