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48 Chrysler front disc brake conversion


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I'm in the process of seriously considering doing a disc brake conversion on my 48 Chrysler Windsor and I'd appreciate a little input please.  Now I know I'm setting myself up for some scolding here for not doing research and using the search engine.  At this point my questions are fairly specific and although I've checked about 8 pages of disc brake conversions on here through the search method I haven't come across any answers.  However I did see a post back in 2016 by 48NWYKR  which is a gold mine of info with great pics of my car.  I was interested in one picture under the hood and c49er noticed that it had an add on brake booster.  That really caught my interest because it's part of my inquiry.

 

I have found a shop that comes highly recommended in my area for doing disc brake conversions on vintage cars and hot rods.  However they have never done my car before so they suggested that I do all the leg work on lining up the components in order to keep the costs down.  I got a quote from Engineered Components INC. Who have been very helpful but here is my concern.  It;s becoming apparent that in order for me to do the conversion I won't be able to add a booster to the new dual cylinder MC. because there just isn't any room for the booster under the floor.  As it is I'm going to have to cut a larger hole in the floor to access the new MC.  Which I'm not crazy about doing since the car is almost original condition.  For that same reason I don't really want to go to the expense of relocating the MC to the firewall.  Up there I could accommodate a booster but I can see fabricating linkage abd a new brake pedal and mounting hardware could get expensive.  So one of my questions is just how difficult is applying foot pressure on the brake pedal to get a car of this weight to stop in a hurry without the assistance of a brake booster.  ECI have assured me that as long as the MC and the calipers are matched up it should be fine. 

I found it interesting as I read the post I mentioned earlier by 48NWYKR that c49er mentioned that he noticed an "add on booster" in a picture.  So were they a common thing back in the day?  I'm wondering if there might be one in a graveyard somewhere in North America?

 

My other concern is that the package that ECI put together for me won't allow me to use my stock wheels.  Apparently I need 13 1/4" dia. at the inside of the rim.  Mine only measure about 12 and a half inches. I have no idea what Chrysler product rims might have that measurement and I can't see myself going to an aftermarket rim.  I love my stock hubcaps and super wide beauty rings.  I contacted Charlie at rustyhope.com and he also said that as long as the calipers are matched to the MC that braking isn't too much of an issue.

 

If I can't do a disc brake conversion I'm thinking I should at least change the MC to a dual chamber one.  One is offered for my car and it seems the clutch and brake rods needs to be spread a little bit to allow for bracketry.   But apparently the existing holes in the floor are big enough to accept the change without making them bigger.  But first I would have to solve an existing problem with my brakes, which is primarily why I'm thinking about making the conversion.

 

Any thoughts and advice is greatly appreciated 

Cheers

Peter

 

 

 

 

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Peter,

I drove a '48 Chrysler Windsor for the first 8 years of our marriage (64 - 72) as my daily driver, with the stock brake system.

Never had any issues. As long as you drive sensibly, they will work fine.

 

If you are determined to switch to disks up front, you really should post in the Chrysler forum, and ask who has done this.

 

Mike in Colorado

Edited by FLYER15015
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Flyer is right, Chrysler brakes are the state of the art for the times and well up to normal traffic in a stock Chrysler IF they are in top shape and adjusted right. This is where most brake jobs fall down, the shoes must be arced to the drums and adjusted so they make full contact. Details in the factory service manual, it is a more involved job than the loose leaf brakes featured by cheaper cars of the times. If the brakes are working right there should be no need for discs.

 

If you insist, it is possible to use a remote booster in addition to the stock master cylinder. 1949 - early fifties Chryslers had such a remote booster as factory equipment. Today you can buy an aftermarket unit. It may be mounted under the floor as Chrysler did, or under the hood, or wherever you like. It is actuated by hydraulic pressure from the master cylinder and needs no mechanical connection.

Edited by Rusty_OToole (see edit history)
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21 minutes ago, FLYER15015 said:

Peter,

I drove a '48 Chrysler Windsor for the first 8 years of our marriage (64 - 68) as my daily driver, with the stock brake system.

Never had any issues. As long as you drive sensibly, the will work fine.

 

If you are determined to switch to disks up front, you really should post in the Chrysler forum, and ask who has done this.

