Quick Change Gears, Ultra-Duty 10-Spline, E9310 Steel, Set of 2 by Quarter Master (All 64 Ratios)

Quarter Master® Ultra-Duty™ 10-Spline Quick Change Gears are the benchmark
for quick change final-drive tuning. Sold as a matched two-gear set (one top gear and one bottom gear),
each set is cut from E9310 aircraft-quality alloy steel, precision hobbed to
AGMA Class B tolerances for a true involute tooth form and high contact ratio, then heat treated,
hand roll tested and inspected. Choose your set from the drop-down below — all
64 ratios from 1.000 through 1.875 are available.

Why racers run Ultra-Duty gears

• Engineered from high-quality E9310 aircraft steel and heat treated for long service life under load reversal and shock loading.
• Precision hobbed to AGMA Class B tolerances — true involute tooth form, high contact ratio, quieter running and lower parasitic loss.
• Proprietary heat treat process, then hand roll tested and inspected before it leaves the factory.
• 64 ratios in 10-spline for sprint cars, late models, modifieds and quick change-equipped road racing and vintage cars.
• Sold as a complete set of two gears — no mixing and matching required.

Fitment

These are 10-spline gear sets, the industry-standard spline count used in full-size quick change
centre sections. They are dimensionally interchangeable with the 10-spline gear sets used in most Winters, Frankland,
SCS, DMI, PEM and Bulldog-style quick change rear ends. Count your splines before ordering —
10-spline gears will not fit a 6-spline midget centre section, and vice versa.

How to read the gear chart

A quick change lets you flip the same gear set to get two different final drives from one pair of gears:

• Big gear on TOP = HIGH (numerically higher final drive, more torque multiplication, quicker acceleration, lower top speed).
• Big gear on BOTTOM = LOW (numerically lower final drive, taller gearing, higher top speed).

The spur ratio is the ratio of the two gears to each other. Multiply your ring & pinion ratio by the spur ratio for the HIGH final drive, or divide by it for the LOW final drive. The table below is worked out for the two most common ring & pinion ratios, 4.11 and 4.86.

Quarter Master® Ultra-Duty™ 10-Spline Quick Change Gear Chart

Engineering & material specification

E9310 is a nickel-chromium-molybdenum carburising steel long used for aerospace and high-load transmission gearing.
Case carburised and hardened, it delivers a hard, wear-resistant tooth surface over a tough, ductile core — the
combination that survives the repeated shock loading of a race final drive. Hobbing to AGMA Class B controls profile,
lead and runout closely enough to maintain a high contact ratio under deflection, which is what keeps the mesh quiet
and spreads tooth loading instead of concentrating it at the tips.

Because of that specification, these sets are also worth a look for engineers outside circle track and road racing
who need durable, off-the-shelf, US-made spur gearing in a wide range of tooth counts — test rigs and dynamometers,
robotics and heavy actuation, ground-support and light industrial drives, and marine or off-highway gearbox work.
Verify tooth form, face width, bore and spline engagement against your own drawing before designing them in.

Ordering

• Price is per set of two gears (one top, one bottom).
• Set weight is approximately 5.5 lbs.
• Made in the USA by Quarter Master®.
• Not sure which ratio you need? Send us your track, tyre circumference, ring & pinion and target RPM and we will work it out with you.