GM Service Manual Online
For 1990-2009 cars only

Using the Clutch

When you are starting to move the vehicle, it is important to begin with the engine speed at idle. Then start to engage the clutch and listen for an engine speed drop of about 100 rpm. At this point, the clutch is engaging, so you should increase the engine speed and fully engage the clutch.

Notice: If you increase the engine speed before the clutch is fully engaged, you could damage your transmission. Always allow the clutch to fully engage before increasing engine speed.

Six-Speed Transmission

The transmission has gears that automatically synchronize when you shift up or down. Choose the gear which will maintain the road speed you want while keeping the engine above two-thirds of the governed speed. When the engine speed drops below two-thirds of the governed speed, shift into the next lower gear before your engine begins to become sluggish. When you shift down, be sure to double-clutch if required.

See "Double Clutching" later in this section.

Eaton® Fuller® Nine and Ten-Speed Non-Synchronized Manual Transmissions

If the vehicle has one of these non-synchronized transmissions, it is naturally somewhat complicated.

The following are driving tips:

    • Always choose an initial starting gear suitable for the load and terrain.
    • Always use double-clutching procedures when shifting.
    • Never move the range shift lever to the LO speed gear position after HI range preselection, or anytime the transmission is in the HI range.
    • Never move the range knob or lever with the shift lever in N (Neutral) while the vehicle is moving.
    • Never make a range shift while moving in R (Reverse).

Double-Clutching

You must use the double-clutching method when you shift an unsynchronized gear set. Disengage the clutch, shift to neutral and engage the clutch. When upshifting, slow the engine until the engine rpm and road speed match. When downshifting, accelerate the engine until the engine rpm and road speed match. Then quickly disengage the clutch and move the shift lever to the next gear position and engage the clutch.

Clutch Brake (Vehicles with Non-Synchronized Transmission)

A clutch brake is used to stop transmission input shaft turning so that 1 (First) or R (Reverse) gear selection can be initiated when the vehicle is at a standstill and the engine is idling.

Press the clutch pedal all the way down to the floorboard to apply the clutch brake.

When using the clutch brake, disengage the clutch pedal and shift the transmission into either the initial starting gear or R (Reverse). If the tooth-butting occurs between the clutching teeth, re-engage the clutch while applying light pressure to the shift lever. This will provide for a smooth shift into either 1 (First) or R (Reverse) gear.

Notice: Using the clutch brake for shifting into any gear other than 1 (First) or R (Reverse) may cause premature wear of the clutch brake and make gear shift effort more difficult. Do not use the clutch brake for shifting after engaging 1 (First) or R (Reverse).