| Re: [GMCnet] trans temp sensor [message #153689] |
Tue, 20 December 2011 08:42 |
Gary Casey
Messages: 448
Registered: September 2009
Karma:
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Senior Member |
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Generally, the oil that is fed to all the valve body, clutches, etc. is called "line" pressure, so I suppose that is what he is talking about. As for what he is calling "circuit" I have no idea, although I suspect that is the passage that feeds oil to the converter and then to the cooler "circuit." I'm not a fan of this for two reasons. One is that at a reasonably high engine speed - like over 1,000 rpm - the pressure regulator valve is sufficiently open that line pressure is already connected to the converter feed. Nothing to be gained. Second, at low rpm (idle) you really don't want anything bled off of line pressure, as you might need all you can get to keep the clutches engaged. Granted, at idle the mod can increase the cooling oil flow, but I wouldn't like to do it at the expense of clutch pressure. As for "starving" the converter I don't see how that is possible, since the pressure is fed in at the hub while the converter is spinning
and "holding" oil at the periphery where it is needed. I once calculated the pressure at the outer portion of the converter with it at zero at the hub. Can't remember what it was, but I remember that it was surprisingly high.
I need to go out in the barn and look for a schematic that I saved to get an exact look at it, but the bottom line is that I don't see any way that the "torque convertor can "starve" for oil when pulling hard up a hill and you can fry the transmission or torque convertor in a heartbeat."
Maybe someone can enlighten me.
Gary Casey
Bob de Kruyff wrote on Sat, 17 December 2011 19:54
> ""Gary,
>
> I have "heard" that the transmission or torque convertor can "starve" for oil when pulling hard up a hill and you can fry the
> transmission or torque convertor in a heartbeat.
>
> Supposedly there is a "hole" that needs to be drilled out or some other mod to prevent that from happening.
>
> Have I got bad hearing or is this info correct?
>
> Regards,
> Rob M.
>
> "" I've never heard of that one Rob--very interesting. The highest temps I see are when I'm stuck in a traffic jam. I suspect the convertor is in total slip mode with very little cooling from the heat exchangers. I'm frequently pulling in the mountains here with max speeds WOT at times of 30 in first gear. Keeping the engine revs up keeps the convertor close to "hydraulic" lockup so the heat generated is less.
A converter builder that I talked to said that a small hole can be drilled. He called it "Line to Circuit" He explained what this little hole does, but it was beyond my pea brain comprehension. Maybe Gary Casey can explain in simplified terms?
--
Larry :)
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