Vibration 10-15mph after adding more caster. Why? (1 Viewer)

[jonheld]

Another reference point.
4" IronMan springs, DVS 4" arms (new OEM bushings and hardware of course).
After the installation of the Delta arms, I picked up a driveline vibration similar to the OP. Since there was no clear timeline to get the Wits End DC front shaft, I went with Tom Woods on the recommendation from other 80 owners.
I have to say that I am a bit underwhelmed. While the high speed float vibration is almost completely gone, the low speed vibes are still present. However, this drive shaft has only been installed for a few days and has only 100 miles or so on it, so we'll see what happens over time. The DC and the slip yolk were extremely stiff when installed, so I'm hoping this is temporary.

 

[Surfdc]

Another reference point.
4" IronMan springs, DVS 4" arms (new OEM bushings and hardware of course).
After the installation of the Delta arms, I picked up a driveline vibration similar to the OP. Since there was no clear timeline to get the Wits End DC front shaft, I went with Tom Woods on the recommendation from other 80 owners.
I have to say that I am a bit underwhelmed. While the high speed float vibration is almost completely gone, the low speed vibes are still present. However, this drive shaft has only been installed for a few days and has only 100 miles or so on it, so we'll see what happens over time. The DC and the slip yolk were extremely stiff when installed, so I'm hoping this is temporary.

Thanks Jon for the input. I’m no expert but it seems it should not be extremely stiff...
Maybe your new u joints were not seated just right? If so hopefully a few miles will fix. Or I’m wrong.
Did you run without a front shaft and with the delta arms to see if vibes went away?

 

[jonheld]

Did you run without a front shaft and with the delta arms to see if vibes went away?

Yes. Smooth as silk without the front shaft at all speeds.
I was very careful about inspecting the new joints on the bench before installation. I had to replace the zirk on the diff side joint because the internal check ball didn't seal correctly and was spitting grease back at me. Not a big deal as I have a bag of those.
Movement of the standard universal joint was tight and smooth throughout all the axis, but the DC felt like it was binding up a bit in the center. Working it by hand on the bench it seemed to free up a bit.
Trying to get the slip yolk to move was a bit problematic, but that started to free up as well.
I'll leave it in for a while longer and see what happens. They have a good warranty.

 

[Surfdc]

Yes. Smooth as silk without the front shaft at all speeds.
I was very careful about inspecting the new joints on the bench before installation. I had to replace the zirk on the diff side joint because the internal check ball didn't seal correctly and was spitting grease back at me. Not a big deal as I have a bag of those.
Movement of the standard universal joint was tight and smooth throughout all the axis, but the DC felt like it was binding up a bit in the center. Working it by hand on the bench it seemed to free up a bit.
Trying to get the slip yolk to move was a bit problematic, but that started to free up as well.
I'll leave it in for a while longer and see what happens. They have a good warranty.

Thanks for this input Jon. Great to hear feedback on the options out there. Keep us posted on if those vibs go away. There has gotta be a way we can get this size lift with the delta arms to work!

 

[jonheld]

Thanks for this input Jon. Great to hear feedback on the options out there. Keep us posted on if those vibs go away. There has gotta be a way we can get this size lift with the delta arms to work!

This is not strictly an issue with the DVS arms. It is caused by caster correction after a lift, regardless of how you properly correct the caster.
After several different approaches to caster correction, the new radius arms are far and away the correct choice for me.

 

[Surfdc]

Agreed. I went threw the same process before arriving at the delta arms.
My castor is 3.6* with the 4” arms and I have a total of 3.25” of lift in the front. Since these numbers are not extreme, I’m hopeful a dc shaft eliminates my low speed vibes. Any ideas if it doesn’t? Or if your low speed vibs do not end up going away?

 

[lasoundguy]

FWIW @landtank has driveshafts in stock, I placed my order with him today and he already shipped it out. I tried to get a DC shaft out of Performance Driveline in Bakersfield but I think they are pretty back ordered right now so I jumped for the known quantity once there was stock to get.

 

[Surfdc]

Thanks. I ordered one today. With the 4” plates in case just the dc shaft doesn’t work.

 

[LandLocked93]

Just curious if either of you had a chance to check rotational play between front ds and rear ds t-case flanges? (overall t-case slop)

 

[Surfdc]

Yes. There is considerable rotational play at both transfer case flanges. From my understanding this is normal.

 

[LandLocked93]

Yes. There is considerable rotational play at both transfer case flanges. From my understanding this is normal.

Same with front third member flange? Considerable play?

 

[lasoundguy]

Hmm I’ll check too when I get a chance. I rebuilt my transfer case with new seals and bearings when I regeared it last May, so hopefully it’s still buttoned up pretty well.

 

[Surfdc]

Yes. There is considerable rotational play at both transfer case flanges. From my understanding this is normal.

Just crawled under there to check and I was wrong. There is no side -to-side or up and down play, and the rotational play is less than 1/2” on both front 3rd and at transfer.

 

[LandLocked93]

Just crawled under there to check and I was wrong. There is no side -to-side or up and down play, and the rotational play is less than 1/2” on both front 3rd and at transfer.

Ok. Let's see what the DC shaft does.

 

[Surfdc]

Installed @landtank dc shaft last night and am happy to report that all vibrations are gone!
nothing at 10-15mph, nothing at 40-50mph. Nothing with deceleration or accceleration or coasting.
Lesson learned is that lifting a truck over 3” (especially one that is stock weight) it may net a higher than advertised overall lift that may require more headache (I mean fun) to dial in.

 

[lasoundguy]

Mine came in yesterday as well (thanks @landtank ) but last night I wrenched on my track car instead (cooked the brakes at Buttonwillow last weekend.)
Should get the DC shaft installed next week prior to a camping trip next weekend...excited for the smooth ride!

 

[Delta VS]

Installed @landtank dc shaft last night and am happy to report that all vibrations are gone!
nothing at 10-15mph, nothing at 40-50mph. Nothing with deceleration or accceleration or coasting.
Lesson learned is that lifting a truck over 3” (especially one that is stock weight) it may net a higher than advertised overall lift that may require more headache (I mean fun) to dial in.

would you do me (and everybody in the future) a HUUUUUGE favor and measure the difference between panhard bolts when parked on a smooth flat surface? like the pic in this thread: Compiling/comparing lift and caster data - https://forum.ih8mud.com/threads/compiling-comparing-lift-and-caster-data.1099600/

 

[Surfdc]

Axle bolt 17 1/4.
frame bolt 21 1/4

so 4” of lift.

 

[Surfdc]

Axle bolt 17 1/4.
frame bolt 21 1/4

so 4” of lift.

My mistake after talking to Dave at Delta, There is generally a 1" difference in this measurement on stock rigs, concluding I am at 3" of lift.
@lasoundguy did the dc shaft fix your vibs? I also added @landtank longer rear LCA's as insurance because my rear shaft, although was not vibrating, the transfer and diff angles were more than 5* off.

 

[lasoundguy]

Sadly my DC shaft improved things but it has a shimmy of its own, and a mild "grr" (far less severe than the original driveshaft though.)

I've confirmed it's the driveshaft as the vibrations and grr go away when I run without any front shaft. It's better with the DC shaft but not great, particularly at higher speeds. Not sure next steps, kind of disappointed.