4L60E torque converter question, better cooler

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stutaeng

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The 4L80E got an upgrade in '97 or '98 that allowed towing in OD. Far as I know, the earlier '80E, and all flavors of 700/4l60/'60E are unsuitable for towing in OD.

Ok, thanks. I got curious and went to look at my '99 1500, and it says the same thing about towing in OD...but the thing is, the manuals are universal because in the axle ratio combination they list 1500, 2500, 3500 models, LOL. What I mean is, the statement applies to both trannies so I think you should use your own judgement!

As far as the upgrade to 4L80e's, are you talking about that oil cooler change? Something about oil not cooling certain components and burning up? I have posted a video recently from Monster Transmission and they discussed that. I seem to remember it was earlier though. Maybe it's something else?

Sorry to de-rail the thread!
 
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Pinger

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I see this a lot: people saying not to tow in 4thOD. My K3500 2000 owner's manual states otherwise.

Is this specific to the 4L60e? I don't know much how transmissions work mechanically, that's why I ask.

As it was told to me, I took it as a generalisation for all auto transmissions with 4th/OD. And kind of threw it out to see if it was endorsed or refuted.

It doesn't directly contradict your manual in that it recommends downshifting manually to 3rd if the box is frequently doing that of its own accord.

My take on all of this if towing would be to gauge how stressed the drive train is and select the gear appropriate ie. 4th/OD level/downhill lightly laden and manually select 3rd if heavily laden and/or climbing/descending steep hills (for engine braking).
Those with towing experience can better gauge if that is a reasonable approach.
 

weaponoffreedom

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So, what's happening when it "shifts down" slightly? I've heard it has to do with the torque converter "locking up?" or "unlocking?"
Yes, the converter is locking and matching the engine rpm. Feels like a "half gear"

You should not tow in overdrive as there is a negative mechanical advantage due to <1.00 gear ratio. Excess heat, less power, less cooling, excessive shifts, etc. But to each their own.
 

Schurkey

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Better to tow/haul in 3rd gear with the converter clutch locked-up, than to tow/haul in OD with the converter clutch unlocked.

When the converter clutch is locked, trans temperature drops dramatically. Fluid is happier, rubber seals are happier.

When the converter clutch is unlocked, temp goes up due to converter slippage, and--so far as I know--the 700/4L60/'60E transmission doesn't lube the geartrain properly when the converter clutch is not applied. This was told to me by the shop that overhauled the '700 in my 88 K1500; but I've never confirmed it independently.

I don't know if the geartrain lube problem also applies to the other GM overdrive transmissions (2004-R, 4L80E, etc.) or to non-GM overdrives.
 
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