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How To’s

Guide To Buying a Transmission for Your Vehicle

The Rise of Hybrid High-Performance Transmissions

How To Buy A Transmission

The first step in purchasing a transmission is to gain a clear understanding of your specific needs and requirements. Begin by considering the type of vehicle you own and its intended use. Is it a daily driver, a high-performance sports car, a heavy-duty truck for towing, or perhaps a racing vehicle? Each of these applications demands a transmission tailored to its unique demands.

Next, you’ll need to decide on the type of transmission that best suits your driving preferences and requirements. Automatic transmissions offer convenience, manual transmissions provide full control over gear changes, and dual-clutch transmissions combine the benefits of both.

Your performance goals are another crucial factor. Are you looking to achieve improved acceleration, enhance towing capacity, maximize fuel efficiency, or achieve a balance of these factors? Your performance objectives will significantly influence your transmission choice.

Lastly, establish a realistic budget for your transmission purchase. While high-quality transmissions like those offered by Gearstar may come at a premium, they are an investment in your vehicle’s performance and longevity. A well-chosen transmission can improve your vehicle’s overall performance and save you money on future repairs.

Research Transmission Specialists

Not all transmission suppliers are created equal, and this step is where Gearstar truly shines. Gearstar has earned its reputation as a leading transmission specialist company renowned for its exceptional craftsmanship and high-performance transmissions. When conducting your research on transmission suppliers, pay attention to the following key aspects:

First and foremost, examine the reputation of the supplier. Read customer reviews, ask for recommendations from fellow enthusiasts, and check the company’s track record in delivering quality transmissions. Gearstar’s stellar reputation in the automotive community is a testament to their commitment to excellence.

Consider the expertise of the transmission supplier. Ensure that the company specializes in the type of transmission you need. Gearstar stands out by offering a wide range of transmission options, including high-performance transmissions customized to meet your specific requirements.

Quality assurance is a critical factor to consider. Look for suppliers that adhere to strict quality control standards and rigorous testing procedures. Gearstar is well-known for its meticulous quality assurance processes, ensuring that each transmission leaving their facility meets the highest standards of performance and durability.

Consult with Transmission Specialists

Once you’ve narrowed down your options to reputable suppliers like Gearstar, it’s highly advisable to engage in a consultation with their transmission specialists. Gearstar’s team of experts possesses a wealth of knowledge and experience, and they can provide invaluable insights and guidance tailored to your unique needs. During your consultation:

Begin by discussing the type of transmission that best suits your vehicle’s characteristics and your performance goals. Explain your vehicle type, whether it’s a daily driver, a high-performance sports car, a truck used for heavy towing, or a dedicated racing vehicle. Gearstar’s specialists can recommend the most suitable transmission type to optimize your vehicle’s performance.

Customization is a key strength of Gearstar. Share your specific requirements and preferences with their specialists, and explore the customization options available. Gearstar is renowned for building custom transmissions that align precisely with the unique demands of each customer.

Inquire about the warranty coverage offered with the transmission. Gearstar is known for its generous warranty policies, which reflect their confidence in the quality and reliability of their products.

Discuss the installation process. Determine whether Gearstar offers installation services or if you’ll need to collaborate with a local mechanic. Gearstar can provide guidance on finding a qualified installer if needed.

During the consultation, don’t hesitate to ask any questions or seek clarification on any aspects of your transmission purchase. Gearstar’s specialists are committed to ensuring that you have all the information you need to make an informed decision.

Review and Compare Options

After consulting with Gearstar or other reputable transmission specialists, you’ll likely have several transmission options to consider. It’s essential to take the time to thoroughly review and compare these options to make an informed choice. Key factors to consider during your review process include:

Price: Compare the cost of each transmission, including any customization or additional features you’ve discussed with Gearstar’s specialists. While quality transmissions are an investment, it’s crucial to ensure that your choice aligns with your budget.

Warranty: Evaluate the warranty coverage offered by each supplier. A robust warranty not only provides peace of mind but also reflects the supplier’s confidence in the quality and durability of their product. Gearstar’s substantial warranty coverage is a testament to their commitment to customer satisfaction.

Lead Time: Check the estimated lead time for receiving your selected transmission. Gearstar is known for its efficiency in delivering custom transmissions promptly, minimizing downtime for your vehicle.

Customer Testimonials: Read customer testimonials and reviews to gain insights into the experiences of other buyers. Positive testimonials can provide valuable reassurance, while any concerns mentioned in reviews should be considered and discussed with the supplier.

During this stage, consider reaching out to Gearstar’s team to address any final questions or concerns before making your decision. Their commitment to customer satisfaction ensures that you have all the information you need to make an informed choice.

Make Your Decision

After meticulously reviewing and comparing your transmission options, it’s time to make your decision. Choose the transmission that best aligns with your vehicle’s needs, performance goals, and budget. For many buyers, Gearstar’s high-performance transmissions stand out as a top choice due to their exceptional quality, customization options, and reputation within the automotive community. Rest assured that a well-informed decision will not only enhance your vehicle’s performance but also contribute to its longevity.

