Author Topic: Converting to the Shelby 2 1/2" drums on early mustangs  (Read 3473 times)

mlplunkett

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Converting to the Shelby 2 1/2" drums on early mustangs
« on: January 24, 2022, 05:41:42 PM »
I found this article on converting the early mustang to the 2 1/2" Fairlane station wagon drums but it provides no part numbers and the drums used have cooling fins which isn't what I see when I look at photos of original Shelby cars. Is it correct that the standard mustang backing plates (even the ones used on 8" axles) work with the wider drums/shoes? Does anybody have a better How-To source for this seemingly simple upgrade including part numbers for what is needed?

https://www.motortrend.com/how-to/how-to-shelby-rear-brake-trick-on-early-mustangs/
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roddster

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Re: Converting to the Shelby 2 1/2" drums on early mustangs
« Reply #1 on: January 24, 2022, 06:47:14 PM »
  Those finned drums are probably from the Ford Windstar mini-van.  You'll get those finned ones should you buy the 10 X 2 1/2" drums at a famous Mustang supplier.
  Backing plates are different as the mounting depth for the wider shoes is different too.
« Last Edit: January 24, 2022, 06:51:35 PM by roddster »

Bob Gaines

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Re: Converting to the Shelby 2 1/2" drums on early mustangs
« Reply #2 on: January 24, 2022, 06:52:33 PM »
I found this article on converting the early mustang to the 2 1/2" Fairlane station wagon drums but it provides no part numbers and the drums used have cooling fins which isn't what I see when I look at photos of original Shelby cars. Is it correct that the standard mustang backing plates (even the ones used on 8" axles) work with the wider drums/shoes? Does anybody have a better How-To source for this seemingly simple upgrade including part numbers for what is needed?

https://www.motortrend.com/how-to/how-to-shelby-rear-brake-trick-on-early-mustangs/
Ford 2 1/2 backing plates were used with the 2 1/2 shoes . The factory looking 2 1/2 drums without the cooling fins are extremely hard to find in usable condition and that is for the mid 66 /67 type with the rectangle hole . The ones with the 3 raised nubs like 65 and early 66 are on a order of 1X harder then the others.  The open track crowd typically use the ones with the cooling fins . I think those are still sourced auto parts store items . Maybe use the ones with the cooling fins until you can find a set of usable vintage type. expect to pay 500.00+ for a usable pair of of the rectangle hole drums . The 3 nub type are much more expensive becuse they are even more rare. Cobra Automotive has a kit they sell that appears to have drums without the cooling fins along with corresponding 2 1/2 inch backing plates..https://store.cobraautomotive.com/10-x-2-1-2-race-drum-brake-kit/
Bob Gaines,Shelby Enthusiast, Shelby Collector , Shelby Concours judge SAAC,MCA,Mid America Shelby

Dynomax

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Re: Converting to the Shelby 2 1/2" drums on early mustangs
« Reply #3 on: February 07, 2022, 05:25:01 AM »
I am well into a '65 GT350 replica build and have just completed the rear brakes. As stated above, the 10" x 2 1/2" backing plates are specific to this shoe width. I used the backing plates from an '84 Lincoln Town Car and they are a perfect fit with the small bearing end 9" housing. These backing plates carry the following markings; LH: Bendix 3206205-L, RH Bendix 3206206-R. Both also carry the "Ford" logo.

Cobrask8

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Re: Converting to the Shelby 2 1/2" drums on early mustangs
« Reply #4 on: February 07, 2022, 07:13:59 AM »
What about F-150 rear drum brakes? I remember hearing this was another way to upgrade the rear drum brakes.

On my 69 SCJ Mach 1, I used early 1960's Galaxie rear drum brakes for more brake capacity, as the rear drums did very little. It was a bolt-on to the 9" housing.

Remember - Once you do this upgrade, your brake system balance and pedal bias WILL change. There are calculations to determine the needed M?C bore and stroke. When I did mine, I ended up swapping to one from a 1960's Ford dump truck. Then the upgraded system was good! Still on the car to this day with it's new owner.

Bob Gaines

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Re: Converting to the Shelby 2 1/2" drums on early mustangs
« Reply #5 on: February 07, 2022, 12:10:06 PM »
What about F-150 rear drum brakes? I remember hearing this was another way to upgrade the rear drum brakes.

