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June 2020

Understanding GM 4L80E Transmissions: Earlier Models & Upgrades


4L80E by General Motors is one of the most popular four-speed automatic transmissions out there. First introduced in 1991, these transmissions went through multiple upgrades that go all the way up to the 2000s. As the transmissions evolved, we got introduced to different characteristics and physical differences. If you are on the market for 4L80E transmissions, you should know about the differences in order to get the right one for your vehicle.


The oldest 4L80E transmission model was manufactured between 1991-94. On the side of the transmission (on the passenger’s side), you could notice the two core line fittings. This was a major design problem, which would burn up the planetaries. The problem was fixed in the later models with a little change in the casting. A newer transmission model was introduced by GM in 1995 where the case was modified. There was an output line in the front and a return line in the back of the case which would go directly into the center support.


Early 4L80E automatic transmission designs had a short linkage shaft, which would just stick out of the case —an inch or so. The later designs had a neutral safety switch mounted on the side of the case, and the shaft was about three inches long.

Electronic Hook Up

Bolt-on harness was built into the earlier 4L80E transmissions but they were later replaced by a snap-on plug which is what GM used all the way up to 2000s. If you have an early transmission that has a screw-on plug, you can get a connector to rewire it to plug into the new switch.

Looking for 4L80E performance transmissions? Get them from Gearstar today! We can custom-build one to fit your need perfectly.

Performance Automatic Transmission Failure: 7 Mistakes to Avoid

Performance Automatic Transmission Failure: 7 Mistakes to Avoid - Gearstar Performance Transmissions

Performance automatic transmission failure may not spring up from thin air. Rather, this failure may be caused by our own making due to certain mistakes. You may have purchased a performance car or truck with one of the best transmissions or even carried out a rebuild.

However, these mistakes could impact on the lifespan of the transmission. Accordingly, we’ve outlined some mistakes to avoid while handling your performance automatic transmission. You’ll find these tips helpful whether you’re a racer or performance enthusiast.

Mistakes to Avoid When Handling Performance Automatic Transmission

Here is a list of things to avoid when dealing with your performance automatic transmission.

1. Using the Wrong Dipstick

It’s entirely possible to use a transmission dipstick that doesn’t take the right oil measurement. When that happens, you’ll be misled to believe that you have enough oil, when in actuality you don’t. Besides, the transmission pan’s width and length in comparison with its shallow depth show that even a quarter of an inch off dipstick reading can be bad. It could mean running your transmission on low oil, which has negative effects.

For starters, you could damage the transmission if you’re using it in a performance scenario with high demand for oil. On the other hand, you can ensure your dipstick gets the right measurement each time by examining the object yourself. You need to fit in the dipstick in place, drop the transmission pan, and then ensure that the full mark is even with the transmission case’s bottom edge.

And if you notice that the original mark on the dipstick is low, proceed to create a new mark on the dipstick. The mark doesn’t have to be something major, but obvious enough for you to spot it out anytime. Now that you have gotten a better-marked dipstick, you’ll get the accurate measurement of the transmission fluid.

2.  Lack of a Transmission Cooler

The regular vehicles come with a transmission cooler located in the radiator. While this cooler may be enough to dissipate heat in regular cars, if your vehicle is built for performance driving, then it needs an extra cooler. The same goes if your engine has been designed to handle high performance or features a higher stall torque converter.

The reason is, the original cooler may not offer adequate cooling to maintain the temperature in a viable range. And heat can lead to major issues in the car, which brings the need for adequate cooling.

To that effect, get an external cooler with a fan which will ensure there is a free flow of air through the cooler. Also, the ideal temperature range of operation for a good number of automatic transmissions is around 165 to 220 degrees.

3. Wrong Line Pressure

The Engine Control Module (ECM) is used by most new vehicles to regulate the transmission’s line pressure and the latter makes such adjustments easy. Tuners may also jack the line pressure up all in a bid to get better shifts, however, there is a need to exercise care. This is because a line pressure that is overly high can lead to hard shifts thereby ruining internal components.

