F35 (MU3) transmission

The F35 is a Saab-designed five-speed manual transaxle built in Saab’s Gothenburg, Sweden, powertrain plant. This extensively tested manual transmission was originally introduced in the 1984 Saab 9000, and today it is used in the Saab 9-3 and 9-5, Saturn Ion Redline, Chevrolet Cobalt SS, Chevrolet HHR SS and various GM/Opel transverse engine front-wheel drive applications.

The F35 features a two-axis conventional transverse layout, with fully synchronized gears, and compact packaging. It features a higher torque carrying capacity than most manual transaxles currently in use by competing North American small cars.

Design features include triple-cone synchronizers on 1st and 2nd gears, and single-cone synchronizers for 3rd, 4th, 5th and reverse gears.

It weighs approximately 99 lb/45 kg and uses 2 quarts/1,9 l of GM 88862472 gear oil. This gear oil is identified in GM documentation as a synthetic 75W-85 GL-4, Castrol Burmah (BOT 0063) manual transmission fluid, and is validated as "fill-for-life". No maintenance is required for normal operation. The gearbox is rated for 260 ft-lb (353 Nm) of engine torque.

The GM transmissions are usually numerically designated in newton metres that means F35 is rated at 350 Nm, the weaker rod shifted SAAB version of the F35, the F25, at 250 Nm, F40 at 400 Nm, M32 at 320 Nm, and so on.

A limited-slip differential is available for high-output applications. GM has sourced Quaife's automatic torque biasing (ATB) torque-sensing (Torsen-style) differential, which is an all-mechanical geared unit that uses no clutch packs or preloading to transfer torque from one axle to the other. The torque transfer occurs automatically and gradually when one wheel loses traction. This type of differential can severely reduce the effects of torque-steer.

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Wikipedia