Keep Manual shift for the LS or swap in an auto?

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Ole Buck

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14 bolt full floater with 5.13 gears and the front Dana 44 will have the same. Tires will be no smaller than 37's. Open book here, I am building a beast but it will see way more asphalt than it ever will see the woods. manual is fine and i like going through the gears but i believe that i would prefer an automatic. Which one to get or should i just leave it alone? I am currently in the under-construction category if you want to see the build.
 

Ifyasquintitsmint

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14 bolt full floater with 5.13 gears and the front Dana 44 will have the same. Tires will be no smaller than 37's. Open book here, I am building a beast but it will see way more asphalt than it ever will see the woods. manual is fine and i like going through the gears but i believe that i would prefer an automatic. Which one to get or should i just leave it alone? I am currently in the under-construction category if you want to see the build.
Sm465/NV4500 are pretty easy to bolt up and run.

If you prefer auto swap a 6L80E. I'd avoid the 4L80E as they are well known to become 4 neutrals.

Edit: TIL I’m wrong!
 
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Bextreme04

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Sm465/NV4500 are pretty easy to bolt up and run.

If you prefer auto swap a 6L80E. I'd avoid the 4L80E as they are well known to become 4 neutrals.
WTF are you talking about? A 4l80 and 6l80 will be similar strength, but the 6l80 will cost about 2-3x as much to build. You would likely be able to go pull a 4l80 right out of the junkyard, put new filter/fluid in it, and run it as-is for many years without an issue.

OP, if your donor engine comes with a 4l80/4l60, then you will want to use a 4l80. If it comes with a 6l80 and you have the cash to build/tune it right, then it will be solid as well. Chances are a Gen 3 6.0 will be paired with a 4l80 and a Gen 4 6.0 would be paired with a 6l90. A 5.3 would most likely be paired with a 4l60/6L80.
 

Matt69olds

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The 4L80 will handle far more abuse than a 6L80/6L90, with half the expense.

Assuming your junkyard 4L80 is in good condition, a shift kit that dual feeds the direct clutch will make a 4L80 reliable to 700plus hp, with room to grow.
 

sickchev

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I have been down this road. First and foremost decide what you want Auto or manual. Don't worry about anyone else's opinion. There is a lot of aftermarket/fourm support for 4l60 or 4l80. Nv4500 is nice because of overdrive if you are planning a lot of highway driving. I went the less favorable opinion and went with a nv3500 from a 2003 silverado. Time will tell if it will hold up to the projected 375 - 400 hp/tq range. Nv3500 was a direct factory bolt up so I know it will work.
 

sickchev

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I have been down this road. First and foremost decide what you want Auto or manual. Don't worry about anyone else's opinion. There is a lot of aftermarket/fourm support for 4l60 or 4l80. Nv4500 is nice because of overdrive if you are planning a lot of highway driving. I went the less favorable opinion and went with a nv3500 from a 2003 silverado. Time will tell if it will hold up to the projected 375 - 400 hp/tq range. Nv3500 was a direct factory bolt up so I know it will work.
 

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Frankenchevy

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What are the planned uses for the truck?

I had a Th400 and swapped to an NV4500.

NV4500 is a well respected truck transmission, but it is not sporty. You want a Tremec or something along those lines if you want sporty.

I don’t really care about MPGs with this truck anymore. I want power and speed. The NV4500 will be coming out soon and likely a 4l80 going in. It doesn’t matter if you have 500hp/tq, the nv4500 will still like you to take your time shifting it. Again, the 4500, sm465, etc are great transmissions for their intended purpose, you’d just be hard pressed to find one in a hot rod.

A long throw manual truck transmission will also render your center seat fairly useless for any person over the age of 5.
 

RecklessWOT

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The 4L80 will handle far more abuse than a 6L80/6L90, with half the expense.

Assuming your junkyard 4L80 is in good condition, a shift kit that dual feeds the direct clutch will make a 4L80 reliable to 700plus hp, with room to grow.
6l90 is quite a bit stronger than a 6l80/4l80, that was kind of the point of that transmission.

