If you "phase" your U-joints as the article describes you'll be one of 3 people in North America doing it. And you'll never find the other two. If using normal tri-oval shaped PTO shafts The entire situation or "phasing" is frozen in the relationships of the ends of the drive link. Some of the other type shafts (a variety of splines, etc) may "fix" the relationship and may not, depending on whether the splines have a Key or on it. doublewide spline. My guess is that you can survey 100 drive line shops and find maybe 1 or 2 that pay any attention to it at all when welding in replacement shafts. Now granted, the motorcycle people probably fine tune all sorts of things. By the way the people who wrote that article failed to know what a CV joint is.
Re phasing:
Many years ago I was new to tractors. Bought a Nuffield 465 while they were still being made which really dates me.
Next acquisition was a McKee 720 snow blower which was brand new and came with a pto shaft with metal shield on it.
The pto shaft was too long and was bottoming out.
The two halves of the pto shaft were square with one sliding inside the other.
What I failed to realize at the time was that the rounded bump at the end on one side on the male shaft was important and I cut the two halves of the shaft thereby eliminating the bump. The bump was like a dowel whose end was ground into a dome.
Put everything back together started the tractor and then engaged the pto clutch. The blower was almost jumping off the ground it was shaking so bad.
The blower had been running before and was smooth. It was only bottoming out when I raised the blower so I knew something I had done was very wrong.
I started to study the two cut off pieces of pto shaft, one with the bump. I suddenly realized the bump only allowed the pto shaft to slide into the female half in one position.
That position had the two u joints in phase. I quickly took the pto shaft off the tractor, pulled the two halves apart, turned the tractor end 90 degrees and re slid the shaft back together.
This time everything was back to running smooth.
I welded a bump on the male shaft to prevent someone else from putting it together wrong but I never forgot what had happened.
Truck shops which shorten or lengthen truck frames to accommodate various aftermarket bodies, tanks, mixers etc pay a lot of attention to the driveshaft and not only do they index it perfectly but they balance it to great precision.
On tractors where the u joint angles are close to flat, you may not notice a phasing problem but as the angle increases, the pulsation does exponentially.
Pto shafts which are required to transmit high torque on large tractor have shafts with more lobes (than the typical tri oval) as it makes the shaft less resistant to sliding in and out under load.
Dave M7040