Installation and Maintenance

With your selected transmission in hand, it’s essential to coordinate the installation process. If you have experience with transmission installations, you may choose to install it yourself. However, if you’re not well-versed in automotive mechanics, it’s advisable to hire a professional mechanic to ensure the installation is performed correctly. Proper installation is crucial to the transmission’s performance and longevity.

Maintenance is a critical aspect of ensuring your transmission’s continued reliability and performance. Follow the manufacturer’s recommended maintenance guidelines, which may include regular fluid changes, inspections, and adjustments. Adhering to these maintenance practices will help extend the lifespan of your transmission and keep it operating at its best.


In conclusion, the process of buying a transmission is a significant decision that can profoundly impact your vehicle’s performance and overall driving experience. By following the steps outlined in this guide and consulting with transmission specialists like Gearstar, you can make an informed decision that enhances your vehicle’s capabilities and durability.

Gearstar’s expertise, commitment to quality, and customization options make them a trusted choice among enthusiasts and performance-oriented vehicle owners. When you choose Gearstar for your transmission needs, you’re not only investing in a high-quality product but also gaining access to a wealth of knowledge and support from their experienced specialists.

Remember that your transmission is a critical component of your vehicle, and selecting the right one can elevate your driving experience to new heights. Whether you’re seeking improved acceleration, enhanced towing capacity, or superior overall performance, Gearstar’s high-performance transmissions are engineered to deliver excellence on all fronts.

5 Tips for Choosing a Transmission Rebuild Kit

5 Tips for Choosing a Transmission Rebuild Kit - Gearstar Performance Transmissions

One of the most challenging repairs anyone can make on a vehicle is rebuilding a transmission. A transmission is a complicated mess of small parts, plates, and synchronization. Some highly experienced technicians or mechanics won’t touch a transmission with a ten-foot pole due to the considerable amount of work involved. Therefore, if you’re a DIY enthusiast and believe you can take on the massive work of rebuilding a transmission, you will need a few things. First, you need the right tools and components, a.k.a. a transmission rebuild kit. However, choosing a transmission rebuild kit is the easiest part. You need a transmission rebuild kit that perfectly matches your vehicle’s model and make. This transmission rebuild kit must come with everything you need to make the rebuild process a success. You need to be careful when you’re about to buy a transmission rebuild kit. Go for one that comes with a detailed instruction manual.

Does Your Transmission Need a Rebuild?

Before you even start the transmission rebuild process, the first question you need to answer is, ‘Does this transmission need a rebuild?’ In some cases, you don’t have to carry out an entire rebuild; all that may be required are replacing a few components and fixing others, and the functionality of the transmission will be restored. But how can you determine what your transmission needs? This is where the professional input of a highly skilled mechanic comes in. If you don’t know the transmission mechanisms, you must take your vehicle to a reputable repair shop for an accurate diagnosis to identify the problems. Fixing several components will undoubtedly cost far less than rebuilding your transmission. Therefore, have the transmission diagnosed at an authorized repair shop. This will save you a bucketload of your hard-earned cash.

How to Rebuild Your Transmission

How challenging can rebuilding your transmission be? As mentioned earlier, many technicians or mechanics shy away from rebuilding a transmission. However, if they decide to take up the task, it will cost you as much as $3,000 or even $4,000, including labor costs. The prices of the damaged components within the transmission are also factors you need to consider. Moreover, rebuilding the transmission of sports or luxury brands like Porsche, Mercedes Benz, or Ferrari is much more expensive than a regular Honda or Toyota vehicle. However, you can reduce the amount of money you spend by handling the entire rebuild process yourself. This is not recommended, especially if you know nothing about rebuilding transmissions. But if you have DIY chops and want to make a go at it on your own, here’s how to rebuild your transmission:

Buy a Transmission Rebuild Kit

This is the essential step you should take on your quest to rebuild your transmission. A transmission rebuild kit has all the tools you will ever need for some replacement components and reconstruction. Four types of transmission rebuild kits are on the market today. Most usually include:

  • Bushings
  • Gaskets
  • Clutches
  • Seals
  • Washers
  • Bands
  • Filters
  • Modulators
  • O-rings

Ensure you purchase the right transmission rebuild kit; this is the one that matches the make and model of your vehicle. Transmission rebuild kits are not expensive. You can get one at a pocket-friendly price at the local repair shop.

Create and Prepare a Dust-Free Work Environment

You need a clean, prepared location free of dust and other contaminants or particles. You can ensure a dust-free work environment by covering your chosen surface with plastic trash bags.

Remove Engine Block and Transmission

The next step is to detach the engine block and unhitch the transmission oil pan and the torque converter before removing the transmission. Do this carefully and ensure you keep track of all the components that look very similar so that you don’t mix them up. Drain the fluid after disassembling everything. Label each component carefully to avoid confusion when reassembling the transmission.

Clean and Replace Transmission Components

Since you choose to rebuild your transmission, you must probably have an excellent idea of which components require replacement and cleaning. Therefore, clean all the components after disassembling the component. Replace every broken or damaged component with brand-new manufacturer-approved products.

