fabricated steering shaft

When all else fails it is a good idea to go to the experts for advice. Two persons guessing and posting what they "believe" to be true. will add to the level of bunk house BS that is way to prevalent on all forums. . http://www.flamingriver.com/index.php/n ... ing-system
Another very good free schooling in these steering designs is your local auto recycler.

I didn't see anywhere on that link where my issue was addressed, if you found it please highlight it. I didn't bring up my concern as "fact" but a concern, call it bunkhouse BS if you want, but it is still a concern that I haven't found addressed anywhere. All they addressed is if you have a multi piece shaft you need a support close to the middle joint, nothing addressing how far from a support an joint can be placed. If you can find something that speaks to that, please post.

As you say, it is your issue.

In otherwords, you have no data to state whether my concern was valid or not, but are willing to condemn it as bunkhouse BS.

The GM Saginaw 525 manual steering box has a long unsupported input shaft. This design was installed in the millions. The longer shaft matched the position of the input shaft splines of the Saginaw power steering box which allowed for one frame mount design and the same steering column could be used on power and manual steering applications.
The steering box in the post looks like a Saginaw 525 .

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 .

You said :I would guess they would be more likely to agree with me than you .
What you said is true. I will not agree with you. If you want to suggest that FR will not agree with me , you might have ended your diatribe "with you".

Sorry, but you lost me on the last post, what are you trying to say?

Thanks for all the input. Couple of things you may not know based on the picture. The stub shaft coming out of the steering gear box is exactly the same as it was used on the Chevy, which is a 69 and had 50k + miles on it. It was not supported in any way and always had that amount of shaft coming out of the gear box. It did have a rubber bushing with 2 bolts rather than a universal. Although the set up now has a more aggressive angle from the shaft to the gear box, the design is stronger and more robust than the original.

Also, the shaft was too long between the universal joints, bottoming out the splines in the slip joint. So I had to cut the shaft shorter, but it still left plenty (8 inches or so) of splines in the receiver end of the shaft. My other consideration was in the event of an accident, having a breakaway point for that shaft so the driver does not get impaled by the steering shaft. My guess is the design will allow that to happen. Problem is when doing all of this custom work, much of it is practical trial and error. Hope I never find out of my design will break away in the event of a serious accident!

Cornbinder, I did not see your longer post when I last responded. You are correct that the original Chevy steering column was pretty much a straight shot from the gear box to the steering wheel. And I do understand your concern of the stress of the unsupported universal shaft "pushing" on the stub shaft coming out of the gear box. The custom universal shaft is supported on the plate that is bolted to the fire wall, but is not otherwise supported with a carrier bearing. Personally, I don't think it will be a problem, but I'm not a ME either.

I was not concerned about the section between the universals, they aren't normally supported in any application. My concern was lets say parking where the steering input force is high, sideloading in input to the steering box. In that case a self aligning bearing placed just below the U joint on the box input shaft, and tied to the frame would eliminate any concern.
As I 1st stated, I don't have an answer as to how critical this may or may not be, but you might consider it.