FAQs

/FAQs
FAQs 2018-10-09T23:14:10+00:00

We are in the process of building our FAQ section, in the meantime please email any queries you have.

How important is the correct release bearing? 2019-05-16T21:40:00+00:00

It can be thought of as the last part of the release mechanism, but must not be overlooked as it plays more than one important role here.

The bearing (or HRB) makes contact with the clutch fingers when the clutch release mechanism is operated, the bearing face must allow for a fulcrum point to be generated so that the clutch fingers can pivot around this point. The PowerTrain Technology bearing is designed to optimise the clutch finger geometry ensuring that force is applied to the end of the fingers which maximises the lever effect and reduces the release load required, this not only helps the drivers left leg, but also the crank thrust bearing.

Other round nose (NOT flat) release bearings can be used, but by increasing the contact point diameter above the recommended 42mm (as per PTT bearing) the release load is increased and modulation is reduced which are both negative effects to clutch use.

Our bearing is extremely high quality and is designed to run down and stop between clutch actuations, this reduces parasitic drag, only high quality bearings can cope with this workload.

A standard OE bearing will need to be in constant contact with the clutch to ensure it is  kept rotating at engine speed, this allows OEM’s to reduce the quality and cost of their bearings, it takes a high quality bearing to live with being accelerated from stationary to full engine RPM in a split second, but our bearing can do this.

 

What causes driven disc keyhole fracturing? 2018-11-10T17:00:25+00:00

It is possible to read a clutch like good engine builders can read a spark plug.

By looking at differing clutch trauma we can tell you about the state of tune of your engine, (too lean, ignition advanced too far, pre-ignition, detonation, etc.)

Keyhole fracturing is a function of detonation and sometimes to a lesser extent pre-ignition.

Picture the friction paddle as being one mass that is separated from the other five (or seven) friction masses by an expansion slot, the slot is a thermal necessity as without the slot the disc will warp up immediately from thermal exposure.

When the engine pre-ignites the combustion charge, instead of nice controlled combustion chamber pressure increase, you get a bang which is a  pressure spike that can sometimes happen before TDC.

Picture in your mind this rapid increase in combustion pressure as being equal to hitting the top of the piston with a sledge hammer.

This rapid increase in pressure is harmful to all components in the engine and driveline.

When the pre-ignition happens slightly before TDC there is a harmful reversal in rotation that is imparted to the crank.

The way that the clutch disc reacts to this nano-reversal is the mass of the paddles try to go backwards instead of forwards momentarily, the mass of each of the six (or eight) paddles stretches the disc core material at the base of the keyhole causing it to fracture.

We can advise with a high level of confidence, that a clutch disc which has suffered keyhole fractures has been caused by an engine running with a pre-ignition or detonation problem, and if this problem is resolved not only will the clutch discs last longer but the life of many other components within the engine and driveline will be extended.

Competition engines are often far closer to the edge of safe running/tuning than many owners/drivers appreciate, and a change of fuel or even weather can often be enough for these high output engines to run into issues as described here.

Why is the PTT Bronze Metallic Friction Material Superior? 2018-10-10T20:21:20+00:00
Our clutch assemblies provide some of the most compact installations along with an extremely low Moment of Inertia (M.O.I), this is due to the extreme care and dedication that goes into not only the design of the clutch, but also the selection of the materials and machining processes involved.
A good example of this is our proprietary (unique to us) friction material, Sintered Bronze Metallic which is used in all our competition applications and should not be confused with the Sintered material which other manufacturers use.
If you look at other Sintered friction discs you will see that the surface finish is quite poor and rough, this means that the clutch must bed in from new and after the first few launches a significant amount of material will be scrubbed off thus shortening the life of these particular discs, the material composition which they have chosen is also far more aggressive and will snatch or grab, so in general users do not give good feedback on how they feel.
PTT friction material has much smoother engagement characteristics and is micro finished so there is no bedding in and as such it has a much longer life than other manufacturers material.
We also see that these other friction materials, being more aggressive, eat up the mating parts whereas our material does not.
On a PTT clutch, you can usually just replace discs when they are worn.
It is rare for us to see a floater plate or pressure plate that has more than .001” of wear.
Floater plates and pressure plates are only replaced when they are warped due to excessive heat.
Cerametallic means that the disc has ceramic material in it which (in a racing clutch application) is little pieces of glass or sand and will eat up the mating parts (floater plate, pressure plate and flywheel) and is why we chose not to use it.
For very extreme applications, we move across to Sintered Iron Metallic friction material if we are looking for every last lb of torque capacity, but it is extremely rare that we need to do this.
Can I slip my Racing Clutch? 2018-10-10T20:01:57+00:00

Every time you slip a clutch, the friction surfaces are generating heat.

You should make every effect to preserve your racing clutch by keeping the heat build up to an absolute minimum, prolonged pull aways where the clutch is being slipped should be avoided and certainly never drive your car onto a trailer as this can be enough to overheat it and cause damage.

A true racing start, where revs are raised and the clutch is engaged smoothly but quickly is less damaging to the clutch then a prolonged period of slipping the clutch in order to pull away.

Remember, heat is a racing clutches mortal enemy!

Why use a pedal stop? 2018-10-09T23:12:23+00:00

A critical element to the final setup of a competition clutch is the clutch pedal stop, this is required to ensure that the clutch diaphragm fingers are not over operated, if this does occur the clutch can be damaged and will require a full inspection and potentially a re-build.

Which Size Master Cylinder? 2018-10-09T23:13:17+00:00

In general, we would recommend using the smallest Master Cylinder size available (typically .625″), the smaller the cylinder bore, the more mechanical advantage gained and consequently less pedal effort required to operate the clutch.

Our competition clutches require only a small amount of travel to disengage, therefore a small bore master cylinder which moves less fluid will be better matched to this installation, it will give improved modulation and control of the clutch around it’s biting point.