Many Mustang owners like either the appearance, sound, or added horsepower that dual exhaust provides over a single exhaust system. Perhaps all three factors are the motivation for this conversion. If this conversion is not performed correctly, it can result in brake failure. We, at K.A.R. Auto Group, have seen brake failure on several occasions directly related to an early Mustang being converted from single to dual exhaust.
When Ford Motor Company produced V-8 1964 1/2, 1965, and 1966 Mustangs with single exhaust, they installed the tail pipe on the passenger side of the car. The rubber rear brake hose was installed on the driver's side of the car. The rear hose is attached to the axle housing and travels to a bracket that is mounted on the driver's side rear floor extension. The front to rear metal brake line enters the brake hose at this bracket. The end of the hose that is attached to the axle housing has a Y fitting on this end. The rear metal brake lines screw into this fitting and travel to each rear wheel completing the system. This works well on single exhaust early Mustangs.
When Ford Motor Company produced 1964 1/2, 1965, and 1966 Mustangs with factory dual exhaust "completely different" front to rear metal brake line, rear axle metal brake lines, and rear flex brake hose were used. In addition, Ford relocated the flex hose mounting bracket 8 to 10 inches further to the left side of the car. This new bracket mounting spot can easily be seen. It is near a stamping mark or embossed line in the floor.
Why were all different metal lines and a different rear flex hose used on early dual exhaust Mustangs and the flex hose mounting bracket moved? The answer is to move the rubber flex hose away from the driver's side tail pipe. If dual exhaust is added and the rear flex hose is not relocated, it will - in most cases - rest on or extremely close to the tail pipe. Heat from the tail pipe will either melt this rubber hose or cause it to dry out and eventually rupture.
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Please note the arrows on these photos showing the proximity of the rubber brake line to the tail pipe. The car is on an overhead lift, so the rear suspension is lower than when the car is on the ground. When the car is sitting on the ground the rubber brake line rests on the tail pipe. Should this brake line fail all brakes will be lost instantly.
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The new metal rear axel brake lines, correct for a dual exhaust 65 or 66 Mustang, have been installed. The arrow indicates their location. |
The bracket for the rear brake rubber hose has been relocated and the correct rubber hose for a dual exhaust car has been installed. Note how this rubber hose is now permanently away from the tail pipe and out of danger. This is now a factory correct and safe installation. |
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1964 1/2, 1965, and 1966 Mustangs were produced with single reservoir brake master cylinders. This simply means that these cars had no backup brake system. If a brake fluid drain occurred, the car lost brakes at all four wheels. A ruptured line could cause this brake loss to occur virtually instantly.
If you are considering converting your 1964 1/2, 1965, or 1966 Mustang to dual exhaust and you do not want to risk an unsafe condition, we suggest you do the following:
- Relocate the rear flex hose mounting bracket.
- Change the front to rear metal brake line and the rear axle metal brake lines to lines specifically produced for dual exhaust Mustangs.
- Change the rear flex hose to one specifically produced for dual exhaust Mustangs.
- Following steps 1 through 3 refill the system with the proper brake fluid and bleed all the air from the system. Insure you have a firm brake pedal and no brake fluid leaks before driving the car.
1967 AND LATER MUSTANGS
There is no need to make any brake line changes to these Mustangs when converting to dual exhaust. Ford Motor Company mounted all brakes on these cars as though every car were to have dual exhaust.
K.A.R. Auto Group checks every early Mustang that we purchase for dual exhaust brake line placement. If dual exhaust has been added and the lines not replaced with correct dual exhaust lines and the flex hose mounting bracket not relocated, we make these changes before the Mustang leaves our facility. If we service or repair a customer's early Mustang, and we see this unsafe situation, we quickly alert the customer to the danger.
KIT AVAILABLE
If you are planning a dual exhaust conversion on an early Mustang and are not certain exactly what you need, please call K.A.R. We can assemble the correct kit for your application. If you are within driving distance of K.A.R., our repair center can perform the brake line conversion for you.
PARTS REQUIRED FOR DUAL EXHAUST
BRAKE LINE CONVERSION |
| Part # |
Item Description |
Cost |
| ZIN 6402 * |
Front to rear metal brake line (drum brakes) |
$32.95 |
| ZRA 6403 |
Rear axle metal brake lines |
$19.95 |
| FH 77 |
Rear flex hose |
$56.95 |
| TOTAL: |
$109.85 |
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K.A.R. charges $295.00 labor to perform this conversion at our shop. Parts plus labor totals $409.85. Total project cost is $450.76 including sales tax and EPA disposal. Once the above preparatory steps are taken to relocate and replace brake lines you are now ready to install the dual exhaust system. This conversion is not as simple or inexpensive as one might initially think if it is to be done correctly and safely.
* Use ZIN 6402 for drum brakes with dual exhaust. Use ZIN 6404 for disc brakes with dual exhaust at the same cost.
NOTE: RELOCATE FLEX HOSE MOUNTING BRACKET
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