3.9 Diff Ratio Crown Wheel and Pinion sets 76/78/79/100/105 and 80

Are They Strong Enough for My Landcruiser?

Yes! These gears have proven their strength in various installations, including a HDJ79 Landcruiser, which achieved an impressive 10.98 second ¼ mile time. Equipped with these diff gears, he managed to break two 4340 chrome moly axles during launches, affirming the durability of PDI gears.

Product Details

Order Includes: This order comes with a front and rear set of crown wheel and pinion gears, complete with solid pinion spacers for both front and rear differentials.

Suitable Models:

These diff ratio changes are recommended for manual transmission vehicles with performance upgrades, including:

• VDJ76 / VDJ78 / VDJ79
• HDJ100 / HZJ105 / HDJ105 (use VDJ79 bearing kit for front and rear)
• HDJ79 / HDJ78 (use VDJ79 bearing kit for front and rear)
• 80 Series** (using 100/79 centre and 80 side gears in rear; front is a direct fit, use VDJ79 bearing kit)

If you would like to run these in your 80 series with a function LSD, PDI stock a TORSEN fitted with 30 spline side gears.

Performance and Benefits

These gears have been installed in Landcruisers exceeding 300rwkw and 1000nm, showing excellent performance under heavy loads. Customers report that the 3.5 ratio provides an ideal balance for everyday driving, resulting in longer legs in every gear and reduced engine RPM on the highway.

Gear Ratio Comparison:

Standard VDJ79 ratio is 3.909 HDJ100 and HDJ79 with standard 4.1 ratios drop RPM at 100kph by 120 RPM. In a 105 Landcruiser (with standard 4.3 ratio) the revs would drop by around 240RPM

Driving Experience:

With the upgraded gearing, 4th gear can now handle towing at 100kph, significantly improving highway driving comfort. In a HDJ79 with 180rwkw, the new gearing allowed for climbing steep hills in 5th gear comfortably.

Additional Considerations

Automatic Transmission: The 3.9 ratio is recommended for automatic transmissions or if using 35-inch tires. If you have a manual transmission and regularly tow over 3,000kg and are taking off up inclines then the 3.9 is a good compromise.

Torsen Centres:

Considering mechanical LSD Torsen centres can enhance power delivery on and off-road, while reducing stress on your drivetrain compared to locking diffs.  These are not auto-lockers, but smooth engaging LSD.