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

Surfdc

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I have been adding the delta icon 3” lift which includes the @Delta VS 4” radis arms.
here is what I noticed:
-Old TJM 2” lift with caster correction bushings=no vibration.
-Added icon shocks=no vibration
-Added delta rear drop bracket=no vibration
-Added radius arms=slight vibration during acceleration from 10-15mph. Then smoothes out.
-Added icon springs=no change.
That completes the items in the kit. I still have the OEM radius arms with caster correction bushings. I could put them back in and see if the vibration goes away? That would tell me the radius arms are too much caster?
not sure. Any input appreciated.
239ABC8F-E455-4A67-9B1A-58E14DFBCE3E.jpeg
 

voodu3

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Have you had it aligned after installing the new parts? If you haven’t do that it will probably fix the vibration. If not it will give you the info on what is out.
 

Delta VS

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I have been adding the delta icon 3” lift which includes the @Delta VS 4” radis arms.
here is what I noticed:
-Old TJM 2” lift with caster correction bushings=no vibration.
-Added icon shocks=no vibration
-Added delta rear drop bracket=no vibration
-Added radius arms=slight vibration during acceleration from 10-15mph. Then smoothes out.
-Added icon springs=no change.
That completes the items in the kit. I still have the OEM radius arms with caster correction bushings. I could put them back in and see if the vibration goes away? That would tell me the radius arms are too much caster?
not sure. Any input appreciated.
View attachment 2512393
Before swapping arms, best thing would be to stop by an alignment shop and have them check the caster (should be 20$ or free if you get tires there). How new are the u-joints?
 
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U joints will sometimes protest to a change in angle if they have been "settled in" at a specific ride height for a long time. A simple U-joint change would likely take care of your issue, if not, then look into a DC driveshaft. But try just greasing your u-joints first. They may settle down a little (even if barely perceptible), which would be a good diagnostic that your problem is in the U-joints.
 
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U joints will sometimes protest to a change in angle if they have been "settled in" at a specific ride height for a long time. A simple U-joint change would likely take care of your issue, if not, then look into a DC driveshaft. But try just greasing your u-joints first. They may settle down a little (even if barely perceptible), which would be a good diagnostic that your problem is in the U-joints.
+1 - Indeed. Was wondering if the front shaft got put back in exactly as it was before - orientation and phase.
If those are correct, try rotating the shaft on the flanges 180 degrees and see whats up. Tho @4" lift...only new u/j's may be the answer. Recommend CruiserTEQ for the Matsuba versions. (there are others of course)
 

Surfdc

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Before swapping arms, best thing would be to stop by an alignment shop and have them check the caster (should be 20$ or free if you get tires there). How new are the u-joints?
Here is the before and after alignment. Done a month ago after new tires, and before lift.
U-joints are 2 months old.
0AF2BAAE-301A-429B-A9E2-2B3AA2CD0AFA.jpeg
 

Surfdc

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Have you had it aligned after installing the new parts? If you haven’t do that it will probably fix the vibration. If not it will give you the info on what is out.
Thinking of doing this today.
 

Surfdc

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U joints will sometimes protest to a change in angle if they have been "settled in" at a specific ride height for a long time. A simple U-joint change would likely take care of your issue, if not, then look into a DC driveshaft. But try just greasing your u-joints first. They may settle down a little (even if barely perceptible), which would be a good diagnostic that your problem is in the U-joints.
New OEM driveshafts front and rear 2 months ago.
 
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Why? You went over 2” in lift. Everyone here has posted sound solutions to try. Your vibration sounds very minor compared to others (me included), so that’s good.
 
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“Why” was your question. Last word in the title of your post. Everyone gave you sound solutions, but no one answered the why part.

Lifting these things over 2” inches has a chance of introducing vibrations because correcting the caster after a lift alters the pinion angle, which is usually the culprit that causes the vibrations.

Easier to address in a linked suspension, but the FZJ80 has radius arms which makes this more difficult.
 
