How Hard Is It To Replace Transmission? Mechanics advice

Replacing your own tranny could save you a bag of money, but can you realistically replace a tranny DIY style? Buckle up and let’s find out.

With the correct equipment removing a transmission from a longitudinal powertrain layout (commonly rear-wheel drive) vehicle is not difficult. Removing a transmission from a transverse powertrain layout (commonly front-wheel drive) is more complex and often requires suspension, steering, and engine subframe removal. 

In general, it is possible to DIY remove the transmission from a rear-drive vehicle, but modern front-drive cars are a ton more challenging. Four-wheel drive adds another layer of complexity. In this post, I’ll explain why front-drive cars are more challenging.

I’ll outline the workflow for manual and auto transmission removal from both longitudinal and transverse models.

Identify Your Powertrain Layout

In order to tell how difficult transmission removal is and if it’s a job you could DIY, we’ll first need to identify your vehicle’s powertrain layout. Most modern cars are front-wheel drive, higher-end models however tend to be rear-wheel drive and crossover-type vehicles maybe two or four-wheel drive.

Whichever type of vehicle you have two-wheel drive or four-wheel drive, your engine and transmission are laid out in one of two ways, longitudinal or transverse.

What’s Longitudinal Layout?

A powertrain is described as longitudinal when the engine is fitted lengthways in the engine bay with the transmission fitted behind the engine. This usually positions the transmission between the driver and the front passenger’s footwell. 

Longitudinal layout maybe two or four-wheel drive and is commonly used by trucks both and also some higher-end cars. It is possible for a longitudinal to power the front wheels but it’s rare, some Audi cars use such a setup. 

Look under the hood, both sides of the engine have generous amounts of working space (except diesel trucks). The plastic engine cover typically hints at the engine layout (front to back).

Check for a hump between the seats running the length of the cabin, that’s where the prop shaft transfers power from the transmission to the rear axle. If you have some of these characteristics, then you likely have a longitudinal layout.

What’s Transverse Layout?

A powertrain is described as a transverse when the engine and transmission are fitted widthways (sideways) in the engine bay. One of the main differences between longitudinal and transverse is the transverse transmission doesn’t encroach into the cabin space.

The powertrain is a compact unit and is by far the most common type of layout.

Transverse maybe two or four wheel drive but front wheel drive is the most common. It’s possible for a transverse to power the rear wheels but it’s rare, cars like Porsche use a power plant transversely fitted to the rear of the car to power the rear wheels. 

Look under the hood, space will appear tight, it will look like it’s all an engine. The plastic engine cover typically hints at the engine layout (left to right). The engine however is for most models fitted to the left side and transmission to the right side. (viewed from the front)

A flat cabin floor is typical in transverse models. If you have some of these characteristics, then you likely have a transverse layout.

Longitudinal Powertrain Vehicles

If your vehicle is rear-drive it is possible to remove the transmission yourself. However, transmissions are heavy, auto transmissions are really heavy. Handling transmissions while laying under them isn’t a good plan, you’ll need some proper kit. 

Without the correct tools, personal injury, vehicle damage, or transmission damage is very likely. (See tools below)

Tools you’ll need to remove longitudinal transmission

To nail this procedure you’ll need the following tools. Access to a hoist would make life easy, but I’ll assume you don’t have one. For removal, I’ll assume you are working on the ground and so I’ll list tools accordingly.

• Axle stands
• Jack with transmission adaptor
• Engine support
• Air wrench
• Impact sockets
• Ratchet and socket set
• Wd40
• Selection of wrenches
• Selection of drivers
• Selection of pliers
• KAM tool
• Creeper tool

I list my favorite tools on the Mechanics tools page.

How to remove longitudinal transmission (rear wheel drive)

As said I’ll approach this as though you don’t have access to a vehicle hoist. We’ll need to disconnect the battery as we’ll be removing the starter motor. But before we disconnect the battery, it’s best to connect a KAM (Keep Alive Memory) Tool. 

