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June 2019

Getting Back to the Basics of Torque Converters

Torque Converters: Getting Back to the Basics - Gearstar Performance

Cars have come a long way from not only offering high horsepower, low emissions, but driveability which was once a bone of contention. These days, fuel economy, power, and speed can be found in auto shift-cars and for those who may have had a hard time abandoning their gearshift, there should be no second thoughts given these enhancements.

However, to get the benefits from today’s technology, you need to select the right torque converter for your automatic. This is because a torque converter does not only link the engine to the transmission, it tunes the connection to give the most power while minimizing heat.

The power of driveability and reliability lies in its hands and as such, choosing the wrong torque converter can twat your dream of a stout gear-bangin’. For this reason, if you have plans to speed up your car and get some fuel mileage irrespective of the shift pattern you’ve settled with, then it begins with falling back on the torque converter basics.

What Is a Torque Converter?

A torque converter transmits the engine’s torque to the transmission which enables you to move along the road. What this means is that it connects the power source to the load by transferring rotating power from a prime mover to a rotating driven load.

Torque converters can be found in automatic transmission vehicles and as such, they replace the clutch in manuals.

How Torque Converters Work

A torque converter’s mode of operation is similar to fluid coupling because it multiplies torque when the rotational speed is low to the point that it allows the fluid that is coming off the curved vanes to deflect off the stator.

A quality converter will minimize stall in other to prevent slushing that may lead to overheating. It can also ensure that the right power band is selected to get you into gear and the stall required is used to enable you to halt when necessary.

Major Parts and Components

The major parts you’ll find in a torque converter are impeller or pump, turbine, and stator or reactor.

The pump is similar to a centrifugal pump and it has several longitudinal fins which help to move the fluid around its outside diameter to the turbine. The turbine is connected to the drivetrain through the input shaft of the transmission and as this component moves, so does the car. The stator, on the other hand, is the fluid director and what it does, is to change the fluid flow between the pump and the turbine.

The Must-Knows

Engines and transmissions have evolved over the years, and so have torque converters that aid in the functionality of the duo. That is why you will find a number of high-end street cars today powered with the same converter that was once considered race-only converter. The latter are converters that use the same technology as steel stator designs to give them the strength to withstand the applications they are used.

Now that’s out of the way, here are some ways on how to speed up your car using the torque converter basics. Today, there are great cars with a promise of high horsepower, speed, and fuel economy, however, car enthusiasts’ expectations for these cars have also soared.

To meet these expectations, there are a number of torque converter basics that can give your car an edge in the competition with millions of others out there. The goal is to aim for the right torque converter, and not just one that is a perfect fit between the engine and the transmission. Accordingly, the basics you should keep in mind are:

Use quality fluid and filter to service your unit.

The use of fluid and filter of good quality can never be overemphasized since it can help to combat excess heat. One thing you may want to be on the lookout for is the amount of heat produced by your car since it could affect how long it services your needs.

Use a cooling system for your transmission.

A cooling system will also help to regulate your engine’s temperature and prevent overheating. Keep in mind that no matter the quality of torque converter you settle for, more priority has to be given to combat heat. Thus, this calls for a cooling system to be paired with quality fluid and filter.

Provide all the necessary information to your technician.

Torque converters may strive to achieve the same purpose, but they are not all built to fit the same car.

Your car being the same as your buddy does not mean that you can use the same torque converter as them since no two cars are the same and one size cannot fit them all.

At this juncture, it is good to know that there are companies that specially design torque converters to fit how the car will be used and the driver’s needs.

These companies have tech lines which you can use to reach out to them to provide as much information as possible about the torque converter you need to be built.

Remember, information can never be enough and the most important include rear end gear and tire size, camshaft specs, and engine size.

Use a lock-up converter.

For reliability, increased fuel mileage, and driveability, a lock-up becomes needful.

It can greatly reduce the transmission’s heating issues as a result of too much slippage from a higher-stall converter.

You’ll find a lock-up converter in an overdrive-style transmission and the converter features a clutch that when engaged, creates a near direct drive effect.

What this does is reduce slippage to a minimal level irrespective of the stall speed which, in turn, helps to combat the heat that could potentially kill the transmission.

