TLok is ford's word for positive traction so that both wheels turn instead of just one when you break traction. In a stock V6 you have an open differential that basically means that the power will go to the path of least resistance, usually the passenger side wheel. So if you are putting power down and the tires break lose one side will spin while the other will not spin (Unless you do a massive burnout). A Traction Lock (TLok) unit uses clutches and gears around those clutches to equalize the pressure. When one axle is spun faster than the other the clutches apply equal pressure. This may sound odd as how can you still turn corners as one wheel must turn faster than the other? The clutches break loose at 250 or so FtLbs to allow this to happen, if you are going straight this wont be an issue.
The SpeedCal is the name for the Dallas SpeedCal unit. Basically you have a sensor on your transmission called the VSS sensor. It tells the car how faster the transmission is turning so it knows how fast the car is going. If you install new rear end gears the transmission turns the same but the rear tires turn faster. The rear gear ratios is the ratio that the rear tires turn in relationship to the driveshaft. So the higher the gear the more revolutions the rear tires make for every one full revolution of the driveshaft. This is how gears make your car accelerate faster. It takes less rotations of the engine (transmission, and driveshaft as well) to make the wheels turn. The negative side is it takes more RPM's to make you go faster so you generally lower your top speed, but not enough to every notice in your case (you will still be able to go faster than you need to). With out a speedcal unit your speedometer will be off a good bit, you will run miles up on your car faster, and you will not be able to over a given speed lower than your previous top cut off (80mph with 3.73s as an example). The speedcal intercepts that signal that tells the computer how fast the transmission is going and slows it down or speeds it up to that it is accurate with the rear gears (or for that matter the size of the rear tires that also offset the final gear ratio) to be accuratly interpreted. The speedcal alters the VSS sensor's information so it is accurate with the rear gear ratio and tire sizes you are running. The install is very easy, you basically put the speedcal unit inbetween the VSS sensor and the computer, its rather straight forward and takes no special tools to perform. The key is to ensure that the power wire that powers the speedcal is secure and will not come loose (use a sodering iron not the little pinch connector the speedcal gives). If the power wire comes loose the car does not know how to control the idle of the car in neutral and the rpms drop like a rock, the speedometer will not work either.
2003 Cobra Vert (Redfire) #3938 of 5082 @ 05/27/2003
472rwhp/493rwtq -Modification List
- Dyno Sheet
2012 Mustang 3.7L M6 (Kona Blue)
2011 Ford Edge Sport (Red Metallic)