6t40 to 6t45 conversion

[JJT*90]

I was curious if anyone knew how hard it would be to swap a 6t45 into a car that originally had a 6t40. I am trying to build my G6 a bit, but I don;t think my tranny will hold to the power long term. From what I can tell they are almost identical, but the 6t45 is a bit stronger. Please help.

[ZerOne]

Hello and welcome to the forums !

As for your question, I am not an automatic specialist, nor have I played around with them much.
From the looks of things, the 6t45 is slightly bigger than the 6t40.
I have no idea the actual dimensions, but from what I have read, the housing has extra ribbing which might effect physically fitting the transmission.

Next, you will need to check the Transmission Control Module electrical connectors from the 6t45, to make sure they are compatible.
The TCM is inside the transmission, and will look after shift feel, shift points and other information.

Sorry I cannot help much more.
I could however look up the workshop manual for your G6, and other GM vehicles with the 6t45 fitted, and try and get some more information for you if you wish ???

[JJT*90]

Thanks for the reply. My current issue is heat in the tranny causing it to slip. For now I'm going to add a cooler and swap the filter and fluid. If that doesn't work I'm going to have to dig into getting a beefier tranny into the car. Thanks for the offer, and I'll try and keep this thread updated with info.