Asking for a little tech help understanding 1961 Chrysler power brakes.

[Treozen]

Hello folks -

I've bought my '61 Newport, haven't even received it yet, and I'm already evaluating a few modifications. First on my list is usually brakes, and I'm fine keeping the drums provided they are working correctly, or can be made to do so, and that their performance is good. I've had some cars where even after new everything and perfect set-up, the drum brakes were frankly marginal here in hilly Washington. That said, regardless of what's at the wheel, I like the idea of a a dual reservoir master cylinder.

Now, my experience with Chrysler is somewhere between zero and zero. So as I was looking at pictures of the brake system, I'm really scratching my head. I'm used to a master cylinder that's bolted TO the booster, the booster providing the added oomph directly to the mastery cylinder when you press the pedal - but that's clearly not happening here with the Newport. I see no direct connection from the booster to the tiny master cylinder, AND I've even found that in many cases the master cylinder is the same part number, whether a power or manual system. So ....I'm not in Kansas anymore, clearly. It also doesn't appear to be a remote system either, like you'd find on a 60's Jaguar.

The only thing I can figure, is that the booster is acting on the brake pedal itself. So rather than give you assist acting on the master cylinder itself (like in a Chevy) the Chrysler system is somehow acting on the brake pedal - almost as though the booster is installed the other way around, vs a Chevy, and so its providing assistance by pushing the pedal linkage, which in turn acts on the master cylinder. Am I close here? or....I don't know....witchcraft?

IF I am right, this also presents two questions:

A) If I were to upgrade to a dual master cylinder, it shouldn't impact the booster at all, as they are effectively independent of each other - unlike a Chevy where you need to match mountings, pushrods, and the like.....right? All I'd need to do is hopefully find a dual master that matches the mounting pattern, linkages and lines....and hey-presto, dual master.

B) If I were to convert to discs - which is something I've done several times - some successes, others not so much (I actually co-authored a pretty definitive install guide for bullet-bird Thunderbirds) I would only need to worry about the wheel-end of things, because I could use the existing power assist booster and master - all be it switched to a dual master, and probably an in-line residual pressure valve for the rear - right?

Thanks,
Allan.

 

[Just Carbs]

The whole 11.75-disc/caliper/spindle setup from a 78 Cordoba works good on my 64. I think it works on the 61 as well. Do check that before jumping in the water.

Other related stuff.

I used the dual master from a 67 drum car because it was on the car from when I was still using drum brakes. The old original 64 booster for the drums works well with the disc. I'm guessing the 67 booster/master stuff don't work on the 61.
The drums worked well after I had them turned right out of the box, had to, they needed it. The 64 is very sensitive to that.

Anyway, the point is.
The drums on the 64 work well if they are in tip top shape. Maybe the 61 will also?
A stock Mopar booster and master of whatever year fits "might" drive the Cordoba disc very well.
And the 78 Cordoba 11.75 disc and calipers work great on the 64. Excellent in fact.

As for what Mopar booster/master fits on the 61, well, good luck with that.

You know, Chevy people say that the parts for Mopar cost twice as much as chevy, but never say a word about the chevy costing three times as much as the Mopar just to get in the driveway.

 

[Big_John]

A couple things to download that will help put the pieces together.

Get a service manual (FSM) and parts manual from MyMopar Get the '60/61 manual and also grab the supplements for the 300 F and G.

While you're there, look at the "Master Tech Service" library. Those are training resources that the dealers used. Look at 1960 and 1961 model years, maybe even the 1962.

 

[CBODY67]

Well, you mentioned nothing about the "Total Contact" dual wheel cylinder brakes.

You might find some factory information and links to a network of Chrysler 300 Letter Car people at www.jholst.net . Perhaps there is an illustrated expanded view of the master cyl and booster in the brakes section of the related parts book. Might give you a more direct answer to some questions.

I fully understand and appreciate your "Chevy" references, but in this case, "Chevy" could be exchanged for "65 Chrysler" as they went to the more modern booster behind the master cylinder orientation of things. That was the year Chrysler finally evolved out of the later 1950s designs of many vehicle operating systems. With a few being fully updated by the 1966 models. BTAIM

For an idea of the on-road braking performance, check out the YouTube video "On the Test Track with the 1957 Chryslers".

If the booster works on the brake pedal linkage, rather than directly to the master cyl, that sounds like the non-integral, linkage assist power steering units which GM used on Corvettes for many years, plus many pickup trucks. Not to forget Ford products (and their dangling power steering hoses).

Just some thoughts,
CBODY67

 

[Treozen]

Well, I've since found this - though granted this is supposed to be mid-50's Dodge, seems to me the parts are in the same general places, so, I could imagine this is how it works on the '61 Chrysler.

