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Why EV conversions of 4WDs still rely on traditional driveline expertise 

EV conversions keep 4WD capability but add new stress to drivelines. Precision balancing and bearing upgrades ensure smooth power delivery, reliability, and comfort when instant electric torque meets traditional tailshaft design.

More Australians are turning their diesel and petrol 4WDs into electric vehicles through conversion programs. It is a way to keep much loved LandCruisers, Patrols, Hiluxes and similar models on the road while removing the fuel tank and installing an electric drivetrain. What surprises many owners is that these conversions often keep large parts of the existing driveline in place.

Unlike new electric utes that are designed from the ground up without a tailshaft, conversions usually retain the original driveline. The gearbox, tailshaft, centre bearing and differentials are left to do their job, only now they must manage torque that arrives instantly from an electric motor. That change in stress patterns is where driveline specialists come in.

One of the biggest challenges is vibration. A tailshaft that was acceptable behind a diesel may show imbalance once paired with an EV motor. This is because the motor delivers peak torque at low speed, so any imbalance is felt more sharply by the driver. Precision balancing is often required, and in some cases, upgraded centre bearings or heavy duty universal joints are installed to cope with the load.

Another key factor is the history of the vehicle. Many of the 4WDs chosen for conversion are already decades old. Mining LandCruisers, touring Patrols and farm utes often arrive with significant wear in their driveline before the conversion even starts. In these cases, rebuilding the tailshaft and replacing bearings is not just a good idea but a prerequisite before the new drivetrain can be fitted.

The safety implications are also serious. A weakened universal joint or failing centre bearing is more likely to break when subjected to electric torque. If a driveline lets go at highway speed, the result can be severe damage or loss of control. That is why inspections are recommended early in the conversion process and at regular intervals afterwards.

EV conversions are still a niche, but they are growing in Australia. Reports show workshops in Sydney and Melbourne now offering packages for popular 4WDs, with forums already documenting both the successes and the mechanical challenges. This trend makes clear that while the fuel system may change, the need for traditional driveline expertise remains.

For 4WD owners investing in EV conversions, the lesson is simple. The tailshaft, centre bearing and differentials are still the backbone of the vehicle, and keeping them in peak condition ensures the electric upgrade delivers both performance and reliability.

Additional Reading

BITRE’s Road Vehicles Australia (January 2024) gives data on the number of registered BEVs and FCEVs, showing EV ownership is increasing sharply.
https://www.bitre.gov.au/publications/2024/road-vehicles-australia-january-2024

Current statistics on the number of EV vehicles by brand.
https://thedriven.io/2025/09/03/australian-electric-vehicle-sales-by-month-and-by-model-in-2025-2

Box 1: How instant torque changes driveline stress

Electric motors deliver full torque from zero RPM, unlike diesel or petrol engines that build gradually. This creates shock loads on tailshafts, bearings, and universal joints that were never part of the original factory design. Without reinforcement or proper balancing, converted 4WDs can experience premature driveline wear or vibration issues.

Box 2: The role of balancing in EV driveline performance

Even a small imbalance in a tailshaft can become noticeable with an electric motor. A driveline that was acceptable in a stock 4WD may cause noise and vibration after conversion. Precision balancing helps absorb torque smoothly, reduces wear on bearings, and improves driver comfort in both on-road and off-road conditions.
FAQs about Driveshafts, Tailshafts and EVs

Yes. In most cases, the factory layout is retained, which means universal joints and centre bearings are reused. These components often need replacement or upgrading, as they face higher loads in an electric setup.

Retaining the differential keeps gearing and 4WD capability intact. It also avoids expensive custom solutions. During conversions, differentials are typically inspected, resealed, or rebuilt to ensure reliability under new torque conditions.

Workshops in Sydney and Melbourne note that driveline vibration and wear are among the most common challenges after an EV motor is installed. Often this is because the tailshaft or bearings were already worn before conversion, and the added torque makes issues surface sooner.

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Identify Transmission

Chrysler – Dodge
727 – 30 Spline 1 11/16″ Seal Diameter
904 – 26 Spline 1 9/16″ Seal Diameter

Ford
C6-T56 – 31 Spline 1 11/16″ Seal Diameter
AOD & C4 & T5 – 28 Spline 1 1/2″ Seal Diameter
4 R 7OW – 28 Spline 1.598″ Seal Diameter

General Motors
T-350 700R4-4LLOE – 27 Spline 1 1/2″ Seal Diameter
T-400-4L80E – 32 Spline 1 7/8″ Seal Diameter

Note: Transmission slip yokes are manufactured with various U-Joint Series. It is important to match Horsepower and Torque requirements to U-Joint Series. For aftermarket transmission applications usually a spline count and seal diameter will identify slip yoke required.

Identify Rear U-Joint

diagram-d

If Pinion Yoke has Placement tabs that retain the U-Joint, measure inside tabs. See Diagram D.

diagram-e

If Pinion Yoke does not have Placement Tabs that retain U-Joint, measure from flat of yoke inside to inside. See Diagram E.

diagram-l

If 4 bolt Flange is used on pinion, measure Pilot Diameter and center to center diagonally bolt hole to bolt hole. See Diagram L.

diagram-a

Universal Joint Size. There are hundreds of U-Joint sizes or “Series” to accomodate many different applications of power and desired longevity for your automotive, 4×4 truck or auto racing requirements, these 4 series of joints cover most needs.

1310 Spicer Series: 1 1/16″ Cup Diameter (Dim C – Diagram A) 3 7/32″ length (Dim B – Diagram A) Certain Ford applications have 2 cups 1 1/8 Diameter. Appropriate horse power range is up to 500 in circle track or road racing, small tire drag racing and 4×4. Also available: Performance Dynamic Cryo Joint.

1330 Spicer Series: 1 1/16″ Cup Diameter (Dim C – Diagram A) 3 5/8″ length (Dim B – Diagram A) Certain Ford applications have 2 cups 1 1/8 Diameter. Slightly stronger than 1310, Used in 5.0 Mustangs. Also available: Performance Dynamic Cryo Joint.

3R Saginaw Series: 1 1/8″ Cup Diameter (Dim C – Diagram A) Retained with internal clip 2 5/8″ (Dim B – Diagram A). Most common GM joint. Horse power range up to 700 in road racing and circle track. Solid drag racing U-Joint can accomodate most sportsman classes. Also available: Performance Dynamic Cryo Joint.

1350 Spicer Series: Manufactured with OEM tolerances and treated with our Cryogenic Process to yeild the strongest U-Joint available. For drag racing applications a solid non-lube design U-Joint is recommended because of the tremendous initial shock load, or short duration of high torque the joint must be able to withstand.

 

Driveshaft Measurements

diagram-n

If PST is supplying you with transmission slip yoke, Pinion yoke and driveshaft yoke measure Dim W. See Diagram N.

If PST is supplying you with transmission slip yoke and driveshaft measure Dim X. See Diagram N.

2 Piece driveshafts use Dim Y + Z. See Diagram N.