If you want to know the difference between a 2WD and a 4WD transmission, then this article is for you. We look at each transmission type in detail and explain if a 2WD transmission can fit in a 4WD truck.
The main difference between a 2WD transmission and a 4WD transmission is the output shaft. The Output shaft of a 4WD is shorter than a 2WD version. The 4WD transmission is also designed to mate up with a transfer case to engage 4WD and Lo-range (4L).
A 2WD transmission can be customized to function as a 4WD transmission with a few modifications. We will look into that a bit later as well as the costs involved to convert a 2WD to a 4WD. We also briefly touch on the process of converting a 2WD to a 4WD and what components you’ll need to successfully pull it off.
But first, let’s look at what the core differences are in more detail between the two transmissions.
Table of Contents
Are 2WD and 4WD Transmissions the Same?
The basic shape, structure, and most of the internals between a 2WD transmission and a 4WD derivative are basically the same. As stated at the outset, the main 2 differences are the output shaft length as well as the ability to mate with a transfer case.
Let’s look at the process of converting a 2WD to a 4WD
Will A 2-Wheel Drive Transmission Work In A 4-Wheel Drive Truck?
The first thing you want to do is remove the entire transmission to give you easier access to the internals. Once out, set yourself up nicely so we can remove the tail-shaft housing. There are usually about 6 high tensile bolts you will need to remove to get the cover off. Save those bolts for reuse later.
You can remove and get rid of the tail-shaft housing since it won’t fit anymore once the modification is complete. The rubber O-ring that seals the housing can be discarded as well. You’ll need a new one.
Next, remove the sleeve that is seated on the tail shaft. Remove and discard that as well. You’ll notice 2 holes and the opening around the output shaft. The seal that sits around the output shaft needs to be replaced with a 4WD shaft seal. Make sure that seal is well-seated and secure. Give it a few good poundings to ensure it’s sitting 100% secure and flush.
Next, you want to close up the 2x holes on the transmission case. You’ll need to find a pin or fabricate a pin to close those holes. Take extra care not to allow any metal shavings to fall into the transmission case. The best way is to tap a thread into those holes and then plug it.
Next, you’ll need to size the output shaft and cut it shorter. You can measure the correct length by using your 4WD adapter plate. Mark the length and cut the shaft.
Converting a 2WD to 4WD transmission summary:
- Strip and remove transmission from truck
- Remove tail-shaft housing
- Discard the rubber O-Ring
- Remove the tail-shaft sleeve and discard
- Replace the tail-shaft sleeve with a 4WD version
- Secure seal properly
- Tap threads into the 2x open holes in the transmission housing
- Plug all holes
- Measure the output shaft length with your adapter plate
- Cut the tail-shaft
Let’s look at the 2WD transmission in more detail now
2WD vs 4WD Differences
So there are some major differences between a 2WD and a 4WD as well as why they operate.
The basic difference is a 2WD is only propelled by 2x wheels, either the front or the rear wheels. There is no transfer case or extra driveshaft in a 2WD. You also won’t have a low range due to a lack of a transfer case with lower gearing. A 2WD is always propelled by 2 wheels and cannot engage the other 2 wheels, front or rear. Whereas a 4WD can drive in 2WD mode and activate 4WD to engage and lock the other 2 wheels to make it 4WD.
A 4Wd is propelled by all four wheels. A 4WD can either be a permanent 4WD or a part-time 4WD.
A permanent 4WD means the vehicle is always in 4H and propels all 4 wheels forward. One way It accomplishes this is by making use of a viscous coupling between the front and rear driveshafts. This is necessary to allow the front and rear drive-shafts to rotate at dissimilar t speeds, which is necessary when cornering on a high traction surface to prevent drivetrain “binding” or “windup”
You can read more about that here: Why my 4WD jerks when turning
Basically “binding” occurs when you are driving a part-time 4WD on a high traction surface like pavement and there is not enough slippage to allow the front and rear driveshafts to rotate at dissimilar speeds while cornering since the inner wheels closest to the corner side will rotate slower than the two outer wheels. This is because the turning radius is smaller on the inside than on the outside.
Next, let’s look at the conversion process for a 2WD truck to a 4WD truck. We’ll use the Toyota Tacoma as an example since it’s one of the most popular pickups that were produced in both 4×2 and 4×4 versions.
Converting Your 2WD to A 4WD (Components & Customizations Needed)
Converting a 2Wd to a 4WD used to be viewed as sorcery and wizardry in previous years, however, it’s becoming more and more popular with companies fine-tuning this craft by specializing in these conversions.
Why would you consider a 4×2 to 4×4 conversion?
- Emotional or Sentimental value
- You’ve overcapitalized on accessories
- Fun project to take on
Notice, cost-saving is not mentioned as an option since selling your 4×2 and buying a 4WD Tacoma is always going to be a faster and cheaper alternative. If it’s a cost-saving you’re after then a 2WD to 4WD conversion is definitely not the way to go. Whatever the reason, the good news is this conversion is possible and becoming more popular.
Conversion process basics and components needed:
YOU WILL NEED:
- A 4WD transmission from a FJ Cruiser with a rear adapter to mate up with the transfer case
- Cut open your floor to allow the transfer case shifter up into the cabin
- A custom cross-member fabricated up since the original or 4WD from a Taco won’t fit.
- New front drivetrain components
- New Front diff
- New Front CV axles along with all the 4wd front hubs, seals and appropriate dust covers
- A RST ADD harness so you can activate your front diff
- 2x Custom front half-shafts
- Custom exhaust work to accommodate the new transfer case
There’s a link below to the guys at Rocksolidtoys who are pioneers and specialize in this type of 4WD magic.
How Much Does It Cost To Change a 2-Wheel Drive to a 4-Wheel Drive
I guess it all depends on what truck you want to convert. Obviously, older trucks are way cheaper and you could source a lot of your components at a salvage yard at a fraction of the price. If you have a donor vehicle, that’s even better since you’ll be able to reuse all the factory wiring harnesses, OEM switches, gear shifters, some of the support brackets, driveshafts, etc. Depending on the chassis/frame differences you could even use the half-shafts and transfer case brackets etc. Some vehicle frames are different between the 4WD and 2WD.
So you can keep costs to a low-low if you shop around.
Let’s take a 2000 model Ford F150 as a cost example. The below excludes Labor and custom fabrication of brackets or electrical wiring.
| Component | Price |
| Transfer Case TCFRD008 | Between $853 and $1810 |
| Front Driveshaft | Between $307 and $647 |
| Drive Shaft center support | Between $108 and $117 |
| TC Shifter | Between $154 and $250 |
| Transfer Case Motor | $102 |
| TC shifter mounting plate and release pins | $74 |
| Transfer Case Gasket Set | $7.99 |
| Transmission Cable Shift (AT) | $73.99 |
| Front Axle | $85 |
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Conclusion
Hopefully, by the end of this article, you’ve learned what the differences are between a 2WD and a 4WD transmission. We also touched on what is involved in converting a 2WD transmission to a 4WD and lastly, we looked at the estimated cost of what you can expect when converting a 2WD to 4WD and which components you’ll need.