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 Post subject: Standing on the brakes
PostPosted: Tue Jul 11, 2017 2:01 am 
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3 Deuce Webber

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For some reason, I am having to push pretty hard on the pedal to stop my 65 Valiant.

Many years ago I swapped out the stock single master cylinder in favor of a dual and, for many years it worked just fine. Last year brake fluid began to magically disappear from it and, around the same time, braking became hard. I had to keep topping it off, yet there were no leaks from the wheel cylinders. I didn't know where the fluid was disappearing to, but I knew I had a problem somewhere, so I ordered a replacement MC (RAYBESTOS MC-36426).

When I removed the old MC, I determined that it was leaking from the push rod hole, which is why I was not seeing fluid anywhere on the wheels. It all made sense. I swapped out the new MC with the hopes that everything would be OK.

Of course this cured the leak, but the difficulty braking has not gone away. I sometimes feel like I need to step on the pedal with both feet and that would still not be as good as the stock single MC that I have on my other Valiant, a 63 that I never converted.

There is no pulling to one side or anything like that. It just seems like I could use an assist from Bigfoot to duplicate the stopping power of the bone stock single MC on my other car. What gives?

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1961, 1962, 1963 and 1965 Valiant 200. The `65 is a `vert.


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 Post subject:
PostPosted: Tue Jul 11, 2017 2:32 am 
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Supercharged

Joined: Thu May 12, 2005 11:50 pm
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Car Model*: 64 Plymouth Valiant
What's the bore of the different master cylinders?

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64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes
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 Post subject:
PostPosted: Tue Jul 11, 2017 5:36 am 
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Did you replace any of the brake shoes/pads before it started getting hard to stop?

Lou

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 Post subject:
PostPosted: Tue Jul 11, 2017 6:10 am 
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How old are the hoses?


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 Post subject:
PostPosted: Wed Jul 12, 2017 8:20 am 
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Supercharged
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You probably have a stuck wheel cylinder or cylinders. Worn linings will also cause poor stopping performance as well.

Loosing fluid:

Could be linings are worn, not adjusted up, causing fluid level in master cylinder to drop. Sometimes a master cylinder that has failed will loose fluid through back of cylinder where it makes it's way under cabin's carpet unnoticed.

I would pull all drums, calipers if equipped, look at cabin end of master cylinder, and inspect everything. Peal back the rubber at wheel cylinders, and look for crud, corrosion, signs of leaks, replace as need, replace any worn shoes or pads. Pads worn unevenly indicate one or more stuck pistons if you have KH four piston calipers, shoes showing uneven wear between primary and secondary indicate stuck wheel cylinder.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

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 Post subject:
PostPosted: Thu Jul 13, 2017 11:26 am 
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3 Deuce Webber

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Dart270 wrote:
Did you replace any of the brake shoes/pads before it started getting hard to stop?

Lou


Not that I recall. This now qualifies as an ongoing problem.

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1961, 1962, 1963 and 1965 Valiant 200. The `65 is a `vert.


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 Post subject:
PostPosted: Thu Jul 13, 2017 11:28 am 
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3 Deuce Webber

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Dart270 wrote:
Did you replace any of the brake shoes/pads before it started getting hard to stop?

Lou


How can I determine that? The current MC is a Raybestos MC-36426 for an early 70's A body.

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1961, 1962, 1963 and 1965 Valiant 200. The `65 is a `vert.


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 Post subject:
PostPosted: Thu Jul 13, 2017 11:31 am 
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3 Deuce Webber

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sandy in BC wrote:
How old are the hoses?


A few years old, but not old enough to be brittle. The car is stored in a closed building.

Could they somehow be the cause of hard braking? I thought about the possibility that there might be some accumulation of rust and gunk in the distribution block or the metal lines. Has anyone had any experience with that?

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1961, 1962, 1963 and 1965 Valiant 200. The `65 is a `vert.


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 Post subject:
PostPosted: Thu Jul 13, 2017 11:45 am 
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3 Deuce Webber

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wjajr wrote:
You probably have a stuck wheel cylinder or cylinders. Worn linings will also cause poor stopping performance as well.


Good suggestion, but if that were the case, wouldn't I also have pulling to one side, or a wheel locking when I brake hard? The problem I have is weak, but evenly distributed poor braking.

wjajr wrote:
Loosing fluid:

Could be linings are worn, not adjusted up, causing fluid level in master cylinder to drop. Sometimes a master cylinder that has failed will loose fluid through back of cylinder where it makes it's way under cabin's carpet unnoticed.