 

Mike in Colorado

Thanks Mike. Perhaps you're right and I should post this in the Chrysler section.  For the most part the car stops fine.  However I do have a reoccurring issue of one of the wheels locking up completely for the first 3 or 4 applications of the brake pedal if it sits for a few days.  I've pulled both wheels and everything looks fine and clean.  No rust at all anywhere.  I've learned to overcome this by putting the car in reverse for a few feet then forward for a few feet and then applying the brake while I'm still in my parking spot.  Once it locks up it doesn't take too much to unlock it when put into reverse gear.  After doing it a few times in my parking spot everything is fine.  Much safer to do it this way then out on the street with traffic and pedestrians.  I'm also holding my breathe as I go down a steep hill knowing that with only one chamber in the master cylinder, if it fails I'm doubtful that the hand brake would do much to stop the car.  The other issue is back in the day people didn't have their head buried in a cell phone as they stepped off the curb.  Panic stops are becoming a common thing these days in an attempt to avoid dwindling off the population of people who don't seem to think that the impact of a car will effect their text messaging.  I think I would feel more comfortable with disc brakes in that situation even though I cringe at the thought of disturbing the ole girl's original function.

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31 minutes ago, Rusty_OToole said:

Flyer is right, Chrysler brakes are the state of the art for the times and well up to normal traffic in a stock Chrysler IF they are in top shape and adjusted right. This is where most brake jobs fall down, the shoes must be arced to the drums and adjusted so they make full contact. Details in the factory service manual, it is a more involved job than the loose leaf brakes featured by cheaper cars of the times. If the brakes are working right there should be no need for discs.

 

If you insist, it is possible to use a remote booster in addition to the stock master cylinder. 1949 - early fifties Chryslers had such a remote booster as factory equipment. Today you can buy an aftermarket unit. It may be mounted under the floor as Chrysler did, or under the hood, or wherever you like. It is actuated by hydraulic pressure from the master cylinder and needs no mechanical connection.

I was reading an old post from 2016 of a fellow in Vancouver that just bought a 48 New Yorker and was doing a disc conversion as well as a lot of other modifications to the car and then heading off to discover the world with his wife and two kids.  In that post he mentions that remote booster you just talked about, and there are a couple pictures of it.  I sent him a message and he got back to me a few hours ago.  But since he's traveling he doesn't always have internet service available.  I'm going to try and find out what components he used.  From a couple pictures I see he managed to get the booster under the floor. So I'm curious what he used.  The dual chamber MC he used is quite tiny too.  Anyways I'm hoping he'll find some time to fill me in on all his scraped knuckle experiences he encountered doing the conversion.  

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Peter,

Your one wheel "lock up" could be a weak return spring in the wheel cylinder, or the return spring on the shoes,

OR a weak spring in the master. Are any of these new ? Have you looked inside any of them? Have you changed brake fluid ?

I would check these first...........

 

Mike in Colorado

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13 minutes ago, FLYER15015 said:

Peter,

Your one wheel "lock up" could be a weak return spring in the wheel cylinder, or the return spring on the shoes,

OR a weak spring in the master. Are any of these new ? Have you looked inside any of them? Have you changed brake fluid ?

I would check these first...........

 

Mike in Colorado

I've only had the car since last summer.  When I bought it the guy said he had just done a complete brake job. Sure enough there are all new wheel cylinders on the car and a new master cylinder and all new brake lines including the short rubber ones to the front wheels.  Yes I did wonder about a weak brake shoe spring, but I have no way of knowing how to test it.  However as I mentioned once I free up the wheel the brakes work just fine.  I seem to think there is perhaps an alignment issue with the brake shoe and the forked piston going into one of the top wheel cylinder.  The reason I say that is when I was putting the wheel back on I slackened off the adjusters and the wheel still wouldn't slide over the shoes.  After a lot of head scratching and many attempts, I took the butt end of my ratchet and tapped on the metal part of the top of the brake shoe.  Not on the lining but just before it and it moved in about maybe 3/16" of an inch.  Then the wheel slide on fine over the shoes.  But to look at that area it looks fine.  If it was rusty, then I would be thinking the rust is not allowing it to return if it gets a chance to grip it after sitting for a few days.  I'm about to pull the shoes off and have a better look. I'm thinking I might take a file and round off the edges of that fork section of the piston rod so to say.  (sorry I can't remember the proper name) All those forked pistons look bright and I'm thinking that they were all replaced when the brake job was done.  Maybe there is a burr from the factory on one that is causing it to bind.  But once it gets moving it is just free enough to operate fine until it sits for awhile.  It's only a guess, but after seeing that shoe pop back in I'd say it's at least  a logical guess.  I sprayed brake cleaner on that area but I was reluctant to put any type of oil or grease, since it would probably find it's way to the linings once the wheel warmed up.

 

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A Dodge pick up of the 60s I was working on built up a ridge of sorts where the shoes rubbed the backing plate.