Consider the camshaft.

Camshafts and converters have a close relationship and they may be helpful in selecting the right converter.

A camshaft can greatly determine the powerband of the engine combination and as such, it plays an important role in helping you select the converter.

Matt Kehoe from B&M, for instance, outlined that before its company can provide accurate converter recommendation, they need to know the exhaust and intake duration at .050-inch lift.

In his opinion, a 2,000 or 2,400-stall converter is a good choice when one considers cam duration up to 248 degrees.

On the other hand, a 2,400 or 3,000-stall converter is a better option for cam duration up to 268 degrees while a 3,000 to 3,600 stall converter is a good way to go for advertised cam duration over 272 degrees.

These values may look vague, but what they actually mean is that to get optimum performance, you need a torque converter with just the right amount of stall that will not generate heat.

There’s also the benefit of allowing the engine to sit idle in gear especially if a stock camshaft is used.

Determine the right stall speed, then choose wisely!

We’ve stressed the need to get the right stall speed in order to prevent overheating, but it might be difficult to ascertain when the stall is right.

That’s no longer the case when you consider a number of factors. The first is determining if your car currently has the right stall speed by determining:

        • If your car clunks when its put in gear.
        • If it slips when accelerated on the highway.
        • If it heats excessively after being driven for long.

Research all your power-adder predicament options.

Performance-enhancing add-ons such as blowers, turbos, nitrous, etc. have a unique torque curve which varies depending on the type of power adder. As a result, if you plan on using any of these, then you need to ensure that your torque converter of choice has been customized to meet that torque curve.

Bringing Speed and Drivability to Your Ride

These torque converter basics will ensure that you get a unit that is just right for your car which is one that can provide optimum performance. You will also be able to determine if the camshaft in your car is the right one and if there are needs for a replacement. It all boils down to this: there are important factors you need to consider before settling for a torque converter that will make you enjoy every minute you’ll spend on the road.

The Bulletproof Ford AOD Transmission

Bulletproof Ford AOD Transmission - Gearstar Performance Transmissions

There is the Ford AOD (automatic overdrive) transmission on one hand, and the Turbo 400 (TH400), on the other. However, car enthusiasts may be quick to settle for the Turbo 400 due to the popular belief that it is the king of performance transmission.

Nonetheless, a good number of car fanatics who have been in the game for decades think otherwise. They are even confident that the Ford AOD transmission can be the performance transmission of the 21st century. It may also be worthy to note that they are not just all about talks because certain manipulations to the AOD can turn it into a sturdier transmission with the benefit of Overdrive which can be a strong competitor with the TH400, and maybe even overtake it.

But why the Ford AOD, one may ask? We’ll get to that shortly!

The Advent of Ford AOD Transmissions

The Ford AOD transmission was evident in cars like the Mustangs, Fairmont, and LTDs around 1980 and 1993, and it was quite unique even though not in a really good way. For starters, it uprooted the Second gear in the shift pattern which left the latter dwindling in the gory land without remarkable performance. While many have pointed out that it was in a bid to curb the cost, it still had a huge effect.

On the contrary, one could still access the Second gear in a manual but that came with a headache of its own. First, you’d need to engage the lever into Drive before moving it to First gear. The result was at the expense of your bands and clutches. The Ford AOD transmission shifting problem, therefore, gave it its unreliable performance reputation.

Nonetheless, it wasn’t all bad things since there are features that will enable the Ford AOD to become a bulletproof transmission some car fanatics have been talking about all the while.

Advantages of Ford AOD Over the TH400

Unarguably, the TH400 is the king of performance transmission, but a closer look at the Ford AOD shows that it comes with more than it lets on. If these features are taken advantage of, then it can potentially offer the level of performance more than what a person would have ever believed it could.

Here’s what it looks like:

1. AOD’s lighter weight compared to the TH400:

The Ford AOD Transmission is 30 pounds lighter than the TH400 because it features an aluminum valve body and also offers a lightweight center support section.

2. AOD’s lighter rotating mass:

Another thing to point out is AOD’s rotating mass which is 4 pounds lighter than the TH400 and its diameter which is 1-inch trimmer. You don’t believe us, then compare the 6 3/4 inches of the TH400 with that of the 5 3/4 inches of the AOD and then do the math.

