tc lock question

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Feb 15, 2008 | 09:24 AM

wmiller

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Joined: May 2007

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From: North East, MD

tc lock question

Just did tc lock mod and love it but have a few questions. When is it safe to lock? Will it cause damage locking to slow speed (rpm or mph) or will it just dog the engine?

Feb 15, 2008 | 10:20 AM

Robbgt

Logistics Pro

Joined: Oct 2004

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From: FL

Well, I wait till about 35 MPH to Lock the TC, and if speed drops below 30ish I unlock. If you have a newer PCM, TDE1, the PCM will do this already, as I found out going from a NAW6 to the newer code. But 35+ lock and 30ish unlock. I'm sure others will chime in too

-Robb

Feb 15, 2008 | 11:06 AM

MADVAN

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From: Levittown

The only real time you have to keep and eye out is with the use of the EBPV as a brake.
I thought most have an auto trans for what it is an auto.
It should do what is needed by itself!

Bill

Feb 15, 2008 | 11:49 AM

wmiller

Thread Starter

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From: North East, MD

The pcm want to unlock below 25. I've been cutting off at 20 and kick it sometime after 20 depending on conditions. I've heard that locking it at too low of speed is bad because of line pressure or something

Feb 15, 2008 | 12:07 PM

Robbgt

Logistics Pro

Joined: Oct 2004

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From: FL

Quote:

Originally Posted by MADVAN

The only real time you have to keep and eye out is with the use of the EBPV as a brake.
I thought most have an auto trans for what it is an auto.
It should do what is needed by itself!

Bill

Very true Bill, But my old NAW6 code was CRAP, the new TDE1 makes the truck shift like it should. I rarely use the TC lock now, just for diagnostics mostly...

-Robb

Feb 15, 2008 | 12:32 PM

Mark Kovalsky

Frmr Ford Trans Engr

Joined: Aug 1999

Posts: 24,696

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From: SE Florida

The pump doesn't have enough output below about 1300 RPM to be sure that the torque converter clutch won't slip. If you try to lock below that speed you run the risk of slipping the clutch, which will damage it.