Input shaft breakability? Locking it up.

Cuda

Cuda

EFIng amazing.
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Sep 29, 2008
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Well fellas, I am wanting to hit the dragstrip soon. Since the trans rebuild, I have been unhappy with the converter that was installed. My new converter will be here in the next couple of days, and I am debating on purchasing a billet input shaft. I know it should be done while the trans is out anyway, but the extra $$ is killing me. My question here is can I lock up the converter on a stock input shaft, and let it shift through the gears. I have allready done the lockup toggle switch, but I have never let it shift while locked. Since its 2wd, and still on a stock turbo and such, I wonder if others have gotten away with this same thing.
Any experience with this guys?
 
i would't suggest letting it shift while locked up. not with a stock input. i would just lock it up as soon as you shift to fourth
 
Forrest Nearing said:
do the input and a laminated flexplate. if you can't afford them now, I'd wait till you can
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Laminated flexplate? Is that a popular breaking item as well?
I guess my next question would be if a converter is very efficient, is there much gain to be had by locking it up? If so, are we only talking about 1-2/10's in a quarter mile?
 
If you dont do the flex and input you will later and it may take the trans with it. dont ask me how I know! hehehe!
 
brokeunput.jpg


Stock input out of my 47rh. Broke with probably a hair less than 300hp.

I was coming home from a truck pull. I was about a mile and a half from the house. I locked the converter, and then hammered down on it in 2nd coming out of a turn, ran it hard through second, it went to shift to 3rd at about 2800rpm and I felt it start to shift and heard a loud bang and it revved real hard:hehe: Oops.

It didnt tear up my transmission. Im still running the same converter and everything. I bought a billet input from Goerend and a laminated suncoast flexplate and it has been good since after several 20psi launches.

Dont lock it unless you are expecting to replace the input shaft soon. Thats really about all there is to it. A 48re shaft might be a little tougher than the 47rh was, but i wouldnt expect it to hold much more.

Eric
 
aircop said:
Get the shaft and flex plate done, whats money. It's made to be spent.
Click to expand...

They print more every day man! I'll call ya sometime soon!

Ok, so not locking the converter then... I hope this new converter makes it pull a lot harder in the lower gears though.. Seems like it doesn't come life till it locks up. Wasted rpm and torque doesn't make for a happy Cummins or driver!
 
The first part I broke on my truck was the flex plate. The truck was stock running a Crazy Larry program and a fuel box. And I was running in 2 wheel drive trying to make the tranny last. It broke when it shifted into 4th no lock up switch at that time.
Get the flex plate and the input too. This is the diesel world plan on breaking stuff if you make much power.
 
You bought a Dodge with an auto. You WILL be spending money on a trans, but at least the motor will hold up.
 
I would suggest the laminated flexplate also with the billet input. I tried to do it piece by peice and skipped the flexplate teh first two go rounds when it was apart. Well needless to say I set my Smarty to not defuel during shifting and the first time I did it it took out the flexplate center. I got lucky nothing else went with it.
 
What about locking it for a dyno run?? Thats the only reason i installed my switch cause my converter would not stay locked during the run
 
the torque breaks the shaft when direct power is applied, as when in lock-up. Its just a matter of when it will break.
 
I figured it would just be a shifting or going into lockup that would break them, it sounds like a few have experienced some severe breakage without locking.. I'm going to the get a quote spot now.
 
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