When it comes to GM’s heavy-duty light trucks over the last 20 years, two things have remained constant, the 6.6L Duramax and the Allison transmission. While they have been refined over the years, there is no denying this combo has proven itself to be one of the best light truck drivetrains on the market. Simply put, they are reliable workhorses that get the job done day in and day out.
Even though the Allison 1000 has proven itself to be a capable transmission and will last a few hundred thousand miles when properly maintained, high horsepower and frequent heavy towing will take their toll over time. At Merchant Automotive, we have seen this time and time again, which led us to create our Merchant Maximum Transmissions for severe work and track use and suffice to say, it will be the last transmission you will need for your truck.
Why Does General Motors Use Allison Transmissions?
Allison Transmission is the world’s largest manufacturer of medium and heavy-duty transmissions, and they didn’t reach that level by making a sub-par product. Simply put, they are known for their engineering and have an established reputation for producing durable transmissions. It should be noted that when the Duramax debuted in 2001, Allison was owned by GM, so keeping it in-house was a logical choice. Likewise, the Duramax was considerably more powerful than the venerable Detroit Diesel it replaced, so a stronger gearbox was needed.
Suffice to say, the Allison 1000 was a leap forward over anything Dodge and Ford had to offer, and it became the envy of the competition. Like the Duramax, it featured a lot of new techs for the time and was without a doubt the most intelligent transmission when it debuted. Likewise, the first versions used behind the LB7 and LLY had five gears (6 for the LBZ and later) for better fuel economy.
Other features were an advanced transmission control module (TCM) that optimized the shift points and improved fuel economy. Simply put, it was strong, durable, and relatively maintenance-free aside from changing the fluid. When properly maintained and not abused, the Allison 1000 will, in many cases, last for the life of the truck.
As the Duramax has evolved, most notably with the LBZ and LML, the Allison received appropriate upgrades to handle the extra power. However, as a credit to its design, it has remained relatively unchanged, even as the new emissions standards took effect in the mid-2000s. In fact, the most significant revision occurred last year when a 10-speed version debuted.
As with most things in the auto industry, fuel economy standards and tighter emissions laws have been behind many recent changes. However, the Allison 1000 is not bad in any way, and it took the competition years to catch up. With that said, the Duramax and Allison transmission are probably the best drivetrain combo that you can find on any light truck today.
Why Do You Need a Transmission Upgrade?
There is no doubt that the Allison 1000 is an excellent transmission, and it can handle some extra power without an issue. However, we all know the Duramax responds well to modifications, and stock is not enough for many owners. While the Allison was revised several times, most notably after the power increases to the LBZ and LML, aggressive tunes and bigger turbos are more than the stock unit was designed to handle.
It should be noted the same holds true for any diesel truck regardless of the make, aggressive tunes and bigger turbos will drastically reduce the transmission’s life. This is especially true if you have a higher mileage truck, you will find yourself needing a Merchant Maximum Transmission sooner than later.
Now you are probably wondering what the breaking point of the Allison 1000 is. As it has been upgraded over the years, we have broken it down by model below:
- 2001-2005 LB7/LLY: The 5-speed version was the weakest of the lot, and generally speaking, 350-400 rwhp or about 100 over stock is usually the limit in terms of reliability. Generally speaking, this is anything beyond a moderate tune and some supporting modifications like a free-flowing exhaust and a cold air intake.
- 2006-2010 LBZ/LMM: Aside from having a sixth gear that improved fuel economy, the Allison received upgraded internals that mirrored the LBZ’s extra power. It did not really become a liability until the 450 rwhp mark.
- 2011-2016 LML: As the LML received a sizable boost in horsepower and torque, the Allison was strengthened to match it. It also featured a more advanced TCM and was generally able to handle 500 rwhp without much issue.
In the end, it comes down to how you drive your truck and how well it is maintained. Likewise, a transmission with 100,000 or 200,000 miles on it will not handle the extra power like a new one. Adding an extra 100 horsepower will put additional stress on the transmission and wear the internal components like the clutch packs or torque converter even faster.
Suffice to say, the transmission will be on borrowed time, so if you plan on modifying your Duramax, one of the first upgrades should be a Merchant Maximum Transmission.
What Makes the Merchant Automotive Maximum Transmission Better?
While the Allison 1000 is an excellent transmission, heavy use will cause it to give out sooner than later. Frequent heavy towing puts more stress on a transmission, especially if you are running higher boost levels. Lastly, if you want to go over 500 rwhp or compete in sled pulls and drag racing, an upgraded transmission is a good starting point as a stock unit was not designed for that type of driving.
What is the Merchant MAximum Series, and what makes them better than a stock unit?
MAximum Work Series
The MAximum Work Series is the perfect pairing for anyone that frequently hauls a load or plans on adding some extra power but wants to retain the feel of a stock transmission. All of the Work Series start as cores that are thoroughly inspected and tested.
In addition, we installed some upgraded components such as friction materials, hydraulics, and a dyno-tested valve body. Likewise, a higher capacity deep sump transmission pans and a single-disc billet torque converter. The end result is fewer torque converter failures and better lubrication for the clutch packs.
MAximum Pro Series
If you are making more power (or plan to do so in the future), the MAximum Pro Series should be the next mod on your list. Like the Work Series, new bushings, bearings, seals, and a dyno-tested valve body are installed, along with some extras like heavy-duty clutches and hydraulic upgrades. In addition, a triple-disc torque converter can handle all of the power your Duramax can throw at it.
For sled pulling and track use, stronger billet input/output/intermediate shafts can be installed as well. Lastly, all MAximum Work and Pro Series transmissions came painted in orange, are fully assembled, and ship with 24 quarts of fully synthetic Dexron VI ATF.
Whether you tow or compete, the MAximum Work and Pro series are a pair of bulletproof Allison transmissions. No more self-destructing torque converters, or worn-out clutches. They can be built to custom specs and are available for all 2001-2016 GM vehicles that came equipped with an Allison transmission.
Merchant Automotive: Leaders in Allison Transmissions
At Merchant Automotive, we know two things: Duramax engines and Allison Transmissions. Having been in the business for over 17 years, we like to think of ourselves as experts. While the Allison 1000 is an excellent transmission, it has its limits once you start turning up the boost. We know more than anyone that stock is not good enough, and this is why we created the Merchant MAximum Transmissions, which are fully rebuilt in-house by our Allison Transmission specialists.
We stand behind our MAximum series and use them in our own rigs, including our 1,700 horsepower UCC competition truck. Whether you are looking for something for the daily grind or for your 1,000 horsepower drag truck, we have you covered, and they can be custom-built to spec. Simply put, the Merchant Work and Pro Series is the last transmission you will need to buy for your truck.
