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Discussion Starter #1
Hey guys,

If given the opportunity to upgrade the rear drums on a 65 street/track mustang, which would be the better choice of the two?
11 X 2 1/4 finned or 10 X 2 1/2 non-finned drum setup?
Thanks for any your comments.
 

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Well, the 1" larger diameter of the 11" drums gives a 10% advantage in leverage. In terms of swapt area, they are almost identical.

Note that brake torque is in principle a function of brake diameter, friction coefficient of pads/shoes and the force with which the pads/shoes are applied to the disc/drum.

A larger swept area makes the brake more resistant to heat (i.e. it takes more braking before it overheats) and heat has a large influence on the friction, so in that way, swept area certainly has an influence on braking performance.
 

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I've got 10"x2 1/2" drums on my race car. I asked many other vintage Mustang racers the same question that you're asking when I was building my car. There was no group consensus and the split between 10"x2 1/2" versus 11"x 2 1/4" was about 50/50. I will tell you that parts for the 11" set-up are probably easier to put your hands on.

If you're just building a street car that will see occasional track time, I doubt you would be able to tell a difference between either.
 

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Which of the two has a broader selection of shoe compounds? Matching the compounds with your front brakes and the amount of bias on the proportioning valve will dictate how much rear brake will be used and the heat they will generate. The 10" will likely have less rotating mass thereby stop better, however the 11" will cool better given the same amount of air around them. Since drum brakes will stop very well until heated past a point of where they start to fade, the question then becomes, who well you can cool them. Cobra Automotive sells a very nice rear brake cooling set up that clamps to the rear axle and ducts to the backing plate.
 

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You guys can get very scientific! It is great to have that knowledge around here.

In the future, I am planning a build for my '65 coupe that will consist of (hopefully) a 400+ horsepower 351W, 4 speed toploader, and a 9 inch rear from a '57 Ford. This would be a street car. Which drum setup would be best for this rear?
 

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I would go for the 10" set up. You would have less rotational weight and good sweep area. Then if you decide that you are heating them up to a point of fading you can add cooling ducts and have the best of both worlds.
 

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Discussion Starter #7
Hey Guys,

...once again, you've proven there is no shortage of knowledge and willingness to assist.

Thanks!
 

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Discussion Starter #10

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Discussion Starter #14
So what backing plate do you use for the 10X2.5" drums?

Hi

I purchased complete rear kits (10 X2.5) in the late 90s from a FORD dealership in NC. These were OEM for full size wagons at the time and were a popular upgrade.
Unless you are looking for Shelby specific OEM correct, there are any number of (10 X 2.5) complete bolt on kits available today for less than $500. There are two ways to go: 10 X 2.5 or 11 X 2"
The following have improved kits:
musclecarbrakes dot com, for one . I think Master Power has them too.

Hope this helps!

Ken
 

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Hi

I purchased complete rear kits (10 X2.5) in the late 90s from a FORD dealership in NC. These were OEM for full size wagons at the time and were a popular upgrade.
Unless you are looking for Shelby specific OEM correct, there are any number of (10 X 2.5) complete bolt on kits available today for less than $500. There are two ways to go: 10 X 2.5 or 11 X 2"
The following have improved kits:
musclecarbrakes dot com, for one . I think Master Power has them too.

Hope this helps!

Ken
Thanks! More curious then anything right now. I don't care if they are Shel who? correct. I read some place, don't hold me to it, just repeating, but the person said or wondered if the front backing plates would bolt to the rear, (small bearing) While my 66 still has drums on the front, I discovered that there is only 1 drum for either the SBF or BBF while the SBF uses a 2.25" shoe and the BBF uses a 2.5" shoe. I found out that the 2.5" shoes fits just fine on the stock 66 set up which is what is on my car. I'm wondering if the front backing plate would bolt to the rear axle and use the front finned drum as well. It would be interesting to find out. The only thing off hand I see would be to drill a hole in the front backing plates for the E brake cable. I have a spare 8" housing but no spare front backing plates to try. Hmmm, maybe I'll have to cruise ebay.
 

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I've got a set off an '82 LTD from Pick-A-Part on my '68. They're 10 x 2.5" and
use shoe #481. They'll fit 8 or 9" Mustang rear axle housings.
The Aerostar has something very similar and even uses the same shoe #
as on the 65 Shelby but there was something I didn't like about the brake
hardware.

The article is old and the photos are gone, but the info is still good.....
http://mustangsandmore.com/ubb/RearBrakesbySamGriffith.html
 

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Discussion Starter #17
Thanks! More curious then anything right now. I don't care if they are Shel who? correct. I read some place, don't hold me to it, just repeating, but the person said or wondered if the front backing plates would bolt to the rear, (small bearing) While my 66 still has drums on the front, I discovered that there is only 1 drum for either the SBF or BBF while the SBF uses a 2.25" shoe and the BBF uses a 2.5" shoe. I found out that the 2.5" shoes fits just fine on the stock 66 set up which is what is on my car. I'm wondering if the front backing plate would bolt to the rear axle and use the front finned drum as well. It would be interesting to find out. The only thing off hand I see would be to drill a hole in the front backing plates for the E brake cable. I have a spare 8" housing but no spare front backing plates to try. Hmmm, maybe I'll have to cruise ebay.
First I will state, I do! admire your ingenuity. I can't say that I gave that a thought,but, If you have the horse up on all blocks and can pull all of his shoes, then try it. The only thing that comes to mind is the wheel cylinders being of different sizes?
Go for it!
 

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7/8" rear wheel cylinders are common on Fords. The stock '68 was
7/8" and so was the LTD. So you don't have that issue. The parking
brake cables on the Mustang fit the same way on the LTD......
 

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Discussion Starter #19
I've got a set off an '82 LTD from Pick-A-Part on my '68. They're 10 x 2.5" and
use shoe #481. They'll fit 8 or 9" Mustang rear axle housings.
The Aerostar has something very similar and even uses the same shoe #
as on the 65 Shelby but there was something I didn't like about the brake
hardware.

The article is old and the photos are gone, but the info is still good.....
http://mustangsandmore.com/ubb/RearBrakesbySamGriffith.html

Hey Bud,
That's a nice article. Thanks for the link.
Ken
 
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