Reassemble Your Transmission

This is where you have to be incredibly careful. If you reassemble your transmission the wrong way, it won’t work. You will have to tear it down again and rebuild it from scratch, which will take a lot of your time and enormous effort. Therefore, ensure you get it right the first time. This is where the labeled components come in handy. It makes it easy to identify what goes where and how during reassembly. After the entire process, perform several pressure tests to ensure you did everything correctly. You can consult a professional mechanic and have your vehicle checked thoroughly before taking it for a spin.

Establish a Transmission Rebuild Timeline

The time it takes to rebuild a transmission depends primarily on your skill level and the pace at which you work. It usually takes one to four days to send your vehicle to the local repair shop, and a trained mechanic handles the entire transmission rebuild process. Of course, the transmission must have been diagnosed before the rebuild began. But it will take a bit longer – i.e., up to four or five days – if the mechanic has to, first of all, discover the problems, ascertain whether or not a transmission rebuild is necessary, remove the transmission if a rebuild is crucial, perform a few repairs, reassemble and reinstall it in your vehicle. This implies that it will undoubtedly take you a bit longer, i.e., up to a week or even more, to rebuild your vehicle transmission by yourself.

The Bottom Line

Rebuilding a transmission is a challenging process that even the best mechanics don’t like taking on the task. However, taking on the challenge can save you a lot of money in the long run. You will need to get your hands on a transmission rebuild kit that is perfect for the model and make of your vehicle. This will help make the entire process somewhat less challenging. Follow the tips shared above, and your transmission will be almost as good as new when you’re done with the challenging task.

Overachieving Overdrive With a 700R4 Transmission Rebuild

Powerful performance with a 700R4 transmission rebuild

A good 700R4 transmission rebuild will leave you with a ride that is more powerful, durable, and with firmer shifts.

In terms of power, you can get over 450 lb-ft of engine torque output than what the stock transmission offers.

But first, you may want to dyno test your current 700-R4 transmission to know if it is in dire need of a rebuild, especially if it has been subjected to severe usage.

If it needs a rebuild, you may notice a decline in Second, Third, and Fourth gears.

The transmission may also start releasing fluid from the breather.

Therefore, you need the right parts to get a 700R4 that is more than impressive instead of switching to a new unit.

Now walk with us as we show you how to rebuild the 700R4 transmission to overachieve overdrive.

Why Rebuild the 700R4 Transmission Instead of a Replacement?

You may be wondering if it is entirely needful to rebuild the 700R4 transmission instead of upgrading to another transmission such as the three-speed automatic, Turbo 400.

If that’s the case, here are some reasons why the 700R4 transmission rebuild is more ideal in a street-strip car.

First Gear:

The 700R4 transmission’s first gear is 3.06:1, which means a car that features a 700R4 and 3.55:1 rearend gearing would move like a car with a Turbo-400 transmission and 4.38:1 rearend.

On the other hand, the Turbo-400 has a first gear of 2.48:1.

Fourth Gear:

A look at the 0.70 overdrive gear of the 700-R4 shows that it provides a cruise rpm, which is the same as the Turbo 400’s 1:1 third gear with 2.48:1 rearend gearing.

Lockup Converter:

A lockup converter is evident on the 700-R4 and this component helps to lock the drive and driven sections of the converter with a clutch above 38 mph.

Consequently, overheating and slippage are totally eliminated.

Fewer Components:

The 700-R4 transmission has fewer components compared to electronically controlled 4L60 or 4L80.

As such, you have fewer electronics to deal with. You do not have to spend more to acquire a transmission controller and wiring harness.

How to Rebuild the 700R4 Transmission

Although the 700R4 transmission is reputably known to be a reliable trans, a rebuild can enhance its performance.

Accordingly, you can rebuild the 700R4 transmission using these tips.


The first thing you’re going to do is to carefully disassemble the 700-R4 to see if there are possible areas that are in dire need of repair.

You may notice a brownish fluid and varnish on the internal components of the transmission due to overheating.

The heat is often produced by the torque converter and at higher converter stall speed, more heat is created before lockup.

Overheating, on the other hand, can cause transmission failure, which is why you should consider using an external trans fluid cooler and a temperature gauge.

The temperature gauge will tell you if your transmission is overheating.

In this case, if the automatic transmission fluid (ATF) has a temperature above 185 degrees F, it may prevent proper fluid flow and component lubrication.

Replacement of Internal Components:

Certain components in the transmission can prevent it from shifting between gears properly.

For instance, if there’s a sticking governor with coated trans-fluid varnish, there may be shifting issues.

Accordingly, proceed to replace the internal parts of the transmission.

You may also want to link the trans cooling lines and radiator heat exchanger to a cleaning machine.

Increased Line Pressure:

Take a look at the hydraulic system in a bid to increase line pressure quickly when power is applied.

The goal is also to eliminate high-rpm pressure drop-off and slippage.

In this aspect, you’ll be looking to improve the transmission pump using a new, hardened stator.

There’s a need to CNC-machine flat both sides of the pump halves to ensure that the stator is perpendicular.

It’ll also provide precision mating of the pump halves thereby eliminating internal pressure leakage.