A little file work fixed that.

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Peter,

One more thing to check are the "anchor" points for the bottom of the shoes. Should be two big bolts going thru the backing plate.

These are adjustable and are used to "center" the shoes, usually with a feeler gage at 3 o'clock and 9 o'clock.

You might have one loose or not adjusted properly.

Just one more thing to drive you nuts..........

 

Mike in Colorado

 

PS; Page 20 of the '48 Chrysler shop manual tells you to use "Lubriplate" on the pins and shoe anchors and all sliding components inside the drum.

       You really should get a reprint or down load a shop manual. II learned my lesson from "Jolly John" years ago when I first got my '40 Buick.

Edited by FLYER15015 (see edit history)
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5 hours ago, FLYER15015 said:

Peter,

One more thing to check are the "anchor" points for the bottom of the shoes. Should be two big bolts going thru the backing plate.

These are adjustable and are used to "center" the shoes, usually with a feeler gage at 3 o'clock and 9 o'clock.

You might have one loose or not adjusted properly.

Just one more thing to drive you nuts..........

 

Mike in Colorado

 

PS; Page 20 of the '48 Chrysler shop manual tells you to use "Lubriplate" on the pins and shoe anchors and all sliding components inside the drum.

       You really should get a reprint or down load a shop manual. II learned my lesson from "Jolly John" years ago when I first got my '40 Buick.

 I do have a shop manual and I've read the procedure on adjusting the brakes several times.  However I don't have that miller MT-19 gauge tool and I've seen a homemade version where an arm is welded to a spindle nut and then another arm dropped from that first arm to the shoes to enable a measurement of 6-12 th. 

 

Thanks Mike for the page reminder of the reference to lubriplate.  Obviously I'll have to refresh my memory by reading it over again. 

 

Regarding the homemade version of that MT-19 Miller tool, I'm curious if the play in the threads of that nut might effect the accuracy of that measurement on the shoe with a feeler gauge.  If I had a machine lathe I could duplicate that miller tool fairly easily with a few hours work,,,,,  well perhaps more than a few hours ,,,,but I don't see paying a machine shop labour rate, to make that tool for the amount it would be used.  

 

When I google lubriplate I get a huge range of lubricants.   Is it considered Lithium Grease?  I've read that Lithium has a drip temperature of 370-430 degrees.  What would be the temperature inside the brake drum when the brakes are applied hard and extensively?  If I'm going to lubricate pivot points inside the drum I want to make sure I'm using the correct product.  If I walk up to the counter at a NAPA auto parts store and ask for lubriplate will I get the right stuff? Or will they tilt their head like a puppy dog hearing a strange sound?

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I have thought of drilling a small 1/8" hole in the brake drum and using a wire spark plug gauge as a feeler gauge to adjust the brake shoe. Some European cars came with such a hole for inspecting brake lining wear and checking adjustment.

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2 minutes ago, Rusty_OToole said:

I have thought of drilling a small 1/8" hole in the brake drum and using a wire spark plug gauge as a feeler gauge to adjust the brake shoe. Some European cars came with such a hole for inspecting brake lining wear and checking adjustment.

Yes I read that recently but how would one determine the correct place to drill that hole, and what measurements would one use?

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10 hours ago, JACK M said:

A Dodge pick up of the 60s I was working on built up a ridge of sorts where the shoes rubbed the backing plate.

A little file work fixed that.

Interesting hummm.....

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5 minutes ago, timecapsule said:

Yes I read that recently but how would one determine the correct place to drill that hole, and what measurements would one use?

In rethinking my question I suppose you would take measurements of where the centre of the shoe was in respect to a point in the backing plate and then but the drum back on and then transfer that measurement to the outside of the drum.  According to the manual that clip that's connected to the adjusting cam can adjust the tilt of the shoe ( I don't have the manual in front of me so I'm not remembering the correct terminology obviously)   I'm assuming the closer you drilled that hole to the centre of the shoe lining the more accurate the measurements would be I suppose. 

Once again I'd have to refresh my memory on the gap measurements and what they are at specific points on the shoe.  

I generally have to refresh my memory every time I unlock the door.  Is it to the right or to the left that I turn the key ???  50 % of the time I get it wrong.  Just something I have to get accustomed to as the decades slip by I suppose.  At least I can still remember which way to turn the key in the ignition :) 

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Na Na nanana.

My '31 Chrysler has a hole cast in the drum big enough to insert a full sized feeler gage.

Supposed to have a tin cover, but it is long gone.

Clearances are .010 at the bottom edge of the shoe lining, and .015 at the top edge of the lining to the drum.

