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Trailblazer SS
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Discussion Starter #1
After much research, I've decided that an 4L80E swap is the best choice for me.
I found a guy selling a low mileage (41k from a 05 GMC Savannah van) 4l80e with torque converter and am planning on picking it up tomorrow. I've read a bunch of threads trying to educate myself and I think I have a pretty good idea of what I'm getting myself into...

Some things I'm still unsure of though. Ill try to keep it simple and thank you in advance for any input you may have.
BTW,I am a total noob when it comes to automatic transmissions.

1) Does the speedometer still work WOT from a stop even with a stock converter? Unlike higher stall converters?

2) Can HP tuners or EFI Live replace the need for the TCM that is listed on the "parts list thread" by JD_SS?

3) Use the 4L80 converter, 4L70 flexplate, and transfer the front cover off my 4L70 onto the 80, right?

4)Will the stall speed change using the stock 4L80 converter designed for a heavier(?) 3/4 ton van when used in my TBSS?

5) Since all the line pressures in the 4L80E are TCM controlled, Is there any reason to install a shift kit since the TCM is effectively doing the same thing, just electronically?

Ultimate goal (several years down the road most likely) is around 500 @ the wheels with a Maggie and a transmission that I don't have to worry about. I want to replace my transmission once and once only. I drive it daily and tow with it several times a year. Should I have it beefed up anyways?

I'm pretty stoked about finally addressing the transmission issues these trucks have. I rarely ever get on it because of this reason and it sucks I cant enjoy the 2nd half of my gas pedal for fear of blowing up my tranny...
I'm hoping with careful planning, some parts trading, and stumbling upon some good deals, I may be able to complete the swap for under $2000.:yay2:
 

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Trailblazer SS
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Discussion Starter #2
Picking up the 4l80E this evening for $400.
Seems like a pretty fair price?
 

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Trailblazer SS
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Discussion Starter #4
Thanks for the response. I'm sure I would be fine with a level 6 but everything I've read has me convinced to go ahead and swap to the 80. I've spoken with the seller and am picking it up tonight.

I tried to call LC32 but no answer. I want to make sure the conversion harness is still available and if the tcm is still required if I get tuned with hpt or efi live.
 

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07 TBSS RWD
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I think Joe is out of town for a few bit. Leave a message or send him an email I'm sure he'll get back to you as soon as he can. Definitely go with one of his TCM's. It's all set up just the way you need it to be really no further tuning required.

Granted my 80e was mildly built, but I like the way it shifted much better than my 70e and for the money I spent on the transmission it has taken a lot of abuse for a long time.
 

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1) Does the speedometer still work WOT from a stop even with a stock converter? Unlike higher stall converters?

It will work off of the rear speed sensor on the 4L80E

2) Can HP tuners or EFI Live replace the need for the TCM that is listed on the "parts list thread" by JD_SS?

Get the TCM and harness and PCM set from Joe at Left Coast and be done, it is a proven combo

3) Use the 4L80 converter, 4L70 flexplate, and transfer the front cover off my 4L70 onto the 80, right?

Wrong, you will need a 4L80E specific flywheel and spacer to use the stock 4L80E converter in your truck. You can purchase an aftermarket converter that is built to use the stock 4L70E style flexplate but your stock converter cannot be adapted.

4)Will the stall speed change using the stock 4L80 converter designed for a heavier(?) 3/4 ton van when used in my TBSS?

Yes, it will be lower in your TBSS than the original application. Most stock 6.0 converters were approximately 2200-2400 flash stall, so your may end up around 2000 in your truck if it has the high stall variant.

5) Since all the line pressures in the 4L80E are TCM controlled, Is there any reason to install a shift kit since the TCM is effectively doing the same thing, just electronically?

Aftermarket kits address shortcomings in the original trans and improve shift quality and durability, these are things that cant be accomplished in a tune. I have seen more "Tunes" kill a 4L80E than any other single modification.
 

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Trailblazer SS
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Discussion Starter #7
Thank you everyone for the responses. I will do just as you guys said and get the TCM/PCM and harness from Joe.
I am gonna start at page 1 on this forum and read up to the present.
I'll try contacting Joe again sometime next week.
THANK YOU AGAIN everyone for the help. I wouldn't even think about doing this swap of it wasn't for the information and support here.
 
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