Thoughts on 700R4 to 6L80-E Swap

[DixieWASP]

Has anyone swapped their four-speed automatic to a six, eight, or 10-speed automatic? I did a quick search and see that more than one company is offering a 6L80-E for retrofits into older cars and trucks. An example is the link below.

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[618 Syndicate]

Unless you're planning on a complete driveline swap you'll need a standalone controller, they're about $1k. Figure 2-3k for a transmission plus labor and it wouldn't be hard to have 5k in the swap.
I have a Duramax/6L in the square dually, my brother in law has a 5.3/6L in his square. I like the transmissions, it just comes down to what you're willing to spend.

 

[Erik the Awful]

L31/6L80e

Well, my first official post here. As the title states, I am in the middle of swapping my 4L60e to a 6L80e, yes, behind the L31. I've done countless hours of research and contacting companies on how and what the swap would entail. Some of this swap is trial-by-error. I haven't really seen any...

www.gmt400.com

 

[DixieWASP]

Unless you're planning on a complete driveline swap you'll need a standalone controller, they're about $1k. Figure 2-3k for a transmission plus labor and it wouldn't be hard to have 5k in the swap.
I have a Duramax/6L in the square dually, my brother in law has a 5.3/6L in his square. I like the transmissions, it just comes down to what you're willing to spend.

I noticed how expensive the six speed automatic transmissions are compared to the four speed automatics. I am a true "skin flint" and try to squeeze every dollar so the price is a deterrent to me.

I was curious if anyone had done the conversion and how they liked having the extra gears.

 

[618 Syndicate]

I noticed how expensive the six speed automatic transmissions are compared to the four speed automatics. I am a true "skin flint" and try to squeeze every dollar so the price is a deterrent to me.

I was curious if anyone had done the conversion and how they liked having the extra gears.

In my opinion there's not a whole lot of difference between the 6 and 4 speed overdrives. Maybe a few hundred rpm drop. I did the math when I was looking at trans swapping my 98 dually, but gears were a better option for the price.

 

[Erik the Awful]

When I talked with @97Centurion about his swap, the 6 speed will allow you to run taller rear gears while still having grunt to get off the line. He said it ran great after getting the transmission tuning finished. It was practically a bolt-in when he was expecting a lot more work.

 

[DixieWASP]

When I talked with @97Centurion about his swap, the 6 speed will allow you to run taller rear gears while still having grunt to get off the line. He said it ran great after getting the transmission tuning finished. It was practically a bolt-in when he was expecting a lot more work.

That is interesting and thank you for sharing the information with me.

 

[Supercharged111]

L31/6L80e

Well, my first official post here. As the title states, I am in the middle of swapping my 4L60e to a 6L80e, yes, behind the L31. I've done countless hours of research and contacting companies on how and what the swap would entail. Some of this swap is trial-by-error. I haven't really seen any...

www.gmt400.com

You beat me to it. @L31MaxExpress is also doing this swap, but is converting his 350 to 58x which is the better way to go about it, though it is not for the faint of heart. I'd love to swap one, but find it difficult to open my wallet for it. The gear spread is the real advantage as Erik pointed out, you can run a taller gear without losing off the line punch. In fact you can gain on both ends. I think OD is about 150 RPM difference gear for gear.

 

[L31MaxExpress]

You beat me to it. @L31MaxExpress is also doing this swap, but is converting his 350 to 58x which is the better way to go about it, though it is not for the faint of heart. I'd love to swap one, but find it difficult to open my wallet for it. The gear spread is the real advantage as Erik pointed out, you can run a taller gear without losing off the line punch. In fact you can gain on both ends. I think OD is about 150 RPM difference gear for gear.

When I ran the Van through the calculator, should drop about 250 rpm at 70 mph. From ~2,200 to 1,950 rpm. That is with a 3.73 gear. It would be a bit more as the axle ratio increases numerically or the tire size decreases. If I had 4.10s I would drop from 2,400 to ~2,100. To get the same pull in 1st would require nearly a 6:1 rear gear.

 

[Schurkey]

I was going to say that it's not worth changing from a 4-speed auto overdrive to a 6-speed auto overdrive.

However, these posts have me reconsidering.

(Not that I would spend the money to do it on my own vehicles.)