Adjustment is made with the lower anchor bolts that are basically a cam bolt.

But I only have 1 wheel cylinder at the top, front and rear.

 

Mike in Colorado

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4 minutes ago, FLYER15015 said:

Na Na nanana.

My '31 Chrysler has a hole cast in the drum big enough to insert a full sized feeler gage.

Supposed to have a tin cover, but it is long gone.

Clearances are .010 at the bottom edge of the shoe lining, and .015 at the top edge of the lining to the drum.

Adjustment is made with the lower anchor bolts that are basically a cam bolt.

But I only have 1 wheel cylinder at the top, front and rear.

 

Mike in Colorado

Are there any pictures or illustrations of this method on line anywhere?

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Peter,

The shoe centering method should be some where around page 20 in the mechanic's hand book.

Do you have one ? If not, you can download it or certainly buy a reprint for a reasonable amount on line.

A definite "must' for any old car................

 

Mike in Colorado

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You will never get a good firm high brake pedal unless the shoe lining arc matches the drum surface 95%.

This if the lining radius is smaller then that of the brake drum.

Thst's why brake shoes were arced to fit each drum for fast wear in and good pedal feel.

Unless this procedure is done when needed proper toe and heel clearances will be wrong or not attainable.

Yes I know those machines were outlawed back in the late 80's because of asbestos.

Today the cost of any old used ammco/Star brake lining arcer is through the roof because of how quickly they eliminate new brake job issues on lockheed style brakes. 

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1 hour ago, c49er said:

You will never get a good firm high brake pedal unless the shoe lining arc matches the drum surface 95%.

This if the lining radius is smaller then that of the brake drum

 

Yes, this.

I have used the sticky back sandpaper inside of the drum method on this problem.

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2 hours ago, JACK M said:

 

Yes, this.

I have used the sticky back sandpaper inside of the drum method on this problem.

 

Now that's cool!!!

Boy, you learn something every day on these "FABULOUS FORUMS".

Question, how do you power the front wheels ?

Oh, I know, you put the paper in all 4 and go for a drive.

You would really have to only pull a front and a rear to check your progress.

Guess I would want to try this on a lonely county road with no other traffic.

But I like the idea.

 

Mike in Colorado

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19 hours ago, timecapsule said:

Yes I read that recently but how would one determine the correct place to drill that hole, and what measurements would one use?

You are trying to measure the clearance between the brake shoe and the brake drum. So, you would need to drill a small hole in the side of the drum where it meets the friction surface. This would allow you to peek in at the shoe and insert a thin feeler gauge or wire gauge between the shoe and drum. By turning the drum you could measure anywhere in its diameter.  You might also want a hole in the backing plate to allow putting a small light bulb inside.

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8 hours ago, c49er said:

You will never get a good firm high brake pedal unless the shoe lining arc matches the drum surface 95%.

This if the lining radius is smaller then that of the brake drum.

Thst's why brake shoes were arced to fit each drum for fast wear in and good pedal feel.

Unless this procedure is done when needed proper toe and heel clearances will be wrong or not attainable.

Yes I know those machines were outlawed back in the late 80's because of asbestos.

Today the cost of any old used ammco/Star brake lining arcer is through the roof because of how quickly they eliminate new brake job issues on lockheed style brakes. 

I'm also working on a 47 Chrysler Royal.  It has 11 inch drums just like my car.  There was a doner car at some point for this car so there are lots of spare parts.  In a box I came across a set of brand new  brake linings. They are the rivot on type. They measure the same as what's on my car.  2" x 11 1/4"  How would I determine what material they are? Is it possible to bond these linings to my shoes, if I should need them?  The next time I pull my drum off I can lay them in to see how the shape compares to the drum. 

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6 hours ago, JACK M said:

 

Yes, this.

I have used the sticky back sandpaper inside of the drum method on this problem.

So what grit paper would you have used?  I would think if you lift the wheel off the ground and get a buddy to sit in the car and apply the brakes a few times while you spin the wheel.  It wouldn't take too long to get a good wear pattern to appear on the lining.   It might be a bit labour intense since you'd have to keep pulling the wheel off to check and then remove the sandpaper just as the entire lining is showing abrasion from the sandpaper.  But it theory it would work I suppose. I'm just curious how many spins of the wheel it might take. 

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Take the drum off, get some 80 grit or so and then sand the shoes manually.

If you lay the shoe in the drum you will get an idea of just how much to take and where.

Driving with the sand paper never entered my mind but might work.

 

Edited by JACK M (see edit history)
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