Driveline angle sensitivity

[95BBC]

The bigger top shaft is in phase. The bottom shaft is 90 degrees out.



Excellent video about it

 

[LandLocked93]

The video is great...
...but did say how to tell by looking if the shaft is in phase?
What are the physical indicators? zerk fittings alignment? u/j alignment end to end?
I'm a little slow when it comes to this.

 

[SNLC]

The video is great...
...but did say how to tell by looking if the shaft is in phase?
What are the physical indicators? zerk fittings alignment? u/j alignment end to end?
I'm a little slow when it comes to this.

Indeed!

Look at the ujoints, end to end on the picture posted right above. See how on the longer shaft the are both the same and on the shorter one they are not?

This is in phase and out of phase.

Cheers

 

[LandLocked93]

Indeed!

Look at the ujoints, end to end on the picture posted right above. See how on the longer shaft the are both the same and on the shorter one they are not?

This is in phase and out of phase.

Cheers

Ok..so if by "Look at the ujoints..." you are saying to look at two of the four points of the ujoint which are in contact with the shaft and NOT the flange...
...I can see that the top shaft has both of its 2 contact points on either end of the shaft in alignment with each other, end to end.
The bottom shaft has its two contact points 90 degrees out from each other.
Is that the answer? lol

And I'm assuming that 90 degrees is the maximum deviation of phase?

 

[LandLocked93]

What is the phasing of your driveshaft?

Good news! Today I found out...

 

[SNLC]

Ok..so if by "Look at the ujoints..." you are saying to look at two of the four points of the ujoint which are in contact with the shaft and NOT the flange...
...I can see that the top shaft has both of its 2 contact points on either end of the shaft in alignment with each other, end to end.
The bottom shaft has its two contact points 90 degrees out from each other.
Is that the answer? lol

And I'm assuming that 90 degrees is the maximum deviation of phase?

Yes and yes

Cheers

 

[nukegoat]

Good news! Today I found out...

Just take a pic and send it

 

[BILT4ME]

And, your front shaft is supposed to be 90* out of phase.

Your rear shaft is supposed to be in phase.

Both shaft are supposed to have the slip yoke to the FRONT of the truck.

 

[LandLocked93]

And, your front shaft is supposed to be 90* out of phase.

Your rear shaft is supposed to be in phase.

Both shaft are supposed to have the slip yoke to the FRONT of the truck.

Wait.

What?? This is huge.

I understand what you are saying. I will check first thing in the morning. Haven't read nor heard this sort of detail. Can I get a second? May I be so bold as to suggest leading with this next time? lol

I know for a fact that the front shaft is in phase and the yoke is toward the front (this is the way to came back from the tranny shop). Have to check the rear in the a.m., but I feel it is in phase with the yoke toward the rear(again, as it returned from that shop.)

 

[BILT4ME]

Wait.

What?? This is huge.

I understand what you are saying. I will check first thing in the morning. Haven't read nor heard this sort of detail. Can I get a second? May I be so bold as to suggest leading with this next time? lol

I know for a fact that the front shaft is in phase and the yoke is toward the front (this is the way to came back from the tranny shop). Have to check the rear in the a.m., but I feel it is in phase with the yoke toward the rear(again, as it returned from that shop.)

The front shaft out of phase was written as an update. There is a copy of it in this forum and some debate about it.

The orientation of the slip yoke being to the front on both shafts is shown in the FSM.

 

[ColoradoBoy]

I 2nd what @BILT4ME said. I'd also recommend focusing less on drivelines initially and focus on replacing the 24+ degraded rubber bushings on all the control arms, panhard bars and sway bars along with engine and transmission mounts, before ever getting into the weeds on the driveline angles. My bet is your new tranny mount accounted for your 3 degree change. My truck tightened up 300% after all new OEM bushings were installed.

I lived the driveline angle nightmare for 2 years and came to the realization that the load does matter but when I set my rear pinion angle (using adjustable LCAs) I set it about 2 degrees negative so that when torque is applied and the axle wrap occurs, it's spot on. My variable weight is 2x people and the other 1/2 of my gear which is probably about 400-500 lbs total. I don't have any vibe issues anymore at highway speed so I must have done things right. For the record, most people use adjustable upper control arms to keep their axle centered in the wheel well but my lowers worked fine for me, the tire only moved about 3/8" and nothing rubs under flex.

The front is another matter. I ended up with a part time kit and love it. It was that or a ball cut and turn which I don't have the talent for. My DC experiments never quite worked out and that 1-2 degree "off" makes all the difference.

I learned so much more than I ever cared to about drivelines and angles but if you do your homework and buy a magnetic angle level, you can wrap your head around it and understand how YOUR truck works pretty quickly. Just remember the secret is in the "Equal but opposite angles". Not much more to it. If the front of the shaft is a 3 degree angle, the rear of the shaft needs to be 3 degrees. If you throw in 500lbs and those angles change (i.e. 4 in front and 5 in back), you may need to get some adjustable control arms and adjust to find your truck's sweet spot.

My buddy lifted his truck the same height (2.5" lift, gainng 4" including OEM spring sag) and never had a vibe issue. I had lots of vibe.

+1 for new bushings- it makes a HUGE difference in truck handling, ride comfort and overall driving enjoyment! Good luck chasing the driveline angles.

 

[LandLocked93]

Bumping for final post...

I want to thank each and every one of you who chimed in to this thread. Today marks the first day that ALL of my driveline demons have been vanquished. And I mean ALL. 'Smitty' finally drives againn like he did when he left Slee's shop almost 2 years ago after a lift.

After the initial suggestion to check shaft phases (and learning whiskey tango foxtrot that meant), I focused in on the front shaft. It was in fact installed in phase. I changed the phase, reinstalled and test drove. At least half of my driveline issues were gone! I was so pleased I decided to hold off there and just enjoy the fact for a few other test drives (t-shooting other things).

Then today, while rotating my tires I went under to get nukegoats pic of the rear shaft that he requested. Low and behold my rear shaft was OUT OF PHASE. I immediately changed it to in phase and test drove.


The angels sang, the heavens opened up, and silence fell upon the land like in a great slumber. NO MORE RATTLE! NO MORE RUMBLE! No more throttle tip-in balance act to keep the horrendous clattering to a minimum at speed. 'Smitty' is QUIET at ANY speed. On-throttle, off-throttle, slowing for a light. ALL QUIET.

He is like he was when I bought him. He is like he was when he was lifted. No change in drive angles done. No replacement of u/j's or shafts. Just phase. That was it. He went from a so-so driver showing age to a normal driver showing much potential. They make THAT big a difference.

Thank you Thank you Thank you everyone.

That is all.