I believe I broke the sunshell in my 99 Sierra because I lost R, 2nd, and 4th gear. Truck has 130K on it and the trans tech at my dad's dealer said he would rebuild it for me since my dad does quite a bit of work for him. However, this guy never ventures into "building" the 4L60, just does stock rebuilds. Since I really don't know much about auto transmissions, is building a heavy duty trans just as easy for him? Like if I want heavy duty 3-4 clutch packs, corvette servo, HD band(s) etc.? If I provide him withe the HD rebuild kit, would he WANT TO and be able to just fix it like he normally does? If you were in his shoes lol?

On that note, does anyone know of a complete HD rebuild kit? BTW, truck is stock but I do quite a bit of pulling with it.

 

I would think if you bought the parts, he could build it up without issue. That's just my $0.02. Doesn't take much extra time to do a "basic" build up. If you're not going buckwild with performance mods for the truck, a basic rebuild with better quality parts would work. Question is, how much are you towing & how often?

I could list a ton of parts, but you may as well check with the builder you're considering. If he's truly savvy with 4L6xE transmissions, then he should know the weak points within the trans (and what to replace with STRONGER parts). The few items you mentioned are a start. If he's going in that deep, may as well go down to the output shaft.

 

Thanks for the reply. I actually tow quite a bit with it which is why I want to beef it up. I might buy my uncles boat this summer so that will mean more towing. I know he always puts "the beast" sunshell in any rebuild he does but I think that is it as far as upgrading. He rebuilt my Trans AM 4L60E and it's been great but the motor is stock. Also rebuilt my dad's S10 trans and it's been great 40K miles later. I know he is good with these transmissions so I guess I will consult with him like you say. I just didn't know if it is a whole new world when you start upgrading transmissions. Thanks.

 

can be a whole new world. Really up to you to see "how deep the rabbit hole goes"!

 

i just rebuilt my 4l60 yesterday and installing corvette servo, HD band, and beefier clutches geta assembled the same as if you were building it stock