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Old 12-21-2009, 03:17 PM   #5
Thealien
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Join Date: Jun 2007
Location: Pine Ridge Florida
Posts: 4,126
Re: LS engine swap info

Transmission info and adapters

If my transmission ever needs a rebuild I am going with these guys. Check out all the pictures and attention to detail!

Finish Line Transmission build thread


Not a lot of info to post here. The harnesses can be changed from either a 4l60 to a 4l80 and the other way around. It is easier to alter a 4l80 harness for the 4l60 but both are doable. The 4l80 has 2 VSS sensors and the 4l60 has one. If you have a 4l60 harness you have to add the other VSS for the 4l80. If you have a 4l80 harness you remove the extra VSS for the 4l60. It matters which one but if you are doing your own harness you will have the pin outs. If you are having it done they should know what to do if not find someone else. In the big round connector there are a couple of wires moved between the 4l60 and 4l80.

HERE IS THE DIFFERENCES IN THE TRANSMISSION WIRING


There is a big switch on the side of the transmission. It is your park/neutral safety switch. Many people remove this and that can be done. The PCM does use that information for more than the safety and gear indicator but from what I have read it is not necessary. Here is what I have found

The PCM uses the signal to adjust idle speed based on whether the car is in gear or in park/neutral.
As soon as the PCM "sees" the car go in gear it drops the idle speed by around 100 rpm to prevent jerking going into gear, and to prevent tugging at the torque converter.

It can be considered as optional on a swap. As long as the line is left open the PCM will always assume the car is in gear, and will drop to lower rpm when the engine is started. This also causes a much quicker rpm rampdown on a cold engine start.

Some aftermarket wiring harness companies that have no clue as to how the PCM works will wire this line to ground which makes the PCM think the car is always in park or neutral. On some applications this allows some diagnostic tests to be skipped (EGR, purge, etc.) so that these items can be left off without setting a code. The problem is that the idle is too fast then, and the car wantts to pull a little when sitting still, as well as other issues.


I have a 4X4 and am keeping the NP205 transfer case in the factory location using the 4L60 transmission. Here are the aprts I needed to make this work.


4L60 to 205



Here are some of those parts being installed(bottom first page)



And here is another thread showing more of that installation


The transmission must be disassembled to install the output shaft. I did not want to move my transfer case shifter or change my almost new driveshafts so this is the route I took. There are a couple of passenger side drop transfer cases that will mate to the 4L60 but I do not have the information on what works and what doesn't. If somebody has information on what works and how they handled the shifter etc I will be happy to include it. With all that being said I may still have driveshaft/transmission pan clearance issues due to being stock height. I will update with pictures when I know.

I am also going to try to modify my stock shifter linkage to work. Some say I won't be able to shift into first? Again I will update when I know.

Here are a couple of shifter linkage solutions


Lokar shift linkage



Lokar cable shift linkage


If you need to run a mechanical speedo with a 4L60 this is one solution


Shiftworks


The fittings on these 4l60/80 transmissions are not NPT but National pipe straight thread

And use fittings like these

Corvette servo information courtesy of Glock35ipsc

Corvette servo

Last edited by Thealien; 01-18-2010 at 12:55 PM.
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