Alright this has been bothing me ever since I blew up my tranny. Someone explain to me how the input shaft on my 4R70W could have snapped into pieces? It's nuts thats a solid piece of hardened steel. I need some closure on this.

Heres some pics if you didnt see before I just dont understand...

 

Snapping input shafts is pretty similar to snapping axles. they are pretty strong but their life wears quickly with instant jolts. Shifting firmness, lots of hard driving, and nitrous usage are all a factor in this. over the hard driving years, the flexing and twisting softens the steel untill you have failure.

Its about as common on trucks as axles snapping on our mustangs because they are put under a similar scenario with pulling big loads, beating on it, or mudding and off-roading.

 

2nd tranny in my 99 f150 broke only the input shaft rest was fine. I should of spent the extra $150 for a hardened one when i had my built tranny made.

 

I did A matter a fact all clutch packs are heavy duty carbon/kevlar from Alto. And the overdrive band is kevlar.

I went ***** out on the new tranny

 

I think it's gawds way of telling you to get a 5 speed.

 

Nah with my new tranny I pull consistant very low 12's with my oh so crappy 2.0 sec 60ft with no traction....

 

When I bought my GT, I was told if I planned on doing any kind of performance mods it would be wise to chage the input shaft that they were know not to hold up to well, ICE how does your tranny with the rebuild drive under normal conditions

 

hope you did something with the valve body? im sure you have the j-mod already and thats perfect.

 

the valve body is what changes the shifting and the firmness of the shifts.

 

Yeah all I did was get a new separator plate that had the J-mod done very well. And got some accumulator springs to firm that **** up a bit. Something else is the tune also firms up the shifts but causes the tranny to heat up pretty bad unless you open up the holes to get the fluid flowing as well.

And my car runs very well with the built tranny it's got a 2800-3000 stall I didnt want to get too nuts with it I still need it as a DD. But it's held up quite nicely.