Wacker 4 Stroke Rammer Bs504As Rev 101 2019 Clutch Drum Replacement Repair Guide

Difficulty

Moderate

Steps

Time Required

                          45 minutes - 2 hours

Sections

Safety Precautions
1 step
Oil Draining Procedure
3 steps
Leg and Crankcase Separation
8 steps
Motor and Crankcase Separation
10 steps
Clutch Drum
6 steps

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BackWacker 4-Stroke Rammer model BS50-4AS (2019)
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Introduction

This model requires up to 0.7 liters of SAE 10W-40 oil to replace drained oil.

What you need

Step 1

              Disconnect the spark plug wire

Ensure the device is powered down and cool to the touch before starting your repair.
Firmly grip the base of the spark plug wire’s connector and pull it away from the spark plug to disconnect it.

Ensure the device is powered down and cool to the touch before starting your repair.

Firmly grip the base of the spark plug wire’s connector and pull it away from the spark plug to disconnect it.

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Step 2

              Loosen the sight gauge

Use a 1-1/16 inch socket to break loose the oil sight gauge near the bottom of the device.
Do not fully remove the oil sight gauge yet with the device in this upright position.
The oil sight gauge doubles as the oil drain and fill plug.

Use a 1-1/16 inch socket to break loose the oil sight gauge near the bottom of the device.

Do not fully remove the oil sight gauge yet with the device in this upright position.

The oil sight gauge doubles as the oil drain and fill plug.

Step 3

              Prepare a drain pan

Lay the device down horizontally with the oil sight gauge facing down.
Position a shallow oil drain pan underneath the sight gauge.

Lay the device down horizontally with the oil sight gauge facing down.

Position a shallow oil drain pan underneath the sight gauge.

Step 4

              Drain the oil

Remove the oil sight gauge.
Let the oil drain until drips are infrequent.
Replace and retighten the oil sight gauge.
This model requires 0.7 liters of SAE 10W-40 oil.

Remove the oil sight gauge.

Let the oil drain until drips are infrequent.

Replace and retighten the oil sight gauge.

This model requires 0.7 liters of SAE 10W-40 oil.

Step 5

              Support the device

Flip the device onto the work surface such that the motor and handles face up.
Place two separate blocks of wood underneath the seam between the leg assembly and crankcase.
Once the two halves separate, each side will need to be supported.

Flip the device onto the work surface such that the motor and handles face up.

Place two separate blocks of wood underneath the seam between the leg assembly and crankcase.

Once the two halves separate, each side will need to be supported.

Step 6

              Remove the leg assembly bolts

Use an 8 mm hex key socket to remove the four bolts securing the leg’s guiding cylinder to the crankcase.
You may need to use an impact driver or breaker bar to break these bolts loose.
During reassembly, ensure each bolt has its accompanying lock washer.

Use an 8 mm hex key socket to remove the four bolts securing the leg’s guiding cylinder to the crankcase.

You may need to use an impact driver or breaker bar to break these bolts loose.

During reassembly, ensure each bolt has its accompanying lock washer.

Step 7

              Begin to separate the halves

Pull the leg assembly away from the rest of the device.
Ensure each half stays adequately supported.

Pull the leg assembly away from the rest of the device.

Ensure each half stays adequately supported.

Step 8

              Reveal the pin

Continue to separate the two halves by compressing the bellows until the nylon plug covering the piston pin is visible.

Continue to separate the two halves by compressing the bellows until the nylon plug covering the piston pin is visible.

Step 9

              Procedure tip

Tip: To compress the bellows, insert a block of wood between the two halves and pivot the leg assembly off of the crankcase to compress the guide cylinder, revealing the pin.

Tip: To compress the bellows, insert a block of wood between the two halves and pivot the leg assembly off of the crankcase to compress the guide cylinder, revealing the pin.

Step 10

              Remove the pin

Use an appropriately-sized punch and a ball-peen hammer to tap the pin out of its hole on the guide piston until it is no longer securing the connecting rod.
Once the piston and connecting rod are separated, the two halves become completely disconnected and will need to be adequately supported.
During reassembly, ensure that both nylon plugs are reinstalled and are flush with the surface of the guide piston.

Use an appropriately-sized punch and a ball-peen hammer to tap the pin out of its hole on the guide piston until it is no longer securing the connecting rod.

Once the piston and connecting rod are separated, the two halves become completely disconnected and will need to be adequately supported.

During reassembly, ensure that both nylon plugs are reinstalled and are flush with the surface of the guide piston.

Step 11

              Remove the leg assembly

Remove the leg assembly from the crankcase.

Remove the leg assembly from the crankcase.

Step 12

              Completely remove the pin

Use a punch and hammer to tap the pin out of the guide piston.
Once the pin is removed, the guide cylinder may spring up due to the compression of the bellows.
During reassembly, the bellows will need to be compressed to uncover the pin hole on the guide piston.

Use a punch and hammer to tap the pin out of the guide piston.

Once the pin is removed, the guide cylinder may spring up due to the compression of the bellows.

During reassembly, the bellows will need to be compressed to uncover the pin hole on the guide piston.

Step 13

              Support the device in an upright position

Use wood blocks to support the device on the work surface, motor facing up.

Use wood blocks to support the device on the work surface, motor facing up.

Step 14

              Remove the engine guard

Use a 6 mm hex socket to remove the engine guard bolt securing the cable guide.

Use a 6 mm hex socket to remove the engine guard bolt securing the cable guide.

Step 15

Pull the cable guide away from the engine guard.

Pull the cable guide away from the engine guard.

