Lockers have been used by racers for a while now, and for the most part, they have grown to a high level of acceptability by racers.However, there was a time, not too long ago, that lockers were viewed as voodoo science.
The reasons for that are blurred, because lockers originally found their way into race cars when they were somewhat more high-tech than the cars themselves. When lockers were first used, they got mixed results, so it led to some misunderstanding and even mistrust of lockers. But competition usually brings out the best in technical advances, and this is no different.
So it followed that it took a bit of persuasion for many racers to move from a spool to a locker in their rearends. However, as time has gone by and lockers have proved themselves, there are fewer nonbelievers.
Circle Track decided that this was a good time to get an overview of lockers, so we spoke with Mike Powell of Tex Racing Enterprises in Ether, North Carolina. Mike and his father, Tex, are gear and transmission experts; we felt they were credible sources for a discussion on lockers. Our goal was to understand how lockers work and to separate the fact from fiction.
How Do They Work?In simple yet accurate terms, a locker is a mechanism that will, during deceleration, unlock the right-rear wheel to permit it to turn free of the left rear wheel in the turns. This is possible because the design of lockers is such that there are two axles, one right and one left, rather than a single axle of a spool third member.
Then under conditions of acceleration, normally coming off the turns and down the straight, the rear wheels lock into synchronized rotation, thus providing power to the ground from both rear tires. This dynamic is made possible by the mechanical locking of the two wheels revolving at matched speed.
As the dynamics of a locker system are played out on the track, a locker functionally allows the rear wheel to drive the car on a groove that the tire stagger wants.
A properly functioning locker, therefore, permits a car to behave "more naturally" and more fully benefit from a properly balanced and set up chassis.
Why Do You Need 'Em?When you examine the dynamics of wheel rotation in a turn, the outside wheels travel farther than the inside wheels. Since the front wheels are independent of each other, they freely turn any distance they want to. However, when it comes to the rear wheels, it's a different situation.
Rear wheels have a natural impediment to this motion, because in spool third-member setups, there is only one axle, and that means both rear wheels turn at the same rate. Of course, stagger helps overcome some of this impediment, but for true efficiency, a single axle is at a disadvantage. This dynamic, in part, is what led to the development of lockers for racers.
Multi-GroovesWith the principles of a locker and a spool stated, it is then understandable that a locker can provide a performance advantage by promoting multi-groove racing.
With a spool third member setup, running in one groove is usually the best you can get. Again, this is because both wheels are turning at the same rate.
But with a locker, running high or low in the turns becomes much more plausible because of the freewheeling action of the right rear wheel.
Lockers Screw Up Tire StaggerNot true. Stagger is still an important tool, but with a locker, stagger is actually slightly less critical because of the freewheeling action that takes place at the right-rear wheel under deceleration. That also means if a tire grows more than expected, a locker stands a better chance of accommodating that phenomenon over a single axle.
Lockers Are UnreliableOne of the myths that still have pockets of acceptance is that lockers are not reliable. But like many of today's race car parts, the state of design and functionality of lockers is very high.
From their inception, locker units have been tuned and tested to produce the product of today, which stand up to very substantial racing demands.
CostIt is a fact that lockers are higher in price than a spool. This is one of those times when a racer has to weigh the facts and options. It's true that running with a spool is less costly, but when you look at the advantage lockers offer in performance, it then becomes an issue of whether an investment in lockers would pro-vide an edge that's worth the extra cost.