Mustang FAQ and How To's
Front Drum to Disc Brake Conversion for Classic Mustangs
Information provided by: Rick Larson
Converting 4-wheel drum brake Mustangs to front disc brakes is a
popular and effective way to increase the braking power of older
Mustangs (and other Ford and Mercury automobiles).
What makes this swap attractive is the fact that the entire spindle and
brake assemblies (but not necessarily the individual parts) of many 1960's
and 1970's Ford, Lincoln, and Mercury autos are directly interchangeable.
Since factory parts are used, the cost is reasonable and everything needed
is available from your local junk yard and auto parts store.
The scope of this document is converting a manual 4-wheel drum Classic
Mustang to front disc brakes. Converting to power brakes and all those
issues (pedal pivot location, master cylinder, feel, ...) are not
covered here. Classic Mustangs are defined as Mustangs made between
1964.5 through 1973.
The following list of parts are needed for the conversion:
Various spindles can be used to replace the front drums.
spindles can be grouped into the following: 64.5-67, 68-69, 70-73.
The early ones have the advantage to be concours correct, while
the latter ones are stronger.
68-69 spindles are larger than the earlier ones but retain the
same outer tie rod tapers.
The 70-73 spindles are much stronger
than the other years and are the best to use for the conversion.
However, the spindle went to a size larger tie rod taper so tie
rod ends from a 70-73 must be used.
Ford 1977-84 Granada/Monarch spindles will bolt up. These
spindles are similar to the 70-73 Mustang spindles.
Versailles spindles will not work. The hole for the ball
joint is larger than the Mustang ball joint and a shim would be
required to make this work.
The Granada/Monarch spindles require Granada tie rod ends.
Get calipers that go with the spindles you choose. Early Mustang
calipers contain 4 pistons (two on each side) and are prone to
stick. Granada single piston calipers float and require
When searching for the "perfect" donor car, be sure to
get one with 11" rotors. Some early Mustangs, 6 cylinder (??)
Granadas come with 10" rotors. If you are going to all this effort
get the bigger rotors.
Various manual master cylinders can be used for this conversion.
The Boss 302 Chassis Modification booklet (a reprint of the
1970 factory booklet showing parts and methods for beefing
up the Boss Mustang for better handling) recommends a '69
F250 2 wheel drive, power front disc brake
MC and Calvin Sanders, has successfully
used this in several Mustangs.
The MC from a 76 6-cylinder Granada bolts right in and works.
Other Granada master cylinders also fit. I suggest if you
use a donor Granada for the spindles/rotors/calipers, get the
master cylinder. You may be able to use a power MC with
some push rod modifications (a power MC has a much shallower
May 1995 issue of Mustang Illustrated lists several compatible MCs.
Raybestos # MC39037 (RH) cast iron 7/8 bore
78-81 Ford Fairmont,Granada,Futura,Zephyer(Merc)
Raybestos #MC39531 (RH) alum 21mm
81-86 Tbird, 82-86 Mustang, 83-86 Marquis (Merc)
Raybestos #MC 39310 (RH) cast iron 7/8 bore
81-83 Escort, Explorer, lynx, Mark VII (Linc)
Raybestos #MC 39027 (LH) cast iron 7/8 bore (LH)
76- 80 GM Monza, SkyHAwk,Starfire,SunBird
The article has a wealth of tips and advice regarding interchangebility and
compatibility and fitting. However, please note which side you
want the plumbing on before you pick a MC. IMHO, you should
get a left hand side MC.
If you have a 1964-1966 model year car
with a single reservoir master cylinder, you should consider upgrading to a
later style dual reservoir master cylinder for safety reasons even if
you don't want to add front discs.
Get either the stock one from the donor car or an adjustable one from
Summit. The adjustable one allows changing the brake bias. Some people
like this, others (like me) use the stock one.
Depending one what spindle you choose, you may need to get new
tie rod ends. When upgrading with either 70-73 Mustang or Granada spindle,
get the tie rod end to fit. Also, tie rod adjusting sleeves may
been needed. Original sleeves on a '66 will not work with Granada
tie rod ends. However, Granada sleeves will thread on the Mustang
inner tie rods.
Depending on what spindle/rotor/caliper choice, you may need
different brake hoses.
When I replaced my drums with the Granada parts, I needed
new hoses. Granada hoses will not mate to the hard lines. I
ended up with hoses from a '73 Mustang. I also replaced the
hard lines and extended the lines to help locate the brake
hoses around the suspension. I swapped the hose/hard line
bracket (left went on the right side, right went on the left
side) and turned them counter clockwise 90 degrees.
Now that you have larger disc brakes, your old 14" wheels may not fit any more.
Mustang owners have had problems with 14" disc-type styled steel wheels,
14x6 Torq Thrusts style wheels clearing the calipers of the new set up.
Be sure to measure this before you make the decision. I had
to get Granada rims to fit over the new disc brakes. The center
hole on the original 14" wheels is smaller than the new rotor.
The following vendors were found in a recent Mustang magazine.
I don't know anyone who has used one of these conversion kits
and can't comment on quality, conversion difficulties, or cost.
Stainless Steel Brake Corp, 11470 Main Road, Clarence, NY 14031.
Master Power, 254-1 Rolling Hills Rd, Mooresville, NC, 28115.
Special thanks goes to Calvin Sanders, Dan Jones, and Ken Corpus for
providing text to this and answering questions on this conversion.
Vintage Power Disc Brake Conversion, Mustang Monthly,
June 1996, pages 34-8.
How To: OEM Disc Brake Conversion, Mustang Monthly,
June 1996, pages 46-51.
Drum to Discs without braking the Budget, Mustang
Illustrated, Spring 1989, pages 16-18, 78.
Canning the Fruit Jar, Mustang Illustrated, May 1995, pages
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