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atmdoc
04-29-2006, 21:46
I'd like to get firmer shifts and have it lock up around 45mph. Anyone with some suggestions?
GMC Hauler
04-30-2006, 05:33
I'd like to get firmer shifts and have it lock up around 45mph. Anyone with some suggestions?

Click on the link im my signature line to see my shift kit. That is the cheapest way to go.
DA BIG ONE
04-30-2006, 05:43
I'd like to get firmer shifts and have it lock up around 45mph. Anyone with some suggestions?

You 4x4, if so what t-case?

Anyway, if you have the AutoTrac (NP-246) there are no options to change lockup except gear changes. The AutoTrac has 3 speed sensors and is intergrated into the ABS control and ECU so aftermarket suppliers will not even consider mods for liability reasons.

If you don't have 4x4, or have another t-case there are some options to change lockup w/stand alone controller. I was in the sweet zone w/my mods until I switched to 33" tires, but I can go back on tires size or go to 3.73 gears.

The 4L80e is a strong unit made even stronger w/available aftermarket kevlar clutches, premium steels, TransGo "offroad/towing" valve body mods. However, keep in mind any changes to valvebody requires reflashing tranny controller or the controller will cut back any changes to pressure, etc.
atmdoc
04-30-2006, 13:29
Da Big One,

Re: Reflashing the tranny controller. Isn't the tranny controller part of the ECM? If so that means I would have to get a new ECM?
DA BIG ONE
05-01-2006, 02:36
Da Big One,

Re: Reflashing the tranny controller. Isn't the tranny controller part of the ECM? If so that means I would have to get a new ECM?

Yep, tranny control tweek is part of Heath's MaxiTorque program but I'm thinking it would not include lockup options because of the NP246. I've been to all the known aftermarket stand alone tranny control guys and can't get what is needed because of the AutoTrac.
rjwest
05-15-2006, 14:11
TCC lock up is controlled by the pcm sense of the drive shaft speed. pre 96 can be forced by a BD torque lock,

96 and newer will set a code if TCC is forced locked..

The lower the the rear gear ratio the highr the MPH at TCC lock up ( actual, not indicated )

I know of no one who had reprogramed the PCM for
TCC lock up, There is a way to get and lower lock up speed in
3rd gear, and also get a lock up in 2nd,, ( but no way to alter TCC lock up speed in O/D , Search TCC lock up in forum.