3. Sets of planetary gears in a single carrier:

Not to burst your bubble, both sets of the AOD’s planetary gears are embedded in a single carrier. On the contrary, you’ll find two sets of planetary gears as well as two carriers on the TH400. The difference between either comes with several benefits but this time around, the AOD is the clear winner.

4. AOD’s thinner pump gear:

The AOD’s pump gear in comparison to that of the TH400 is thinner. You may be wondering, how is that an advantage over the Turbo 400? The thing is, the thinner gear pump helps to reduce the drag for particular line pressure. You can also look forward to a beefier intermediate sprag on the AOD.

So with all these benefits, what’s the way forward? Read on and you’ll soon find out.

Limitations of the AOD

In order to understand what the AOD can achieve with some upgrade, it is useful to know what it can currently do and to what extent.

First, even the best Ford AOD transmission screams unreliability and that can be attributed to several reasons. AOD moves between the Drive and Overdrive in traffic which does not really speak of safety. Another bone of contention is its complicated twin input-shaft system. This system’s mode of operation is one where the outer shaft controls the First, Second, and Reverse gear clutches using the torque converter. On the same note, the inner shaft which is driven directly off the engine plays a role in controlling the Overdrive. Finally, the Third gear is divided between two shafts, where 60 percent is concentrated in a small inner shaft that is susceptible to breakable.

The setup of this system allows only 450 hp to be supported before it finally gives way to breakage. If you’ve been able to get a sturdier single-shaft arrangement which prevents the converter from locking up while in the Third and Fourth gears, then you would’ve successfully boosted the AOD into the 600hp range.

However, some car fanatics may not be totally satisfied with fixing the single-input shaft or settling with this range and may be looking at some around 1,000 hp and even more. But let’s see what the fuss is all about.

Improving the Ford AOD’s Transmission Reliability

A real-life scenario has shown that a good knowledge of the AOD transmission and valve body engineering can go a long way in improving the Ford AOD’s transmission reliability. Think of it as a transmission rebuild, but something less complicated.

An instance is the case of Len Bertrand, a car expert who has employed an AOD, the Ford parts catalog, and valve body re-engineering to create a transmission that can support over 1,200 hp. How did it come about?

1. Re-engineering of the valve body:

The first thing is a re-engineering of the valve body to engage the Reverse and Third clutches at the same time when the AOD is in its Third gear. As a result, the stress on the small inner input shaft is reduced.

2. Locking the Reverse sun gear to the Forward sun gear:

Another modification is in the forward sun gear. Instead of locking only the Third-Fourth planetary carrier to the forward sun gear, the Reverse sun gear can also be locked to it. What this does is to enable the transmission to trigger the beefy end of the input shaft.

Benefits of Modifications

With these two arrangements in place, you can get a 58.5 percent more clutch area in comparison to the TH400 just by using this setup. That being the case, you can also look forward to twice the power potential of the Turbo 400 which is suitable for street and race applications. And hey, you may have successfully eliminated the problem of the AOD bopping into the Drive and Overdrive which in traffic. Pick a gear and you’ll be sure that it’ll stay there. In addition, you will be able to upshift automatically and manually depending on what you’re out to get and not because you have been limited on an auto box.


The bulletproof nature of the Ford AOD transmission can be unraveled just by knowing the right buttons to push. When that has been put in place, you can boost its performance from about 400 hp to as high as 1,200 hp which makes for excellent speed while racing. There’s also no longer the option of whether to settle for a manual or automatic just to be able to upshift since either can now ensure that you can. What’s even better, is the potential the Ford AOD has in overtaking the TH400 performance transmission.

Essential Tips When Choosing a Performance Transmission Technician/Shop

Choosing a Performance Transmission Technician - Gearstar Performance Transmissions

Have you ever found yourself wondering how to find the best performance transmission technician or shop out there? We know we have at some point. Like us, you may have also realized that performance upgrades don’t come cheap especially when you consider the fact that you could be spending around $1000 to $4000, if not more. The money might be the least to worry about when there’s also the potential of ending up with an engine or trans that is worse off than what you began with. These risks and many more can be averted by arming yourself with some essential tips when choosing a performance transmission technician/shop.