What I discovered when I replaced the MC was that the old one had been leaking from the push rod hole.

wjajr wrote:
I would pull all drums, calipers if equipped, look at cabin end of master cylinder, and inspect everything. Peal back the rubber at wheel cylinders, and look for crud, corrosion, signs of leaks, replace as need, replace any worn shoes or pads. Pads worn unevenly indicate one or more stuck pistons if you have KH four piston calipers, shoes showing uneven wear between primary and secondary indicate stuck wheel cylinder.


Other than the MC and the distribution block, the brakes are stock 65 Valiant, 9" drums. I have inspected the wheel cylinders and have found no leaks. I adjust the brakes manually as needed. I am constantly fiddling with the brakes on this car, trying to squeeze as much stopping power as I can from it.

The brakes have never been great, but they have grown markedly worse in the past couple of years, since I began to notice the fluid disappearing. When that began, I checked all of the wheel cylinders. I have looked for leaking at the wheels and have taken it out for a few hard stops to try and determine if there are any weak points. It seems that the stopping is evenly distributed, but not as sure as it should be. The stopping power of the system in my 65 pales in comparison to the bone stock system that I have on the 63.

I thought that when I replaced the leaking MC, the problem would be cured, but that proved not to be the case.

Thank you all for your suggestions thus far. I hope that we can eventually solve this mystery and I can once again fully enjoy my favorite ride.

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1961, 1962, 1963 and 1965 Valiant 200. The `65 is a `vert.


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 Post subject:
PostPosted: Thu Jul 13, 2017 4:16 pm 
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Supercharged
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Many replacement brake shoes are too hard and require excessive pedal prrssure, especially those sold as heavy duty or lifetime warranty.

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Joshua Skinner, formerly SrA US Air Force


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 Post subject:
PostPosted: Fri Jul 14, 2017 11:38 am 
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Raybestos MC36426 is a 1-1/32" bore. This is slightly larger than the stock single MC (1"), but it shouldn't reduce your hydraulic advantage that much. I've done this exact conversion on more than one 4-wheel drum car. I don't think that's your issue unless your car came with power brakes and you're still using the power brake pedal with a manual master.

I would echo the others in that there may be something wrong with your shoes, like too hard a friction surface or glazed over or something.

That being said, are you sure that all four brakes are actuating? Can you lock up any of the wheels when you stand on the pedal? If you got some crud in one of the hard lines going to just the front or just the back, that could knock out two wheels without causing you to pull one way or the other. You could put the car on jackstands and try to turn each wheel while someone else pushes the pedal, just to verify.

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Somehow I ended up owning three 1964 slant six A-bodies. I race one of them.
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 Post subject:
PostPosted: Fri Jul 14, 2017 10:59 pm 
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3 Deuce Webber

Joined: Tue Apr 05, 2011 11:34 am
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I have had it up on the stands and checked and the brakes all actuate. They just don't seem to grab very well when on the road. I will have to look at the shoes again. That is the simplest thing to check and it is quite possible that there could be a glazing issue here. Since that is the majority vote, I will try that. I will post my results whenever I get to it, which will hopefully be soon.

While I have you all, do you have a suggestion for a particular brand of shoe?

The brakes on this thing are a nightmare. I have a brand new set of drums that I would like to put on the front. At the moment, I have a left hand thread drum on the right side because that is all I had available when I discovered a warped drum a while back. Used to be when you bought a replacement front drum it came with the hub, but now you have to reuse your old ones and I don't have the tool to cut the studs off, so that project has stalled.

Nothing but problems. It is a good thing I love these cars or I would never have the patience to keep them going.

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1961, 1962, 1963 and 1965 Valiant 200. The `65 is a `vert.


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 Post subject:
PostPosted: Sat Jul 15, 2017 9:31 am 
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Turbo Slant 6
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Location: Houston, TX
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If you need the swedge-cutting tool, Charlie posted a link to the company that sells them a little while back:

http://slantsix.org/forum/viewtopic.php?t=61171

I haven't bought brake shoes in a while, but I think I put regular Raybestos organic shoes on the rear brakes of my racecar, and they still have plenty of material 3 years and ~10 endurance races later. With big front discs they probably don't do a whole lot of the work, though. You probably want to avoid anything ceramic.

