Hydraulic Throwout Bearing Vs Slave Cylinder Bearing

Hydraulic throwout bearings and slave cylinder bearings are two components used in hydraulic clutch systems.

Hydraulic throwout bearings are integrated with the clutch release mechanism and operate using hydraulic pressure to engage and disengage the clutch. Slave cylinder bearings, on the other hand, use hydraulic pressure to actuate a separate clutch release mechanism.

While both types of bearings operate using hydraulic pressure, hydraulic throwout bearings offer several advantages over slave cylinder bearings, including simpler installation, reduced clutch pedal effort, and smoother and more consistent clutch engagement. However, hydraulic throwout bearings are generally more expensive than slave cylinder bearings.

In this article, we will do a detailed comparison between hydraulic throwout bearings and slave cylinder bearings considering all the critical factors like structure, function, maintenance, cost, lubrication, application, lifespan etc.,

Differences Between Hydraulic Throwout Bearings and Slave Cylinder Bearing

1. Structure

A slave cylinder bearing is a simple mechanical component that consists of a piston and a cylinder. The force from the clutch pedal is transferred to the release fork by the piston, which is connected to a release fork that engages and disengages the clutch. The piston moves back and forth inside the cylinder.

The slave cylinder bearing is made to withstand high temperatures and pressures and is typically made of cast iron or aluminum.

In contrast, a hydraulic throwout bearing, also referred to as a concentric slave cylinder, is a more intricate component made up of various pieces. It has a smaller piston, a cylinder, a seal, and a bearing.

The clutch pedal’s force is transferred to the release fork by the piston, which is connected to the release fork and moves back and forth inside the cylinder.

The clutch release bearing and the bearing, which is fastened to the end of the piston, are in contact. The hydraulic throwout bearing is made of premium materials like high-grade steel, aluminum, or plastic and is made to withstand extreme temperatures and pressures.

2. Application

The slave cylinder bearing is commonly used in older vehicles with manual transmissions, particularly those with cable-operated clutches. In contrast, more recent vehicles with hydraulic clutches use the hydraulic throwout bearing.

The reason for this difference in application is that while slave cylinder bearings rely on a mechanical linkage to achieve the same result, hydraulic clutches use hydraulic fluid to engage and disengage the clutch.

3. Operating method

The clutch is engaged and disengaged by the slave cylinder bearing through a mechanical linkage between the clutch pedal and the clutch release fork.

The mechanical linkage pushes against the slave cylinder bearing when the clutch pedal is depressed, which moves the release fork and disengages the clutch.

On the other hand, the hydraulic throwout bearing activates and deactivates the clutch using hydraulic pressure. Hydraulic fluid is forced through the lines to the throwout bearing when the clutch pedal is depressed, which moves the release fork and disengages the clutch.

4. Function

The basic purpose of the slave cylinder bearing and the hydraulic throwout bearing is to engage and disengage the clutch. However, compared to the slave cylinder bearing, the hydraulic throwout bearing typically operates more smoothly and efficiently.

This is because the clutch is engaged and disengaged by the hydraulic throwout bearing, which offers a more reliable and precise operation that enhances overall performance and increases comfort while driving.

On the other hand, the slave cylinder bearing might subject the clutch system to more deterioration over time, which might lead to a decline in performance.

5. Cost

3. Slave bearing vs Throwout bearing - which is cheaper

In general, the hydraulic throwout bearing is more expensive than the slave cylinder bearing. A cylinder and piston make up the slave cylinder bearing, which has a straightforward design and does not need a master cylinder or additional hydraulic lines.

On the other hand, the hydraulic throwout bearing has a more intricate design and needs extra parts like a master cylinder, hydraulic lines, and fittings. The price of the hydraulic throwout bearing is increased by these extra parts.

6. Durability

2. Which is more durable - Hydraulic throwout bearing or slave cylinder bearing

In general, the slave cylinder bearing is less resilient than the hydraulic throwout bearing. The hydraulic throwout bearing is made to withstand high levels of heat and friction, which over time may cause the bearing to deteriorate.

Additionally, the hydraulic throwout bearing is made to self-adjust as it ages, extending its life. On the other hand, the slave cylinder bearing has a straightforward design and might wear out more quickly as a result of its inability to self-adjust.

7. Friction

The slave cylinder bearing typically has more friction than the hydraulic throwout bearing. The clutch can be engaged and disengaged more smoothly with the hydraulic throwout bearing because it uses hydraulic fluid to do so.

Contrarily, the slave cylinder bearing utilizes the mechanical clutch pedal to engage and disengage the clutch, which can result in increased friction and bearing wear.

