Driveshaft alignment

[dhirocz]

Finally be headed home in the next couple of days. Army thought it was a good idea to send me to school for a month to learn how to be a truck driver...:huh:

Before I left, I noticed my main driveshaft was crooked. What I mean is, it's phased properly, but it is off maybe 3 or 4 degrees compared to the intermediate shaft, at the carrier bearing. Driveshafts were recently rebuilt with Spicer components and balanced.

It rides much better, but there is still a little shake to it, only over 50. I'm thinking I may need to make a tool to make sure the main shaft and intermediate shaft are straight with each other. Any particular input on this?

Also will be using an angle meter and seeing what my driveshaft angles are at. I know when I got the truck, the ride height was too high and it rode like shi#t as a result. I brought it back down to kw spec and it handled much better. I'm kind of thinking to adjust the ride height to get as close to an identical angle reading between the two as possible. Your thoughts?

Truck will be paid off next month. I want to make sure I'm taking good care of it.

[arch_stanton]

I wrote about this same thing in another thread, I have owned this pete 378 since 2002 running as a dump truck and it has always had a little vibration that I could not find looked at drive line angles, carrier bearing,ect after another guy posted about his drive shaft off center line causing a vibration so I put a string line from center of trans u joint to center front drive u joint and I found 2 things. The carrier bearing was offset to the passenger side and the front driver was off set to the driver side caused by installing a torque rod wrong. I drilled 2 new holes in the carrier bearing mount and remounted the vibration is gone

[dhirocz]

String? That's just too easy. Didn't know if there was a more scientific method here Is should have been looking at.

What about the driveshaft angles? I'm thinking about adjusting my air ride to get it as close to a zero difference as possible on the angles, instead of adjusting based on chassis height alone. I may wait and take some measurements next time I get it under a load and see if the angles are different under load or not first.

[Chamberpains]

Dhirocz I'm probably wrong in the way I'm reading what you're asking. But if you're checking the angle of the 2nd drive shaft, intermediate shaft, to the rear end. There is going to be an angle in that shaft because that's the whole purpose of the U joint at the carrier bearing. To correct the difference in angle of the rear end suspension moving up and down and the angle between the transmission and the front rear end yoke. So some angle difference is always there.

That's the whole reason they don't use one long drive shaft from the transmission to the rear end. It would put the angle of the shaft at too far of an extreme all the time which would cause the U-joints to burn up from moving to much.

I wouldn't get too crazy about setting them at zero degree of angle. They are rather large and rather long drive shafts. So it would take a hell of a lot of rear end movement up and down to pull them out of the proper angle.

Now the rear drive shaft between the front rear and the rear rear is important to set up correctly both empty and with a load on. Because the travel in the 2 axles suspensions is so great that it can easily be put into extreme angles and burn U joints and bearings up.

[snailexpress]

Some angle in driveline settings is necessity to make U-joint bearing needle rotation. If you have doubts go to dealership and take look on brand new truck.

[dhirocz]

No I was referring to the shafts being inline, parallel between the rails. Not up and down movement, though the ride height was just checked.

My carrier bearing was almost 1" offset to the passenger side. I'm rather amazed by that right now. I had to grind the bracket a bit with a carbide burr to get enough adjustability in it to straighten it out. Now both shafts are perfectly inline.

Carrier bearing bracket was also in a slight twisted position, so I'll make sure it's not holding the bearing cockeyed.

I'll be confirming everything tomorrow, then taking it out for a drive before I begin my next round of repairs tomorrow.

[Chamberpains]

Some Chassis manufacturers slotted the carrier bearing mounts just so you can adjust the position of them for off set rear ends and power dividers.

[dhirocz]

Mine were slotted to allow forward/rearward movement, but none side to side. Mine needed to move to the drivers side by a good bit.

No more odd shakes and vibrations! Rides like a new truck, under a load. Makes me wonder if the drives were swapped at one point, it's hard to think that misalignment might have been factory...but then again, maybe not.

I haven't noticed any significant wear in the torque rods that would allow it to be off that much, however, I plan on upgrading them later in the year. I'll recheck the alignment at that time.

[Magard]

Don’t think that a new truck is right when it is sent out the door. Quality control sucks in this world anymore. Look for some way of getting all of your angles as straight as possible. Set ride hight by the shaft between the two rears. Try and split the difference between the two. They go opposite directions as you go up and down. Then compromise that with the front driveline coming into the front of the power divider. After that seems to be as good as you can get. Then fix the carrier bearing mount location trying to get it as straight as possible. I don’t think you can get it perfectly straight anyhow. Factory ride hieght might not work because bushings wear and angles might not be right anymore. Sometimes just eyeing it with a small square to see angles is all you can feasibly do.