I have 4100 lb car that I am going to throw about 900 hp at next year. My question what has everyone seeing when the 4340 input shafts are breaking and going to a 300m then aermet. After doing some research it appears not all 300m shafts are created equal.

 

@Jake's Performance manufactures and sells 4340 input shafts. They would have the most experience on this subject and could tell you if their 4340 shaft is up to the task.
Be warned...many of the options you will see on summit/jegs/etc will SAY they are 300m...but they most definitely are not actually 300m.

personal opinion, the 4340 from jakes would live in your setup just fine. But they'd tell you for sure

 

Listen to maroon he’s a smart dude. If he thinks it will live it will live but can’t hurt to call Jake. Worst case you order one of their 300m inputs instead of the 4340.

 

Thanks maroon monster, I have learned a lot from your posts and I was planning on calling Jakes this morning. I have read several posts about the exact same thing that you are talking about with the 300m shafts, not all being created equal.

 

Called jakes and they said 4340 would do the trick. The input shafts are rated at 1000 hp in a 4000 vehicle.

 

Just to Post regarding Input-Shafts... or strength in general.

The Alloy/ Metallurgy alone does not dictate the Strength of a Part or Input-Shaft for example.
First, all Alloys have small varying amounts of the Elements/ Compounds that form the Alloy.
Next the method of manufacturing the Input-Shaft will affect the strength... One example being, what method or tooling formed the splines
The design of the Input-Shaft will affect the strength... One example being, the design of which way Splines end/ or transition into the un-splined areas.
Surface/ Heat Treatments, as well as Cryo Treatments will affect the strength.
Stress-Relieving Treatments will affect the strength.

Also there are multiple ways in which strength can be observed.
Some examples are:
-Resistance to pulling.
-Resistance to compressing.
-Resistance to twisting.
-Resistance to bending.

So to me... No Input-Shaft can be called equal/ compared by type of Alloy alone.
There are too many variables to consider.

Your best bet is to use the Data that is already established from other people who have used a similar Part...
or better yet, rely on the Transmission Builder for a recommendation.

Jake of Jake's Performance would be the Ideal Person to ask for a recommendation...
as he not only sells multiple types of Alloys (Input-Shafts), but He also manufactures them, Dynos them, and Tests them in Vehicles.