But wait a second; unlike local transmission repair shops, you’ll be focusing on technicians that can make your car use its power optimally in order to give high-speed and long distance driving. You also need a trustworthy professional who can handle the heart of your car to give you satisfaction and worry-free.

So, how can you find a good performance transmission shop? Read on, we’ll tell you in a bit!

Who Is a Transmission Technician?

Transmission technicians are also known as mechanics. They focus on the diagnostic, repair and maintenance of couplings, hydraulic pumps, as well as gear trains of transmission systems. These car experts that are believed to know automobile transmissions like the back of their hand and as such, they can easily spot out the problem and its possible solution. Therefore, the job in itself is quite important because, without the transmission, the car will not start. That aside, mechanics, work in an auto dealership, auto repair shop, or a specialty transmission repair shop.

Tips to Consider When Choosing a Performance Transmission Technician/Shop

Unarguably, there are several honest, reliable, and independent transmission technicians who are not just out for what they can get out of your wallet. On the contrary, there are some that are only out for what they can get from you.

But how can you tell the difference? By giving the tips we’ve outlined below your utmost consideration before taking your car to a performance technician or shop.

1. Get Recommendations

Unarguably, there are performance transmission shops near your location, however, you are not just going to settle for just about anyone. A better option is to rely on the experience already garnered by your family, friends, colleagues and other mechanics. Give or take, they may have also employed the services of the shop either for a transmission repair, brake repair, or some other services. Thus, they can point you to a professional technician or shop and also recommend shops with fair prices and good customer service.

2. Use a Shop Linked to Larger Company or Association

After getting a reference from family, friends, and online sources, you may want to take the extra step to check if the transmission shop is linked to a larger company or association through its certification since it may go a long way to show its credibility. That being the case, you need to consider if the technician has been certified by the National Institute for Automotive Service Excellence (ASE). If so, it goes to show that they took the extra step to guarantee customers of their professionalism. On top of that, you can be on the lookout for technicians that have been certified by the Automatic Transmission Rebuilders Association (ATRA). ATRA is a test for transmission specialists and the difficulty that comes with obtaining it means the technician/shop has been rigorously examined.

Now if the shop meets either requirement,  you may be more confident that your car is in the right hands.

3. Use a Vocational School

If you still want the best performance upgrade for your car transmission and your budget is not really on the high side, finding a vocational school can also be helpful. Here, you’ll be relying on the expertise of students who work under a certified teacher to enhance your car’s acceleration. A school of this nature comes with the perk of lowering the cost even though it may take a longer time to have your transmission worked on. Therefore, if you’re not in a haste and on a low-budget, but still want a considerable amount of work to be done, then vocational schools and colleges will be a good choice.

4. Get an Estimate

If you’ve planned on settling for a particular car repair shop, then it would be a great move to get a written estimate from the mechanic even before work begins. What this does is to insure you against fees which may spring up by surprise. The good thing here is, a mechanic cannot add additional cost to what was already estimated since it is illegal to do so.

Now, an experienced transmission shop will be able to ascertain how much is required to boost your car’s performance and then give you a rough estimate of the cost of the parts and labor that will be needed for the enhancements.

5. Avoid Cheap or Overly Expensive Services

In a bid to find transmission shops near you, be sure not to settle for one that is extremely expensive or cheap. It may be expensive but that does not mean that the shop is being honest to you since it could be a rip-off. Hey, you may not be able to tell since a bunch of services might be thrown in to give you the impression that you need them when in actuality, you don’t.

The same can be said about shops that offer cheap service since they may end up not buying quality parts to fix your car. The quality of work may end up being sloppy and in the end, you may be left with a car whose performance is far from impressive.


Now that you know the essential tips to consider when choosing a performance transmission technician/shop, you can be sure that your care is in the best hands. You do not have to hold out on professionalism or settle for an overtly cheap or expensive service in order to find a credible mechanic.

The bottom line is this: Your car’s performance can be enhanced if you give the recommendations we have outlined above your utmost consideration while in your quest to find a reliable transmission repair shop in near your location.