700r4 LS1 5.3L swap

[EDGECRUSHER]

I have a '92 K1500 with a tired 5.7. If I remember right I have a 700r4 behind it with the np241.

I've never had any issues with my trans so far, cross my finners, and I'm wondering what's the smart thing to do driveline wise when I go to swap a 5.3L LS1. I admit I when it comes to driveline I really don't know much about compatibilities.

IS the 700R4 strong enough to handle the 5.3L especially off-road?
If not, what should I replace it with?

I see a lot of write-ups about the 4l60e but what extra parts are needed to match the 700R4 with the 5.3L?

I've spent over a week searching google and my eyes are buggin out. please help.

 

[EDGECRUSHER]

just goes to show, after some more searching I've realized my tranny has a vaccum modulator which would make it a 400 not a 700. ugh.

edit: wrong again, was thinking of my motorhome. truck does have a VM though...

 

[1993GMCSierra]

I think the only year of the TH400 was the 1988 or 1988-1989 models. Your 1992 has a 700R4.

I have no idea on what all is needed though. The 5.3L is an OBD-II engine, and if you can find a 4L60E that was originally paired to a 5.3L, if you swap over the computer and wiring harness, it might be a "bolt on" swap, since you are putting in a "matching" powertrain, and using the correct computer/harness.

Might have to tweak/replace the engine mounts though....of course, I'm only guessing. You'll need a new fuel pump (and possibly fuel lines) too, to provide the pressure needed. (45+PSI, vs. 8-15)

 

[EDGECRUSHER]

thanks. that's what I figure. From the sounds of it though the 700 isn't too bad, a TV cable modification is needed which from what I've seen can easily be incorporated into a direct cable throttle mod. I guess adjustment is crucial though.

I just don't want to be one of those guys who always seems like he's blowing up his tranny having fun beating on his truck. I've always babied my truck because of this but it'd be nice to get rid of that worry. I'm gonna research the 700R4 mods a bit further and see just what is involved in 'beefing' it. If it's as simple as dropping the pan and installing shift kit type stuff I'm good. If it's going to be a full rebuild of internal clutches and such which I bet it is I bet it still might be worth it.

From what I've read the 4L60E is basically the same tranny but with electronic lockup control, so it'll last just as long. Using a 60E doesn't make too much sense since this is an OBS and all I'd be gaining is the initial ease of setup, but also the initial expense of the 60E and having to use the factory harness.(I'm on the fence - Megasquirt/OEM computer)

Since the 60E and R4 are same design, I'm assuming the adapter/spacer is the same to mate it with the 5.3L or 6.0L (if I can find a deal). As far as motor mounts, I see a lot of companies making them and even adjustable ones but I love welding and think it'd be more fun to just make my own like the ployeurethane tube/pivot style with oversized chassis plate. I assume at this point if the tranny is left in it's stock location the back of the motor should clear the firewall fine and the only crucial step is to make sure the motor is supported well. I haven't seen just what the measurement is regarding how much shorter in length an LSx is, however.

There doesn't seem to be much interest in this on the Transmission Forum so I'm prolly just talking to myself lol

 

[1993GMCSierra]

From what I've read the 4L60E is basically the same tranny....so it'll last just as long. U

And that's what you should be worried about. Trans #3 here, truck is 130K young.... I also baby my truck....as in, treat it as if it's the last surviving one.

The 4L60E isn't really a good transmission, IMO. If I could easily (and somewhat cheaply) swap it for something more durable, I would.

 

[Tempted]

Use a 4L80. And you don't need any parts to adapt your trans to the LS motor(it isn't an LS1, by the way). It bolts right up apart from one housing bolt that you can leave off and not hurt anything. There are also stand alones for the LS and 4L60E. The easiest way to do it is with a carbureted LS intake manifold drilled for injectors and running the MSD LS ignition control box. The cheapest way is to get the LS carbed manifold and ignition box and bolt your TPI on it. Its a serious performance loss but you won't have to worry about a PCM. Just use the one in the truck. This will also let you keep the 4L60 without needing to run a stand alone.




Edit- Forgot to mention the a 700R/4L60 is better off road than on it. It has a fairly low 1st gear which means it doesn't work the motor or torque converter very hard at low speeds. The highway is where it burns up, especially if you use it to haul. I've had good luck by over filling the trans by 1/2 a quart or so and by adding trans coolers. The gear that I've had fail most often is 2nd because I tow very large loads and when I encounter a hill I'll have to go WOT to keep speed, which in turn causes the trans to drop a gear. I used to deliver bouncy castles in Chattanooga. The loads were all in excess of 5,000lbs and most of the time it was going up or down hills.

You will drastically increase the life of the trans by leaving it in 3rd gear as much as possible. It does kill fuel mileage, which is already pretty bad. And use your parking brake. Put it in neutral, set the P brake, release the brake pedal and then put the truck in park. This will take pressure off the driveline while the truck is parked.

 

[EDGECRUSHER]

that's a first for me, someone putting TBI on an LS. thanks for the ideas but it sounds counter productive to what I'm trying to accomplish. gain performance/simplify.

 

[Horns]

Agreed, that's counter productive. If you have a 700r4, it's mechanically controlled, you don't need to worry about it.

 

[Tempted]

It is counter productive in terms of power but its the easiest way to get it to run. Essentially it is converting the LS to run on an electronic carb. Better cold start and emissions than a carb, easier to get results than a full MPFI swap. From there you can start getting the rest of the parts together while being able to drive the truck.

 

[Darkrider]

that's a first for me, someone putting TBI on an LS. thanks for the ideas but it sounds counter productive to what I'm trying to accomplish. gain performance/simplify.

Deven and i had this exact conversation on another forum we are both on. If you want an LSX engine you are far better off doing the extra wiring and gaining the MPFI.