How to Change a Gearbox and a Clutch

The gearbox is a device which increases the torque of the engine while the clutch regulates the transmission process.

Replacing a gearbox and a clutch is an arduous task; this article tries to assist you by providing you with clear and concise details on the entire process.

Before you commence the process, ensure you disconnect the battery.

Elevate the vehicle using a jack while keeping the vehicle stationary using a handbrake.

Endeavor to chock the rear end of the vehicle by placing wedges at the back of the tires to avoid the car moving backward.

Avoid going underneath the vehicle if it is supported by only the jack rather always ensure you place a jack stand underneath each side of the vehicle.

It should be noted that unlike the gearbox which just one component, the clutch consist of 3 parts in one: The clutch pressure plate, the

The replacement procedure requires you get access to the gearbox and the clutch. To access both devices you will need to remove the following components of the car:

Intercooler air outlet pipe

Temperature air sensor connector

Starter wires

ABS sensor connector

Reverse gear connector

Steering column

Lamps fog

Air filter outlet air pipe

Lower gearbox mounting bolts

Speedometer pin

Rear mounting support

Front right-hand wheel arch liner

Air filter box air inlet pipe

Air filter unit.

Power assisted steering pipe mounting

Power assisted steering pipe union

Gearbox selector rod

Exhaust downspout

Turbocharger air outlet pipe

Front wheels of the car

Track rod

Mounting bolts of the driveshaft gaiter

Lower ball joint

Brake caliper and its accompanying screws

Driveshaft

Tie rod between the sub frame and the side member

Steering rack mountings

Heat shield

Gear box left hand suspended mounting

Clutch cabling

Shock absorber of the lower mounting bolts

TDC sensor connector

Mounting bolts of the gearbox and starter

Mounting nut of the engine on the gearbox

Hose connector of the expansion bottle

Speed sensor

Horn

Bumper

Power assisted steering pipe mounting bolts on the sub-frame

Sub-frame

Meanwhile, disable the steering of the vehicle and endeavor to drain the gearbox by placing a bucket under its location. Attach the steering rack to the vehicle while supporting the engine block from underneath. Adjust the starter and its wires to allow you access the gearbox and the clutch.

Block the engine

Unclip the wiring harness channel for the sub frame

Detach the gearbox from the engine. The bolts holding the clutch pressure plate should be removed. Support the sub-frame using a jack stand prior to its removal. Then move the gearbox selector rod to one side. Strap the gearbox to a workshop crane so it can be gently carried down. Attach the cooling radiator to the vehicle.

Remove the gearbox, clutch plate and the clutch thrust bearing from underneath.

Replacing the old gearbox and clutch

Check that the new gear box is identical to the removed gearbox. Usually, there is a code on the gearbox which should match those on the old gearbox.

Remove the new dowels from the new gearbox should the old dowels remain on the engine. Collect any hardware missing in the new gearbox from the old one. If the new gearbox has any fluid within, drain it would be ideal. Strap the new gearbox to a workshop crane or any lifting device then lift the gearbox into position. Remove the stud on the engine so the gearbox can be connected back to the engine then refit the stud. Refit the mounting nut on the engine.

For the clutch, clean the flywheel of the engine with brake cleaner. Check the new clutch has the three components stated earlier. The clutch plate has a side marked fly wheel which should be attached to the engine side while the other side should be attached to the gearbox. Align the clutch properly and refit the clutch with the flat side to the engine. Center the clutch plate using the clutch alignment tool. Screw the clutch pressure plate clockwise. Block the engine so you can tighten the clutch pressure plate to torque. Use grease to lubricate the transmission output shaft and the clutch thrust bearing to reduce friction.

Now refit every component removed when the old gearbox and clutch was removed:

Sub frame

Starter

Steering column

Tie rods

Power assisted steering pipe union

TDC sensor connector

Clutch cable

Mountings of the gearbox

Rear mounting support

Speedometer pin

Gearbox selector rod

Horn

Front right-hand wheel arch liner

Driveshaft

Lower ball joint

Shock absorber

Brake caliper and brake pads

Track rod end

Driveshaft gaiter

Reverse gear connector

ABS sensor connector

Wheels

Turbocharger air outlet pipe

Air filter box outlet air pipe

Air filter unit

Temperature air sensor connector

Intercooler air outlet pipe

Battery

Endeavor to release the steering wheel before you refit the steering column on the steering rack.

Connect the starter wires

While refitting the lower ball joint, use locking pliers if the ball joint rotates freely.

Ensure the components of both wheels of the car are refitted accordingly.

Fill the power assisted steering circuit with the necessary fluid. Do the same for the cooling circuit. Fill the gearbox.

Replacing a gearbox is not an easy process, and it requires you possess most tools found in a workshop. If any welding is required please ensure you have the correct safety gear like a welding helmet and an appropriate welder. If you are unsure what type of welder you need you can check out the buying guide at Welder Station where they point out the best welders for specific jobs.

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