Hardened-steel pump-guide rings can be installed to disallow pressure drop above 5,500 rpm.

Likewise, it’ll enable the driver to manually control shift points without negative effects.

Another important installation is with a 10-vane pump rotor and an upgrade to an oversized 0.500 low-boost and 0.290 reverse-boost valves.

Also, consider the use of Teflon-coated front bushings and heavy-duty stator support bushings.

An enhancement to the pump-regulator valve and installation with a stiffer pressure-regulator spring can improve flow.

Decrease Internal Slippage:

Focus has to be given to the 2-4 gear band assembly by stepping it up to a wider 3/8-inch Kevlar band with a reinforced anchor.

This upgrade will eliminate slippage on shifts under full power and enhance the transmission’s durability.

There’s a need for an improved governor to increase automatic WOT shift points to the 5,200 to 5,600 rpm range.

Also, a heavy-duty, 29-element input sprag clutch is needed to withstand the solid shifts.

Other upgrades include the improvement of the 3-4-gear clutch pack to nine friction and nine steel plates.


Improved shifting is also brought about by recalibrating the part-throttle, throttle-valve accumulator circuits in the valve body, and the spacer plate passages.

This will also provide more precise pressure regulation and firmness.

The line-bias system is upgraded in a bid to improve shifting.

Road Testing:

It is important to road test the transmission after the rebuild to see how well it works before its final use.


It is entirely possible to overachieve overdrive with a 700R4 transmission rebuild, especially if you do it the right way following the steps we’ve outlined.

You’ll be dealing with more power and firmer shifts after this upgrade.

The best part is, you’ll be spending less on a rebuild compared to getting an entirely new transmission.

On the other hand, it’s better to work with a car repair shop if you have little knowledge about fixing cars to ensure you don’t cause more harm than good to your unit.

It’ll save you money in the long run and help you avoid transmission failure.

Shifting Your 4L60E Transmission From Weak to Wicked

4L60E Transmission inside a white and blue muscle car driving on the highway

Rebuilding your 4L60E transmission can transform it into a tougher performance transmission.

It’ll have more durable components, increased torque and horsepower, and be more rugged for the road.

A rebuild of this nature allows you to gain the full benefits evident on higher transmission models.

On the other hand, the 4L60E denotes a “4” four-speed, “L” longitudinal installation, “60” light-to-medium-duty use, and 6,000-pounds gross vehicle weight that is “E” electronically controlled.

This transmission is based on the 700-R4, which was launched to handle fuel economy.

The 4L60E as a computer-control system features a powertrain control module (PCM) that aids in control using sensors like the throttle position sensor (TPS) and vehicle speed sensor (VSS).

A rebuild of the 4L60E will make it a more reliable, solid transmission.

How to Improve the Performance of Your 4L60E Transmission

The goal is to give your 4L60E transmission a greater torque capacity and horsepower to improve its performance.

Accordingly, here’s what you need to begin:

1. Disassemble Parts:

Rebuilding your 4L60E transmission requires that you disassemble its hard parts and lay them neatly on a bench.

You’ll notice that this transmission has a close resemblance to the 700-R4, 4L60, 4L65E, and even 4L75E transmissions.

Nevertheless, there are still slight differences between the 4L60E and the aforementioned transmissions.

2. Sun Reaction Shell:

The 4L60E has its factory sun reaction shell, which is less durable than a customized sun shell.

The factory shell may fail easily and end break around its hub.

To that effect, opt for a thicker sun shell whose center hub is stronger to ensure that the component stands the test of time.

Your shell also needs to have a radiused spline area and Torrington bearing. The latter helps to reduce friction in the area, as well, as heat.

3. Front Planet and Ring Gear:

Increasing the torque and horsepower capacity of the 4L60E transmission by 20% requires that you upgrade to a five-pinion front planet and ring gear.

This means you won’t be relying on the four pinions front planet.

The result is evident in a spread of torque across a larger mechanical surface area.

An increased torque can also be tied to the 400-500 horsepower support you’ll be getting from using a five-pinion front planet.

This torque capacity is comparable to that of the 4L65E/4L75E transmission.

A 29-element sprag for 700-R4, 4L60, and 4L60E is another useful component that will offer you more torque capacity.

4. Clutch Apply Piston:

A more enhanced hydraulic holding power and stability can be derived from the use of a larger 3-4 clutch overrun clutch apply piston coupled with an input drum reinforcement sleeve.

There’s also the need to use a Teflon-impregnated stator support bushing which offers more stability and smoothness.

Over and above that, opting for forward clutch apply pistons should be of the best quality (steel) to reduce the potential for failure.

5. Second and Fourth-gear Band Servo Pistons:

There are Second and Fourth-gear band servo pistons that are larger, which you can opt for.

These ones will give your transmission around 18 percent more band-apply capacity.

Other components to consider include Raybestos forward, overrun, and reverse input clutches and steels.

Raybestos clutches come with friction materials which reduce heat faster.

6. Input shafts:

Rebuilding your 4L60E requires the use of multiple-input shafts.

These are a hardened 4L60E input shaft, heavy-duty late-model 4L60E input shaft (4L75E), and stock 4L60E input shaft.

