What kind of differential does nascar use

A locking differential allows the two wheels to be locked together under certain conditions, but to unlock under other conditions. Advanced locking differentials may have viscous couplings , electrical or electromechanical mechanisms that control how well coupled the two axles are.

Despite being really neat ways of allowing a little slip but not too much , none of these types of locking differentials are allowed by NASCAR. NASCAR restricts teams to a particular type of locking differential that uses a mechanical means of keeping the two wheels.

The Detroit Locker has a mechanical sensor that locks both wheels together as if they were on a solid shaft when the car is going straight, but allows them to turn at different speeds when wheel slip occurs as happens during cornering. The locker locks both wheels together when they are rotating at the same speed. The locking differential is actually applying drive torque through the inner wheel as the car goes around the corners.

An unlocked differential provides the same torque to each wheel, but allows them to rotate at different rates. A locked differential forces each wheel to rotate at the same rate. This locking process, which is controlled entirely by mechanical means, is crude and often very loud.

The car basically switches between the drive coming from one and two wheels as the car corners, which can make the car handling unpredictable. Playing with the throttle often done to help the car turn can cause an unpredictable switch.

They also make a loud clicking noise when engaging or disengaging. Small differences in rear slip ratio can be achieved with tire pressure adjustments, but you can assume the rear slip ratios to be constant in this case. Upon throttle application, the rear eventually locks back up. During testing, we can run torque sensors on the axles, or, better yet, full-blown wheel-force-transducers.

This instrumentation accurately captures the locker behavior. If you watch for it, sometimes you can see it happen exiting the corners in qualifying at a few tracks. When Elliott Sadler qualified Josh was his crew chief at the time , we heard a very loud pop as Elliott was coming out of turn 2 on his first lap.

Now I know that this was the differential unlocking. No doubt it also helped explain why the No. If you are powering through a turn, it does not unlock and provides power oversteer. If you let go of that gas quickly, and it chooses to unlock, you better adjust to the loss of power oversteer FAST. That is all to say that I am continuously amazed at how smooth these drivers look in general with such a difficult piece of gear to control.

It really must lead to more wrecks than we give it credit for. Leo: Thanks for the insight. A spool ensures both left and right tires rotate at exactly the same speed. A spool gives you good traction accelerating on a straight line, but the handling of the car is compromised during turning. When going around a corner, the outside tire has to travel a longer distance. So, the inside is forced to rotate faster than it needs for the turn radius and hence spins. This causes stress wear on both tires and the drive train.

In terms of handling, this causes understeer when decelerating, and oversteer when accelerating. Spools are typically used in karts, drag racecars, some oval race cars and some road race cars. Notable road car examples on iRacing are the V8 Supercars. Open differential A completely open differential allows the left and right tires to rotate entirely independently.

This helps with turning. The open diff also allows more torque to be transferred towards the less loaded tire. This is quite unfavorable when one tire is on a slippery surface like mud, grass, ice or wet track markings, as the tire on the slippery surface will end up spinning, consuming most of the available engine torque. First, for some background. Our first view of the new car came at Richmond Raceway back in October when Austin Dillon tested it and shared a few pictures of the car.

Based on those pictures, it was readily apparent that the wheels were indeed bigger, as NASCAR had announced, and that some aerodynamic tweaks had been made: a stepped splitter on the front end of the car, a new design for the side skirts, and the addition of a large rear diffuser.

The second test was completed more recently, and we got a much better view of the car since NASCAR stripped off the camouflage and released a bunch of pictures of it.

The shifter can be tapped forward and back in order to change gears and it has a lockout handle on the front that, when engaged, allows the driver to shift into reverse. We can also see the linkage leading from the shifter going towards the back of the car. Because of the way the shifter linkage is mounted, we can also deduce that the sequential gearbox is most likely packaged as a transaxle in the back of the car.

We took this information and spoke with a variety of engineers and technicians who work for suppliers that produce sequential gearboxes.

Though these representatives wanted to remain anonymous, they did confirm that this new car is running a rear-mounted six-speed sequential transaxle. While multiple vendors were in the running to supply the new unit, options from vendors such as Albins and some local shops in North Carolina no longer appear to be in consideration.

We heard from vendors that Xtrac will likely be the chosen supplier, and that a unit from Xtrac is currently being tested in the car. Luckily, Xtrac had an example of this transaxle on display at PRI, so we took a closer look. This transaxle unit is very compact and weighs less than pounds in its standard configuration. In the Supercars configuration, it offers sequential selection of six gears and supports up to pound-feet of torque. This rating is probably based on the maximum torque produced by the Supercars engines and likely has a built-in margin of safety.

The Xtrac P transaxle uses an aluminum case that contains a cassette-type gear cluster, spiral bevel gear final drive, and tripode output flanges.