Which size drums on 69 Dart? And some other brake questions.

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cb474

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I have a 1969 Dart with a 225 slant six (I think it's the 225, it's stamped 28068302 on the block).

I need to replace the cylinders in the rear drums, which are both leaking. It seems like in oder to get the correct cylinder, I need to know what size drums I have. My Haynes manual says that with the automatic transmission, my car should have 9 inch drums, front and back. Is that correct?

I just don't want to order the wrong cylinders. It also looks like I need to know the drum size to get new brake hoses for the rear.

Also, is it possible to get the cylinders out, without completely removing the shoes? I've seen some YouTube videos where people do this on newer cars, just by removing one spring. It looks pretty similar to the Dart drum parts.

All that aside, any tips and tricks people have on replacing the cylinders woud be appreciated as well. Thanks.
 
you have a 55 year old car. Thinking that the drums have never been upgraded to 10 inch brakes (an easy upgrade to make) is a fools errand. Pull a drum and measure the inside diameter of the drum...
 
Yup- it SHOULD be 9 inch, but could have been ordered with HD brakes... you've got it apart, just measure the inside diameter. It won't be exactly 9 or 10 inches, but you'll be close enough to know.
There is only one hose going to the rear- the rest is all hard lines.
You could replace the cylinders without removing the shoes, but why? You should probably replace the shoes too, especially since the cylinders were leaking. Brake fluid does not play well with the friction material of the shoes...
 
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str12-340 said:
you have a 55 year old car. Thinking that the drums have never been upgraded to 10 inch brakes (an easy upgrade to make) is a fools errand. Pull a drum and measure the inside diameter of the drum...
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My mother is the original owner of the car, so I amazingly do actually know that the drums were never upgraded. But yeah, I guess I should measure them.


Professor Fate said:
Yup- it SHOULD be 9 inch, but could have been ordered with HD brakes... you've got it apart, just measure the inside diameter. It won't be exactly 9 or 10 inches, but you'll be close enough to know.
There is only one hose going to the rear- the rest is all hard lines.
You could replace the cylinders without removing the shoes, but why? You should probably replace the shoes too, especially since the cylinders were leaking. Brake fluid does not play well with the friction material of the shoes...
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Yeah, I put the wheels back on so I could put the car back in the garage overnight. I don't know why I didn't think to measure them before that. I think I was frustrated after spending five hours getting one drum off (long story).

The brakes were done not that many miles (a few thousand), but many many many years ago. So the shoes are in pretty good shape. It didn't really look like brake fluid was getting on them. But maybe I shouldn't be lazy about it. :)

Thanks for the replies!
 
let us know what they turn out to be. Should be 9 inch from your explanation, but with Mopar I've learned never to say never...
 
cb474 said:
The brakes were done not that many miles (a few thousand), but many many many years ago. So the shoes are in pretty good shape. It didn't really look like brake fluid was getting on them. But maybe I shouldn't be lazy about it.
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Yeah, don't be lazy- these are your brakes after all. Another $20 to make sure two tons of steel will actually stop is a good investment in my book.
 
I agree just measure the inside of the drum. It could also have a casting size on it that states max size for truing. If it starts with "9. something it's a 9" and it it starts with "10. something it's a 10" . Good luck you can do it
 
Professor Fate said:
Yeah, don't be lazy- these are your brakes after all. Another $20 to make sure two tons of steel will actually stop is a good investment in my book.
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I was just checking the repair receipts and the rear shoes and drums were replaced 4000 miles ago (that was 2011). If I replace the shoes 1) should I do all the other hardware, like springs, adjuster, etc.? 2) Do I need to turn the drums after so little miles?

At the times, in 2011, everything was replaced on the front, including the cylinders. I noticed the mechanic said the flexible brake tubes on the front (I guess that means between the cylinder and the hoses) were cracked and replaced. If I don't see any leaking or cracks on the flexible tubes on the rear is there any reason to replace them?

Also, any brands for the brake cylinders that are considered good quality?
 
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adjusters - no, but the springs have been under tension for 14 years and fatigue over time. I would particularly replace the front hoses, I presume that you are using old style brake fluid. Hoses can look fine and delaminate inside the hose and cause all sorts of grief. If you are going to replace the front wheel cylinders, you are going to have to take them loose anyway, so I'd replace them.
 
