I have a TH400 that I had rebuilt a number of years ago with a bunch of bells and whistles put into the rebuild. I know it has a shift kit but the whiz kid that did it for me had a couple of other tricks that he liked to do and I gave him the goahead on it. Something with a valve closing different or time different or...
At any rate, the Q I have is can I replace this 400 with the 4L60E that I have in there now with adding anything off the OEM that I would need for the computer and/or everything else that would make it complete and just as it is now dtock but with the tricked out tranny?
Can I get some input from you all, both pro and con. If this is NOT a good idea, could you tell me why you think not or if it is and I can make even further improvements or additions, please let me know those also.

As usual, thanks to all who reply.

 

Great idea, unfortunately you have some major obsticals to overcome. Like the TH400 is longer then the 4L60E tranny, this means new driveshafts, front and rear. This also might mean a new tranny cross brace, or at least moving your current one and modifiing the way it mounts to the tranny.

The next major area is the shifting of the tranny. The 4L60E is electronically controlled, the TH400 is vacuum and kickdown cable controlled. I am not sure if you can just unplug the tranny. I think it has to be plugged in to make the puter work correct. Plus yours has a cable, and no mechanical shift linkage from the colum like the TH400 is used to. Might be able to make the cable work, if not, you might need a new steering column.

You will also have to figure out a way to make your back up lights, and brake lights work. On the 2000, they switches are attached to the tranny.

Your fuel mileage will drop tremendously. The TH400 does not have a overdrie gear. Would be like driving around in 3rd (D on the shifter) all the time.

And lastly, the TH400 is serious overkill. No way your 4.3L engine will ever put out enough power to warrent that tranny. Not even if you get a blower. Your 4L60E can be built to handle the power of a blower. The 4L60E can be built to handle 450 pounds of torque, not horsepower, but torque. Thats almost 200 pounds of torque more then what your stock 4.3L is putting out, almost double the engines current torque.

If it where my tranny, I would sell it.

 

I agree the 4L60E is used in more than just the S-10's, it was used in trucks up to 2.5 tons and the Corvette so just keep it. Sell the TH400 and get stronger parts for your tranny if you need to make it stronger....if it were me that's what I would do.

Hanr3:

On my 2000 LS 4dr 4X4 column shift D is overdrive 3rd=3 2nd=2 1st=1....maybe I got the wierd one....

 

No, yours isn't weird. All 700R4/4L60/4L60E are the same. OD on the shifter is 4th gear, overdrive, a 70% reduction gear. All D on the shifter is Drive gear, 3rd gear, a 1to1 ratio. Don't cofuse torque converter lock up with overdrive, they are not related. Torque converter lock up can happen in 3rd and 4th gears, and I hear on the newer trannies also in 2nd gear. When the torque converter locks up, it is locking itself to the engine, no slippage, gives better gas mileage, and reduces the amount of heat generated.