There’s the GM 4L60E, for instance, whose input drum and the input shaft is aluminum and steel respectively. Consequently, the slam shifts of the transmission could crack the drum right where the two parts spline together.

4. Irregular Servicing of the Transmission

It is important to change the transmission fluid and the filter each year. The same applies even if the vehicle is driven irregularly or has been left idle for a long time. For instance, if you tend to use the vehicle on the weekends, the fluid needs to be changed at about every 12,000 miles. There are several reasons why regular change is important.

First off, the engine oil may break down after a while and therefore, not serve the purposes it was intended. These purposes include lubricating the transmission to reduce wear and serving as a hydraulic medium that enables the transmission to function.

The transmission fluid also absorbs heat generated within the transmission and then radiates the heat through the case of the cooler. It is worth noting that the transmission fluid will still serve its purpose as hydraulic fluid over time, but it may not lubricate or dissipate heat properly due to the breakdown of the fluid.

That aside, the filter has to be changed since mechanical parts wear out and create debris that contaminates the fluid. And changing the filter will allow more of this debris to be trapped without entering the oil. A change in the filter is even better than only a transmission flush. This is because the accumulated debris can be removed, thereby unclogging the filter to enable the free fluid flow.

5. Wrong Installation of the Transmission

It’s possible to have wrongly installed the transmission and even the torque converter. Nonetheless, a better approach to install the torque converter is to pour in some ATF into it enhance flow at the first start-up. A quart of fluid should be poured into the converter even before you install it in the transmission. After installing the converter, check if the dipstick reading is correct.

Alternatively, it is important to install the torque converter into the transmission fully before the transmission is placed on the engine block. And do not use force to tighten the transmission to the block by tightening the bolts of the bell housing. You’ll easily know that the torque converter has not been well inserted into the transmission if it won’t fit in place.

6. Bad Throttle Valve Adjustment

Transmissions like the 700R4 fail mostly due to the improper adjustment of the detent cable. The 700R4 uses a cable and fulcrum setup when stroking the throttle valve (TV) in a bid to adjust the line pressure. An increase in the throttle leads to a rise in the line pressure. Contrastingly, the 4L60E uses an electronic pressure control solenoid (EPC) to control the line pressure.

As the throttle increases, this valve causes line pressure to rise for more clutch holding power. Adjusting the valve the right way involves removing the pan and adjusting the cable. This adjustment will ensure that the gas pedal when it is pressed to the floor, the TV valve is completely stroked in.

7. Full Throttle Lockup

The tuner or dyno tester may hit the lockup at full throttle. This setting is not needful if you have more engine power, as well, as a lockup converter. You should not also have the expectation that one lockup clutch can easily handle more horsepower at full throttle.

There are also two options you can select from, and that is choosing between a triple-disc converter or hire a tuner to program the ECM to ensure that there is no full-throttle torque converter lockup.

The Bottom Line

Following the tips outlined above, you can avoid performance automatic transmission failure especially those that stem from mistakes. You’ll know just the right time to change the oil, replace the filter, adjust the line pressure amongst other things. Therefore, if you’ve spent heavily on a high-performance transmission, it can stand the test of time.

GM 4L80-E Transmission Swap Tips and Tricks

GM 4L80-E Transmission Swap Tips and Tricks - Gearstar Performance Transmissions

GM 4L80-E transmission swap tips are needful for anyone looking to revamp the performance of their transmission. The same goes if your ride is used for off-road and racing applications. These tips are from car enthusiasts and lovers of vehicles that can handle the high load that will be thrown at it.

Therefore, you’ll be relying on the most important tips and tricks out there, instead of trying just about anything on your transmission. In the end, the level of performance you’ll get will be more than impressive. With that in mind, here are some of our tried-and-true tips and tricks for swapping GM 4L80-E transmissions that you can try today.

GM 4L80-E Transmission Fluid Levels

If you’ve dedicated the time, money, and energy to your GM 4L80-E transmission swap, it is useful to ensure you have enough oil in it. How can you do that? It’s by using the correct dipstick measurement given that some of these units may not measure the right oil level.

