4L60E: 98 vs. 02 programs

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Jan 12, 2005 | 02:39 AM

tici

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From: Zurich - Switzerland

4L60E: 98 vs. 02 programs

Last week I made a huge excel spreadsheet to see the differences between the models (F & Y bodies, 97 – 02), this in the hope to have some benefit from the newer programs.
I loaded now the complete transmission settings of the 02 Corvette (almost the same as the 02 F body) and I really like it.
The torque management isn’t too bad, what I really like is the new Positive Pressure vs. Temp table.
It has higher numbers at low throttle and lower at WOT.
I almost don’t feel the shifts, very smooth… totally opposite to the stock 98 feeling (sometimes too hard, especially at low transmission temperatures).

Here my question: do the cars have the same transmission? (My 98 Trans Am and the 02 F and Y bodies?). If not what are the differences?
The only problem I can imagine is that I’m using now a program that allows more slippage with mechanical parts that aren’t built fort that.

Right now the engine is stock (I disconnect the blower during winter), so the power should be in an acceptable range for this transmission.

Tables that I copied (LS1 Edit):
Positive pressure vs. torque
Desired shift time
Base pressure vs. torque
Upshift torque reduction
A4 TCC

This for the same gear ratio (2.73)

Thanks - Stefano

Jan 12, 2005 | 05:59 PM

BADFNZ

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From: Dyess AFB, TX

Yes, the transmissions are basically the same. Some say the Vette has a different servo and others say all f-bodies come with the Vette servo. Other than that and the fact that the Vette uses a torque tube, they are the same. But not feeling shifts could be a bad thing. In order for the shift to be "smoother" usually the tranny has to slip more between shifts.

Jan 13, 2005 | 12:51 AM

tici

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well, "don't feel" was maybe the wrong words. With the 1998-2000 positive pressure vs temp table you can feel a much harder shift than with the 2002 settings. Especially a part throttle when you don't really need it.
Right now (new settings) you still feel the shift and there is no surge during the shift or slip after the shift. IT's just more quite (like any other automatic transmission car I know).
Should I monitor the inlet/outlet transmission shaft speeds to see if it slips?

Jan 16, 2005 | 06:23 PM

ToplessTexan

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From: Murphy, TX

Quote:

Originally Posted by tici

Should I monitor the inlet/outlet transmission shaft speeds to see if it slips?

That won't do you much good. The input and out output speeds are both derived from the VSS and will always agree modulo gear ratio. I.e., the input shaft speed OBD-II PID is an approximation of the real physical quantity, there is no direct measurement of it. The approximation is only accurate assuming the phenomena you're interested in (slip) isn't present.

Just enjoy your new tune.

Jan 16, 2005 | 11:30 PM

tici

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Ouch! Is there a way to know if it's slipping? It doesn't feel so, but how to be sure?
The program is there since a week now and I really like it

I just copied the Normal Mode, do you know if the 02 Corvette has a selectable Performance Mode also? I think later models have it. Do you know how does the difference feel?

Jan 17, 2005 | 07:27 PM

ToplessTexan

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From: Murphy, TX

Quote:

Originally Posted by tici

Ouch! Is there a way to know if it's slipping? It doesn't feel so, but how to be sure?
The program is there since a week now and I really like it

I just copied the Normal Mode, do you know if the 02 Corvette has a selectable Performance Mode also? I think later models have it. Do you know how does the difference feel?

There's no way to measure directly. You *could* collect some data now showing your current relationship between engine speed and vehicle speed under various conditions. You *could* then compare future data to this. That said, if you have slipping components it will eventually trigger a DTC.

Assuming you keep your fluid cool, I wouldn't worry about it much using a near stock tune. The performance mode tables are usually either duplicates or empty. You might check out the Aussie guys' boards, they may have some decent insight into useful details for this.