What does friction modifier do?

[PUFF00]

What does gear oil friction modifier do? Does it increase or decrease friction?

If you don't use it, how does this alter how the limited slip locks up?

Does it increase or decrease the effectiveness of the gear oil in terms of protecting the gears?

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2001. 5 3500 QC 4X4 6-speed HO 3. 55 black
1998 Jeep TJ black http://www.nm4w.org/members/puffer.htm

 

[dmurdock]

Decreases friction and keeps lsd clutches from chattering

 

[PUFF00]

I'm putting in LE 607 today. It is reported to be excellent gear oil. If it is so great, then why would I need to decrease the friction of the oil for the LS? Why wouldn't LE put this in their gear oil to begin with? If the friction modifier decreases friction, then why wouldn't all oils already contain this as an additive?

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2001. 5 3500 QC 4X4 6-speed HO 3. 55 black
1998 Jeep TJ black http://www.nm4w.org/members/puffer.htm

[This message has been edited by PUFF (edited 04-14-2001). ]

 

[DocStressor]

Most differential/transmission lubes contain some type of friction reducing agent as part of the additive package. These agents generally adhere to metal surfaces and reduce friction under boundary lubrication conditions. The amount and type of anti-friction additive blended with the base oil varies between different lubes. Most manufacturers seem to have optimized their own formulations of viscosity index improvers, extreme pressure lubricants, stabilizers, and friction reducers. There is no such thing as a free lunch. Too much of one type of additive can affect the performance and/or solubility of other components. And too much additive blend can reduce the hydrodynamic lubrication properties of the base oil. So adding more of one component does not necessarily make things better.

A limited slip differential presents a particular set of problems for lubrication engineers. The optimum amount of friction reducer for a particular application depends on the type of differential and the load that will be applied. And that load can vary all over the place when you consider the different types of vehicles that use say the Dana 80. Thus, many lube manufactures like LE design their product for an open differential and let the user titrate in the proper amount of friction reducer for proper operation of the LSD mechanism under their specific operating conditions.

Some synthetic products, such as Amsoil 2000 and Mobil, add enough friction modifier to their blends for MOST APPLICATIONS. I have seen posts on this board indicating that some members using these products do not need to add additional friction modifier and yet others do. Variations in gear tolerances, LS clutch wear, and load are probably the determining factors.

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1999 Quad cab 2500, SB, SLT, 4X4, 5-speed, 3. 54, tow and camper package, Lance 820 camper, Lance cabover stabilizers, Rancho 9000s, Airlift airbags,Reese Titan V hitch, Mag-Hytec differential cover with Amsoil 2000 75W-90 lube, Amsoil air filter

[This message has been edited by Lee Weber (edited 04-14-2001). ]

 

[PUFF00]

Thanks Lee.

 

[Texasdeere]

Thanks Lee, and thanks Puff, I was wondering the same thing... MH