I agree with LSMITH on the warranty issue and will barrow his Jr Diesel Commando guy to illustrate a point about input shafts. But first let me say that it is not impossible to break an input shaft shifting locked but it is the exception not the rule. Allison transmissions in the Dmax shift locked after 24mph. They are set up this way from the factory. Obviously Allison has tested locked shifts enough to know that they will not bankrupt the company on warrantee issues. OK let’s get back to Mr. Jr Diesel Commando and use this fictional character to illustrate what I understand is main cause of input shaft breakage. Mr. Jr Diesel Commando gets into his truck that he just bolted on and plugged in the stuff to get him into the 375 to 425-horse power level. Mr. Commando is also a faithful reader of the TDR and reads earnestly everything he can find on launching off the line. He doesn't realize he is reading posts from guys who set up their trucks to drag race and have all the expensive goodies like billet shafts and sponsorships to cover things like twisting a shaft off now and then. So he jumps in the truck with his buddy and power brakes the engine until he gets 10 pounds of boost and then lets off the brake and floors it. Wow that was neat look at all that smoke, and black marks too! So being a Redneck Mr. Jr Diesel Commando says to his friend “hold my beer and watch this”. (Famous redneck last words) Now I wana try 20 pounds of boost. So he applies brakes and fuel --- SNAP, CRUNCH WHAM and his stomach sticks in his throat and $$$$$$ flash in front of his eyes. After all he just spent 3000 bucks on the transmission.
And then there may be the case of damaging the shaft while power braking at 15 pounds of boost and finishing it off with a good solid locked 2-3 shift at WOT. Again there are exceptions but most of the shafts that I have heard about, have been twisted off while launching. Lets not give shifting locked a bad name by blanket generalities. The overall rule is pay before you play and you will have more fun.
Well I better add a disclaimer just in case someone feels slighted or slandered.
(This illustration is not based on any one event or an actual person. )
Edward
And then there may be the case of damaging the shaft while power braking at 15 pounds of boost and finishing it off with a good solid locked 2-3 shift at WOT. Again there are exceptions but most of the shafts that I have heard about, have been twisted off while launching. Lets not give shifting locked a bad name by blanket generalities. The overall rule is pay before you play and you will have more fun.
Well I better add a disclaimer just in case someone feels slighted or slandered.
(This illustration is not based on any one event or an actual person. )
Edward
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