With these shafts in place, make an upgrade to a high-volume 13-element (vane) pump to support the pressure and volume.

7. New Soft Components:

There’s a need to get new soft parts including seals, bushings, and clutches.

The hard parts of the transmission can be inspected and then upgrades made to it.

Also, give consideration to the anti-chatter spring since it can impact the performance of the 4L60E.

8. Clutch Drum:

Clutch drums need to be resurfaced to support better band engagement.

If the clutch drum is beyond resurfacing, then it should be left aside.

The reverse input clutch drum consists of Raybestos high-performance clutch frictions to reduce friction and heat.

These Raybestos high-performance frictions offer more without slippage, while also supporting better power transfer.

On the other hand, heat can impact negatively on your transmission’s life.

9. Teflon Sealing Rings:

Teflon sealing rings are a better option to iron sealing rings.

The reason lies in the fact that iron sealing rings are not durable and break easily while those made of teflon last longer.

Nonetheless, you’ll need a bit of knowledge to properly install the teflon sealing rings since they are harder to install compared to iron sealing rings.

10. Reverse Input Drum:

You can load the reverse input drum onto the input drum.

The input drum should be fitted with a hardened input shaft to ensure it is durable and can support the 400-500-horse capacity of this transmission.

There’s a teflon sealing ring installation tool that can make your installation even easier

11. Installation:

Proceed to install the Raybestos Pro Series band and tie it to the servo while also adjusting it properly.

And even before the torque converter is installed, proceed to install the 13-element high-capacity front pump.

While choosing your torque converter, give great consideration to the stall speed, your engine’s torque curve, and your car’s usage most time.


These are the components and list of steps you need to make your 4L60E a more rugged transmission.

It’ll have durable components that can better dissipate heat while at the same time offering more torque and horsepower.

The result is improved performance while you hit the road.

It also follows that you do not have to upgrade this transmission to a more modern one since a simple rebuild of this nature will improve its torque.

Nevertheless, resort to the car repair shop if you’re unable to handle this rebuild yourself to ensure you don’t damage the transmission’s components.

Start Your Own Ford AOD Transmission Rebuild

ford aod transmission rebuild - Gearstar

The oil crisis in 1973 brought a very harsh reality for motorists in America: fuel was going to become more expensive. And the only way out is to manufacture cars that use less without really sacrificing power more than necessary. And even when the oil crisis repeated itself much later within the decade, the Ford AOD (automatic overdrive) transmission came into the picture.

What to Do Before Your Ford AOD Transmission Rebuild

Before you start up a Ford AOD building project, you need to get your hands on the tools that will enable you to do the job. And a proper work setting is vital in order to make the project a success as well.

This is because automatic transmissions are known to cover a wide variety of incredibly tiny precision parts such as balls, valves, clips, pins, springs as well as other items. You need to also ensure that your workshop is impeccably clean, orderly, neat, and of course, well lit.

This last aspect is vitally important because some parts are tiny, and you can easily overlook them. This is why your shop environment should not have low lighting or lots of clutter. Every component is vital, especially when it comes to automatic transmissions. If you discover any parts left on your workbench when you are done with everything, then your fate is sealed: you are in deep trouble.

Once again, cleanliness is crucial and should never be taken for granted when working with automatic transmission. This is because the smallest grit or dirt can throw you off as it disturbs automatic transmissions’ precision tolerances. And when this happens, it can lead to severe malfunction and extremely poor performance.

Tiny grains of sand or house dust can cause a seal to tear or a valve to stick unceremoniously. All these could have severe impacts on the transmission function. And this is the primary reason why automatic transmissions should be bagged at all times, especially when you are not working on them.

If you live in an area known to be dusty, you should consider bagging your transmission and stowing it away in a clean storage room.

Safety Precautions to Stick to When Working On an Automatic Transmission

Ford AOD transmission rebuild also come with several safety issues that you will do well to keep in mind. Bear in mind that components and vehicles in general can maim or kill you if you are not so careful.

But you can avoid getting killed or maimed if you follow these suggestions carefully:

  • Use Only Nitrile Gloves

These are somewhat similar to the latex gloves commonly used in clinics or hospitals. Use nitrile gloves to protect your hands from solvents or other harsh chemicals. Undue exposure to these substances can cause severe skin dryness and even cancer.

Nitrile gloves also protect your skin from sharp edges of aluminum and iron castings.

  • Use Muffs or Earplugs

Power equipment can emit high-frequency noises which are severely damaging to the human ear. Therefore, use muffs or earplugs to protect your ears from the din of the equipment, electric motors, compressors, or gear and belt drives.

  • Protect Your Eyes and Face

Use goggles, safety glasses, along with a full face shield in order to protect your eyes and your entire face from flying debris, metal, and other foreign matter.

Keep rotating equipment away from you.

How you hold a cutting wheel and grinder is also vital and determines how safe you are. Therefore, make sure you keep the rotation of your cutting wheel/grinder away from you.

  • Get A Good Respirator

You should also protect your lungs with a suitable respirator since you may be working with alcohol- or petroleum-based cleaning solvents. Use respirators with charcoal cartridges to keep all particulates and chemicals away from your lungs.

