Driveline phasing and angles explanation - Great video!

Ian Anderson

Lifetime Premier Supporter
#6
Wont need to with CV joints Walt, only U-joints or any combo with a U-joint.
Hey Jac
So original GT40 have a UJ on the outboard end, which would put the phasing in 90 degree chunks


Next to the gearbox they had a rubber doughnut. From memory it had 3 bolt things through from each side giving a 60 degree phasing if I calculate it correctly

How does the phasing work so it is not jerking/vibrating?

Perhaps angles are so minimal that it is not a problem

Cheers
Ian
 

Jac Mac

Active Member
#7
Hey Jac
So original GT40 have a UJ on the outboard end, which would put the phasing in 90 degree chunks


Next to the gearbox they had a rubber doughnut. From memory it had 3 bolt things through from each side giving a 60 degree phasing if I calculate it correctly

How does the phasing work so it is not jerking/vibrating?A single U-joint run at an angle & driven at constant speed on one shaft will induce an uneven rotating speed on the other side of the u-joint, that uneven rotating speed changes twice in each revolution and that uneven amount increases with u-joint angle increase. When you complte the shaft with the second u-joint the uneven rotational speed changes are canceled out on the outer shaft. However the uneven rotational speed still remains in that middle shaft at any time the angles remain, to further confuse things as shown in the video if th angles are not the same some difference in speed will be induced in all shafts and it depends which end of the shaft has the most resistance/weight attached to it as to where those forces will felt.

Perhaps angles are so minimal that it is not a problem

Cheers
Ian
Hi Ian, The rubber doughnut can be considered to be a CV joint, but with the added feature of being able to absorb any shaft speed differences that are induced when the outer U-Joint runs at any angle during suspension movement. So it is/was the best solution in early model cars with lower engine power levels. When Ford went to the MKII & T44 Transaxles etc the U- Joint size went up, but it appears that they managed or found it necessary to incorporate a form of rubber cushion setup into the inner U-joint flange- probably something similar to citroen ID19 for example.
Another factor that creeps in here is with high power inputs the axles will twist in torsion and any built-in alignment of the inner /outer U-joints will disappear and you get vibration under hard acceleration.
 

Jac Mac

Active Member
#8
Hey Jac
So original GT40 have a UJ on the outboard end, which would put the phasing in 90 degree chunks


Next to the gearbox they had a rubber doughnut. From memory it had 3 bolt things through from each side giving a 60 degree phasing if I calculate it correctly.[[[ NO, due to being elastic this is considered to be a CV joint even though it is really like a torsional twist absorber for want of a better description.]]]


How does the phasing work so it is not jerking/vibrating?A single U-joint run at an angle & driven at constant speed on one shaft will induce an uneven rotating speed on the other side of the u-joint, that uneven rotating speed changes twice in each revolution and that uneven amount increases with u-joint angle increase. When you complte the shaft with the second u-joint the uneven rotational speed changes are canceled out on the outer shaft. However the uneven rotational speed still remains in that middle shaft at any time the angles remain, to further confuse things as shown in the video if th angles are not the same some difference in speed will be induced in all shafts and it depends which end of the shaft has the most resistance/weight attached to it as to where those forces will felt.

Perhaps angles are so minimal that it is not a problem

Cheers
Ian
Hi Ian, The rubber doughnut can be considered to be a CV joint, but with the added feature of being able to absorb any shaft speed differences that are induced when the outer U-Joint runs at any angle during suspension movement. So it is/was the best solution in early model cars with lower engine power levels. When Ford went to the MKII & T44 Transaxles etc the U- Joint size went up, but it appears that they managed or found it necessary to incorporate a form of rubber cushion setup into the inner U-joint flange- probably something similar to citroen ID19 for example.
Another factor that creeps in here is with high power inputs the axles will twist in torsion and any built-in alignment of the inner /outer U-joints will disappear and you get vibration under hard acceleration.
 

Pat

Silver Supporter
#9
When I replaced my steering rack the u-joint phasing on the steering column was pretty important. Before I hooked it up the rack, I tinkered with different phasing while the clamps were loose. It was surprising how you could actually feel the bind out of phase.
 
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