Easily Confused Terms

TRACTION CONTROL, TRAK-LOK, and SECURILOCK

• TRACTION CONTROL is Ford's name for its electronic braking and engine control system that monitors rear wheel slippage and prevents loss of traction when accelerating.   If a Mustang has traction control, it must also have 4-wheel anti-lock brakes (ABS). Traction control consists of all the components of the ABS system, plus a powertrain control module (PCM) and a traction control ON/OFF switch.   Here's how it works:

  When traction control is turned on, the PCM monitors the speed sensors at the wheels and at the transmission and compares rear wheel speed to the car’s road speed.   If the rear wheel speed exceeds road speed (loss of traction) the PCM slows the rear wheels until they regain grip.   It does that either by applying ABS braking to the rear wheels to slow them down, or by sending less fuel to the engine, which has the same effect.   Traction Control is optional on all models except the Cobra.  The Cobra has Traction Control as standard equipment.

• TRAK-LOK is Ford's name for the clutch-type limited-slip differential that is installed as standard equipment in the 8.8" rear end on the Mustang GT and Cobra.   It is a mechanical system.  (No ON/OFF switch)   The Trak-lok differential includes all the components of an open differential, plus an S-spring and a set of clutches .  The S-spring pushes the clutches up against the side gears, which causes the clutches to engage whenever one rear wheel turns faster than the other.   In a situation where one rear wheel has little or no traction and the other one has good traction, the clutches engage and provide torque to both wheels.   Two wheel burnouts...

  The base (V6) Mustang comes with a 7.5" open differential (without Trak Lok) as standard equipment.   In the situation described above, this differential will apply all of the car's power to the wheel with little or no traction.   That wheel will spin and the other wheel will not.   One wheel burnouts...

• SECURILOCK is Ford's name for the Passive Anti-Theft System (PATS) that has been installed on all Mustangs since the 1999 model year.   It provides a unique electronic signature for each car and truck by matching a specially coded ignition key with a sensor located in the vehicle.   A miniature transponder that contains an antenna and an integrated circuit is embedded in the ignition key.   It uses wireless radio technology to transfer a code between the key and the car.  When the right code is recognized the engine will start.   If the code is not recognized, the engine will not start.   In the case of a hot wire attempt or the removal of the ignition lock, the system recognizes that the correct key has not been used; it shuts the engine down within a second and eliminates the possibility of it being restarted.  A very sophisticated and secure system.

BUMPSTEER or TRAMLINING?

• BUMPSTEER causes your steering wheel to turn slightly as your front suspension cycles up and down, as when the car goes over a bump, or when the body rolls in a corner, or when the front end dives during heavy braking.   This "self steering" happens because the tie rods and control arms are moving in different arcs.   Instead of tracking with the lower control arm, the tie rod pushes or pulls the steering arm as the suspension goes up or down.   That changes the steering angle of the wheel and makes the car respond exactly as if the steering wheel had been turned by a small amount.
  Ford designed the Mustang's front suspension and steering to minimize bumpsteer.   As shown above, the steering rack (green) is positioned so that during normal suspension travel the arcs travelled by the tie rods (red) and the lower control arms (blue) are congruent.   The tie rods and control arms remain approximately parallel throughout their range of travel, and there is no bumpsteer.
  Shown above is a Mustang that has been severely lowered.   The tie rods and control arms now travel outside their stock design parameters, and at the top of their travel, their arcs diverge.   Note the toe-out of the wheel at the top of its travel.   That's bumpsteer.   If you were driving this car and the right front wheel went over a bump, you would feel the steering wheel pull to the right.  

  If a Mustang's suspension is modified to the point that you experience bumpsteer, it can be reduced or eliminated by installing a kit that raises/lowers or lengthens/shortens the outer tie rods as needed to restore proper suspension geometry.

• TRAMLINING causes your front tires to follow ruts or longitudinal cracks in the road surface, forcing you to fight the steering wheel to keep the car going in the direction you wish.   Tramlining is related to tire size and tread design.   Some tires tramline very badly, and others not at all.   High-performance, wide, low profile tires are often the worst.   Tramlining can be reduced or eliminated by changing to a different tire design.   More information on tramlining can be found in this article at www.tirerack.com.