Accordingly, if the measurement reads ‘full’, the dipstick has to be level with the pan rail. This is the case’s flat part where the pan bolts. Therefore, you can take this measurement with the dipstick mounted in the car. Here, you could get the transmission in and bolted to the cross member.

The next step is to drop the pan and assess the stick. Mark a new line on the stick if the right measurement was not gotten correctly. Now you’ll agree that this is an easier process that can save you from damaging your transmission in the long run.

Automatic Transmission Accumulators

It’s possible to block the third or fourth accumulators using a wide range of options. An option is to purchase an accumulator delete plate that will offer high-level performance.

This plate is also not so pricey and it comes with the promise of excellent performance each time. Another option is to resort to the stock accumulator housing and block the feed holes. This blockage can be done with the help of a set screw such as a 5/16″-18 tap and set screw.

It’s worth pointing out that the bore that lacks the pin is for the third accumulator whereas the hole that comes with the pin is for the 4th. Coupled with that, the 2nd accumulator is the case and there’s no need to block it.

GM 4L80-E Transmission Pressure Booster

The GM 4L80-E transmission pressure can be increased using a boost valve. In this case, if you’re getting less than 1khp to the tire, it’s useful to use a valve and sleeve while maintaining the stock pressure regulator spring. Contrastingly, you need to resort to the sonnax spring if the transmission is making over  1khp.

Transmission Snap Ring Enhancement

There’s another enhancement you can carry out and that is the improvement of the intermediate clutch snap ring. Although there is a stock ring, the latter may be too weak to handle the performance required.

Accordingly, settle for a snap ring from a TorqueFlite 727. since it has a level of thickness that will impact positively on your ride. Also, if the clearance is overly tight with the .106, you can opt for a thickness option of .088.

GM 4L80-E Transmission Valve Body Separator Plates

You could take the extra step to drill the plate separator since it can also up performance. Here, the 5/64″ (.078) is suited for lighter cars and even lower power units for 2nd gear. Also, the 3/32 (.093) is ideal for the heavy vehicles around 4k+ lbs.

The 3rd can be fixed in the 7/64 (.110), which is suited for most vehicles, When it comes high hp/heavy, you can resort to 1/8″ (.125) and the same can be said for the 4th. Needless to say, these numbers may vary from one car to the other.

On the other hand, it is worth pointing out that a bigger hole may result in firmer and faster shifts. And if the accumulators have been blocked, it’s ideal to settle for the smaller hole options since shifts will be faster and firmer due to the block on accumulators.

Once that is done, you should also consider replacing the electronics and harness. It’ll not cost an arm and a leg to get this replacement down and you can even replace the EPC solenoid. The latter is useful in controlling GM 4L80-E transmission pressure.

GM 4L80-E TransGo HD2 Kit

The TransGo HD2 Kit may not be the most ideal part to resort to. This is because it dual feeds the direct clutch while also increasing the line pressure. Also, the direct clutch is useful in the reverse gear and the third gear.

Coupled with that, there are two chambers in the apply piston for this clutch. And in the reverse gear, both chambers are used and it’s able to get full apply force. But when it comes to the 3rd gear, only one chamber is used, which helps in reducing the apply area and the holding power.

That being the case, dual feeding the clutch will enable the chambers of the apply piston to also resort to the 3rd gear. On the other hand, if you plan on removing the center lip seal of the apply piston, it may be needful to remove the 2nd sealing ring on the center support.

You may also have to connect the case passage with a 3/8 cup plug in. Likewise, you could tap the center support and install a set screw. And while at it, ensure that the set screw is linked below flush to prevent the non-sealing against the case.

The Bottom Line

Relying on the GM 4L80-E transmission swap tips and tricks above can help you create a transmission that will handle all the load posed at it. These tips can serve you anytime, whether you’re using a new or old transmission. The goal is to ensure you end up with a ride whose performance is impressive. Now if that’s what you’re out to get, try these tips.

