366 Locker Springs Detroit Lockers When you have the right spring rate in a locker, no differential works better. Why do I say that? All other differentials “split” the power to the inside tire & the outside tire by some percentage. Some are 75%/25%. Some are variable. Regardless, any power split other than 100%/0% is not optimum in the corner, off throttle. On track, with the hammer down, we want 50/50 power split to the rear tires. When we come off the throttle, brake & turn into & through the corner … we need one tire to be 100% completely disengaged … and the other to have full drive. (Remember, the power is off.) If one tire is not fully disengaged from power … like with a clutch posi or helical gear differential … we are contributing to a tight/push condition. We would have to give up suspension grip mid-corner, to make the car turn well, which would reduce our grip on exit, under throttle. When we go to the throttle, we don’t want 75/25 or anything other than 50/50. Only a locker is 50/50 under power & 100/0 when turning. That is optimum. It just requires the correct spring rate. Detroit Lockers come from the factory with a 78# spring, which is too stiff for most autocross & road course applications. My locker spring rate recommendations are:  9"+ Street Tires/8” Slicks for Street & Autocross: 40# AutoX-Star Locker Springs  12"+ Street Tires/10" Slicks for Road Courses & 1/4-1/3 Mile Ovals: 55# Track-Star Springs  12"+ Slicks for Road Courses & 1/2 Mile Ovals: 65# Track-Star locker Springs  10"+ Slicks for 3/4 to 1 Mile Ovals: 78# Factory Locker Springs  10"+ Slicks for 1-2 Mile Ovals: 85# Speedway-Star Locker Springs  10"+ Slicks for 2+ Mile Ovals: 110# Speedway-Star Locker Springs Locker Tuning Springs A ton of racers have dialed in their lockers & swear by them. A lot of “other guys” have tried lockers, had problems and swear at them. LOL This part is simple. If the spring is too stiff for the inside rear tire grip you have … and it won’t unlock in the corner … just about any diff is better. If you have the right spring & disengage one wheel through the corner … no diff is better. Hey! Here’s an idea! Let’s put the right springs in your locker!  Springs fit all lockers regardless of brand, exceot tiny 7.5” rears & lockers from the 70’s & older  You need two springs for a locker / They come as a pair / You’re set  These are not too hard to install yourself / But many shops will do it for $50 with locker in hand PLC Part # LOCKER SPRINGS Price RST 4404-40 AUTOX-STAR 40# RED/BLK LOCKER SPRINGS 99.99 RST 4404-55 TRACK-STAR 55# ORANGE LOCKER SPRINGS 89.99 RST 4404-65 TRACK-STAR 65# BLUE LOCKER SPRINGS 89.99 RST 4404-78 78# REPLACEMENT YELLOW LOCKER SPRINGS 89.99 RST 4404-85 SPEEDWAY STAR 85# PURPLE LOCKER SPRINGS 99.99 RST 4404-110 SPEEDWAY STAR 110# WHITE LOCKER SPRINGS 99.99 RST 4404-OLD65 65#REPLACEMENT OLD RED LOCKER SPRINGS 79.99 Drivetrain