Decided to LS swap

[Erik the Awful]

Pretty sure the 6L80 is longer, but I may be wrong. That would require trans crossmember mods, and a custom driveshaft. When these trucks came with a 4L80, and the cheapie non adjustable LS swap brackets work fine too.

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

 

[RDF1]

Doing tons of research here. So I’ve managed to locate a couple of 4L80e “rebuildable” cores within a 1 hour drive of my location. They range anywhere from $300-750. A couple of them listed say “no first gear” no price but to call. I’m thinking this might be the better route considering the general consensus on this particular transmission.

Id hate to pay 750 for a "core" but recently they have been bringing that much.
If you can find one for under 500 then have it freshened up, you would be set. They dont need anything fancy to hold a substantial amount of power either. Just tell whoever is rebuilding it that you would like it setup for towing and they should know what to do. hopefully.

 

[RDF1]

Gear ratio is 2.73 (GU2)

If you want to keep running those size tires, id suggest going to atleast a 3.23 gear. That would put rpms back around 2000 @ 70mph.
3.42s might would be easier to find and slightly more pep.

 

[open_road_toad]

If you want to keep running those size tires, id suggest going to atleast a 3.23 gear. That would put rpms back around 2000 @ 70mph.
3.42s might would be easier to find and slightly more pep.

Thanks for that. It’s something I am going to have to consider. For now I’m just doing the engine swap. In another year I’d like to do a 4/6 drop with 20” wheels. I’m assuming I’d have to change the rear end gears again?

 

[open_road_toad]

$1200 is him assembling the bottom end?

Yes

 

[open_road_toad]

Id hate to pay 750 for a "core" but recently they have been bringing that much.
If you can find one for under 500 then have it freshened up, you would be set. They dont need anything fancy to hold a substantial amount of power either. Just tell whoever is rebuilding it that you would like it setup for towing and they should know what to do. hopefully.

I talked to the transmission guy about what to look for. Like if the transmission doesn’t work how do you tell how bad it actually is. He said as long as the fluid doesn’t smell like ammonia and make your eyes water you’ll be ok. Im assuming that most of these “burnt up” HD transmissions just got used hard and the clutches gave out on them.

 

[open_road_toad]

Thanks for that. It’s something I am going to have to consider. For now I’m just doing the engine swap. In another year I’d like to do a 4/6 drop with 20” wheels. I’m assuming I’d have to change the rear end gears again?

I should’ve check the calculator before posting. A 275/40-20 is pretty much the same diameter as my current wheel/tire setup. Those gears would work for either. Thanks again.

 

[open_road_toad]

Figuring out how to attach and operate a 6L80E will add time, complication, and expense to your build, but maybe the efficiency gains over time would negate the expense part.

For just about the cost of the controller for that trans, you could go to the yard and yank an entire bolt-in 4L80E setup.

I just got done reading the 14 page thread from a guy who did a 6L swap. I agree with you and I’ve reconsidered that. I’m gonna pick up a non working 4L80 from a local wrecking yard and have it rebuilt for my needs.

 

[open_road_toad]

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

Just got done reading this. Thanks for linking it. I’ve reconsidered my transmission choice and I’m gonna pick up a rebuildable 4L80 from a local auto salvage yard and have it rebuilt to my needs.

 

[Alteca]

I should’ve check the calculator before posting. A 275/40-20 is pretty much the same diameter as my current wheel/tire setup. Those gears would work for either. Thanks again.

I’m running that size up front and 315/35r20 rear(exact same height) and it’s gutless with a 3.27 rear gear. I would recommend a 3.42 at the least, unless you end up with 6l80-90 then the 2.73 would be fine off the line but 6th might useless most the time. It would be 1500rpm at 70mph.