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How Does A NASCAR Transmission Work? (Fully Explained)

Like any road car, NASCAR cars have a transmission system, and for decades, it remained the same. When the Next Gen car debuted in 2022, the transmission was one of several features to get a redesign. Knowing this, you may therefore wonder how a NASCAR transmission works on the Next Gen car. 

NASCAR’s Next Gen car has a manual, 5-speed sequential transmission provided by Xtrac, with a transaxle at the car’s rear. The sequential transmission allows for faster shifting via a push-pull lever, allowing the driver to push the lever to shift down, and to pull when shifting up. 

Below, we will elaborate on how the transmission works on the Next Gen NASCAR car. We will also discuss what kind of transmissions NASCAR cars use, who makes them, explore how they work, and finish up with explaining how NASCAR drivers can shift gears without pushing the clutch pedal. 

What Transmissions Do NASCAR Cars Use?

NASCAR cars use 5-speed sequential transmissions. This type of transmission offers several benefits, allowing NASCAR drivers to simply shift to the next gear in the sequence, making it harder to select the wrong gear, and much easier and faster to shift between gears. 

They are also safer than the old, H-shaped transmissions that were popular in NASCAR before they brought out the Next Gen car. The four-speed H-pattern gearboxes of the past did not allow drivers to shift gears as quickly, which affected the drivability of the cars.

Enter Xtrac

Before 2022, NASCAR rarely used sole vendors for its car components, but starting in the Next Gen Era, NASCAR has since outsourced many components single vendors, and the sequential transmission was no different. Longtime partner Xtrac got the nod to manufacture and distribute the gearboxes and transmission units, including the clutch shaft, driveshaft, and transaxle. 

Xtrac burst onto the NASCAR scene in 2002, so they are a familiar in the sport. Following NASCAR’s briefing in the late 2010s, Xtrac went on to develop the new sequential transmission to be Next Gen-ready. 

They came up with a rear-mounted, longitudinal P1334 transaxle, plus a controlled-unit gearbox, minimal ratio options also at NASCAR’s request, and one that can be adjusted as-needed at the track. Like many of the Next Gen car’s latest components, the transmission is meant to be cost-effective to make things easier for teams. 

Are NASCAR Transmissions Manual Or Automatic?

NASCAR has always used manual transmissions. Drivers tend to prefer this, since it gives them more control over their car’s performance. The Next Gen cars use a 5-speed sequential manual, but past generations used a 4-speed H-pattern gearbox. 

There are times where NASCAR drivers barely need to shift gears, since keeping the car in the highest gear is sufficient enough to complete lap after lap on the track. However, at shorter tracks with narrow turns and lower banking, or on road courses, you will see drivers constantly shifting gears given the varying speeds their cars are forced to accommodate to. 

NOTE: NASCAR drivers will also need to shift gears when they come into and leave the pits, and if they need to slow down for a caution period

The Transmission’s Role 

The basic role of transmissions is to transfer power from the car’s engine to its rear transaxle. Transmissions are in your road car, though you may rarely use them since many cars have automatic transmissions. 

This means your road car, depending on the situation in which you are driving, will automatically transfer the appropriate power from the engine and into the transaxle. You often only need to worry about shifting the car into drive and reverse. 

Some road vehicles have manual transmissions (which are more common outside of the US), meaning the driver must push a clutch pedal, then shift to the correct transmission to keep the vehicle running. This is similar to what you see in NASCAR, although most manual road cars will feature H-pattern gearboxes rather than sequential shifters.

When Drivers Need To Shift Gears

NASCAR tracks vary in length, ranging from 2.5 mile (4 km) superspeedways to half-mile (0.8 km) short tracks. At high-banked superspeedways like Daytona, a driver may keep their car in the highest gear during all green flag laps, shifting down only during a pit stop or caution. 

However, short ovals like Martinsville require the drivers to shift gears at every turn. One thing to note regarding Martinsville is that Xtrac uses what they call a 4-speed Martinsville cluster, given the track’s four low-banked, narrow corners. 

Road courses, with their many turns and lack of severe banking, provide a unique challenge to NASCAR drivers, and you will see them shifting gears frequently when they race at places like Sonoma and Watkins Glen. In the past, NASCAR predominantly ran at just these two road courses, but they have increased that number in recent years. 

Therefore, when NASCAR outsourced the transmission to Xtrac, they also wanted them to build the transmission with road course racing in mind. With the sequential transmissions, not only can the drivers shift gears faster, but it also lets them dive into both left and right-hand turns more smoothly than the old H-shaped four-speeds. 

KEY POINTS

• NASCAR cars currently use a 5-speed sequential manual transmission

• In the past, the gearboxes were 4-speed manual H-pattern setups

• NASCAR drivers shift gears a lot on road courses, but much less often on ovals

How The NASCAR Next Gen Transmission Works

If you look at NASCAR’s old gearbox, it had four points on each end of the H-shape, meaning the driver may have had to pull or push the gearshift out of one gear, pull or push the gearshift across the H (i.e. neutral), then push or pull it into the next gear. With a sequential gearbox, the driver pushes the shifter away from them to shift down, and they pull it towards them to shift up.

The five-speed transmission also called for a different transaxle layout, which resides at the car’s rear, and is combined into one unit. Given the engine’s position, this layout gives the Next Gen car more balanced weight than its predecessor, a combination that is present in some sports cars. You will also find two half-shafts that float on the Next Gen car’s rear suspension. 

Implications Of The New Gearbox

This redesign also gave NASCAR room to insert a full-length underwing, a new safety feature that allows the car to achieve 1,000 lbs (455 kg) of extra downforce. This helps the car suffer less when running behind other cars, and can lead to higher speeds in the corners, especially on road courses.

NASCAR designed the Next Gen car with an improved racing product in mind. This means that, although the cars are slower than their Generation 6 predecessors, the Next Gen car focuses more on the race itself. With a drivetrain estimated to be between 50% and 60% stiffer, plus the redesigned gearbox, the shift times with this new transmission are considerably shorter.

How NASCAR Gearboxes Allow Clutchless Shifting

When you look at a vehicle with manual transmission, you will notice three pedals instead of two, with a throttle, a brake, and a clutch. NASCAR cars are no different, and you may think that drivers shift gears the same way one would with a production car, by pressing the clutch pedal before shifting up or down. 

However, NASCAR drivers rarely use the clutch pedal and engage in what is known as clutchless shifting. Clutchless shifting, better known as rev matching, is a technique that allows a driver to match their engine’s revolutions per minute (RPM) with their car’s speed. Once the driver matches their RPM and speed, the gearboxes allow the driver to shift up or down a gear smoothly without using the clutch. 

There are times when the driver must use the clutch, and it occurs when they shift into first, the lowest gear. This explains the addition of, but limited use of the clutch pedal. And the clutch is often used for the parade laps, cautions, and when a driver first exits their pit box. So even if the clutch appears to be nothing more than an add-on, it is still used in specific circumstances.

KEY POINTS

• The NASCAR transmission is a sequential manual, rather than an H-pattern manual

• There is a clutch pedal, although many drivers will rarely use it

• Many drivers use a technique called rev matching to change gears

Final Thoughts

NASCAR transmissions are 5-speed sequential manual gearboxes from Xtrac. Drivers use this kind of transmission by pushing the gear stick to shift down, and pulling it to shift up. It offers faster shifting than the 4-speed H-pattern transmissions that previous NASCAR generations used.