1990 K1500 5.7 TBI, Transmission upgrade options?

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1990Z71Swede

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Did a testdrive the other day after some overdue maintainance, just to verify everything was fine. Which it was, well sort of, at least for now :).

The transmission in the truck, a 4l60 without the E is showing some of its age I think. The 2-3 shift is taking a little bit longer than I would like, but IDK maybe that is normal-ish on these trucks with some miles on them? No flare or other obvious weirdneses and only does it when gunning it, part throttle shifts are distinct, but not hard.
The WOT shifting in the 2008 Suburban with 4L60E is a lot faster in comparison.

And since I have some plans for the motor, nothing extreme just some extra omph in the 280-290 hp range, I realize that this gearbox is not going to make it very long under those conditions.

So what is the smart way to go here?
I'm very tempted to go the EBL route for engine managment, that means swapping out the ECM
Would it be at all possible to go with an ECM that does Transmission control or do the "E" transmissions have their own TCM in the GMT400 to? Meaning I need both.

What I have in mind is going for a 4L80E, overkill I know, but built 4L60E's in Sweden are pricey.
I dont think the higher first gear is a problem the way we use the truck, my only concern is what impact the 4L80E has on milage, 1-2Mpg less is fine but more than that makes other options more interesting.

On the other end of the spectra is trying to build a TH700R/4L60 myself:eek:

Something I have never done, so that would be fun and interesting. :cool: The non E part of such a transmission is of course apealing as it makes for less things that can go wrong. And since I'm not doing anything crazy I guess I can get away with just a few upgrade parts like a Corvette servo and whatever else is needed for a little bit of extra durability. I'm well aware that such an endevor can be a disaster, but worst case, I'll just swollow my pride and take my parts to someone that knows what they are doing...

Maybe something in between the 4L80E and DIY-700R4 is way smarter? IDK...
 
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tayto

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I would DIY the 700R4 myself. if you want to control shift points you can get a 4L60E and upgrade to a '7427 pcm. you will need to repin the connectors and add the 4L60E wiring. The other option is an aftermarket controller which you could use on a 4L60E or 4L80E. EBL is an excellent upgrade but will not control a 4L60E.

You can modify the 700R4 to shift at higher RPM but you will need to source the correct shift valves and governor. I usually find it easier to source a complete valve body. I have the 700R4 in my squarebody setup to shift @ ~5500 RPM and the part throttle shifts "hold" the gears longer which is nice.
 

df2x4

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I dont think the higher first gear is a problem the way we use the truck, my only concern is what impact the 4L80E has on milage, 1-2Mpg less is fine but more than that makes other options more interesting.

In my experience you shouldn't see much difference in MPG between the two. I swapped from a 4L60E to a 4L80E in my red truck (1997 C1500 4.3L) and haven't observed any significant drop in fuel efficiency. I have to use a little more throttle to get moving off the line than I did with the 60E, but the 80E will hold 4th gear on an incline much better. I think everything kind of equals out.
 

Caman96

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In my experience you shouldn't see much difference in MPG between the two. I swapped from a 4L60E to a 4L80E in my red truck (1997 C1500 4.3L) and haven't observed any significant drop in fuel efficiency. I have to use a little more throttle to get moving off the line than I did with the 60E, but the 80E will hold 4th gear on an incline much better. I think everything kind of equals out.
I think he meant when buying one, the mileage on the transmission might be high or unknown.
 

df2x4

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I think he meant when buying one, the mileage on the transmission might be high or unknown.

I took that as a fuel efficiency question, check the quote I referenced. I don't think he would've mentioned MPG and the different first gear ratio otherwise.

If I'm wrong I'm wrong...
 

1990Z71Swede

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I took that as a fuel efficiency question, check the quote I referenced. I don't think he would've mentioned MPG and the different first gear ratio otherwise.

If I'm wrong I'm wrong...
You are not wrong, Fuel consumption was my main concern with the 4L80E. Thanks for your input.:waytogo:
 

1990Z71Swede

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I think he meant when buying one, the mileage on the transmission might be high or unknown.
Well yes that too, But in my first post I was asking about the MPG,s. That was sort of the main dealbreaker for me. Buying any used transmission is I guess always sort of a gamble.
 

Caman96

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I took that as a fuel efficiency question, check the quote I referenced. I don't think he would've mentioned MPG and the different first gear ratio otherwise.

If I'm wrong I'm wrong...
Sorry D, I’m wrong.
 
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