OK, will take your 4 applications, and demonstrate how
much little they have in common with MrHonda's wet clutch...now remember, MrHonda's wet clutch is there to lock up solidly, have a zero speed difference, and transfer the full torque.
Your clutch is essentially engaged the vast majority of the time, and slips only on starts, and slightly through gear changes.
As previously explained (and ignored), you do not glaze and blue clutch plates without the clutch being slipped, or slipping...zero speed difference, zero heat generation...and zero bluing.
Slip = heat = bluing.
Originally Posted By: BusyLittleShop
- engine oils
Included first, as it's the topic at hand.
Here's why they are introduced into engine oils, and why they are in EC oils.
The cold thick oil protects with full hydrodynamic lubrication. As the oil warms and thins, the parts start to make contact (boundary), and increase wear and drag.
Friction modifiers take the point at which contact is commencing, and form very easily sheared "soapy" layers that reduce friction and minimise wear (still allow more than hydrodynamic).
e.g.
NB : the engine parts are moving with respect to each other and in now way are equivalent to your locked clutch...the reduction in friction IS relevent to your clutch.
Originally Posted By: BusyLittleShop
- Limited Slip Gear Oils for limited slip differentials and transaxles
In a limited SLIP differential, the clutch packs are designed to operate in a SLIPPING mode...the absence of friction modifiers means that they grab and bang, as the friction in the clutch is high, torque through differences in wheel speeds winds up the axles like a torsion spring, and when the clutch finally releases, it lurches and bangs badly.
The inclusion of friction modifiers drops the friction between the clutches, and allows the clutch to slip, allowing smooth operation.
Relevence to Mr Honda ?
Nil really...except that FMs clearly reduce the torque holding capacity of the clutches.
Originally Posted By: BusyLittleShop
- Multipurpose tractor fluids for wet brakes
Again, consider that the tractor brakes are generally sliding...exactly the same as MrHonda's clutch isn't...yet.
The friction modifiers are installed in the lubricant so that as the brakes are applied, and start to slow the tractor, they don't suddenly reach the rising torque area of boundary lubrication and suddenly grab.
Again, the FMs are there to REDUCE the static friction of an applied brake, and make it slip easier.
Originally Posted By: BusyLittleShop
- Automatic Transmission Fluids (ATF's or those designed for smooth clutch engagement)
Again, the clutches and bands in an automatic are sliding, and again, as they approach engaged, have a quickly rising torque characteristic and grab.
FMs are installed in their lubes, again to reduce the static friction, and as a result reduce the ultimate torque carrying capability...to make the transmission shift smoothly, and slip more.
Drag racers quicken the clutch engagements to minimise the slip (slip = heat) that occurs on a shift, and sometime choose non FM oils...or they burn clutches.
The four areas that you quote are exactly the opposite of what you want from your wet clutch.
They are all REDUCING FRICTION, which by definition reduces the capacity of a wet clutch to transmit torque.
They all do it for a reason, that the static friction co-efficient is markedly higher than the dynamic, and they are trying to reduce that friction to create smoothness.
