Clutch Slip

6th November 2004 - 1:44am

First Case Study

20v flywheel - lighten from 6.8 kg to 5.8 kg - mated with standard 4A-FE clutch pressure plate as well as clutch plate found with the chop EXEDY + AISIN and made in japan.

Take a look at the left flywheel. Ignore the right flywheel as it is literally new. Unused.

Notice the surface has some markings like rings and different on the inner edge and outer edge. While the inner surface is some what ........ don't know how to describe. More bite ???

It is guessed that - there are some problems with the clutch pressure plate. The cause of the dark color as well as different level of ring are due to the lack of grip by the clutch pressure plate.

This clutch assembly was used only for 8 days.

The driving feeling was not good at all. There are many scenarios. e.g. below: -

Upon change of gears the engine rev would drop very quickly - some times below the point of drive train speed. Where the rev suddenly picks back up after releasing the clutch pedal.

Every time upon release of clutch pedal to engage gears the engine rev sound and feel of the car's movement doesn't tele. It feels like slipping.

Upon acceleration, there is a slight delay before the car actually plunges forward. Notice I said "plunges" forward. It doesn't move from slow to fast. It doesn't move and moves very little, wait for a while then suddenly moves. The plunging effect is heavily exaggerated, however very noticeable the car doesn't / struggling to move upon release of clutch and acceleration.

Acceleration did not improve significantly. The response of this modification of lighten flywheel couple with standard clutch system was not promising at all.

Saying this - the understanding at this time was that the 6.8 kg flywheel coupled with TRD semi racing clutch was much better. Although it lacks the slight acceleration improvement, but the grip was constant and gave a constant acceleration, while the above was wage - some times good acceleration, some times bad.

The saddest part is that it does not accelerate when you need it and performs pretty well when you don't need it.

The mating of lighten flywheel with standard clutch system is a failure.


Second Case Study

20v flywheel - lighten from 6.8 kg to 5.2 kg - mated with modified heavy clutch pressure plate as well as modified 3 pucks NA full-racing carbon copper clutch material.

The initial feel of the clutch was heavier than the previous TRD semi racing by 20%. However upon release of clutch and drive, the feel was fantastic. Very predictable, very stable, very smooth. Engine power is immediately delivered to the drive-train and successfully transmitted to the group without lag what so ever. The response is brilliant and that the engine rev does not drop down as quickly as the 5.8 kg flywheel effect.

It is suspected that the clutch pressure plate have different weight and contribute to the difference between the engine rev dropping effect. However upon examination and recall of weight, they are literally the same with no more than 100 grams difference. Hence It is not possible for the 5.2 kg flywheel to out weight the 5.8 flywheel clutch assembly.

Just a note: -

Standard 4A-FE clutch pressure plate is 4.1 kg

Standard 4A-FE clutch plate is 1 kg


Conclusion - as of writing

Probably it doesn't matter how heavy is the flywheel, but there must be sufficient weight at the outside perimeter to maintain enough momentum so that engine rev would not drop drastically.

If this is not that case, then the clutch pressure plate must be efficient and not slip so that regardless of acceleration or deceleration that the engine rev is nearly always matched to the drive train speed closely.

Else the possibility of having both - where a lighten flywheel should be mated to heavy clutch pressure plate scenario.

i.e. heavy flywheel should mate with light clutch pressure plate

i.e. lighten flywheel should mate with heavy clutch pressure plate



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