8. Reliability

Generally speaking, the slave cylinder bearing is less reliable than the hydraulic throwout bearing. Clutch engagement and disengagement are made more comfortable by the hydraulic throwout bearing.

9. Size

Depending on the vehicle application, different sizes of slave cylinders and hydraulic throwout bearings may be used. The slave cylinder bearing is typically smaller than the hydraulic throwout bearing because it doesn’t need any hydraulic lines or fittings.

The size of the hydraulic throwout bearing can increase due to the need for additional parts like a master cylinder, hydraulic lines, and fittings.

10. Lubrication

The hydraulic throwout bearing uses hydraulic fluid to engage and disengage the clutch, so it doesn’t need any additional lubrication. However, extra lubrication is needed to protect the slave cylinder bearing from deterioration.

11. Maintenance

Compared to the slave cylinder bearing, the hydraulic throwout bearing requires more maintenance. Maintenance procedures for the hydraulic throwout bearing include bleeding the hydraulic lines and changing the hydraulic fluid on a regular basis.

The slave cylinder bearing, on the other hand, needs less maintenance because of its straightforward design and lack of additional hydraulic parts.

Slave Cylinder Vs Throwout Bearing [Comparison Summary]

Bearing Type	Hydraulic throwout bearing	Slave cylinder bearing
Mode of Operation	It disengages the clutch by pushing against the clutch diaphragm spring using hydraulic pressure from the clutch master cylinder.	The clutch is released by pushing on the pressure plate diaphragm fingers using a hydraulic slave cylinder.
Principle of operation	They need hydraulic fluid in order to engage and disengage the clutch.	To achieve the same outcome, they rely on a mechanical linkage.
Application	They are frequently used in more recent vehicles, mostly rear-wheel drives, with hydraulic clutches.	They are frequently utilized in older manual transmission vehicles, especially those with cable-operated clutches. Front-wheel drives are the most common.
Pedal Pressure	Less pedal pressure is needed.	They demand more pedal force.
Operating conditions	They operate at a lower temperature because they are located outside the clutch cover and are not in direct contact with the clutch.	They operate at a higher temperature. This is because the slave cylinder bearing is in direct contact with the clutch cover, which can reach temperatures of up to +482 °F
Noise	They operate quietly and smoothly because it uses hydraulic pressure to engage and disengage the clutch. Typically (5–10 dB)	They are noisier because they rely on mechanical linkage. They generate great noise and vibration. with noise levels between 5 and 20 dB.
Design	Their designs are more intricate. It consists of a cylinder, a bearing, a seal, and a smaller piston. which makes it work more smoothly and efficiently.	They have larger pistons, are typically made of cast iron or aluminum, and are designed to withstand high temperatures and pressures.
Friction	As a result, they experience less friction. For smoother clutch engagement and disengagement, they use hydraulic fluid to engage and disengage the clutch.	They rely on the mechanical clutch pedal force to engage and disengage the clutch, which can result in increased friction and bearing wear.
Lubrication	Since hydraulic fluid is used to engage and disengage the clutch, it doesn’t need any additional lubrication.	To keep the bearings from deteriorating, they need additional lubrication.
Location of use	The transmission input shaft is mounted with hydraulic throwout bearings.	The bell housing has slave cylinder bearings mounted inside.
Reliability and Durability	They have been created to withstand prolonged friction and heat, which may result in damage to the bearing over time, as well as smoother engagement and disengagement of the clutch.	Due to exposure to high temperatures, they live shorter lives of about 50,000 miles.
Cost	Because of their more intricate design, they need extra parts like a master cylinder, hydraulic lines, and fittings. Their price is increased by these extra parts. Generally speaking, they can range in price from around $50 to $200 or more.	In general, they cost less. The cost of the slave cylinder bearing may also depend on whether it is sold individually or as part of a clutch kit, which may include other components such as the clutch disc, pressure plate, and flywheel.
Maintenance	additional maintenance is necessary	less maintenance is necessary
Size	Because they need additional parts like a master cylinder, hydraulic lines, and fittings, their size can be larger.	Since they don’t need hydraulic fittings or lines, they are smaller.

Conclusion:

In summary, the hydraulic throwout bearing and the slave cylinder bearing are two crucial parts of the clutch system of a vehicle. Despite the fact that each type of bearing has pros and cons of its own, the hydraulic throwout bearing is typically more robust, has less friction, and offers better performance than the slave cylinder bearing.

However, compared to the hydraulic throwout bearing, the slave cylinder bearing is typically less expensive and needs less maintenance.