Th400 or 4l80e

[2011laramie]

Plan on a 4" lift with 35" tires with the 4.10 gears in my 3/4 ton 4x4. Im leaning towards the th400 for costs wize and think ive decided on a stock 6.0ls. Wont be used for daily driving, just a casual trip here and there.

Ive been told that with the 35's a 4l80e might be in and out of overdrive and id be better off with just a th400.

Would i regret choosing the th400 and losing the OD. How much fuel mileage realistically would i gain if i had the OD?

[SkinnyG]

Using this calculator: https://www.ringpinion.com/calculators/Calc_RPM.aspx

You'd be cruising 2425rpm at 60mph with the TH400.

1653 with the 4L80E.

1600 seems a bit low for a lifted brick at speed.  If it were me, I'd stick with the TH400, and bask in the knowledge that it's hugely strong, and very simple, and no extra electronics or complexity.  Do you have the TH400 already?

I had a small mileage improvement going from 3.07 gears to 3.73 - because my cam really doesn't like being below 2400rpm.

[ehjorten]

My 1991 V3500 has 4.10:1 rear gears, 35" tires and a 4L80e.  I love it!  OD kicks in at around 60 mph and I'm turning just over 1,600 RPM.  The peak torque of my 454 is at 1,600 RPM.  Now I am in the process of putting in a 6.0L LS and they are a little more high-strung.  Peak torque is at a much higher RPM, but the torque curve is more flat, so there is more useable torque in the lower RPM band, but it still is not going to make gobs of torque down low like a Big Block!  I may consider going to 4.56:1 gears in the future.

If you do much cruising on the freeway I would seriously consider a 4L80e and if you are going LS the PCM is already setup to control that transmission.

Incidentally, the 2004 GMC Yukon Denali XL 2500 that my 6.0L LQ4 came out of had 265/70R17 (31.6") tires, a 4L80e and 3.73:1 gears.  60 MPH cruising RPM is about 1653!

My 1991 V3500 with the 454 and 4L80e on 35" tires and 4L80e, 60 MPH cruising RPM is about 1653!

I have driven lots of trucks with low gears and no overdrive.  After having driven one with overdrive, it is hard to go back and when I do, I realize how fatiguing it is to drive them!  I love my '77 K20 with 4.10s, but I really wish it had an overdrive!

[Captkaos]

The 4L80E is electronic shifted, it doesn't hunt gears like a 700R4 does.  If you need OD the 80E is the way to go in my opinion.