LM7 5.3 with 700R4 - can't get the transmission to shift right

[paradigm]

depending how far you want to go with this, maybe at the least to start is getting a dongle is best for starters. you can get stock tunes all over if that is what you have going on. i don't have any more details on your project to tell you any more.

I am going to get the dongle so I can play around a little bit.

I am going to have to modify the harness to get the transmission connector for the 4L60e.

I am wondering if I should be pulling my 5.3 and mounting the trans to the motor outside of the vehicle, or trying to just drop out the 700R4 from below and installing the 4L60e from below?

Is there a reason why people go with the 4L80e over the 4L60e other than the higher HP handling? I am reading a 4L60e should be able to comfortably handle 400hp which is the goal of this project?

 

[nycutlass]

so let me ask you a few things and then i can answer you correctly what are you going to do with this car 90% of the time?

 

[paradigm]

so let me ask you a few things and then i can answer you correctly what are you going to do with this car 90% of the time?

90% of the time I will be cruising with it, 10% of the time I will be driving it hard.

If I could just get my 700R4 to shift right, that would be the least amount of work for me. There is a kit sold online from bowtie overdrives, but I am not sure if it will solve my problem of incorrect shift points, and I am not sure if the damage has already been done to the 700R4 where I will need to replace it down the line anyway. It has been driven for at least 150 miles with incorrect TV geometry.

 

[nycutlass]

so if you have less than 450 TORQUE .. then you can use a 4L60E with success anything more than that torque i would do the 4L80E and you will be done. these both are over drive transmissions. if you don't need a over drive transmission and your gearing is low you can use a TH350 for less torque or a TH400 for more torque.

 

[nycutlass]

If I could just get my 700R4 to shift right, that would be the least amount of work for me. There is a kit sold online from bowtie overdrives, but I am not sure if it will solve my problem of incorrect shift points, and I am not sure if the damage has already been done to the 700R4 where I will need to replace it down the line anyway. It has been driven for at least 150 miles with incorrect TV geometry.

i don't ever see a 700r4 lasting very long. they barely lasted in stock cars from GM lol .

 

[paradigm]

so if you have less than 450 TORQUE .. then you can use a 4L60E with success anything more than that torque i would do the 4L80E and you will be done. these both are over drive transmissions. if you don't need a over drive transmission and your gearing is low you can use a TH350 for less torque or a TH400 for more torque.

Oh you were asking how I planned to modify the car?
I am hoping eventually to do bolt-ons; mild cam kit, long tube headers, etc. I am hoping to hit around 400hp.
I am also hoping to keep costs down. I would assume a 4L80e is more $ than a 4L60e? And then my Gforce crossmember for my 700r4 will work with the 4L60e but not with the 4L80e.

 

[64nailhead]

Oof. The TV cable controls line pressure, not shift points. It does change the rate of the shift process, aka shift feel. If it isn’t shiftng at WOT, then it’s broken. If the previous owner drove it spiritedly without the TV cable hooked up, then that’s game set match - needs to be gone through.

Before throwing in the towel, hookup a gauge to check line pressure and see if it’s in spec.

 

[nycutlass]

if your planning to build the car up i would do the 4L80E and let it grow with you and the car

 

[Fred Pitz]

In the past 14 years I have done 4 LS swaps. The first, a 2003 Sonoma with a 2004 Corvette LS1, the original 4l60e, original ECM, Original 7.5" 10 bolt 3.42 rear axle with a new Posi added. I drove it 10k miles and always worried about the stock V6 trans. Second was a 1980 Malibu "M80" with a 2006 GTO LS2 engine, 4l65e trans and a 7.5"" 10 bolt posi with 3.73 gears. Third was a 1981 Cadillac Coupe de Ville with a 2013 L98 6.0 with an LS3 intake system, another V6 4l60e transmission with a shift kit and Corvette servo added, an 8.5" 10 bolt posi with 2.92 gears and complete 1996 Impala SS steering and suspension (the Caddy is lighter than the Impala SS). The Cadillac was such a good combination that I replaced the LS1 in the Sonoma with a LQ4. Kept the LS1 intake system and everything else the same. I had a shift kit, and a Corvette servo added, and a complete inspection done just in case. The V6 transmission looked like new, and we just replaced the seals. This turned out to be a huge improvement overall, although it doesn't pull like the LS1 at higher RPMs. Fourth is a 1981 Malibu coupe. It got a 2018 L69 with the complete LS3 intake system, another v6 4l60e, and 8.5" 10 bolt posi with 3.42 gears.

Bottom line. I have played with enough of these combos to have fairly valid opinions, and IMO for a car that is driven, not seriously raced, and not a big HP build, the 4l60e from a V6 powered vehicle is the way to go. They are the least expensive of the 4l60es in the junkyards and they hold up very well unless you beat it to death. Just go through it correcting any existing wear, add the shift kit & servo and save the extra $$$ and weight.