Transmission opinions?

[Jawzjeep]

So I've got some choices to make and I could use a little help trying to figure out what's best. I realize preference can come into play but I've still just got to ask people what they think.

My 91 Suburban is an off-road camping snow pleasure rig. That's the focus. Its a 350/700r4/241 combination. Has swapped in 3/4 ton 10 bolt/14bolt sf. 6 inch lift. 37x12.5r17s. 4.10 gears. 75% street driven.

I have a 92 or 93 4x4 with a tbi 454 that will be donating its big block to my burb at some point. It (454) runs and drives fine so im in no hurry to do the swap. Plus we've seen gas prices, yes.

Here's where I need help. The 700r4 isn't gonna last long now, much less with future big block power. I have 3 choices of transmission that I
currently have in my possession.

1. The 454 truck has a 5 speed in it. Its a complete running driving truck so any parts I need from it I have.

2. 4l80-e bought a while ago. From 92 4x4 suburban. I have no electronics to run it. Its of unknown condition.

3. Turbo 400 from 84 k20 drove the truck and know it works.

What would you use and why? I'd prefer an auto for this kind of 4x4 use. Easier to check out the scenery with the family. Only reason the nv4500 is really an option is because I can't deny its strength and its already bolted to the 454 right now. Alright, lay it on me.

 

[Matt69olds]

I’ll say it again, I wouldn’t hesitate to run a 700 behind a mild big block if it’s built correctly. The truck is already set up for it, the low 1st gear helps get heavy trucks moving, the overdrive tames the 4.10 gears. Have it built with a wide band, corvette servo, upgraded 3-4 clutch, input sprag, drive shell, and some valve body upgrades, run a big oil cooler.


4l80 is about as durable as you can get. It is no big deal for good junkyard 4L80 to live with 800hp with nothing more than a valve body kit. Unfortunately, they are heavy, need a computer to run, have no provision for a speedometer (not a problem with a 4x4)

The 400 is probably the cheapest/strongest option. Disadvantages: no overdrive. It’s going to suck driving long distance with the 4.10 gears.

My vote would be the 700, assuming the big block is pretty mild. If it’s under 400hp/500lbs torque, I think it would live a reasonable life.

If you make than that, or just plan to work the truck like it’s a borrowed mule, go 4L80, especially if it’s already a good unit. If it needs rebuilt, the cost of the electronics to run it probably will cost about the same as the upgrades for the 700.

My last choice would be the 400, only because no overdrive with steep gears gets uncomfortable on the highway.

 

[bucket]

With 37's, the lack of overdrive is no big deal at all.

Is one of the biggest goals to spend less and use just what you have already?

 

[Honky Kong jr]

Th400HD simple and strong

 

[78C10BigTen]

Th400HD simple and strong

Holy crap! A ghost of gmsb past!!?

 

[Jawzjeep]

Matt69olds
Thanks for your input. The 454 will remain pretty much stock. I do like the point the 700 is already there. Hard to argue with logic. I dont plan on beating on it.

The 4l80 is of questionable condition so I'd take it to a shop to be rebuilt and still need electronics. Ouch! $

 

[Jawzjeep]

With 37's, the lack of overdrive is no big deal at all.

Is one of the biggest goals to spend less and use just what you have already?

Yes. Ive collected a bunch of good parts through the years at good prices. Its time to apply them and sell off what I dont need to help fund moving forward.

 

[Jawzjeep]

Th400HD simple and strong

Hmm. I like simple. I like strong.

 

[Honky Kong jr]

Holy crap! A ghost of gmsb past!!?

Lol

 

[AuroraGirl]

You must be registered for see images

@78C10BigTen
]

I mean it’s funny how I’m saying that but reminded me lol

 

[Rusty Nail]

I vote Turbo 400.

 

[Honky Kong jr]

I vote Turbo 400.

Because it’s a wise choice unless your going full race then PG it is.

 

[Honky Kong jr]

You must be registered for see images

@78C10BigTen
]

I mean it’s funny how I’m saying that but reminded me lol

He is a rookie

 

[RoryH19]

Also note if you plan on using the np241c from the 700r4 the spline count will be 27.
The 4l80e and TH400 will be 32. You would at the very least have to change the input of the np241c.

 

[bucket]

Yes. Ive collected a bunch of good parts through the years at good prices. Its time to apply them and sell off what I dont need to help fund moving forward.

If the gear and tire combo is going to stay the same, just run the TH400 whenever the 700 decides to fail. Swap to a 32 spline input in the 241.

My personal choice of all that would be the NV4500 with the same np241 and also a gear swap to 5.13's.