TomM

iTrader: (56)

Seeking some help from the vast unpaid research dept. here on tech.....

Have a L99 with a 6l80E, want to swap to a 4L60E. Will the trans fit, what do I need to change? I know flywheel and converter, what else, will the L99 starter work?

I got the part about harness etc...mainly a mechanical question...

99.9% sure it will work, just need verification of plan...

T,

cam

iTrader: (9)

Bolts right up with the corresponding flex plate and converter. You could run the ECM&TCM from an 11+ 4.8L Sierra they use the 4L60e with a VVT engine ( if your retaining VVT ) or you could ditch it and run a static grind and use the lingenfelter 58-24x converter box and run any PCM you want.

But one question. Why would you ditch the 6spd for a 4spd? 4L80e I get but 4L60e is generally considered less than a 6L80e in strength, not to mention 6spds>4

Just curious.

TomM

iTrader: (56)

Don't need 6 speeds. Going in to a 66 Nova, hangs about 4-5 inches below the floor, even with the tunnel cut out, no ground clearance to speak of. Even the 4L80 causes clearance problems. The 6L is definitely stronger than the 4L, but strength isn't an issue. My trans builder can build it to withstand the power.

It's all about reliability and service after swap. The 6L has known problems, such as overheating and starvation.....supposed to be addressed now..who knows. Just too problematic to deal with for this build...

Thanks for your help.....

T,

cam

iTrader: (9)

Fair enough. Keep the 2-3 shift below 6400 RPM and she'll last the distance. Corvette Servo and a couple other stock bits and your good.

If you dont mind when you get the 4l60 can you compare the flex plates between the two? Not sure if they cross over or need to be changed. Converter definitely but flex Im not sure and dont feel like spending the hours and hours of searching for whats likely already out there.

TomM

iTrader: (56)

Sure, I'll post some pictures...

T,

Bo185

You might need a 4l60e with a ISS. Although I thought people were just deleting the ISS codes and getting by with out one using the earlier 4l60e's. Search Input speed sensor.

Why not just get a 4l70e?

G-Body

iTrader: (4)

I thought the 6spd would be cool....until I drove a new camaro with a 6 spd for a week. By the end of that week I was annoyed by the trans downshifting 2 gears everytime I even looked at the gas pedal. I had read that the 6 could skip down over gears (IE: 6th to 2nd) which was supposed to eliminate the lag when you mashed the pedal from a roll. It may have been skipping over the gears, but it still had as much lag as the 4l60e in my el camino.

cam

iTrader: (9)

The stock shift points on factory 6spds NEED tuning for sure. They are all over the place trying to keep the engine in that fuel mileage sweet spot.

TomM

iTrader: (56)

More research reveals the 60E won't work with DOD or AFM....does anyone know of a trans that will?

T,

cam

iTrader: (9)

The early GMT900 5.3's still ran the 4L60e and had AFM ( dod ) but no VVT so you could run one of those ECM's and do a VVT delete on your engine? Its pretty much the 4l60, 4l80, or the two 6L transmissions. Not much else out there thats a bolt on and has an overdrive

henry38

It is my understanding that your GEN IV ECM will communicate with a TCM from a 2008 or later model unit that had the newer 4L60e tranny (new CAN socket and internal ISS).

I plan on mating a 2012 LMG 5.3L (keeping AMF and VVT) engine to a 2010 4L60e. The engine originally came with a 6L80; The 4L60e was behind a 2010 with a 4.3 V6. I will need a newer TCM.

MHS1

I live in the mountains in New Hampshire. I had a 2010 Silverado 6L80 with a 5.3. Every time I went around a corner and up hill it would shift into 2nd or third and I would have to stomp it to the floor and it would hesitate to down shift I ran with tow haul on to get away from this. The gas mileage was ok but Still only around 20. I replaced it with a truck with the 4L60 and at 19 mpg it works better and tows better. The 2 extra gears just made constant shifting but no noticable extra power.

G Atsma

Cam hasn't been here for 3 years...

EDIT my Moderator: Exactly. @MHS1 As just pointed out, please don't post on long dead threads. This one is 12 years old. Therefore I have closed it. You are always welcome to start a new thread.