Organizing the Components

Now that everything is set, you should start working on your AOD/AODE/4R70W build. Steels and clutch friction discs must mate with utmost precision. Ensure sliding valves glide right through the valve body without any hassle. Clean seals and servo pistons, and ensure they bind well since dirt can cause tolerance issues.

Tools, Equipment and Supplies

Ensure you have enough tools, equipment, and supplies for your work on the Ford AOD transmission rebuild. Most professional transmission workshops have ideal transmission-holding fixtures designed to support all transmission cases during assembly and disassembly.

You need compressed air for clearing debris. Check clutch pistons for perfect function. This is why it is highly advisable to carry out this entire process at a professionally-equipped workshop.

A Step-By-Step Method to Follow for Transmission Removal

Step 1: Get rid of any item in the way

Automatic transmission removal starts with removing any item that may get in the way. So, begin by removing exhaust systems, parking brake cables, wiring, H-pipe assemblies, etc. The latter may be difficult – but not impossible – to remove if it is welded together.

Step 2: Get rid of crossmember

As soon as the automatic transmission has been supported, unbolt and remove the crossmember. Replace crossmember bushings and then mount it with anything that ensures you win mileage and time.

Step 3: Dispatch the driveshaft

Create reference marks at the yoke and flange. This enables you to reinstall them easily in the same position by aligning the reference marks. This is where you rebuild the driveshaft and balance it with a slip yoke and new universal joints.

Ensure a professional check out the driveshaft for run-out or any other stress issues.

Step 4: Disconnect all accessories

Unplug the TV cable and shift linkages. Take a quick note of both the TV cable adjustment as well as the installation and cable manual-shift linkage before disassembly.

Step 5: Remove the Exhaust heat shield

The next step is to remove the exhaust heat shield. This makes it far easier to remove the automatic transmission. The job of the heat shield is to prevent the onslaught of extreme catalytic convert heat. When it is time to reinstall, you can reuse the heat shield.

Step 6: Remove the starter and Unplug the battery

Unplug the negative cable of the battery and then remove the starter. The small trigger lead always fires the solenoid in this application.

Step 7: Remove dust shield and bellhousing

Remove the flexplate/torque converter dust shield. This reveals the entire converter-to-flexplate locknuts and studs. You will set eyes on 4 locknuts. Replace them with new ones.

Rotate the engine manually, and you will be able to access the 4 locknuts.

Step 8: Disconnect the torque converter and flexplate

Remove the locknuts that keep the flexplate in place in order to free up the torque converter and automatic transmission. Make sure you use an excellent thread locker as well as new locknuts.

Step 9: Disconnect all transmission cooler lines

Disconnect every transmission cooler line. You need to replace both the cooler and the lines even if your automatic transmission did not fail. Band friction material, metal, and other debris can quickly become trapped in the cooler and lines. This could severely damage the new transmission.

Step 10: Unfasten bellhousing and lower transmission

Removing the bellhousing bolts may require the use of a 5/8-inch socket. You can remove most of these bolts right from underneath. Removing the top 2 bolts requires box-end wrenches, though this depends significantly on the firewall clearances.

Step 11: Examine the flexplate

Examine the flexplate for ring gear damage, cracks, and proper installation. You should also inspect the starter drive and search for the pan gasket leakage on the engine as well as the rear main seal.

If there are any problems or issues, correct them before you start the reassembly process.

Step 12: Get set to teardown

After removing the automatic overdrive, it becomes ready for a teardown. Teardown gives you the opportunity to learn more about transmission failure, i.e. if any has occurred. It also gives you the chance to scrutinize wear patterns that could cause severe problems in the future.

Step 13: Remove and inspect electrical components

Remove all sensors, fittings, and switches. Strip the transmission case completely bare for cleaning.

If you are carrying out the ford aod transmission rebuild at home or any other place other than your workshop, make sure all the parts have been cleaned professionally. Pressure-wash them with a suitable solvent if you are on a tight budget.


This is the step-by-step method of rebuilding and modifying a Ford automatic overdrive transmission. Make sure you adhere strictly to the steps and precautionary measures before you embark on the project.

What Is Transmission Slipping? Signs To Look Out For

Transmission Slipping - Gearstar

Transmission slipping must be dealt with as soon as possible in order to avoid major repairs. Learn what to look out for.

The transmission is responsible for converting power from the car engine into motion for the vehicle to move. Vehicles come with a manual or automatic transmission. If you drive a car with an automatic transmission, the gears change for you while you may have to put a car with manual transmission into gear via its gear selector.

However, one of the common problems associated with transmissions is known as a slipping transmission. This article covers what transmission slipping means, its causes, signs to watch out for, how to prevent the problem, etc.

Transmission slipping: What does it mean?

Transmission slipping refers to a situation in which your vehicle slips into gear without corresponding to its current speed. This can be discomfiting and troubling. In many cases, it is a signal that your vehicle needs thorough maintenance. This is why it is usually risky to leave your transmission unchecked.

What causes transmission slipping?