But, if it's gonna see 90% road driving and with 37s I'm assuming not a lot of towing, I don't see any advantage of an automatic. You said it yourself, you like going through the gears. If you were one of those people (like my wife) that simply can't be bothered to deal with the hassle of that extra pedal and shifter despite knowing how to use one then I'd say sure swap it whatever floats your boat.

But the fact that you like it, why change? There are no benefits to having an automatic. Unless you're creeping through the woods (and even then a standard is still more fun even if harder to work with) or maybe towing a lot, an auto won't gain you anything. No added performance or mileage or fun or strength, literally no benefit besides "I don't have to shift anymore". But you did say you like going through the gears, so you would be losing something you enjoy. Also by sticking with the trans you already have you are saving money and aggrivation, no buying another trans/adaptors and no fooling around with wiring/swapping mounts and all the other nonsense. In that case, I vote no, stick with your real transmission that you already own.
 
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NickTransmissions

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Sm465/NV4500 are pretty easy to bolt up and run.

If you prefer auto swap a 6L80E. I'd avoid the 4L80E as they are well known to become 4 neutrals.
There is no universe where the 6L80 is stronger and more reliable than the 4L80E.
 

Ole Buck

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Holy cow! Lots of information there, so with that being said I believe that I will find me an NV 3500/4500 so i can at least have an OD/5th gear and just leave well enough alone. I must realize that this is going to be a big truck with beefy parts and few hundred horsepower and not a straight-line mud machine. But when i do push down on that accelerator I want that sucker to move. Second or third gear roosters on a mud flat would be nice. I thought i was supposed to grow out of this?
 

Matt69olds

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I personally have never messed with a 6L80, but the stamped steel carriers and clutch housing tells me all I need to know about them.

Compare the flimsy stamped steel stuff to the machined steel carriers of the 400/4L80. It’s a night and day difference.
 

NickTransmissions

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I personally have never messed with a 6L80, but the stamped steel carriers and clutch housing tells me all I need to know about them.

Compare the flimsy stamped steel stuff to the machined steel carriers of the 400/4L80. It’s a night and day difference.
Agree 100%

It takes a metric ton of effort (upgrades, updates, corrective measures) to get a 6L80 to anywhere near as capable as a 4L80E in terms of durability/reliability, IMO.

To All contemplating an auto swap and considering one of those two transmissions:

Here's my short 4L80E list of things that make it handle 600 hp without breaking a sweat:

1) dual feed direct clutch internally
2) rollerize rear of the case
3) shim planets and fwd hub-direct drum as needed
4) Sonnax LB4L80 boost valve
5) Drill plate per application
6) Rollerized billet or forged fwd hub (ive even done 4L80es that have the stock piece and survive at 550-650 hp S/S applications)
7 A518 direct clutch snap ring (.088-.110, depending) for intermediate clutch
8) high rate return springs in direct clutch (and int if necessary) {.050 bleeder hole in dir drum if rpms 5500+ routinely}
9) block-off plate for 3rd and 4th acc if application calls for it
10) choice lube mods
11) sleeve forward drum (sleeves are $5 or so)
12) set end play (front/rear) per spec - i run everything on the tighter side of spec (6Ls were designed to not have end play adjustable and many come in sloppy)

Apart from the billet rollerized forward hubs, all the stuff listed adds up to less than $100

Here's my list for the 6L80, just to get it to the point of reliablilty, lol - folks will need to spend even more for 4L80E-like strength and torque handling capacity.

I actually enjoy working on the 6L transmissions but they (other than perhaps the 6L90 w/the performance converters) were designed to max fuel economy whereas the 4L80 was designed for max durability. Lots of design and materials compromises made w/the 6L80 as a result...

My .02 (or maybe .05)
 

Craig Nedrow

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I have a 465 in the International 1600 loadster, rebuilt it a couple times, old tech, parts are getting scarce, no OD. I will build my 454 with a 4l80e, and 6.0 LQ4 which came with a 4l80e. I love to shift too, but not truck trans. Muncie, t5, t56, all ok, but will need pretty expensive parts to upgrade torque and big tires break transmissions. I like lightening fast shifts. So on this road for performance i will use the 4l80e. This one 45000 miles, 500 bucks.
 

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