Re: {Chrysler 300} HELP! Need front brake backing plate for 1957 300C

Good morning,

I am glad to hear the questions with the big Chryslers' old braking systems. Although I cannot really contribute at the moment because I have not attempted the switch over to disc brakes yet, I will be attempting it soon...hopefully in the next few months. I have several 1965 Chrysler 300L cars, several 65 non-letter cars, a 68 Charger, 69 Dart, and 69 Roadrunner as well. So, if this conversion is successful other cars will benefit too. On 1 particular 300L I will be changing the single reservoir master cylinder to a dual master cylinder and new booster. Probably something similar to what I have on my 68 Charger. I will also put a new dual proportioning valve, lines and 4 wheel disc brakes.Then I will be trying the 'military' DOT 5 silicone based brake fluid in the new system. I am not sure of the diameter of the rotors yet, but I do have aftermarket 17" wheels on the car to avoid any clearance issues.

It is a car that I will drive a lot, and I really enjoy it so I am not worried about having a totally original letter car. I am more concerned about having a car that I can hop in at any time and go wherever I want with family and friends. I can drive to car shows, work, whatever. It is not a restored car. None of mine are, but it is a solid, original paint, driver car that I want to make safer and more reliable. I am aware of the drum brakes that grab from time to time and pull to the left or right at times. I am also aware that with proper install and maintenance this usually can be fixed and avoided, but I have a set of 4 wheel disc brakes sitting around collecting dust so let's try it. I also have finally realized that a single reservoir master cylinder is not the best solution, and I also believe my brake booster will need to be rebuilt or replaced. For all of these reasons I will attempt a 4 wheel disc brake conversion on the car I have attached pictures of.

This car is very dear to me. Dad drove it everyday before he passed. He really enjoyed it, and I want to share that enjoyment with my wife, my 3 girls, and the rest of the community that is not aware of how nicely these cars ride and how stylish they are compared to most modern cars.

Any contributing ideas or setups for this transition are appreciated. I will remember to take lots of pictures and maybe even videos to document this transition and let everyone know if it was successful or not.

Thank you,

Rick Beckman

Cleveland, GA

On Wed, Jul 10, 2024 at 7:35 AM John Grady <jkg@xxxxxxxxxxxxxxxxx> wrote:

agree with Henry , the problem with dual leading shoe brakes is experts who are not . Incompetent work is almost the rule .
The small discs that fit inside 14” rims are marginal at best , and pedal feel or security are just not there on small discs taken from a dart . I have that .
However 15 with larger discs it gets maybe equal . But frot to rear balance is not there and long pedal travel
I have two F with 17 “ wheels and larger discs . I often question why I did the disc part , but the 17” wheels and michelin on them are an unquestioned step up.
Part of braking , if not most of it is tires . As is handling .
Depends what you want , right?
Another aspect is incestuous validation ; someone who worked hard to put discs on is seldom going to admit it’s a poor or marginal result
A full wilwood big system is no doubt superior , including booster etc , but why ?
Big red that 62 went 150 with stock brakes . Built by smart people
jg

On Jul 10, 2024, at 3:21 AM, Henry Schleimer <henry.schleimer@xxxxxxxxxxxxxxx> wrote:

I have previously asked for proof (even one brake test) that fitting 11” discs instead of 12” drums is a measurable improvement. All I’ve heard is crickets... I recall discussing this with Gil Cunningham years ago. For 1957, Chrysler actually designed a brilliant braking system for the era. Go look at the test videos on YouTube. While superior, it was not as mechanic friendly and was more costly than the Bendix system that replaced it. And 60 years later, you can’t go to your Chrysler dealer to buy parts. I get it.

But even mechanics such as Uncle Tony realise that engineers aren’t stupid. They design for more than a single stop on dry pavement. See https://www.youtube.com/watch?v=7q5jhIgGjoU

As an engineer I won’t be fitting half of a braking system designed for a car that was 800 pounds lighter and fitting a proportioning valve to the rear brakes to actually reduce its braking capacity to match the front, unless someone bothers to test it to show it works better. Please show me where even Willwood have test results for their expensive systems that can be scrutinised.

If you really, really wanted better brakes you might start by taking the complete braking system off a late model 300C. Oh no! Then you would have to use 20” wheels and low profile tyres and that wouldn’t be original would it...

Just my opinion. I can drive older cars within their limitations. Do what you like - but please test modifications properly and thoroughly. While you may never have to do a panic stop on a curving wet freeway with your whole family on-board, it was something that engineers had to consider, even 60 years ago.

Henry

From: chrysler-300-club-international@xxxxxxxxxxxxxxxx [mailto:chrysler-300-club-international@xxxxxxxxxxxxxxxx] On Behalf Of Gary
Sent: Wednesday, 10 July 2024 3:41 AM
To: '300 Club'; Ray Melton
Subject: Re: {Chrysler 300} HELP! Need front brake backing plate for 1957 300C

I would consider disc brake conversion, not allot of money. Gary

From: Ray Melton
Sent: Tuesday, July 09, 2024 5:02 AM
To: '300 Club'
Subject: {Chrysler 300} HELP! Need front brake backing plate for 1957 300C

Hello All -
Following an extensive restoration of virtually every system on my late father's 1957 Chrysler 300C convertible, I have endured five maddening years of the right front brake dragging, pulling, and sometimes even locking up hard enough to stop the wheel from turning! I've replaced wheel cylinders, shoes and return springs to no avail.   Last month the RF brake locked up hard enough to skid the tire at 5 mph in a parking lot, and I only could get it unlocked by backing up a few feet, but then it would either drag hard or lock up again as soon as I went forward.   I was lucky to nurse it a few miles back home, where I had to again skid the jammed RF wheel 20 feet into the garage.   I won't dare drive it again until I get it fixed for good! Everything looks OK when I pull off the drum (although the lining on the trailing shoe is worn down to 1/8" after less than 1000 miles on the restoration - that's how bad the RF brake has been dragging all this time!   With nothing obviously wrong, I just didn't know where to go from here.
Just today I came across a very old article from George Riehl that described my symptoms exactly and diagnosed that one of the long, square-section springs within the backing plate had broken, and the only fix is to get another complete centerplane backing plate - suggesting that one from a 1957 New Yorker or perhaps even a '57 Dodge or DeSoto would work (must specify for 12" brakes).   This is the link to that article:   FRONT BRAKE BACKING PLATES with 12" brakes (ch300imp.com)     That article includes photos of the backing plate I need.
My problem is that I don't know exactly the terminology for what I need and don't know the best places to start looking for such an old part. I can provide a photo of the backing plate I (think) I need, but can't post it with this message on the listserver.
Can anyone please help me clarify exactly what to ask for and perhaps even more importantly, who/where might be the best place to start looking?
Ray Melton Las Cruces, NM 1957 Chrysler 300C cvt      s/n 3N572517 (April 1957)     (575)642-3151
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