Sat Mar 24, 2018 2:03 pm by cornbinder89
Yes, I agree BUT and this is my point, the factory had the input from the column inline with a simple rag joint between the input shaft and the column, with only rotational force applied to the input shaft.
The 1st post said that this is a C40 chassie with a K cab on it. The columns are in two different locations so the need for the double jointed shaft. Please correct me if I have this part wrong.
I have seen plenty of long input shafts esp before power steering became universal, it allowed for one column to be used for either, I agree
I have also seen plenty of double jointed steering shafts used, just about every heavy truck made in the last 40 years or so use them. WHat I have never seen is the two mated, where there is a high angle direction change with a long input shaft.
To illustrate my point take a universal socket on a long extension, place it on a fastener and put in inline with the bolt, the ratchet will have no trouble turning the fastener, even if there is slop in the socket or wear on the hex of the bolt. Now put the extension at 45 degs and the socket will try and "cam out" or "walk off" the fastener, the force applied in no longer only rotational, but there are side forces on the system. The same thing is happening here, the long shaft is fine when pure rotational forces are applied, but may not be when forces in any other direction other than rotational are applied.
Just as it is easy to bend a fence post by applying force 6' from the ground, but almost impossible to do by applying the force close to the ground, moment matters in this. increase the moment, the less force required to deflect the object.
My fear is not that the system will not work or will bind, but that over time will cause a stress fracture at the point where the input leaves the support bearing. The result of a sudden failure on this system can be deadly, and the place where it is likely to fracture is hard to inspect.
In my years I have seen 100's of shafts, in all kind of applications, but I have never seen a the combination of long unsupported shaft used with high angle joint. That is why I expressed my concern.
Neither you nor I have ME (mechanical engineer) after our name, so neither is in a position to pass judgement, I was not, but rather raising the point that the OP'er might want to bring it up with an ME.
Flaming River might be in a position to judge if they had all the facts, shaft size, joint angle, distance from bearing to center of joint, etc, but since they are also in a position to sell the "fix" I would guess they would be more likely to agree with me than you .