Disconnecting the battery on some vehicles without using a KAM tool may cause issues like high idle, transmission issues, power window issues, HVAC issues, ABS, power steering issues, etc. Losing learned values for most vehicles isn’t a problem, the values are relearned as you drive.

However, some vehicles will require recalibration and that often requires a visit to the main dealer.

Fitting a KAM tool is easy, connect it to the car battery using crocodile clips provided and connect the other end to the OBD port located under the driver’s side dash. I’ve listed the KAM tool I use on the Auto electrical repair tools page.

Removing the tranny looks something like this, obviously, some vehicles will differ slightly, exhausts system for example may need to be removed.

• Fit KAM tool
• Disconnect battery
• Remove starter motor
• Remove flex plate to torque converter bolts
• Remove bellhousing bolts top
• Fit engine support
• Set vehicle on 4 axle stands
• Remove prop shaft 
• Remove selector cable
• Remove transmission wiring harness
• Support tranny using jack and tranny jack adaptor
• Remove cross member
• Remove lower bellhousing bolts
• Lower jack and wiggle transmission free (may need to adjust engine support so as to allow engine pivot rearwards)
• Roll transmission out on the jack

Getting it back in is more challenging and will likely require a helper, but all is still doable without a hoist. Before refitting transmission it’s always a good idea to replace the torque converter seal.

Manual transmissions are easier to handle however they require additional work removing the clutch assembly and gear selector interior trim.

4WD vehicles are fitted with a transfer case that is bolted to the rear of the transmission. The transfer case will need to be removed before tranny removal.

Transverse Powertrain Vehicles

A transverse powertrains’ special talent is how compact it is. That’s great for the customer, there is a ton more room inside the cabin, but it’s bad for the technician. Transverse vehicles are very tight under the hood, especially large engine transverse vehicles.

I’ve been a mechanic for a lot of years and I wouldn’t attempt to remove a transmission on a modern car without a hoist. The challenge with modern transverse cars is the engine, transmission, half shafts, steering rack, and suspension are all built onto a subframe and then bolted to the car later in the assembly process.

While this is an efficient way to build cars it does make removing a component such as the tranny a tad more difficult. (See below)

Tools you’ll need to remove transverse transmission

You’ll need access to a hoist for front-drive transverse removal. 

Here’s a list of tools you’ll need:

• Hoist
• Transmission stand
• Transmission jack
• Engine support
• Air wrench
• Impact sockets
• Ratchet and socket set
• Wd40
• Selection of wrenches
• Selection of drivers
• Selection of pliers

Check out Mechanics tools page where you can find out more about the price and delivery of the tools I use.

How to remove transverse transmission (front wheel drive)

The general flow of work goes something like this:

• Fit KAM tool
• Disconnect battery and remove if required
• Remove air box
• Remove starter motor
• Remove flex plate to torque converter bolts
• Remove selector cable
• Remove transmission wiring harness
• Remove bellhousing bolts top
• Fit engine support and support engine weight
• Raise vehicle
• Remove front wheels
• Remove drive fasteners
• Free front drop links
• Free both front lower ball joints from knuckle
• Free both steering tie rods from knuckle
• Remove half shafts
• Refit lower ball joints and thread fastener loosely
• Support steering rack to chassis using zip ties or similar before removing rack to subframe fasteners
• Using zip ties or similar support radiator to chassis
• Use transmission jack and stand to support subframe
• Remove subframe fasteners
• Remove jack and support, using a helper thread off ball joint fasteners and remove subframe
• Support tranny using tranny jack
• Lower the engine support to allow transmission pivot lower
• Remove lower bellhousing bolts
• Lower jack and wiggle transmission free
• Roll transmission out on the jack

Before refitting transmission it’s always a good idea to replace the torque converter seal. Manual transmissions are easier to handle, however, they require additional work removing the clutch assembly and gear selector interior trim. 

Transverse all-wheel-drive vehicles generally use a transmission with an integrated transfer case. This obviously makes the assembly heavier and bulkier. Additionally, AWD vehicles will require prop shaft removal.