Tracking driveline vibration
Former Vendor
Joined: Nov 2005
Posts: 683
Likes: 1
From: Mounds View Minnesota
One thing I want to remind people of is why it matters that the angles are the same.
It's like this, as a U joint rotates though a 360 degree circle it accelerates and decelerates in a sinusodial pattern at 4 times( or is it twice ) the shaft RPM. This causes vibration proportional to the angle of the U joint.
U joints are always arranged in a pair 90 degrees out of phase so as one is accelerating the other is decelerating.
This cancels out the vibration as long as the u joint angles are equal and oppesite.
I used the protractor method and measured the angle of the pinion to the drive shaft and made them equal. It rear is really hard tough though...
So what I did is this. I glued a scale to the drive shaft and put a heavy wire under the U-joint bolt so as you rotate the drive shaft you can measure the angle change Use a mirrorto see the angle at the top.
Get the front and rear angles the same and all will be good.
It's like this, as a U joint rotates though a 360 degree circle it accelerates and decelerates in a sinusodial pattern at 4 times( or is it twice ) the shaft RPM. This causes vibration proportional to the angle of the U joint.
U joints are always arranged in a pair 90 degrees out of phase so as one is accelerating the other is decelerating.
This cancels out the vibration as long as the u joint angles are equal and oppesite.
I used the protractor method and measured the angle of the pinion to the drive shaft and made them equal. It rear is really hard tough though...
So what I did is this. I glued a scale to the drive shaft and put a heavy wire under the U-joint bolt so as you rotate the drive shaft you can measure the angle change Use a mirrorto see the angle at the top.
Get the front and rear angles the same and all will be good.
Drifting
Joined: May 2005
Posts: 1,629
Likes: 4
From: Somers CT
I used the protractor method and measured the angle of the pinion to the drive shaft and made them equal. It rear is really hard tough though...
So what I did is this. I glued a scale to the drive shaft and put a heavy wire under the U-joint bolt so as you rotate the drive shaft you can measure the angle change Use a mirrorto see the angle at the top.
Get the front and rear angles the same and all will be good.
So what I did is this. I glued a scale to the drive shaft and put a heavy wire under the U-joint bolt so as you rotate the drive shaft you can measure the angle change Use a mirrorto see the angle at the top.
Get the front and rear angles the same and all will be good.
This happened to my car and I fixed it by slotting the transmission mount and moving the transmission towards the drivers side about 3/4".
And how did you do this without modifying the motormounts to allow the engine to move sideways?
Last edited by TopGunn; Jan 6, 2007 at 09:42 PM.
Former Vendor
Joined: Nov 2005
Posts: 683
Likes: 1
From: Mounds View Minnesota
Ok here is a 'drawing' It shows one end of the drive shaft...
I made a scale out of a piece of cardboard with lines every 1/8" and glued that to the driveshaft. You don't know the actul angles but you just want to make the front and rear angles the same.
unlike Norval, I use stock rubber locking engine mounts and just pushed the engine over towards the side
Does this make sense?
I made a scale out of a piece of cardboard with lines every 1/8" and glued that to the driveshaft. You don't know the actul angles but you just want to make the front and rear angles the same.
unlike Norval, I use stock rubber locking engine mounts and just pushed the engine over towards the side
Does this make sense?
Drifting
Joined: May 2005
Posts: 1,629
Likes: 4
From: Somers CT