I'll also download the manuals.

 

[Sixpactogo]

I don't have any good leadership for you but my 60 Dart had the same brake setup as your 61 Newport with the dual cylinder front brake system and the bellows booster. I fought with those brakes for a few years trying to get them to play nice but had no luck getting them adjusted to my satisfaction. Tried new cylinders and a couple different brands of shoes with zero improvement. There was no rhyme or reason with them. If you had to stop fast, you had no inkling as to which side would lock up first. The car was either going to dive to the right or left and it seemed to take turns so I ripped the front drums off and replace them with a set of discs from a 1980 Aspen. I knew the single bowl master had to go but I could not find a disc master cylinder that would fit under my booster so I had one machined down about a quarter inch. I lost some fluid volume because of it but it works 10 times better than what I had. That system has been on my car now for 20+ years with no problem except the bellows booster really doesn't have enough boost to lock the wheels up. Although, I can't lock the brakes, it is more like the newer cars with ABS and IMO much better than the white knuckle driving I used to experience. If I were you and could live with those drums, I would leave em alone but I would definitely upgrade to a dual master cylinder. Even machined down to fit under the booster, you would have more fluid and a better chance of not losing your brakes totally than you have now. What ever Master you use, make sure you adjust the push rod to match. If I remember correctly, I had to adjust mine out about 1/4". Here are a couple pics of my set-up.
PS: After looking at your last post, I remember I got rid of that pressure switch for the brake light and installed a switch on the brake pedal from a newer car.

 

[CBODY67]

Suspecting the aluminum-body master cylinder liks is on my '80 Newport might work too? It's a bit smaller in cross-section.

CBODY67

 

[Treozen]

I knew the single bowl master had to go but I could not find a disc master cylinder that would fit under my booster so I had one machined down about a quarter inch. I lost some fluid volume because of it but it works 10 times better than what I had. That system has been on my car now for 20+ years with no problem except the bellows booster really doesn't have enough boost to lock the wheels up. Although, I can't lock the brakes, it is more like the newer cars with ABS and IMO much better than the white knuckle driving I used to experience.

That a very clean-looking set up for sure. I never thought about machining down the master - thats a good idea. Do you have any idea what over height you ended up with? Could help finding a flatter master cylinder.

 

[Treozen]

Suspecting the aluminum-body master cylinder liks is on my '80 Newport might work too? It's a bit smaller in cross-section.

CBODY67

Hmm, I'll look at that too. I mean.... I don't even have the car here yet.....but....I like to think ahead ;-)

 

[Sixpactogo]

That a very clean-looking set up for sure. I never thought about machining down the master - thats a good idea. Do you have any idea what over height you ended up with? Could help finding a flatter master cylinder.

The bowl height is about 3". The lid and bail adds another inch. That is where the problem arises. If you had a flat lid without the bail you could probably get by without cutting it down. Plenty of ways to skin that particular cat but I used what I had. Like I said, no good leadership for you.

 

[Treozen]

The bowl height is about 3". The lid and bail adds another inch. That is where the problem arises. If you had a flat lid without the bail you could probably get by without cutting it down.

OK, thanks. I actually found a few MOPAR-mount masters that look as though they might be shorter, and a few with the flat lid that secures with a nut. I've not looked at these in terms of bore or fluid volume, or in fact if they are the right mount for a '61 - I'm just eye-balling it and browsing on "height" at the moment, lol.

 

[Sixpactogo]

Looks like either of those might work. For sure better than the single pot unit. They look like drum brake cylinders but I see they mention both applications.

 

[Treozen]

Looks like either of those might work. For sure better than the single pot unit. They look like drum brake cylinders but I see they mention both applications.

Yeah - I suspect this is one of those situations where they have no idea what they are talking about. There are situations where you can use a disc master for drums, but its rarely the other way around, and these masters don't look like they have a fluid capacity - maybe. Beyond capacity though, sometimes drum masters have residual pressure valves, and you wouldn't want that in the disc circuit. More investigation is needed.

 

[Just Carbs]

Yeah - I suspect this is one of those situations where they have no idea what they are talking about. There are situations where you can use a disc master for drums, but its rarely the other way around, and these masters don't look like they have a fluid capacity - maybe. Beyond capacity though, sometimes drum masters have residual pressure valves, and you wouldn't want that in the disc circuit. More investigation is needed.

I remover the valves on the 67 drum master to work with the 78 Cordoba disc and calipers.
The plan was to replace it with the 67 disc master, but it's working fine for now. I may never change it.
The Cordoba caliper is 3 inch, I think.