On my 69 SCJ Mach 1, I used early 1960's Galaxie rear drum brakes for more brake capacity, as the rear drums did very little. It was a bolt-on to the 9" housing.

Remember - Once you do this upgrade, your brake system balance and pedal bias WILL change. There are calculations to determine the needed M?C bore and stroke. When I did mine, I ended up swapping to one from a 1960's Ford dump truck. Then the upgraded system was good! Still on the car to this day with it's new owner.
+1 on the bias changing. The GT350's had the stock adjustable proportioning valve adjusted differently then a stock Mustang to compensate for the larger rear brakes. It is hard to make adjustments using that original valve . The easily adjusted, commonly available and inexpensive after market adjustable proportioning valve is the preferred choice for track cars and clones alike. Here is a typical one out of many from Summit .https://www.summitracing.com/parts/sum-g3905. You can plumb it into the system where the stock one went or many dedicated track cars put it along the tunnel inside in easy reach of the driver.
Bob Gaines,Shelby Enthusiast, Shelby Collector , Shelby Concours judge SAAC,MCA,Mid America Shelby

gt350hr

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Re: Converting to the Shelby 2 1/2" drums on early mustangs
« Reply #6 on: February 07, 2022, 04:00:23 PM »
2002 Ford Rangers have an optional 10-2-1/2 rear drum without fins. I do not know if the backing plate would work with a 9" Mustang housing but I plan to find out.
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s2ms

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Re: Converting to the Shelby 2 1/2" drums on early mustangs
« Reply #7 on: February 07, 2022, 05:39:40 PM »
My 2009 Ranger 4x4 has 10x2.5" rear brakes. Some day I'll check to see if they will work on the GT350.
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gt350hr

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Re: Converting to the Shelby 2 1/2" drums on early mustangs
« Reply #8 on: February 07, 2022, 07:07:14 PM »
  We used to use Aerostar drums too.
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mlplunkett

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Re: Converting to the Shelby 2 1/2" drums on early mustangs
« Reply #9 on: February 15, 2022, 03:05:21 PM »
Tasca parts shows that they sell the 84 town car backing plates but the part numbers don't match what is given in this post. Can anyone in the know verify that these are the right parts?
https://www.tascaparts.com/v-1984-lincoln-town-car--base--5-0l-v8-gas/brakes--rear-brakes
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Scode67FB

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Re: Converting to the Shelby 2 1/2" drums on early mustangs
« Reply #10 on: February 16, 2022, 01:13:01 AM »
A lot of cars and trucks from the 80s and 90s used them. Of course, they're not the same as the ones used on Shelbys.
Rangers, Towne Cars, Explorers, Aerostars, LTDs and more used them. The Rangers and Explorers typically had non-finned drums. The others had the finned type. There are plenty of articles out there describing the swap. I don't remember the specifics, but I think it involved slightly enlarging the mounting bolt holes on the backing plates and getting centering rings for the axle hubs.

TA Coupe

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Re: Converting to the Shelby 2 1/2" drums on early mustangs
« Reply #11 on: February 16, 2022, 02:32:02 AM »
F150 drums were mentioned but they won't work because they have a 5.5 bolt pattern. You might be able to Redrill them to work and I can send one out if someone wants to try.

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tinman

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Re: Converting to the Shelby 2 1/2" drums on early mustangs
« Reply #12 on: February 16, 2022, 08:03:14 AM »
I also think F150 brakes (1990ish)are 11" x 2".
Mike

shelbydoug

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Re: Converting to the Shelby 2 1/2" drums on early mustangs
« Reply #13 on: February 16, 2022, 01:07:23 PM »
Tasca parts shows that they sell the 84 town car backing plates but the part numbers don't match what is given in this post. Can anyone in the know verify that these are the right parts?
https://www.tascaparts.com/v-1984-lincoln-town-car--base--5-0l-v8-gas/brakes--rear-brakes

The backing plates are Fairlane Station wagon parts.
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roddster

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Re: Converting to the Shelby 2 1/2" drums on early mustangs
« Reply #14 on: March 23, 2022, 04:13:25 PM »
  The key to the usable drums in the center, or "pilot hole".  The one in an original 67 Mustang S code car is 2.415. (Ford 9" axle).  So, before ordering your headache, make sure you know the diameter of that hole on the drum you are ordering.