the 80 is almost an end all be all solution. If you want to set it and forget it get an 80. If you wanna constantly be worrying then get yourself a built 60 and baby it

 

I priced out a built 4l60e, then ended up with a 4l80e swapped in way cheaper, including a new transfercase and a circle d converter. I could've save a whole lot by just doing an input shaft on my tcase, and using the oem 4l80e converter.

The only issue i have with the 4l80e is the tall 1st gear; I am currently n/a, and I hear that 1st gear is a non issue with boost.

The speed engineering 4l80e crossmember worked perfectly; I would do the wiring myself. I tried a conversion plug incase I ever wanted to return to stock, but the harness was wired wrong. The pin swapping is actually very simple. The hptuners segment swapped is simple too. The most aggravating part to me was removing the torsion bars for my tahoe because of how close the 4l80e pushed the tcase back. Oh, and waiting for the shorter driveshaft.

 

I had always heard about the 4L80's "problem" being first gear, but now that I think about it and driving them in several of my trucks, I don't really think it's an issue. It's actually very close to the other manufacturers' 4 speed transmissions of that generation if you compare it. The 0.75 4th ratio I think is an advantage. Overall, the gear ratios I think are just fine I mean, you'd still want some 3.73 or 4.10 or something equivalent for doing heavy hauling or towing (or racing?)

Truthfully, I think the real problem is the relatively high (numerically) first gear of the 60e, along with the wide gap between 1st and 2nd. I've read that drastic gear shift is one reason why it stresses hard parts so much. But I admit I'm no transmission expert.

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The 1st gear was extremely noticeable in my tahoe, but converter both exaggerated the issue and helped fix it. At part throttle, it seems like the truck just does not want to go. However, get in it and let the engine rev and it moves out. Circle D actually told me many have asked them about it seemingly straining to take off at part throttle with the 4l80e swap, especially in a bigger truck with larger tires; thst is why they are so specific of your setup when they recommend a converter. I am running a full weight 2004 tahoe z71 4x4 with 3.73 and 33" tires.

 

i need to weigh my truck again. Last time I weighed it was 5830 with me in it. The 80 swap is a solid move. I’m not too excited about the first gear but it’s my daily and I probably won’t notice it too much anyways

 

Has your truck been on a diet? Why would you need to reweigh it?

 

Unless it was a manual, every 99-2007 classic 8 lug 6.0 truck or suv came with the 4l80e; suburban/yukon 2500s and 1500hd trucks usually had 3.73s. I think every 8 lug van did too, even with the 4.8. Even with the stock heavy torque they do decent.

Like I said, my convertor exacerbates the issue if i baby the throttle; but of i get on it a little, the higher stall and the hit of the convertor takes care of it, and I only have around 400hp. I personally have logged 1000s of miles on 2500hd trucks towing heavy, and th 4l80e has done great. My buddy finally needed one in his 2500hd at 250k miles,but that truck is on 35s and he has pulled a stupid heavy camper to the mountains a few times.

From what I have read on here, if you are heavy and powerful enough to break a correctly tuned and good shape 4l80e, even a built 4l60e is a ticking time bomb.

That said, there is a little work involved in the swap.

 

Even the 8 lug 2500 5.3s came with the 4L80 lol

 

Correct. The decision was based on GVWR. Anything with 8 lugs and 8600 GVWR or higher got the 4L80e, as far as I knew. Of course, unless it was a diesel or the 8.1 in the HD trucks. Although @1FastBrick has posted a door tag of an 8 lug with a 7200 GVWR (?).

The only exception that I know of is the Hummer H2, that one got 8 lugs but with the 4L65e. I'm not sure what the GVWR is. 🤷 I'm really puzzled why GM went that route on such a heavy vehicle, especially considering the premium price tag back then. Maybe it was a cost-cutting measure?The military Humvee also got the 4L80e, although I " think" that one had a special specification for military use.

The 1500HD are really a 3/4 ton truck (GVWR 8600 IIRC.) They were a marketing tactic to get into the crew cab market and compete with the other manufacturers that were making crew cab 1500s. Makes sense, since all of the 1500HD were crew cab configuration.

 

there were a lot more modifications done after my initial weigh in