The following situations or conditions may cause your transmission to start slipping:

  • Solenoid problems
  • Worn-out gears
  • Broken or worn transmission bands
  • Burned, low, or worn-out transmission fluid
  • Clutch problems
  • Torque converter issues

Signs of transmission slipping to look out for

As with most automotive issues, the earlier you deal with it, the more successful you will be at avoiding major repairs. The longer you put off fixing your slipping transmission, the more damage you will likely compound. This will eventually cost you lots of your hard-earned money to fix.

This is why this section deals with the signs to look out for to inform you that your transmission may be slipping:

Unauthorized switching of gears

One of the signs that reveal that your transmission is slipping is that your vehicle suddenly and unexpectedly switches gears as you drive. In some cases, a change in pitch or a noise accompanies the unauthorized switching of gears.

If your car switches gear out of the blue while driving, it can be a potentially life-threatening situation. This implies that your car is unreliable and may start shaking.

When your vehicle feels sluggish

If your car is not accelerating as quickly as it should or feels somewhat sluggish, you could have a slipping transmission problem on your hands. It may also have other issues related to your transmission. This is why you should waste no time in having your vehicle checked by a professional mechanic.

Inability to change gears smoothly

Another symptom or sign of a slipping transmission is when your vehicle finds it difficult to change gears smoothly. You will hear a thud or clunk as your automobile goes down or up in gears.

When there is a delay before movement

If you experience a delay before your car starts moving, it could signify that your transmission has slipped.

As soon as the gear shift moves from ‘Park’ to ‘Drive,’ a long lag ensues before your vehicle starts moving. During this period, the car engine revs but goes nowhere.

When the clutch stops working

This is for those who drive manual transmission vehicles. When you depress the clutch pedal, and nothing happens, your clutch assembly may have been damaged, or something could be wrong with the transmission system.

When the transmission fluid leaks

When you notice a red fluid on your garage floor, coupled with some of the symptoms shared earlier, your transmission may have a problem.

This is because when there is a transmission fluid leak, it results in a slipping transmission.

Is it safe to drive your vehicle when the transmission is slipping?

When you have a transmission slipping issue, it is not safe to drive that vehicle. This is because the safety of the vehicle is highly unpredictable. It can slip into different gears without giving you any warning, shake, or even cause severe damage.

Therefore, get your vehicle checked out immediately when you observe the signs or symptoms of a slipping transmission.

How to prevent transmission slipping

You can prevent transmission slipping. But you need to be sure that fluid leaks or worn-out bands are not behind the problem. If this is the case, you may have to replace either the worn-out gears, the solenoids, the clutch, or the torque converter.

Any of these repairs will cost you a lot of money, especially if a transmission specialist handles it for you. Having an older vehicle will not be in your favor, and this is why you should check out every other possibility first.

Your automobile’s onboard diagnostic computer can inform you of the problem if you own a newer vehicle. This is true if the problem the solenoid is behind the transmission problem.

However, if your newer vehicle transmits error codes, ensure you check them out first in order to determine what they tell you about your transmission’s status. 

If you still can’t pinpoint the problem, consider examining the transmission bands. Replace any worn or broken transmission band. If you have to replace a single band, then ensure you replace them all. This is to prevent dealing with this particular issue within the next few weeks or months.

You can also get right under your hood to confirm the level of your transmission fluid. Ensure the fluid is at its correct level.

If the transmission fluid level is lower than it should be, try and locate the primary source of the leakage. You may find that a seal is loose or discover holes in one of the fluid lines. The transmission pan can also spring a leak, or you may have a faulty transmission pan gasket.

If you are a keen DIYer, you can replace these faulty parts on your own. However, if you discover a cracked torque converter, you may have to invite professionals for a look-see and in-depth repairs.

Identify the origin or source of the leakage and fix it as soon as possible. You can also consider adding an excellent transmission leak sealing solution the next time you refill the transmission fluid.


If your transmission is slipping, you can easily get tempted to make attempts at fixing it on your own. But if you are inexperienced or feel uncomfortable working on your transmission, the best decision you can make is to allow a transmission specialist to handle the repairs for you.

Transmission specialists have the tools and experience to detect the causes behind the slipping of the transmission. Once they diagnose the problem, they can quickly fix it within a short period, and you can get back to your day-to-day lifestyle.

What Is Rear End Gear Ratio and How Is It Calculated?

Rear End Gear Ratio - Gearstar

Rear end gear ratio is boiled down to lower numerical values giving better acceleration, torque, top speeds, and better fuel economy.

The first time you wade into the gears’ universe, you will encounter several terms such as gear ratio, rear end, gear systems or ‘trains,’ etc. Knowing how to calculate the rear end gear ratio to choose the right one is not a must but an advantage, and this is because you can find the gear ratio in the product description.

However, if you understand precisely how it works, your choice becomes much more calculated. Let this article serve as a guide or flashlight into this universe, and you will never get lost.

Let’s get started with the basics, shall we?

What is a Rear End Gear Ratio?

Most automobiles use gear ratios in the drive axle and the transmission to multiply power. When you multiply the two ratios, it equals the final drive ratio.

