Thread: Vibration in my butt with Tom Wood's shaft :)

My flanges look like this , well very similer T/C flange points more twards the sky .

Originally Posted by Dockstrada

So I just fitted a Tom Wood DBL Cardan shaft today and I noticed a vibration only under heavy acceleration at around 60kph then it smoothens out after that. I’m thinking I still need radial arms to re position the diff to its normal position. I'm yet to contact Tom for advice. Any ideas?

Maybe it's slightly out of phase? Or is it one of those where that's not applicable?

Originally Posted by Dockstrada

Nice picture, do you have one for a standard shaft ?

I am struggling to understand the role of the DC joint in your picture. With that said, I just looked at mine and it also appears to be per your picture.

My "long winded"explanation is solely based on advice from Cumming Trucks machine shop. Who advised to perform the caster correction for longjebity of the DC shaft, the machine shop manger spoke at length about 3 degree maximum variation in flange angles.

Originally Posted by Drover

Nice picture, do you have one for a standard shaft ?

I am struggling to understand the role of the DC joint in your picture. With that said, I just looked at mine and it also appears to be per your picture.

My "long winded"explanation is solely based on advice from Cumming Trucks machine shop. Who advised to perform the caster correction for longjebity of the DC shaft, the machine shop manger spoke at length about 3 degree maximum variation in flange angles.

yeah im just thinking outside the square at the moment .

Just checked the angle of the T/C flange using the iphone level and it was aprox 11 degree diff flange was aprox -3.6 degree and shaft angle was aprox 15.5 degree .
so if anyone can work that out, great . let me know if im in a world of hurt .


Pic as requested .

Originally Posted by Naks

Maybe it's slightly out of phase? Or is it one of those where that's not applicable?

Ok Il ask ! what's out of phase mean ?

Dockstrada,

Try this

Originally Posted by Dockstrada

Ok Il ask ! what's out of phase mean ?

It can occur when the slip joint is pull apart and not put back together in original position misaligning the splines, causing the uni to be out of phase.

Normally the to halves of the shaft will have an indicator on each to align to. Sometimes it is just a painted mark.

This drawing is correct for when a double cardan joint (also known as constant velocity or CV joint) is used.

The pair of joints in the double cardan joint are forced (by the centre ball) to work at equal angles. Because the angles are equal the angular velocity of the driveshaft is the same as the transfer case output shaft (this is why they are also called constant velocity).

The standard cardan joint at the diff end should only have a small angle change. As stated less than 3 degrees, but less is better. Some people like a slight change so the needle rollers don't stay static.

Only at zero angle will the angular velocity of the diff pinion be equal to the angular velocity. As angle change increases, the angular velocity changes 4 times per revolution. Change in angular velocity = angular acceleration and this is what causes vibration in this case.

The first pic (Tom Woods shaft) and this drawing show the 2nd joint of the double cardan joint and the joint at the diff in phase. This is how it should be.