Quote:
Originally Posted by zstroken
So if you were able to precision balance the shaft would you be able to get a longer one to survive? Or is it because of the weight/length that they begin to bow in the middle, and I can see bad things happening at that point.
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Weight is the main issue and why you don't see steel making longer than 70" runs in one piece.
The same diameter in stl that is done at say 3000 rpm, AL will usually go an additional 800 to 1000 rpm more where CF will go usually any additional 2500 rpm
We could put any tube at any length, when it gets to a certain rpm the weight of that shaft and its diameter causes it to, lets use the term flutter, if you were able to watch the shaft under a high speed cam as it gets to that critical speed where the weight is to much for that diameter at that speed the shaft will appear as if its like a rope material and it'll look like its waving and then as that is happening it is quickly weakening...
Then it goes BOOM like an explosion, then it cuts what ever each end comes in contact with.
So to not have this happen you need to know length and overall speed the vehicle is capable of, then by knowing gearing and trans one can know if you can safely use a 2", 3", 4", 5" , 6" diameter shaft to span whatever distance you need the shaft to couple the diff to the trans or t-case.
Usually a 1" change in diameter enables an additional 1200 to 2400 rpm, so what won't work in 2" may be risky at 3" but not a problem at 4".