Here is where during your frustration you should take and post some pictures. They're ALWAYS worth at least 1,000 words.
 
cb474 said:
I was just checking the repair receipts and the rear shoes and drums were replaced 4000 miles ago (that was 2011). If I replace the shoes 1) should I do all the other hardware, like springs, adjuster, etc.? 2) Do I need to turn the drums after so little miles?

At the times, in 2011, everything was replaced on the front, including the cylinders. I noticed the mechanic said the flexible brake tubes on the front (I guess that means between the cylinder and the hoses) were cracked and replaced. If I don't see any leaking or cracks on the flexible tubes on the rear is there any reason to replace them?

Also, any brands for the brake cylinders that are considered good quality?
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Unless the drums are grooved, warped, or worn funny, I'd just reuse them the way they are. No point intaking metal off them if it isn't needed. The rear will just have one hose, from the center of the body to the top of the rear axle housing. I'd replace that if it's original. The hard lines are anyone's guess at this point. If they aren't nasty/rusty looking, and fluid passes through them ok, I'd reuse them as long as the flare nuts are still in good shape. If you replace them, I'd get regular steel lines unless you're in a bad rust area, then I would probably go stainless. If you can find any NOS American made cylinders, I'd go that way. First, I would hone out the originals to see if just a kit would do the trick.
 
str12-340 said:
adjusters - no, but the springs have been under tension for 14 years and fatigue over time. I would particularly replace the front hoses, I presume that you are using old style brake fluid. Hoses can look fine and delaminate inside the hose and cause all sorts of grief. If you are going to replace the front wheel cylinders, you are going to have to take them loose anyway, so I'd replace them.
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Thanks for the suggestions. Yes, I'm using Dot 3 fluid. Looking again at the maintenance records, it looks like the front hoses were replaced in 2011 (4000 miles ago). You think I should replace those based on time alone? The car is in a very mild environment and always garaged. The rear hose I don't know when that was replaced. For whatever reason the mechanic in 2011 did not think it needed to be replaced then (he specialized in pre-1975 cars). My mother does have the maintence records back to 1969, so I guess I could go through them.


cudamark said:
Unless the drums are grooved, warped, or worn funny, I'd just reuse them the way they are. No point intaking metal off them if it isn't needed. The rear will just have one hose, from the center of the body to the top of the rear axle housing. I'd replace that if it's original. The hard lines are anyone's guess at this point. If they aren't nasty/rusty looking, and fluid passes through them ok, I'd reuse them as long as the flare nuts are still in good shape. If you replace them, I'd get regular steel lines unless you're in a bad rust area, then I would probably go stainless. If you can find any NOS American made cylinders, I'd go that way. First, I would hone out the originals to see if just a kit would do the trick.
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Thanks for the thoughts. I'll look around for NOS cylinders.
 
Well, I've temporarily put on hold replacing the wheel cylinders, because I injured my ribs twisting around and lying on the concrete garage floor, during my five hour struggle to remove the rear left drum. I'm not exactly young anymore.

But in the meantime, what is the signficance of the color of the brake fluid in the rear bowl on the master cylinder (see photo)? The front bowl is clear, because I was adding fluid due to the rear cylinders leaking. But I bled all the lines a year ago and now the rear bowl is this dark amber color. Is that just due to moisture? Is that surprising after only a year? Or is it due to rust somewhere? Or something else?

brake.fluid.jpeg
 
Now's the time! you don't want to bleed the brakes multiple times. Do the whole front system - wheel cylinders, hoses, springs under tension. You should at least consider the Master cylinder since there has been contaminated fluid sitting in it for so long. I'd do at least the front lines - heck do all the lines. This is the one system in the car that you really can't afford to have fail.
 
I was looking at the master cylinders. Apparently the 69 Dart had a master cylinder with a 1" bore.

I find the Dr. Diff aluminum master cylinderes appealing. But they only come with either the 15/16" or the 1 1/32" bore. How different would those be from the correct 1" bore?

To be honest, I don't know what the current master cylinder is. From images online it looks like a lot of them, including the Raybestos one that does have a 1" bore. I do remember when this master cylinder was put on there in 2011 being surprised how hard the brake pedal was and that the brakes in the car were never like that before.

The other alternative seems like one of the reproduction Bendix sytle master cylinders with a 1" bore. Or just another Raybestos type one. Not sure which way to go.
 
As a general rule, the smaller the bore, the less effort it takes to apply the brakes. The pedal movement is usually a bit longer though too, and slightly less firm.
 
I would inspect the wheel cylinders you have. If they are not pitted badly, just run a wheel cylinder hone through them and put new wheel cylinder kits in them.
 
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