3 Signs That Indicate Your Need for a Transmission Upgrade


While modern-day cars and trucks are very durable and can offer years of reliable service with the right care and maintenance, they do require major repairs as they age. The transmission, for example, might start giving problems and you may need to consider rebuilding or replacing it. Whether your transmission requires rebuilding or a complete replacement depends on a variety of factors. Here are 4 signs, apart from lit-up warning light, that show your transmission needs an upgrade-

  • Transmission slipping– When there is a problem in a manual transmission, it becomes harder for the driver to change gears, or the shifter just pops out of gear. In an automatic transmission, you experience transmission slipping while driving, or a loud thunk when you put it in the drive.
  • Fluid leaks– Pay attention to any puddles or stains underneath your vehicle and try to figure out where they are coming from. The fluid can travel across parts and the frame, making it difficult for you to determine its source. You can try placing a pan underneath the leak overnight and ask a mechanic to look for the problem.
  • Burnt smell coming from transmission fluid– It is important to keep a check on the transmission fluid to ensure that it is healthy for the system. It should have a transparent bright red color and a syrupy thickness. Check if there is a burnt smell or the fluid appears cloudy or brown. It may be a sign of a problem in the transmission.

If you found any of the above-mentioned signs, it’s time you repair or upgrade your transmission system to avoid costly damage. Whether you need Ford, GM, or Mopar performance transmission parts for a muscle car, pro-touring beast, modern performance machine, restoration project, or a daily-driver – Gearstar has got you covered.

GM 6L80E/6L90E Transmission Problems And Performance Upgrades Offered By Gearstar


Starting in the 2006 model year, General Motors released the 6L80E and 6L90E transmissions that developed several issues that tend to frustrate transmission as well as body shop technicians servicing them globally. In this blog, we will try to shed some light on these issues and how you can fix them.


  • The vehicle not releasing from “Park”
  • Transmission gear shift not moving to “Park”
  • Transmission randomly pops out of “Park” with no one in the vehicle.
  • A loud rattling sound when transmission engages reverse
  • Upon removing the transmission to change the filter, or doing any service to the transmission requiring a refill of the fluid, vehicle not wanting to move or engage the transmission in any range.

The plucking rod actuator assembly GM part number 24200173 has been known to fail and cause most of these concerns. Spring-loaded bullet ends slide off or develops a burr causing the rod to jam. When performing an overhaul, remove the rod and closely inspect for wear or damage. If the vehicle doesn’t move in any range, once you eliminate all other possibilities, the output shaft splines in the 6L80E transmissions or 6L90E transmissions may be stripped away.

Another common problem seen on most wheel drive cars and four-wheel-drive trucks is that moisture gets trapped on the spline and destroys both the trans output shaft as well as the transfer case 4-wheel drive unit splines. On the later versions, hydramatic put an O-ring on the shaft to address this concern. If you are servicing an earlier design shaft with no O-ring, and there is no wear on the splines, you can put an O-ring on the output shaft splines to counteract moisture.

6L80E/6L90E Performance Transmissions Upgrade

If you are looking to get the most of your vehicle with 6L80E /6L90E transmissions and considering a major trans upgrade, Gearstar has the best products available on the market. Our high-performance transmissions —including GM 6L80 (level 1 and 2) and GL90 — are built to the horsepower, torque, and rear gear ratio specs of the engine that it will be matched to. Also featuring a torque converter, the transmissions come with a complete master overhaul kit with new gaskets, seals, rings, and pistons. Wide inlet filter, bearing and bushing kit are also included. If we talk about the clutch, you get expanded capacity1-2-3-4, 4-5-6, 2=6 and3-5 low/reverse clutch packs with latest generation friction and steel.

Other important upgrades consist of:

  • Updated AC Delco pump cover (stator support), body (bell housing), and vanes with hardened rings
  • Hardened Rear Planetary Ass’y
  • Upgraded line boost valve and slide spring
  • Performance-tuned solenoid valve body with new ACDelco transmission control module

All performance transmissions offered by Gearstar are designed for optimum precision, durability, and custom-built by our master technicians from start to finish. They are DYNO-tested with torque converter (the equivalent of 100 miles) to make sure the package stays in perfect operating condition.

Apart from General Motors, we also offer top-quality Ford and Mopar transmissions. Let us help you with what you are looking for!