Jim Smart
October 1, 2008
Photos By: Mark Jeffrey

Convertible top replacement and adjustment isn't for the weak of heart because it mandates patience and a solid understanding of how convertible tops fit and function. However, you can do it yourself if you have the right tools and patience. We decided to visit Mustang Country in Paramount, California, for a look at how professionals replace Mustang convertible tops, which combines mechanical repair and fabrication on almost every level.

First, protect your Mustang's decklid and quarter-panels by laying down a furniture pad or blanket. Installing a new top can get messy, and there's the risk of dropping tools and fasteners on your Mustang's finish. Don't forget to disconnect the battery, and be cautious with the power top mechanism when you connect the battery to check operation.

California Mustang provided us with a basic convertible top kit along with all of the repair parts necessary to fix a power top. Tools required for the job include Phillips and common screwdrivers of all sizes, a 3/8-drive socket set, combination wrenches, a heavy-duty industrial stapler (for upholstery work), a test light, and a heavy furniture pad or blanket.

Before you can replace a convertible top, you need solid mechanicals. Anything that is worn out must be replaced or you can count on frustration. There must also be adequate lubrication on moving parts to ensure smooth operation. Convertible top mechanisms don't work properly when they suffer from bent linkages, worn bushings and pins, broken parts, and improper adjustment. Run the existing top up and down while examining the entire mechanism for binding and improper adjustment. If there's binding, check individual links for trueness. You're also going to need to inspect bushings and pins for excessive wear.

Manual and Power Tops
Manual tops are generally easier to repair and adjust because there's no hydraulics to consider outside of the counterbalance mechanisms, which make it easier to raise and lower your top. Power tops are nothing more than a hydraulic system (fluid under pressure) that includes an electric pump, a two-way switch, lines, and two hydraulic lift cylinders (actuators). The pump runs in one direction to raise the top and reverses to lower.

Anytime you are servicing the convertible top mechanism, make safety your first priority. Never remove the counterbalance cylinders with the top down, always disconnect the battery whenever you're servicing the power top mechanism, and keep your hands clear whenever the top is in motion.

Before you can install a new top, bow positioning must be spot-on to achieve proper top tension and position. Stay pads maintain bow positioning and absorb sound. As a rule, there are four bows from front to rear on most convertibles, which Ford assigns numbers to-header bow (windshield; No.1), second bow (No. 2), third bow (No. 3), and rear bow (No. 4). Each side has a front side member, a horizontal side member, and a diagonal/vertical top frame member.

Bow Dimensions*
If you're stripping down a convertible top, we suggest measuring top bow dimensions to see how they compare with ours. What matters most is a top that will fit perfectly when it's time for installation. There are specified distances you need to have between top bows for good fit and function. These measurements aren't center-to-center, but from trailing edge to leading edge. Here's how measurements stack up.

No. 1 bow to No. 2 bow: 16 1/2 inches
No. 2 bow to No. 3 bow: 16 3/4 inches
No. 3 bow to No. 4 bow: 15 1/2 inches
No. 4 bow to stainless molding: 20 1/2 inches
No. 4 bow to drain trough: 22 1/2 inches

If you examine your '65-'73 Ford Shop Manual, you can fabricate a bow locating gauge from plywood, which will enable you to position bows to factory specifications.

Top adjustment isn't all that difficult according to Richard Smykay. There are five ways to adjust the top mechanism:Bow No. 2 up/down adjustment
Side rail camber eccentric at balance link
Side rail camber set screw at hinge
Header to side rail adjustment (fore and aft length adjustment)
Frame bracket to body bolts (side to side adjustment)
* Information courtesy Richard Smykay at smykayrich@yahoo.com

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