Which Transmission with a vortec conversion???

[gpetry]

I am planning a 6.0 vortec conversion and already have a low mileage 2008 LY6 engine for my 1979 FJ40. The donor truck had a 6l90 trans behind it which was not an option since there are no adapters to the Toyota T-case (79 FJ40 stock case) that I am aware of. I had planned a 4l70e transmission since it is rated for the torque (380lbs, 360hp) and can be controlled by the LY6 computer. The 4l60 is essentially the same tramnsmission, but is not rated to withstand the torque that the LY6 puts out.

The problem is, there are no 4l70e transmissions to be found - we have been looking for 2 months. I am friends with the owner of a local salvage yard and he has been running it everyday. I have also searched and put out a request on car-part.com and have gotten nothing. the body and frame are ready to go to media blasting, but I would like to mock up the engine and transission and weld in the brackets with the tub on before I sent the body and frame out - the frame will also be powdercoated at the shop that is doing the media blasting.

After much searching - here, on pirate, and on ls1tech, it seems that my options are 4l80e, NV4500, HF55 toyota 5 speed, or stock 4 speed. My original configuration was going to use the Downey kit with the 4l70 to keep driveshaft length as long a possible. I prefer an automatic, but have no problem shifting gears if I need to. What are the downsides to the 4l80e? are there any interference issues with the tub/ trans hump (I have an Aqualu tub)? How much total length difference will I see compared to the 4l70 and downyadapter vs the 4l80 with an advance adapter? Is driveline length going to be adversly affected? Any other known problems issues I should be aware of?

Really need some input from the collective wisdom here to make the right decision. I'm tired of banging my head against a wall trying to weigh out all of the options. I much prefer to do it right the first time than to pay more tuition in the school of hard knocks by doing it again.

 

[chicago]

I know very LITTLE on this topic, but from what Im to understand is that the 4L80 is similar to the TH400 and is somehow stronger than the 700R4/ 4L60E.
Ill be running the 5.3 vortec with a 4L60E.
I decided to go with the 4L60E cuz it was the trans that was mated to the motor. As I recall reading in the AA lit, there was another advantage to using the 4L80E, but...dont recall right off the top of my head. It had something to do with eliminating an adapter, or not needing an adapter for a low gear option....

Chicago

 

[Isotel]

normally if the truck it came out of still has the tyranny on it it can be had for pretty cheep when combined with the purchase of the motor.

Auto and V8 is the way to go, i will never go back to a Clutch in wheelin rig..

 

[gpetry]

Problem is that the donor truck the engine came out of came with a 6l90 six speed and there are no adapters for the 6l90 to toyota tcase. Fortunately, I am friends with the salvage yard owner, so he is working with me on finding something and being pretty fair on price. Just need to figure out what we can make work and get moving forward.

 

[gpetry]

I have talked to advance and PM'd orangefj45. Looks like a viable option - just looking to see if anyone has and caveats or gotchas that make this conversion a pain. It seems odd that more people aren't using this trans if what I am seeing so far is true - heavier duty and a little shorter than then Advance 4l60 conversion, so driveline length is not a problem. I keep waiting for the hammer to fall on something like "it will work but you need to also add a body lift or redo the trans tunnel" or some other major time/fabrication project to make it work.

 

[riverrock]

Auto Trans Vortec Combo

Sounds like we're all in the same part of a build as far as engine /trans combos are concerned. We are welding up my new pacol body for my '79 and getting ready for engine and transmission. I wanted to go NV4500 but after driving my wife and business partner crazy with the shopping thing and endless research I am going to go with the 5.3 vortec and 4L60E combo for a number of reasons. My original drive train is fine, but I plan on using it for fishing (pulling jon boat) and camping and general weekend fun trips so I feel that the Vortec/ auto is the most practical choice. 5.3s are a lot more readily available and lower priced and the power is pretty close. Everybody I know that has one swears by them too. I just got the advance adapter conversion book which looks like it will help a lot. I know many people had rather stay pure stock but I have always gone that way on restorations and am ready to try a different approach. Good luck and I hope all us Vortec converters can pool our experiences to make it easier.

 

[gpetry]

Lil John - to clarify - the 4l70e is actually an updated heavier duty version of the 4l60e and any of the 4l60e conversion adapters will work with it. The problem is that there are no used 4l70e transmissions to be found and a rebuilt without a core is $2300++ There are 3 versions of the 4l60e now - the original 4l60e (which is a descendant of the turbo 350 and 700r4) the 4l65e which has heavier duty internals and is rated for more power than the 4l60e and the 4l70e with is heavier duty than the 4l65e. The other kicker is that the 2007 up engine management computers (which also control trans shifting) are also looking for an input speed sensor on the trans which is only on 2007 and newer vehicles. The other problem is that GM is moving everything to 6 speed automatics and the aftermarket has not yet caught up with adapters or programming to use these on any vehicle other than the original.

The 4l80e is a descendant of the turbo 400 and does use the same adapter.

It looks like my best option is a 2007+ 4l80e since it more common than the 4l70e, has the power rating, has the dual speed sensors and adapter for the toyota tcase. Just making sure I do all of my due diligence before I spend more money. I have way more time invested in this than I should have. Hopefully this dissertation on the fine points of late model GM transmissions will save someone some headache. I probably would have been better off doing the 5.3 and 4l60e combo, but I am hardheaded and have the 6.0 on the floor.

 

[gpetry]

Right - the 2008 LY6 6.0 was available with the 4l80e in both the Chevy Express and GMC Savannah vans. I have found the following link from GM powertrain indispensable in figuring out what combos were available from 2003-2009:

GM Powertrain guide

Click on a year and it will show you every engine trans combo available that year as well as all of the specs and info for both the engine and trans including a torque / horespower graph. Pretty cool stuff.

 

[Combat Chuck]

I would say go for the 4l80e, word has it that it's descended from the TH400, which is legendary in offroad circles. I'm none too happy with my own automatic transmission experiences, but this seems the best from my angle.