Step 16

Use a 6 mm hex socket to remove the three remaining bolts securing the engine guard: two on the outer edge and one near the crankcase.

Use a 6 mm hex socket to remove the three remaining bolts securing the engine guard: two on the outer edge and one near the crankcase.

Step 17

Remove the engine guard.

Remove the engine guard.

Step 18

              Remove the motor nuts

Use a 13 mm wrench to remove the four nuts securing the motor to the crankcase, two on each side.
When removing the nuts, the crankcase bolts may also become unthreaded, preventing its accompanying nut from being removed. This is fine.

Use a 13 mm wrench to remove the four nuts securing the motor to the crankcase, two on each side.

When removing the nuts, the crankcase bolts may also become unthreaded, preventing its accompanying nut from being removed. This is fine.

Step 19

              Move the muffler shroud

Use a 10 mm socket to remove the bolt securing the muffler shroud.

Use a 10 mm socket to remove the bolt securing the muffler shroud.

Step 20

Lower the muffler shroud away from the motor, down onto the crankcase.
Do not fully remove the muffler shroud.

Lower the muffler shroud away from the motor, down onto the crankcase.

Do not fully remove the muffler shroud.

Step 21

              Separate the motor from the crankcase

Tilt the device down onto its side, supporting both the crankcase and motor with blocks of wood.
The motor is loose from the crankcase, so support the motor as you lower the device down.

Tilt the device down onto its side, supporting both the crankcase and motor with blocks of wood.

The motor is loose from the crankcase, so support the motor as you lower the device down.

Step 22

Hold the crankcase steady and pull the motor directly away from it.
Ensure each half stays adequately supported.
The motor is still attached to the rest of the device via various hoses and cables, so don’t attempt to completely remove it.

Hold the crankcase steady and pull the motor directly away from it.

The motor is still attached to the rest of the device via various hoses and cables, so don’t attempt to completely remove it.

Step 23

              Remove the crankcase cover bolts

Use an 8 mm hex socket to remove the four bolts securing the crankcase cover.

Use an 8 mm hex socket to remove the four bolts securing the crankcase cover.

Step 24

              Separate the crankcase cover from the crankcase

Any excess oil that did not drain out of the drain plug may leak out here. Be prepared with a shop rag or shop towel to catch any drips.
Insert a flathead screwdriver into one of the side gaps between the crankcase cover and the crankcase.
Twist the screwdriver to begin to pull the crankcase cover away from the crankcase.
Repeat for the opposite side gap, and repeat until the crankcase cover comes loose from the crankcase.
During reassembly, check that the crankcase cover O-ring is in good condition, and replace it if it is cracked or deformed.

Any excess oil that did not drain out of the drain plug may leak out here. Be prepared with a shop rag or shop towel to catch any drips.

Insert a flathead screwdriver into one of the side gaps between the crankcase cover and the crankcase.

Twist the screwdriver to begin to pull the crankcase cover away from the crankcase.

Repeat for the opposite side gap, and repeat until the crankcase cover comes loose from the crankcase.

During reassembly, check that the crankcase cover O-ring is in good condition, and replace it if it is cracked or deformed.

Step 25

              Remove the crankcase cover

Use your fingers to pull the crankcase cover off of the crankcase.
Feed the connecting rod around the clutch drum shaft and out through the crankcase cover hole.
During reassembly, feed the connecting rod around the clutch drum shaft and ensure the helical gears fully mesh.

Use your fingers to pull the crankcase cover off of the crankcase.

Feed the connecting rod around the clutch drum shaft and out through the crankcase cover hole.

During reassembly, feed the connecting rod around the clutch drum shaft and ensure the helical gears fully mesh.

Step 26

              Remove the clutch drum snap ring

Use a pair of snap ring pliers to remove the snap ring securing the clutch drum to the crankcase bearing assembly.
During reassembly, ensure the clutch drum shaft is fully seated in the bearing assembly before attempting to reinstall the snap ring.

Use a pair of snap ring pliers to remove the snap ring securing the clutch drum to the crankcase bearing assembly.

During reassembly, ensure the clutch drum shaft is fully seated in the bearing assembly before attempting to reinstall the snap ring.

Step 27

              Tap out the clutch drum

Use a rubber mallet to tap the end of the clutch drum shaft through its hole on the top of the crankcase until it becomes loose enough to be moved by hand.
During reassembly, reseat the clutch drum into the bearing assembly by tapping it by the drum end.
Oil the new clutch drum shaft to ease installation.

Use a rubber mallet to tap the end of the clutch drum shaft through its hole on the top of the crankcase until it becomes loose enough to be moved by hand.

During reassembly, reseat the clutch drum into the bearing assembly by tapping it by the drum end.

Oil the new clutch drum shaft to ease installation.

Step 28

              Remove the clutch drum

Push the clutch drum shaft with your fingers until it can be gripped from the top of the crankcase.
Since the motor is still connected to the crankcase, you may need to shift the motor’s position on the wood blocks in order to fully remove the clutch drum.
Remove the clutch drum.

Push the clutch drum shaft with your fingers until it can be gripped from the top of the crankcase.

Since the motor is still connected to the crankcase, you may need to shift the motor’s position on the wood blocks in order to fully remove the clutch drum.

Remove the clutch drum.

To reassemble your device, follow these instructions in reverse order.

After reassembly, tilt the device upright and check the oil level through the sight glass. The oil should cover 1/2 to 3/4 of the sight glass to be considered full. This model requires up to 0.7 liters of SAE 10W-40 oil.

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                    Carsten Frauenheim

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