Steve Magnante's 1001 Mustang Facts. Steve Magnante
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atop the outboard ends of the rear axle housing. The rear floor was cut open and the bars entered the car; the bars were then bolted to beefy steel mounts welded to the floorpan. Because they are located above the axle and leaf springs, this arrangement has come to be known as the “overrider” traction bar. Thanks to the GT350’s no-back-seat mandate (the SCCA didn’t accept the Mustang with its standard back seat as a sports car), conflict with rear-seat passenger’s feet was a non-issue. What was an issue were the many man-hours required to fabricate and install these complex traction bars (see Fact No. 7 for more).
84 Although all 561 of the 1965 GT350s received the time-consuming overrider traction bar conversion, Shelby reconsidered his traction bar strategy for 1966. Instead, more conventional under-rider–style traction bars were sourced from the Traction Master Company of nearby Burbank, California. A pioneer in bolt-on traction aids since the mid-1950s, Traction Master bars were also factory installed on the Sunbeam Tiger and certain high-performance Studebakers. Mounted entirely under the chassis, the only welding involved a single mounting bracket (per side). Even though the first 252 1966 GT350s retained the elaborate overrider bars, the Traction Master bars were phased in as a running change and the vast majority of the 1966 GT350s (2,378 built) used them.
85 Getting back to the complexity of the 1965 overrider traction bar program: The necessary pass-through slots cut into the Mustang’s rear floorpan had to be patched with a flexible cover in order to meet Ford Minimum Standards Regulations for road noise and cabin sealing while also allowing 6 inches of up-down suspension travel. No fewer than three strategies were employed. The first involved simple flat sheets of rubber; the second called for specially formed fiberglass boxes (the most time-consuming and costly); and the third, a pair of molded rectangular rubber boots sourced from a Ford heavy-truck application. Because of their tall, rectangular form, the truck-sourced boots gave the steel tubes the look of much larger Fairlane Thunderbolt traction bars when viewed from inside the car. The switch to Traction Masters in 1966 was well timed with the SCCA’s easement of its prior (back seat) restriction. The 1965 overrider bars interfered with the bottom cushion.
86 As evidence of Shelby’s new-found (1966) focus on manufacturing efficiency and simplification, the cast-iron bracket locating the axle end of the Traction Master tube to the shock absorber/spring plate and U-bolts was cast with three ears instead of four. This allowed installation of the traction bar without dropping the leaf spring plate and, subsequently, the rear axle, thus saving time. Uneducated Shelby swap meet shoppers often assume the missing ear signifies a broken part. In succeeding years, the Shelby Mustang’s add-on traction aids were simplified further as Ford evolved Mustang’s rear suspension for better axle control at the factory level. I explore this in the next chapter.
87 Even though the 1984 Mustang SVO hosted the showroom debut of four-wheel disc brakes, Ford is known to have experimented with the superior stoppers on first-generation Mustangs. The only disc-equipped survivor from the 1960s is the 1968 Shelby “Green Hornet.” Unique because of its hardtop body style, the 428 test car (born an S-code 390) also served as a development mule for throttle body-style electronic fuel injection and independent rear suspension. Overseen by Shelby American chief engineer Fred Goodell, each of its innovations saw production, albeit years later (EFI in 1983, IRS in 1999). The Green Hornet has been fully restored and occasionally appears at major Mustang shows.
What sets early 1965 brake master cylinders apart from late 1965 units? Fact No. 88 reveals all.
88 Early 1965 Mustangs were fitted with a very unique brake master cylinder with the brake light trigger switch and wiring built into its body. Surprisingly, buyers who wanted power assist (a $58 upgrade) were restricted to drum brakes. The first power-boosted Mustang front disc brakes didn’t arrive until 1967.
