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Transmission Spotlight: 6L80E/6L90E


Here is a six-speed automatic transmission that has been developed by General Motors. Both the 6L80E and 6L90E models are designed for all-wheel-drive vehicles that are rear biased and have a longitudinal powertrain orientation. Both transmissions are meant to conserve fuel, and each is controlled via a six-speed automatic transmission that is a quality successor to the SL family of transmissions.


6L80E/6L90E Transmission Overview

The Hydra-Matic transmission has a modular design, and it shares some components that allow it to accommodate varying torque levels, engines, and applications. Each of the versions that have been developed has a unique gear set that is configured to allow for a wide range of ratios when compared to a more conventional type of gear set inherent with many automatic transmissions today. This enables the transmission itself to allow for great fuel savings, while at the same time permitting the vehicle to accelerate nicely.

General Motors decided on a modular concept for these transmissions in order to allow for common components to be able to be used interchangeably, thereby allowing for tools to be used during the manufacturing stage that allows for four variants within the six-speed family of transmissions. All of the versions on the market today use three gear sets. This includes one gear set that is a simple input planetary design, while two are output gear sets.

Some of the applications do allow for Performance Algorithm Shifting. This type of shifting can sense how assertively a driver is using the output of the engine in order to make a determination as to whether or not an upshift or downshift is necessary based on the engine speed. There is also a Driver Shift Control that will permit the driver to actually shift the transmission, similar to that of a gearbox that is clutches and manual. There are electronic safeguards built into to keep the driver from over-revving the engine in the event that the incorrect gear is selected by accident.

One other interesting component with these transmissions is the Advanced Control System. This is what allows the temperature to stay constant in comparison to a module that is mounted on the body. Since the transmission and the module are actually assembled at the same time and together, there are not any additional steps required during the assembly process for the vehicle.


6L80E vs. 6L90E

When comparing the two transmissions, it is important to keep in mind that the 6L90 is more heavy duty than the 6L80, even though both are six-speed automatic versions. The former also comes with a stronger input gear set. This has two more pinion gears, which gives it six in total. The output gear set on the 6L90 is also wider than the 6L80, giving it more flexibility. The 6L90 also has one more clutch plate that can match up with the requirements of certain applications when necessary.

It is interesting to note that the 6L90E transmission does share roughly 75 percent of the same parts as that of the 6L80E transmission. The case on the 6L90 is a bit longer, and it can make use of more fasteners for the transmission and the corresponding transfer case. This tends to lead to better drive performance and less noise and vibration.

Which transmission you end up choosing depends on your vehicle and your unique needs. If you need a bit more power, you might look at going with the 6L90E transmission. If that is not something you are after, the 6L80E transmission will likely suit you just fine. Both are built for performance, and they will each give the driver the power they need to excel on both long and short journeys.

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Signs of a Bad Torque Converter

If you drive a vehicle with an automatic transmission, then chances are you have a torque converter and don’t even know about it. Of course, you probably wonder just what a torque converter actually is, simply because it’s not really a topic of a dinner conversation.

The best analogy for a torque conversion part would be that it is basically doing the same work that a clutch does in a manual transmission. This part will essentially keep the engine running when the wheels come to a stop. If this torque part does its job, you won’t even notice it. However, if it is going bad, then you will have some serious problems. Luckily, there are plenty of signs that will help you tell if your torque is going bad.


Signs of Torque Converter Problems

There are many signs that your torque converter is starting to have problems. One major concern would be engine overheating. If you are noticing that the temperature gauge is exhibiting strange fluid pressure, it could be a symptom of bad torque.

Another sign that this part is going downhill would probably be slipping. If you are driving along and you occasionally notice your acceleration dropping considerably, it could be a sign of this part going out on you.

If your vehicle appears to shudder when you are driving between 30 to 45 miles per hour, this could be another sign. If you have checked the engine fluid and there are large amounts of black materials present, that too could also be a sign your torque is faltering.

Finally, if it appears that it is taking the transmission longer to engage the engine and if you are hearing a number of strange clicking or revving sounds, then it might be time to replace a bad torque converter.


How to Test for Torque Converter Problems

In some older vehicles, you could do what is called a stall-speed test. In this procedure, you simply rev up the engine for no more than five seconds while you also have the brake pedal fully pressed down to the floor. Make sure not to do this for more than five seconds, and be sure to avoid this type of test with vehicles that have traction control or anti-lock braking system.

Another procedure would be to first let the engine warm up for about five minutes, then gently press on the accelerator while the vehicle is in the park position. Let the engine go back to idle and then immediately shift it into drive and listen for any abnormal sounds. Finally, take the vehicle for a quick test drive and see if there is any unusual sounds or lurching movements.


Causes of Torque Converter System Problems

Different parts can play a role in causing a torque converter system to break down.

First of all, one item to consider would be the needle bearings. If these bearings fail, it could cause some metal to metal contact and might make the whole entire system fail. A damaged torque system seal will usually mean that fluid will leak from the casing. If this happens, you can rest assured that your torque system will either overheat, slip or have irregular gear shifting.

If you have a damaged clutch, it can overheat the gears and make them stay in gear at all times, even when you don’t want them to be in gear.

Finally, if the solenoid malfunctions, it can cause an uneven pressure rotation in your torque system.


Torque Converter System Replacement

One of the trickiest things about repairing a torque converter system would probably have to be the fact that replacing it is often quite a bit less expensive than replacing it. Talk to your mechanic to discuss your options, but realize that a total replacement can often lead to a smoother ride in your vehicle and a system that is more durable overall.


Tips on Picking a Torque Converter

Finally, picking a torque conversion should be considered as well. In short, go for one that will have a maximum of 500-750 RPM’s. Finally, realize that most compact cars will do best with a 2400 RPM conversion system.


Keep this information in mind and you are sure to be wholly prepared if you ever have a bad torque converter issue with your vehicle.