Quote:
Originally Posted by swazi_matt
just going off the sales pitch of suspension oils, does the ATF have the non foaming properties of suspension oil? and also longevity (and consistency iro not fading) of being forced through valves multiple times per second
I don't know the answers, but just two questions i would be trying to find answers for
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I was an engineer with GM's Hydra-matic (aka, High-dramatic) automatic transmission division in the 1980s. I spend alot of time with ATF.
1. Yes, ATF has anti-foaming agents. Foam entrains air in ATF, which reduces its bulk modulus (stiffness), which affects clutch timing (rate of engagement/disengagement) as the fluid "pushes" against a spring. Automatic transmissions have significant spinning elements, all of which work to "whip" the oil. Foam also causes pump cavitation, which causes excessive wear on the pump as well as adversely affects shift quality. Foamy oil is very detrimental to performance, so anti-foam elements are added to everyone's formulation.
2. ATF also has to deal with the pump, pressure regulator/relief valve, and the valves which operate in the valve body. All of those operate at relatively high frequency (pumps at much higher frequencies) than oil passing through a shim stack, so a suspension application won't pose a problem for forks/shocks.
ATF also contains solvents/detergents which keep the hydraulic valves in the transmission clean, free from sticking, and generally happy. That will work to keep your shim stack clean.