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How to Diagnose a slipping clutch;

1) Be aware of your clutch's action. Although a clutch/pressure plate system wears gradually over time, eventually the clutch's performance may become noticeably diminished, and by paying close attention to how it engages, slippage should be apparent to a competent driver. Here are some simple signs to watch for:

  • Change in engine speed without noticeable acceleration. If you rev your engine and the car hesitates before accelerating, it can mean your clutch isn't delivering the boost in RPM through the transmission to the drive wheels.
  • Change in the clutch pedal height where the driver feels the clutch begin to engage.
  • Change in perceived engine power when pulling a load. A slipping clutch reduces the amount of power delivered to the drive wheels.

2) Notice if you smell something burning coming from under the bonnet. This may be the result of an oil leak or even damaged electrical wiring (both serious, but not clutch-related issues), but it can be a sign of a slipping clutch.

 

3) Push down on the clutch pedal. Your clutch may need to be replaced if it takes only a little of the pedal movement to disengage it. In this case you should try to adjust it first and make sure that there is about an inch or two (2 to 4 cm) of free movement of the pedal before the clutch starts to disengage. This is an indicator that your clutch is not riding (i.e., is not partially disengaged) when the pedal is not depressed.

 4) Take the car for a drive. See if it takes more RPM from the engine to achieve a certain speed. This can also be an indicator your car needs a clutch replacement.

  • While driving down the road in 3rd gear, put the car in 2nd gear, then let out the clutch. If the RPM of the engine don't immediately go up, it may be time to replace the clutch.

5) Inspect the clutch face on any vehicle that has an inspection port on the clutch housing. Although the clutch is normally nested between the pressure plate and the flywheel, thus invisible unless dismantled, some vehicles may have an exposed clutch surface that can be visually inspected without removing the clutch.

 

 

Flywheels and Dual Mass Flywheels

The flywheel is a metal disc which is fitted directly onto the crankshaft between the engine and the clutch. Its purpose is to help provide a smooth transfer of power from the engine to the drive train. In essence, the flywheel gives your vehicle enhanced momentum and a smoother driving experience.

Indications of a worn flywheel are:

  • Visible Grooves
  • Visible glazing and/or cracks

We, along with the leading clutch manufacturers worldwide, recommend that whenever a clutch is renewed, your flywheel should be inspected and, where necessary, skimmed or replaced. 

Dual Mass Flywheel

Most new vehicles now come fitted with dual mass flywheels. These are essential components that allow an enhanced performance in the vehicles drivability. Additionally, these new components reduce harmful vibration.
A worn dual mass flywheel will affect the performance and efficiency of the new clutch and almost certainly result in premature failure.

Indications of a worn Dual Mass Flywheel are:

  • Irregular noises
  • Vibration
  • Intermittent clutch slip  

 

Here are a few tips to prolong the life of your clutch;

 

Don’t rest your foot on the clutch pedal while driving, you will take up the slack between thrust and release bearings and wear them out.

Don’t leave the car in gear with your foot on the clutch at traffic lights for the same reason.

Don’t hold the car on a hill by slipping the clutch for longer than absolutely necessary when doing a hill-start. You will wear out the friction surface.

Release the handbrake gradually with your thumb on the release button as you lift the clutch and press the accelerator.

Don’t slip clutches deliberately to avoid changing gear.

Make sure that there is a little free play in the pedal movement before you start to feel the weight, if there is no slack you may need to adjust the cable housing or the

clutch rod.

If you have hydraulic clutch control, make sure the reservoir fluid level is correct.

 

Bedding in a new clutch;

We strongly recommend bedding in your new clutch this can help prolong the life of the components

There is no set proceedure for bedding in however we recommend at least 200-500 miles of mild stop start driving (more if you doing motorway miles.)

We often get complaints of slip straight after a clutch has been fitted this is usually due to the following;

Contaminated disc (mechanics often have greasy hands which transfers on to the friction material) this will burn in the bedding in process.

Spirited driving straight after installation, this will not allow the clutch to bed in and may glaze the disc which will result in further slippage.

 

 

 Sintered Disc;

Recommended for motorsport use. 

 

  • Technical Details
    The SACHS Racing clutch discs with sintered metal plates have a higher friction coefficient than plates with organic friction material. That allows for higher transmittable torque and makes them very dirt and oil resistant.

    Their aggressive start performance makes them very suitable for endurance races, hill climbing, slalom and rally's. Installed together with the SACHS Performance clutch cover, you´ll have the perfect combination for a great race track experience.

    The SACHS Performance clutches are assembled by hand. This guarantees at all times the highest quality attributes in clamping load and release characteristics.

  • Organic discs do not give off the tell tale clutch burning smell therefore we do not recommend for road use heres an example of a sintered disc that has been melted due slipping caused by stop start road driving followed by an aggressive start,

 

 

Organic Disc;

 

  • Organic is a soft friction lining and therefore gearbox protective but not very temperature resistant. This type of material is not used in extreme race conditions.

 

  • Advantages

    Easy on the transmission, soft clutch engagement and a low wear on the flywheel friction surface

  • Quality - Made in Germany

    The clutch systems from ZF Sachs Race Engineering have brought motor sports teams worldwide to the forefront, from mass sports to Formula 1.

    The knowledge gained from these race series has been flowing into the development of High Performance products for years.Partners of SRE:

    Alpina - BMW - Brabus - Carlsson - Ferrari - Hamann - Heico - Hartge - Porsche - Ruf - Seat Sport - Volkswagen and more.

 

 

  SAC - Self Adjusing Clutch 

This is a wedge mechanism in the pressure plate that over time & clutch wear, will adjust itself to keep the engagement point of the clutch at the same point.  More importantly, it keeps the holding force consistant, but that's not what the driver really relates to most of the time.

The reason it needs to be set/checked prior to install;  This mechanism can be jarred out of alignment, and can be incorrectly installed in a "worn" position.  If that's the case, it will have less room for travel to release the clutch, and you can end up with several odd symptoms.  Hard to shift with clutch pedal all the way down, Clutch pedal won't go all the way down to start the car, and grinding noises with the clutch all the way down, to name a few.  This condition can also smoke your brand new clutch in 4,000-5,000 miles if not corrected.

The pressure plate can be jarred out of position with simple vibrations.  A nice drop will do it too, so if you see the UPS guy drop it on his truck, kick it across the room once, or if it falls to the floor while it's being installed, it'll be out of adjustment.  Also, the adjustment piece is rather fragile IMO, so don't go prying on it too hard!

 

 

 

 

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