SAAC Forum

The Cars => Replicas and Tribute => Topic started by: mlplunkett on January 24, 2022, 05:41:42 PM

Title: Converting to the Shelby 2 1/2" drums on early mustangs
Post by: mlplunkett 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/
Title: Re: Converting to the Shelby 2 1/2" drums on early mustangs
Post by: roddster 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.
Title: Re: Converting to the Shelby 2 1/2" drums on early mustangs
Post by: Bob Gaines 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/
Title: Re: Converting to the Shelby 2 1/2" drums on early mustangs
Post by: Dynomax 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.
Title: Re: Converting to the Shelby 2 1/2" drums on early mustangs
Post by: Cobrask8 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.
Title: Re: Converting to the Shelby 2 1/2" drums on early mustangs
Post by: Bob Gaines 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.
Title: Re: Converting to the Shelby 2 1/2" drums on early mustangs
Post by: gt350hr 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.
Title: Re: Converting to the Shelby 2 1/2" drums on early mustangs
Post by: s2ms 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.
Title: Re: Converting to the Shelby 2 1/2" drums on early mustangs
Post by: gt350hr on February 07, 2022, 07:07:14 PM
  We used to use Aerostar drums too.
Title: Re: Converting to the Shelby 2 1/2" drums on early mustangs
Post by: mlplunkett 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
Title: Re: Converting to the Shelby 2 1/2" drums on early mustangs
Post by: Scode67FB 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.
Title: Re: Converting to the Shelby 2 1/2" drums on early mustangs
Post by: TA Coupe 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.

     Roy
Title: Re: Converting to the Shelby 2 1/2" drums on early mustangs
Post by: tinman on February 16, 2022, 08:03:14 AM
I also think F150 brakes (1990ish)are 11" x 2".
Mike
Title: Re: Converting to the Shelby 2 1/2" drums on early mustangs
Post by: shelbydoug 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.
Title: Re: Converting to the Shelby 2 1/2" drums on early mustangs
Post by: roddster 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.
Title: Re: Converting to the Shelby 2 1/2" drums on early mustangs
Post by: gt350hr on March 23, 2022, 05:28:56 PM
  If the hole is too small it can be opened. Too big is a no no.
Title: Re: Converting to the Shelby 2 1/2" drums on early mustangs
Post by: mlplunkett on November 21, 2022, 06:27:31 PM
Thought I'd throw this out there for those who may want to follow the spirit of the Shelby modification but but not necessarily the letter of the law. I got this off a mustang forum that was trying to solve the same problems we are. If 11x2.25 is close enough to 10x2.5 then a complete kit including loaded backing plates and parking brake components with your choice of "racing" or "street performance" shoes is available for less than $500 at https://opentrackerracing.com/shop/11-x-2-25-drum-brake-for-small-bearing-ford-rear/ . I gotta say that looks pretty attractive for a tribute car.
Title: Re: Converting to the Shelby 2 1/2" drums on early mustangs
Post by: 68stangcjfb on November 21, 2022, 08:50:24 PM
Those are 1979 to 1990 LTD Crown Victoria rear brakes from a station wagon, or a police car. I have them on my Fairlane station wagon and I took them off a 1984 Ford full size station wagon. You can probably get them at a junkyard for a lot less money.
Title: Re: Converting to the Shelby 2 1/2" drums on early mustangs
Post by: SFM6S on January 26, 2023, 08:57:37 AM
The Ranger drum mentioned above has a centering bore of 2.808 inches. 3/8" inches larger that a vintage drum. perhaps a sleeve could be swaged on the axle hub to accommodate for the difference.
Joe
Title: Re: Converting to the Shelby 2 1/2" drums on early mustangs
Post by: TA Coupe on January 26, 2023, 04:29:47 PM
Google hub centric rings. They make them in lots of different sizes and if you can't find one the right size there are places that make custom ones. You can get them in plastic or metal.

        Roy
Title: Re: Converting to the Shelby 2 1/2" drums on early mustangs
Post by: mlplunkett on February 02, 2023, 06:51:15 PM
Found a pretty good article on the vintage mustang forum

https://mustangsandmore.com//ubb/RearBrakesbySamGriffith.html

Found a good video on Youtube

https://www.youtube.com/watch?v=IVNfHXiqAgA
Title: Re: Converting to the Shelby 2 1/2" drums on early mustangs
Post by: roddster on September 26, 2023, 05:55:58 PM
Late news.  I found this out recently.
  Bought what was advertised on Ebay as backing plates for the 10" by 2 1/2" rear brakes.  Not so.  The drum ends at the edge of the backing plate with about a 1/8" gap between the plate and the drum.
  Bendix # 320 9029-R/320 9028-L. DO NOT USE THESE
   Bought these on Ebay like 6 years ago.

  One other thing:  that motor trend article doesn't say a word about the backing plate offset.
Title: Re: Converting to the Shelby 2 1/2" drums on early mustangs
Post by: roddster on October 08, 2023, 12:11:18 PM
  After spending a few hours at a U-Pick yard, taking measurements and such, rule out the Ford Ranger pick-up backing plates as a viable option.  Same measurements as above.  Looked at 95's, 99's, 2000's. 4 X 4 and two wheel drive. Ain't gonna work.
  And here in the rust belt, there are NO Fomoco products earlier than 1990.
Title: Re: Converting to the Shelby 2 1/2" drums on early mustangs
Post by: shelbymann1970 on October 09, 2023, 08:26:06 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.
Yep, that setup still works great on Dan's old car. I believe the M/C is a F650 model? Of course since Dan and his Ex used to use my car at SAAC track events he installed a proportioning valve behind the rear seat and adjusted it accordingly for high speed braking.
Title: Re: Converting to the Shelby 2 1/2" drums on early mustangs
Post by: roddster on December 14, 2023, 05:41:10 PM
  My final Update as I figured it out for my tribute car
 12/14/2024

  Here is what I have: backing plates # 3209029/3209028 (Bendix). I have no idea what Fomoco product it is off as I bought them about 6 years ago on Ebay.  A U tube video suggested to use backing plates from an 85' Full size Ford.
  The usual refrain is to use Ranger rear drums, but those leave a 1/8" gap between the backing plate and the drum.  Not going to work. 
  I ran into a U tube video and the person said to close the gap, buy rear drums that are from a 69 Cyclone with a 428.
 These are part number 1639R (Raybestos).  Rock Auto had these and yes, the gap is closed and fits correctly.  So, there you go, this is what works.  BUT: seems these drums are about 3 pounds heavier than the Ranger drums.  At least you get the larger swept braking area.  Go figure: it's 3/4" wider times 10" Pi.
  Small issue with the drum.  Just like on the Ranger drum, there are raised cooling fins along the entire perimeter of the Cyclone drum.
   Hint: also seems that the brake combi kit (that's the return and hold down springs folks) come with the pins that hold down the shoes are a little short.  The correct pin length for the 2 1/2" shoe is 2 15/32".  You can order those at the local O'reilly's.
  Had a conversation with a popular East Coast parts supplier.  They informed me that the people who were stamping the backing plates for them went out of business.  They were looking for a new supplier.