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Grease the new joints again, drive it hundreds of miles for wear in and report back. My 5k front oem joint still lightly vibes on decel only, no caster, no arms. It had to wear in.
The original joint had 180k and was Grrrring both ways for a thousand miles after 850 heavy springs. Was progressively quieter with time. Basically disappeared.
My exhaust vibes some during that speed accelerating. 🤔Nice list of go slow parts btw.
 
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@Surfdc I recently put taller springs (went OME 2.5" up to Tour Flex 3") and also have a slack throttle "grr" right now I'm chasing down--not much in the way of vibration, more just noise, but I think it's a different manifestation of the same problem.

I was going to try and jump straight to sourcing a DC front shaft but this thread and some others has me thinking I might as well do the front U-joints first in case spending $100 now can save me spending $600...

I'm pretty sure it's the axle rotation caused by the Delta arms that introduced the issue more than the springs, getting the caster back to stock increases the pinion angle. I suspect if I went back to my original radius arms with OME caster bushings the "grr" would go away but the truck would not drive as well.

Not founded in science, just what I've observed going through a similar journey in the past two weeks. Keep us posted how you make out. I got my truck aligned last week and my caster is sitting at 3.9º driver / 4.6º passenger.
 

Surfdc

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“Why” was your question. Last word in the title of your post. Everyone gave you sound solutions, but no one answered the why part.

Lifting these things over 2” inches has a chance of introducing vibrations because correcting the caster after a lift alters the pinion angle, which is usually the culprit that causes the vibrations.

Easier to address in a linked suspension, but the FZJ80 has radius arms which makes this more difficult.
Ahh. I see. So in my case correcting the caster did just that, but increased the pinion angle. Which may be the cause of the vibration. Which a dc shaft would fix. Or if I understand correctly if I go back to my old radius arms and less caster the vib would be gone again? (Pinion angle less) I could do that , I guess the sacrifice would be the better handling from corrected caster...
 

Surfdc

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Grease the new joints again, drive it hundreds of miles for wear in and report back. My 5k front oem joint still lightly vibes on decel only, no caster, no arms. It had to wear in.
The original joint had 180k and was Grrrring both ways for a thousand miles after 850 heavy springs. Was progressively quieter with time. Basically disappeared.
My exhaust vibes some during that speed accelerating. 🤔Nice list of go slow parts btw.
I will grease and report back. But there was no vib before the radius arms? Well greasing takes 2 min anyway.
 

Surfdc

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@Surfdc I recently put taller springs (went OME 2.5" up to Tour Flex 3") and also have a slack throttle "grr" right now I'm chasing down--not much in the way of vibration, more just noise, but I think it's a different manifestation of the same problem.

I was going to try and jump straight to sourcing a DC front shaft but this thread and some others has me thinking I might as well do the front U-joints first in case spending $100 now can save me spending $600...

I'm pretty sure it's the axle rotation caused by the Delta arms that introduced the issue more than the springs, getting the caster back to stock increases the pinion angle. I suspect if I went back to my original radius arms with OME caster bushings the "grr" would go away but the truck would not drive as well.

Not founded in science, just what I've observed going through a similar journey in the past two weeks. Keep us posted how you make out. I got my truck aligned last week and my caster is sitting at 3.9º driver / 4.6º passenger.
Do you have the delta 4” arms?
Did you not have the throttle “grr” before adding them?
 
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I'm going to say you, my caster bushings were trashed and I had to cut bolts to get them out (seemed like they wore a taper in the bolt sleeve or something, it would freely slide in one direction but bind up *hard* in the other.)

I'm ordering new U-joints today from @cruiseroutfit to see if that fixes it, otherwise chasing down DC options but would prefer to pause on the cash throwdown.
 

Surfdc

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Ok. agreed. My castor correcting bushings are fine. I did not budget for a dc driveshaft nor did i think i needed it as part of this lift. So would rarther not have to buy one as well. I get an alignment tomorrow, will note the results, then most likely swap out the radius arms. In the meantime, i will grease my u joints and will post the results.
 

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