PROPSHAFT PHASING

Ron, I would need that translated into English as she is spoke by us lay persons. If a shaft with 2 ujs can handle, in phase, input and output axes displaced in one plane (eg vertical, which I think is true?), does another displacement (ie horizontal) cause problems that need the ujs out of phase?
When I used to do race car scrutineering it was common to see driveshafts on open wheelers - short, with sliding joints - out of phase, and different from one side to the other.
 
Everybody overlooks the propshaft angles !
Quote from Spicer page, Driveline angles should be equal to or within 1° of each other.
Measuring Angles | Spicer Parts

When I measured the angles on my car the difference was 5 degrees ! How many people bother to check ? none !
And yes the correct spacers were all present. Eventually I got the angles to within 1 degree.
Oh yes the theory behind Rover phasing is interesting, but the shaft is as it is, you are not going to cut it up and change it, but you can do yourself a favour and limit the amount of difference in the flange angles to improve the situation.
Or you can read a load of equations and still have driveline vibration.

All the universal joints have to be perfectly free in all planes without any side to side movement to also ensure smooth operation.
Just throwing in a replacement joint is sometimes not enough, there are different thicknesses of circlip available to set the side to side tolerance on a joint.
 
cobraboy said:
Everybody overlooks the propshaft angles !

Hi Mark,
That is the angle subtended by the axes of each section that I mentioned in my post and is explained mathematically within the attached pdf.

jp928 said:
Ron, I would need that translated into English as she is spoke by us lay persons. If a shaft with 2 ujs can handle, in phase, input and output axes displaced in one plane (eg vertical, which I think is true?), does another displacement (ie horizontal) cause problems that need the ujs out of phase?
When I used to do race car scrutineering it was common to see driveshafts on open wheelers - short, with sliding joints - out of phase, and different from one side to the other.
Click to expand...

Hi John,

Imagine two shafts joined by a universal joint. When the axes of each shaft is within the same plane, that is to say that they align perfectly, turning the input shaft to the universal joint means that the output shaft turns exactly in the same way. Now, if we change that orientation by purposely introducing an angle between the input and output shafts in any direction, then as you turn the input shaft you will feel the rotation of the output shaft is no longer the same. For every 360 degrees of rotation of the input shaft, the output shaft will both speed up and slow down which seems impossible, but the impossible happens. The greater the angle between the two shafts, the more pronounced these accelerations will be. To eliminate the effects that not having the two shafts aligned means we need to introduce a specific amount of phase shift into the placement of another universal joint at the far end of the driven shaft. This is what the Rover engineers devised, given that sliding joint, the tailshaft, and the pinion do not all lie in the same plane, i.e., their axes do not align. This phase shift takes into account the speeding up and slowing down of the tailshaft meaning that the pinion will now spin with the same speed throughout each 360 degrees of revolution as the sliding joint.

Ron.
Click to expand...
 
harveyp6 said:
Both have the angular displacement, but manual cars will only be 144 degrees, it's the autos that have the two offsets, but it's only the very early cars that are 107 degrees.
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I have seen the excerpt from a version of the workshop manual showing the required yoke offset. The version of the Rover manual I have for my '68 2000 TC states "Ensure that the yokes on the propeller shaft are in line with each other. Check that the arrows on splined sleeve and the outer tube are in line with each other." I have looked repeatedly and can find no arrows on my prop shaft to facilitate reassembly. I am experiencing a vibration in the car when driving between 80 and 90 kph. With the contradictory information from the manuals, I am in a bit of a quandary as to which way to go. Once I set the yoke angle I want, I will have the shaft rebalanced, so don't want to do this repeatedly. Is there a definitive answer and is my August 1967 version of the Rover Workshop manual simply out of date?
 
There is a reasonable chance the alignment arrows are still there, just painted over. I have half a dozen newly reconditioned p6 Prop shafts and every one is incorrectly aligned with the yokes in line.
 
mikecoombs said:
There is a reasonable chance the alignment arrows are still there, just painted over. I have half a dozen newly reconditioned p6 Prop shafts and every one is incorrectly aligned with the yokes in line.
Click to expand...
I have looked carefully with a magnifying glass for the alignment marks with no success. I guess I will try strip the paint and try again. Are the marks very small and shallowly pressed into the metal?
 
This is what you're looking for. -

index.jpg

Colin

Edit: Although I have seen a raised arrow on the yoke forging.
 
cobraboy said:
It is worth removing the driveshafts from the diff to hub and checking the joints are perfect with no tight spots. a sticky joint there will cause vibration.
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Thanks for the advice. During my rebuild project I rebuilt the rear hubs. With the half shafts fully removed, I took the opportunity to replace all of the U joints and have the 2 half shafts balanced. It is possible that one of the new U joints has failed prematurely, I will pursue the alignment of the prop shaft first and if I have no success there, I will check the half shafts for any stickiness.
 
I have 2 spare shafts and one on the car (from a 2000 -the part no is stamped on it) and the arrows on all are pretty poor. On one the straight line is visible, the arrow head is marginal.
 
jp928 said:
I have 2 spare shafts and one on the car (from a 2000 -the part no is stamped on it) and the arrows on all are pretty poor. On one the straight line is visible, the arrow head is marginal.
Click to expand...
The part number on mine is impossible to miss. It was marked well and deeply into the metal. If only they had been a diligent with the arrows.
 
Finding the alignment mark on the yoke end was easier and was aligned with the grease zerk. After stripping the paint from the propeller shaft, I was able to spot the mark on the shaft. Only half of the arrowhead was marked and it was stamped right over the part/serial number. It looked more like a poorly stamped N than an arrow and a number 1. Now to repaint, reinstall and road test to see if there is any difference with the vibration I am experiencing.IMGP4708.JPG
 
After repainting I reassembled the prop shaft and with the arrows aligned, the yokes are also aligned. So much for phasing.....
 
I would say that there is no appreciable difference. When I was under the car I also took the opportunity to make a small adjustment to the engine mounts to ensure that the gearbox rear mount was centered in the snub rubber. There is still a vibration right around 90 kph that disappears once the speed exceeds 85 and then is smooth through to 120 kph. I will have to continue looking for the source.
 
Demetris said:
I don't remember if we have discussed this before, but how is the diff front mounting?
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We have not discussed this before. I replaced all 3 of the differential mounts during my rebuild project. I believe that everything is tight and proper.
 
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