When you hear car drivers refer to numbers – such as 3.08:1, 3.73:1, or even 4.10:1 – they discuss the ring-and-pinion gears’ ratio within the rear axle. This ratio refers to the number of teeth on the ring – i.e., driven gear – divided by the number of teeth on the pinion – i.e., the drive gear.

Therefore, this implies that a ring gear with 41 teeth and a pinion with ten teeth results in 4.10:1. In other words, for every single turn of the ring gear, the pinion rotates 4.10 times. The rear end gear ratio has to do with the relationship between the pinion gear and the ring gear. 

But is there a chance that the system may incorporate more than two elements? Yes, the intermediate gears are known as ‘idlers.’ They can be used to keep – or change – the direction of rotation.

You can easily apply the gear ratio formula to every pair of wheels, but the truth is that you do not have to do so. Regardless of how many idlers there are within the train, the final gear ratio is between the ‘driver’ and the ‘driven’ wheel.

How Gears Work

The wheel was first invented before the gear came into play. Gears became functional for any of the following reasons:

  • To accurately reverse the direction of rotation
  • To decrease or increase the rotation speed
  • To synchronize the rotation and keep it that way
  • To change the rotational motion to a different axis

Although gear systems came into play as far back as four ages BC in China, many still believe that the first invention could be much older. Gear systems have developed over the centuries and are readily divided into dynasties.

The primary purpose of rear end gears is to multiply the torque the engine and transmission delivers. If you think of gears as complex mechanical levers, you won’t be far off the mark. This is because gears provide mechanical advantages that swiftly multiply torque in order to assist the engine’s power in moving the automobile.

Therefore, high gears are thought of as short mechanical levers that provide less mechanical advantage, while low gears are just like longer levers with more mechanical advantage.

Calculating the torque multiplication that your axle gears provide is quite easy. You can do this by multiplying by the gear ratio. For instance, if both the engine and transmission deliver up to 100 ft./lbs. of torque to the pinion gear and the gear ratio of the ring-and-pinion is say 4.12:1, the output torque is 412 ft./lbs. i.e. 100 x 4.12.

In the same vein, if the gear ratio is 3.04:1, the output torque will be 304 ft./lbs. As you can see, the lower 4.12:1 gears invest more power to the ground than the higher 3.04:1 gears.

Note that no changes occur in the engine’s power, though the available torque to the tires has done so.

How to Calculate Gear Ratio

The first gear that is attached to the motor shaft is known as the ‘drive’. But the ‘driven’ gear is the one that is attached to the load shaft gear.

In order to calculate the gear ratio, you need to do the following:

  1. First of all, get each part and count the number of teeth they have. Let’s say the small drive has up to 21 teeth while the driven gear has 28 teeth. Bear in mind that when experts discuss spur types, the one with more teeth is referred to as the ‘gear’ while the other one with fewer teeth is called the ‘pinion.’
  2. Divide the number of the driven gear teeth by the number of the drive gear teeth. In this example, it is 28/21 or 4:3. 

This gear ratio indicates that the smaller ‘driver’ gear must rotate or turn up to 1.3 times to get the much larger ‘driven’ to make just one complete turn.

Take note that a high numerical gear ratio is referred to as a ‘low gear.’ But a low numerical gear ratio is called a ‘high gear.’ Low gears engender fast acceleration and are highly appropriate for smaller engines.

However, high gears cause higher top speeds and better cruising and are suitable for more powerful engines.

You should heavily consider the following factors – which can affect the gear ratio – before changing the existing rear end gear ratio:

  • Tire diameter
  • Transmission type as well as individual gear ratios
  • Torque converter stall speeds (automatic), etc.

This is why it is highly essential to learn how to choose the right gear ratio for your drag racer or muscle car. 

What Do ‘Short Gear’ and ‘Tall Gear’ Mean?

The terms’ short gear’ and ‘tall gear’ can be somewhat misleading; this is why clarifying them is important.

A ‘tall gear’ gives you much better-cruising speed as well as fuel economy, while a ‘short gear’ always gives you excellent acceleration but at the cost of efficiency and cruising speed.

The Advantages That Geared Transmissions Offer

The geared transmission offers several advantages compared to other forms or types of transmission. 

First of all, a geared transmission provides incredibly high performance when efficiently transmitting motions and forces along with high reliability and extended service life.

However, what makes geared transmissions stand out from others is the astonishing accuracy of their gear ratio. This means that they can easily be utilized in precision machinery since gear ratios in geared transmissions are incredibly precise.

Moreover, unlike mechanisms – such as pulleys or chains – the size of geared transmissions is small. This makes it easy to install them in large and small machines and spaces and places that are somewhat difficult to access readily.

Finally, their maintenance is not complex in any way, and this is why geared transmissions remain one of the most prevalent systems within the automotive – and other – industries today.


Learning gearing lingo is important, especially if you want to know more about rear end gear ratios and how it calculated, how gear ratios affect mileage and acceleration, etc.

Rear end gear ratios can be boiled down to one statement: higher ratios – i.e., with lower numerical value – give better acceleration/torque and lower ratios yield to better fuel economy and higher top speeds.