JBA Racing here in San Diego sent me to a tranny shop since they don't do automatic tranny work there. I show the owner my Magna-blown 2003 Avalanche and tell him I want to beef up my tranny so I don't have to worry about anything bad happening. I tell him that I may want to do some additional mods later that could add HP, and I just want to be safe rather than sorry.

I tell him that, at minimum, I want to do a 4L60E-HD shift kit with a Corvette servo. I am also considering a large-scale build-up similar to what BenKey is doing here - again, just to be on the safe side.

So anyway, the guys says he doesn't want to jump the gun, installing something without knowing exactly what's going on inside. He says he doesn't know what they did when they reprogrammed the PCM for the blower (I think all they did is remove all the TM), so he first wants to do a diagnosis. He said he is against just throwing in a shift kit and a servo without knowing exactly how the thing is behaving.

Says it will take about a day. I can drop off the truck, or stay there all day if I want. I can even sit in the truck and see what they do, while they do it. He says he wants to hook up some gauges (I guess there are connections already on the tranny) and take a bunch of readings - tranny hot, tranny cold, truck going, truck stopped, 20mph, 40mph, shifting, etc. And, he says this initial diagnosis will not cost me a penny.

What do you guys think?

 

I think he just wants a reason to go beat on your truck a little.

Seriously, I don't know why he'd want to do this. It doesn't matter what tests he wants to do... A stock trans isn't gonna hold up for long.

 

Find someone who does high performance builds on 4L60Es on a regular basis,if they tell you that a 4L60E can hold up to 750hp in a truck go somewhere else,because it won't.

 

Anyone else want to weigh in on this?

 

I wonder why he won't even give you a rough estimate for a tranny build. Seems like most of the upgrades to the 4L60E are pretty standard - shift kit, servos. For the xtra blown power you can add stuff like 5gear planetary, hardened shafts/shell, etc.

If you have the time, it might be interesting to go spend half a day or so and watch him do the "free" diagnostic tests. Both to see what hes testing and to make sure he doesn't abuse your vehicle. I still don't see how testing line pressure, shift points and such would give you any information for what mechanical upgrades you need...?

 

i think hes gonna go black out an empty parking lot in socal with some Avalanche figure 8s .....tell him to go to hell. call up chuck at FLP he'll take care of you...but with such a big vehicle...id be looking at a 4l80 conversion...i thought my little standard cab short bed sierra was to much weight for my built 4l60 and my 6.0 has a centrifugal ATi on it suposbly not as hard as a manga would be on the trans...