That's what he told me too. Said the weakest link is the forward hub cuz of the oil relief groves in the splines and the intermediate shaft cuz it's the smallest shaft in the trans. We didn't put any billet shafts in my tranny when he built it cuz I don't really plan on abusing it that hard, And he's in my back yard, so if it breaks, he said bring it back and we'll make it stronger!

 

Do it! if i can build one you definitely should be able to do it.

If you want i have 2 really good manuals for the 4L80 i can send you.

 

Well now ya tell me! I just bought the ATSG one off amazon. I assume that is one you have, whats the other?

 

It is one i found online. I used the combination of the two when i assembled mine. PM me your email address and i will send you both. I believe i have the electronic.

 

Interesting, because according to Jake (Jake's transmission) the input shaft is the weakest shaft. Says the stock main shaft is good to 1200 hp versus 750 on the input shaft. The output shaft is nearly unbreakable.

 

When i built mine Vince B. helped me i think i remember him mentioning the input shaft upgrade was not needed in my case since i was not planning on locking the converter at WOT and i dont have a Tbrake. That was along time ago sooo i could be remembering wrong.

 

If you look at the forward hub, its a pretty brittle looking piece. That really should be the first upgrade. As for the shafts, you have to consider what the shafts experience... The input shaft at maximum engine torque is only operating in a short RPM range, basically whatever your shift extensions are. But the intermediate shaft experiences more instantaneous changes in RPM, and that's what breaks shafts. So that's why that shaft is what is upgraded first. Also, stock48 has run 1000hp through his stock input shaft for the better part of a decade now

 

I thought that may have been the sonic boom when you break the sound barrier?

 

Yep I'm the same way, thats why I was asking. I thought you had build your 4L80e before gilbert did it..? Or am I mistaken?

 

I originally bought it from performabuilt, then when it didnt work sent it to Gilbert, then when I wore out the clutches, I had blake rebuild it, so now its my turn.

Just got the trans out, input shaft about half an inch of axial play and spins smoothly and freely, I can tell the other end isnt attached to anything.