CONVERTING STOCK REAR BRAKES TO 10 X 2 ½ INCH DRUMS
By Sam Griffith {AKA Sigtauenus}
After converting the front of my car from drum brakes to disc brakes, I
wanted to make an upgrade to the rear brakes as well. After emptying the
wallet on the front brakes, I didn't want to spend the money on a rear disc
brake conversion kit or go to the expense of a Versailles rear end either.
So, what I did was upgrade from 10 x 1 ¾ " brakes to 10 x 2 ½" brakes. The
kits for this in the mustang catalogs and magazines go for upwards of $400,
but I did it for around $200 and here's how:
I started with the premise that Ford used the same 5 lug bolt pattern on a
LOT of its cars, and that some of these cars were bound to have a 10 x 2 ½
brake on the rear. I went to the junk yard and through trial and error found
a 1984 Lincoln Town Car that had what I was looking for. I bought the
backing plates for $50 for the pair.
Next I researched the 68 cars that came with 10x2 ½ brakes (like the 428
Mustangs) to see what brake cylinders, brake pads, etc, I would need, and
what I was specifically looking for was a brake cylinder that used the same
line fitting that mine already had so I wouldn't have to cut and re-flare the
brake lines. What I actually found was that the same brake cylinders are
used for 10x 2.5 as 10 x 1.75, with 7/8 " pistons. I could have used the
same ones I already had but opted for new parts all the way around, including
new axle seals. Obviously this could be done even cheaper if I had looked
further for a donor car that had usable drums, re-used my brake cylinders,
etc.
I wish I had a picture of the backing plates to compare, but trust me, there
is a difference in the off-set for the bigger brakes. The backing plates
from the 84 Lincoln bolted right up to my axle housing and had the same holes
as my original backing plate for the wheel cylinder, parking brake cable,
etc. I chose to buy the hardware for the 84 Lincoln (the only real
difference is the two springs that hold down the brake shoes via the "nails")
because they were in stock and the 68 set wasn't.
The first picture shows the passenger side almost completed...looks like
regular drum brakes do. In the second picture you can see the difference in
the sizes of the brake drums and the shoes, and also see how the 84 Lincoln
drums have the fins for cooling.
I know 84 Lincoln Town Cars work, but for other donors, here's what I found
at the parts house using their old book (the computer doesn't help for this):
68-70 Mustang
80-89 Full size Fords (Custom, Galaxie, LTD, Crown Victoria, Country Sedan, Country Squire)
66-75 Elite, Fairlane, Torino
69-71 Station Wagon
63-65 Station Wagon
61-67 Econoline E150/100
66-74 Ranchero
Now, here's the fun part. Not all of these cars always came with 10 x 2 ½"
brakes, but some of each model listed above did. Make sure you measure the
brake shoe before going to the trouble of tearing anything apart. I realized
driving home that I forgot to check the Lincoln section in the parts book, so
there's even more cars that are potential backing plate donors. Also, when
you go to buy parts, make sure the drums you buy are the right 5 lug bolt
pattern. For example, just because the Econoline van has backing plates that
will work does not mean that the drums have the same lug pattern as your
Mustang (trucks/vans have a bigger 5-lug pattern).
For extra-extra fun, if you've already converted your front drums to discs,
you could see if the backing plates from the front drum brakes (10 x 2 ½")
will work on the back. I thought of this while driving home and realized
that if the front backing plate bolts up to the rear axle all you'd have to
do is drill a hole for the parking brake cable and save all the junk yard
hassle. I'll leave that job to someone else though.
Pep Boys was right down the street so they were my supplier, here's my parts
list and expenses:
Source Item Part number Unit Cost Total
Junk Yard Backing Plates $25 $50
Pep Boys brake drum 0-30999-08250 $54.99 $109.98
Pep Boys wheel cylinder 0-30999-09464 $9.99 $19.98
Pep Boys re-lined brake shoes 0-30999-09061 $10.99 $10.99
Pep Boys axle seals 0-30999-1101292 $5.92 $11.84
Auto Zone brake hardware 7224 $5.29 $5.29
Total $208.08
Autozone actually had cheaper prices but didn't have everything in stock.
Pep Boys had everything in stock so I had them price match to Autozone's
prices. Here's Autozone's part numbers for the drums and shoes:
Drums 8896 $54.99
Shoes 481 $10.99
I don't have any scientific data for whether or not this conversion really
helps braking, but I can say that when I had 4 wheel drum brakes I was on
more than one occasion literally scared for my life. Since converting the
front to disc and putting bigger brakes on the back, I am 100% confident in
my Mustang's braking ability and have had no problems at all with getting it
to stop.