Jeep 6-Speed Manual Transmission Problems – Good or Bad Gearbox?

Jeep vehicles are top-rated among American drivers. The carmaker has also made a name for itself across Europe, Asia, and any other part of the globe you can think of. Jeep has had its fair share of troubles in its journey to becoming one of the greatest car makers in history.

Jeep 6-speed manual transmission highlights

• Average lifespan:250,000-300,000 miles
• Reliability Score:High
• Prone to minor issues:No
• Price for repair after failure:$500-$900
• Price for replacement:$1,200-$2,300
• Availability of parts:Average
• Common problems:clutch failure, hard shifting, noisy bearing at high mileage.

The Jeep 6-speed manual transmission

The Jeep 6-speed transmission has a long history and has been reliable over the years. Jeep picked the NSG370 transmission in 2005, initially sourced from Mercedes. This is an overdrive transmission and is used on several vehicles like Wrangler TJ and JK, Liberty, and Dodge Nitro.

The Jeep 6-speed transmission is longitudinally loaded and boasts an overdriven 6th gear and a direct 5th gear. The top-shifting transmission comes with helically cut gears for all speeds.

The Daimler-made transmission weighs 89 pounds and has an overall height of 18 inches. The case is made of aluminum and doesn't come with a PTO port, but it boasts an input torque rating of 272 ft. lbs. Another key feature of this transmission is its x-to-1 gear ratio and a total fluid capacity of 1.9 quarts. Depending on your car model, the output torque will range between 1100 and 1300 ft. lbs.

The NSG370 transmission can be equipped with the NP231, NP241OR, or NP241J transfer cases. It has a 23-spine spline output shaft, making it compatible with the 23-spline version of the aforementioned transfer cases. The transmission is compatible with Jeep 4.0L I6 engine, but it should be equipped with the proper bell housing. A 3.8L V6 will also go well with the NSG370 transmission. The NSG370 transmission also has its gears fully synchronized.

What are the Jeep 6-speed manual transmission problems?

The Jeep 6-speed manual transmission has some problems that every prospective buyer should consider before buying. This is especially the case for used Jeep buyers. Knowing these issues also helps the owners of these cars handle the said problems effectively. Here are the issues;

1) The clutch pressure plate failing

Jeep Wrangler and Gladiator built between August 2017, and January 2021 are likely to be affected by this problem. The pressure plate of this vehicle, bolted to the flywheel, exerts pressure onto the clutch disc. The clutch pressure plate tends to overheat and can even break, which can then cause the clutch disc to rapture. In severe cases, the clutch disc can start a fire.

This was a serious issue because it affected tens of thousands of Jeep vehicles. Jeep issued a recall notice in 2021 for a total of 42,000 jeeps equipped with the 6-speed manual transmission. Of the 42,000, 36,692 Jeeps were manufactured between 2017 and 2021. According to Jeep, drivers can smell a burnt clutch smell just before the clutch fails.

The solution

Jeep came forward and issued a recall for the affected vehicles in 2021. The company said in its recall notice that the problem wasn't the pressure plate but a software failure. All the transmission components work all right, but a software malfunction is the one causing the pressure plate to overheat and subsequent failure.

For all the affected vehicles, the Jeep company advises drivers to visit an authorized Jeep dealership. The technician will add software which ensures engine torque capability is reduced when the clutch assembly temperatures rise and reach a certain point where damage to the pressure plate happens.

2) Gear shifter popping out of 1st gear

Jeep Wrangler owners, particularly the Wrangler JK, have reported the gear shifter popping out of the 1st gear. Some drivers say this mainly happens when pulling away from a stop.

The solution

An effective solution to this problem is to pull out the gear shifter knob and remove the gear shifter boot. This is best done using a simple screwdriver. You will find an inner boot. According to an online video that addresses Jeep issues, one can solve the problem in their home. The problem was caused by the inner boot getting unhooked from its position and part of it moving between the shifter and housing where the first gear is.

This then prevented the shifter from going all the way into the first gear. You should put a carpet-like piece to serve as a cushion to prevent the stick from burning the inner boot and also keep the noise down that is usually associated with the problem.

Even though the above-proposed method does the trick in many instances, there are cases where the problem is in the transmission itself. In another online video, the problem was solved by replacing the shifter. Visit the nearest Jeep dealership and have the issue looked into further if your diagnostic tricks hit a wall. Remember that besides replacing the 1-2 gear synchronizer, you should replace the snap ring.

3) Popping out of reverse gear

There have been several complaints from Jeep drivers of the reverse gear popping out. The problem is similar to the gear shifter popping out of 1st gear. On the gear shifter, you find that the 1st and the reverse gear are on far opposite sides. The same issue of something likely blocking the 1st gear from fully engaging also applies to the reverse gear. It is worth noting that you are more likely to experience this problem after doing a body lift.

The solution

The solution to this problem is more or less the one applied when the 1st gear pops out. Remove the outer boot of the shifter and the inner one as well. Move the shifter into reverse gear and see if the stick is touching or hitting anything. Also, check whether the inner boot has moved out of position. The inner boot may require cutting to ensure the shifter fits perfectly. Where the issue is with the shifter itself, you need a new reverse gear assembly.

4) Premature wear and tear of internal transmission parts

The manufacturer of the NSG370 has used bronze synchronizer collars hence making the transmission overly sensitive. For drivers who use ordinary over-the-counter lubricating gear oil such as Pennzoil synchromesh, they may experience premature wearing out of the transmission components. This transmission only uses MS-9224 gear oil. This is necessary to avoid premature wear and tear and keep the warranty valid. Using the wrong gear oil can cause a lot of gear-shifting problems too.

Tricks to make your manual transmission Jeep last longer

To get the best value out of your 6-speed manual Jeep, you should follow a number of rules. A well-maintained transmission means a smoother ride for you, and you are less likely to be stranded due to transmission issues. These are the tips to help you get the best out of your Jeep;

• Use the correct gear oil - As stated earlier, always use MS-9224 gear oil. Remember, the NSG370 has sensitive bronze synchronizer collars that get damaged when the right oil is not used.
• Check the gear oil levels - Confer with your owner's manual on when to check gear oil levels. Many technicians will advise that you check yearly, though.
• Avoid stepping on the brake unnecessarily - Always resting your foot on the brake pedal makes the engine and the transmission overwork, and this causes premature wearing out of transmission parts.
• Use the right gear - Understand the correct gear ratio of your Jeep to avoid overworking certain gears over others.
• Make proper use of the parking brake - Parking prevents the vehicle from rolling down a hill. When parked downhill, use the parking brake and engage the reverse gear as an additional precaution.
• Towing can cause problems - Even when done right, towing causes a lot of strain on the transmission of your Jeep. Check the recommended tow weight in the owner manual to avoid overstraining the transmission. Towing causes the transmission to overheat, and over time this can cause many issues on your vehicle's transmission.
• Let the car warm before driving off - When you start your vehicle in the morning, let the engine run for a minute or two before driving off. This should be the case during winter. Cold oil is viscous and will not move as required to the engine and transmission parts. Idling the car makes the oil flow easier and allows it to reach all the transmission parts.

Conclusion

The 6-speed manual transmission Jeep is reliable and will handle all manner of terrains you can think of throwing its way. The rugged exterior of the Jeep complements superbly with the sturdy manual transmission. The transmission problems faced by users of the NSG370 are not severe.

Though irritating, these problems are easy to solve. The cost of solving this problem can be anything from 50 bucks to $1,000 if the shifter needs to be replaced.