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Somehow I ended up owning three 1964 slant six A-bodies. I race one of them.
Escape Velocity Racing


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 Post subject:
PostPosted: Sat Jul 15, 2017 11:19 am 
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Supercharged
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Location: Downeast Maine
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Quote:
wjajr wrote:
You probably have a stuck wheel cylinder or cylinders. Worn linings will also cause poor stopping performance as well.


Good suggestion, but if that were the case, wouldn't I also have pulling to one side, or a wheel locking when I brake hard? The problem I have is weak, but evenly distributed poor braking.


Not necessarily

Quote:
wjajr wrote:
Loosing fluid:

Could be linings are worn, not adjusted up, causing fluid level in master cylinder to drop. Sometimes a master cylinder that has failed will loose fluid through back of cylinder where it makes it's way under cabin's carpet unnoticed.


What I discovered when I replaced the MC was that the old one had been leaking from the push rod hole.


Yup, MC not able to generate full pressure due to blow-by resulting in long stopping stopping distances. This finding still doesn't negate the need to inspect all wheel cylinders. Once you find degraded a brake part suspect all others not to be up to snuff.


Quote:
Other than the MC and the distribution block, the brakes are stock 65 Valiant, 9" drums. I have inspected the wheel cylinders and have found no leaks. I adjust the brakes manually as needed. I am constantly fiddling with the brakes on this car, trying to squeeze as much stopping power as I can from it.


That is the reason we urge upgrading 9" brakes to front disks. Those 9" brakes never stopped well off the show room floor because they were under sized. Spring ahead 50+ years where probably 98% of today's new cars (& pu trucks) achieve stopping distances from 60 mph of 120' and less, and in some cases closer to 100'. In 1970 stopping a passenger car in 120 feet from 60 mph was considered to be very good, and unattainable by most cars on the road.

I had a 67 Dart in early seventies with 9" drums, they sucked than, but the traffic in those days all produced long stopping distances so it was a relative sucking; also required consent adjusting and were sensitive to moisture in the worst way.

Drums need to be perfectly round, and smooth within spec thickness or stopping distances will be long. Friction material used on shoes also dictate stopping distances. Shoes contaminated from brake fluid, oil, wheel barring grease, or dirty hands during installation kill stopping distances, and or promote premature lock-up on humid days.

Josh's recommendation on shoes is right on.

_________________
67' Dart GT Convertible; the old Chrysler Corp.

82' LeBaron Convertible; the new Chrysler Corp

07' 300 C AWD; Now by Fiat, the old new Chrysler LLC



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 Post subject:
PostPosted: Sun Jul 16, 2017 2:53 pm 
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3 Deuce Webber

Joined: Tue Apr 05, 2011 11:34 am
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Quote:
That is the reason we urge upgrading 9" brakes to front disks.


Yes, I agree and, in theory, it makes a lot of sense. In fact, I made that upgrade with the 62 Valiant. Discs off a 74 A-body. That changed my bolt circle to 4 1/2", which caused a mismatch with the stock 4" bolt circle rear end.

Upgrade rear ends with 4 1/2" bolt circles are hard to find and impossible to find cheap. I live in Mississippi, where these cars were never very popular. I've heard from locals that the Chrysler dealer had a bad reputation back then and, possibly as a result of that, EVERYONE here loves Fords and Chevies. You can get Mustang parts all day long, but a Valiant? I have to explain what it is to most parts guys.

Anyway, any rear end I might find would have to come from some other state, incurring horrible shipping fees for a rear end I would have to buy on blind faith. So scratch that.

Because of the mismatch, I had to find some wheels that I could visually match up in spite of this. Stock steel wheels from a post 73 car seemed to be the answer. So I began to search. Turned out all of them had been crushed long ago. After searching for months, I found a set in a junk yard in Indiana. They weren't that expensive, but the shipping was a killer.

Of course, they were used wheels, so I had to blast and paint them before I could have tires mounted.

So now I have to carry two spares in that car. Such fun.

My hat is off to those who have changed their brakes. Maybe you live someplace where more parts are available. Maybe you put some $$! aftermarket kit on it. But here in parts starved Mississippi, there is **NO WAY** I am ever doing that again.

I have a front end with 10" drums around, and I have considered putting those on, but I have read in these pages where that is a waste of time.

_________________
1961, 1962, 1963 and 1965 Valiant 200. The `65 is a `vert.


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