89 The lone exception to the manual disc-only rule came from Shelby. Standard GT350s were built with manual front disc brakes (upgraded with metallic pads). When Shelby won a lucrative contract for 1,000 Hertz GT350-H rental cars (1,001 were actually built), Ford hadn’t finalized its power-boosted disc brake testing (to be released for 1967). Shelby was on his own to find the needed brake booster and install it. The solution came from a compact two-stage master cylinder made by the Minnesota Automotive Company (MICO). Unfortunately, the unit’s piston-within-a-piston design delivered a non-linear (hard-soft-hard) pedal feel that confused many rental customers. About 400 MICO-equipped cars were delivered before all parties agreed to return to the standard Shelby manual disc brake setup. Those Hertz-spec GT350H Mustangs remain the only pre-1967 cars factory equipped with power front disc brakes.
90 Headaches plagued the GT350H brake program. Because the MICO master cylinder’s triangular mounting flange differed from the Mustang’s four-stud firewall mount, Shelby was forced to fabricate an adapter bracket from two pieces of formed sheet steel. The early units were thin and flexed visibly during firm pedal application. Shelby hastily made a thicker replacement and installed them under a recall program.
91 The MICO brake master cylinder didn’t have a separate brake booster unit. Rather, its internal dual-piston construction served as the force multiplier. This is why novices who expect to see a big vacuum booster on Hertz Mustangs are confused when they see them at shows. Aside from its square reservoir (Mustang reservoirs are round), the MICO unit resembles a basic manual brake master cylinder. One ray of light was the MICO’s cost. At $39.58 per unit ($50 less than early projections), the 400 units purchased saved the GT350H program some $20,000. Today, original MICO units are extremely rare and highly sought after among GT350H restorers.
92 After the decision was made to stop using the MICO master cylinders and return to standard manual disc brake components, the hard brake pedal pressure required to effectively activate (cold) Shelby brake pads triggered the creation of a specific foil dashboard sticker warning drivers to be cautious. It reads, “This vehicle is equipped with competition brakes. Heavier than normal brake pedal pressure may be required.” Cars built after the MICO termination received the sticker and they were also sent to Hertz rental outlets for field installation. This special gold foil sticker has become a key element of the GT350H mystique.
93 The brake drums fitted to 6-cylinder Mustangs were 9 inches in diameter and offered 131 square inches of lining area. V-8 cars received an upgrade to 10-inch drums with 154.2 square inches of area. When the vacuum-assisted power booster was ordered, the drums remained unchanged, although pedal pressure was reduced about 30 percent for less strenuous application.
94 The Mustang’s optional front disc brakes were made by Kelsey-Hayes and featured 9½-inch-diameter rotors and four-piston cast-iron calipers. Although their lining area measured only 114.3 square inches, the exposed braking surface rejected heat far better than did shoes trapped inside conventional drums. The swept area was 212 square inches. A January 1965 Motor Trend road test of a 1965 2+2 with the optional manual discs went from 60 to 0 mph in 150 feet. A drum brake test car covered 172 feet in the same test, “the difference between having an accident and avoiding one,” according to story author Bob McVay.
95 The stock Mustang steering ratio was either 27:1 (manual) or 22:1 (power assist, $84.47). For $30.64, Ford offered a Special Handling Package, part of which was the faster-ratio 22:1 power steering box, installed minus the hydraulic-assist ram and its pump. To speed things up even more for the GT350, Shelby’s team added longer (by 1 inch) steering and idler arms. The effect was an increase in tire movement for the same amount of steering wheel rotation.
96 Another 1965 Shelby GT350 handling trick was the relocation of the upper suspension A-arms to 1 inch higher on the frame rail/spring tower surface. This lowered the nose of the car (and the center of gravity) while also improving the roll center. This modification was time-consuming: it necessitated suspension disassembly and a total re-alignment. It was no longer performed on 1966 Shelby Mustangs after the first 252 cars were completed (they were built on leftover 1965 bodies).
97 The firm Koni adjustable shock absorbers selected by Shelby caused their share of complications. Because they lacked internal extension stops, extreme suspension rebound could pull them apart.