Vibration 10-15mph after adding more caster. Why? (2 Viewers)

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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...

Correct, It’a highway wandering vs potential driveline vibration when getting over 2” in height. Two inches and caster correction and 4” in height, a DC shaft and correct caster are the usually the sweet spots.

There are some really old threads here of guys correcting it my putting their front driveshaft in phase and rebalancing it was enough.

Of course dunderheads like me started running 3” lifts, 3.5” lifts, tapered springs, etc and started muddying up the water.
 

Surfdc

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Correct, It’a highway wandering vs potential driveline vibration when getting over 2” in height. Two inches and caster correction and 4” in height, a DC shaft and correct caster are the usually the sweet spots.

There are some really old threads here of guys correcting it my putting their front driveshaft in phase and rebalancing it was enough.

Of course dunderheads like me started running 3” lifts, 3.5” lifts, tapered springs, etc and started muddying up the water.
Ha! Then consider me a dunderhead!
 

bajaphile

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I'm not 100% clear on how adjusting toe in (getting an alignment) would fix this issue. I understand the axle has rotated slightly now with the new radius arms, which would then slightly impact toe, but not to a measurable amount to create a vibration.

Most vibrations after lifts come at higher speeds as well, not at 10-15 mph. From my experience, a vibration at that speed will generally be unevenly worn tires. A vibe that is at high speed, but goes away is tires and/or balance. A vibration that comes on around 50 and stays there is driveline related. However, it does sound like it is related to the front drive shaft and the new pinion angle.

To double check, you removed all previous bushings/plates before installing the Delta arms, correct?

If I were you, I'd do the following:
1) Rotate tires, see if there is any change
2) Engage CDL and see if there is any change at 10-15 mph.
3) Remove front drive shaft and see if it goes away
 

Surfdc

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I'm not 100% clear on how adjusting toe in (getting an alignment) would fix this issue. I understand the axle has rotated slightly now with the new radius arms, which would then slightly impact toe, but not to a measurable amount to create a vibration.

Most vibrations after lifts come at higher speeds as well, not at 10-15 mph. From my experience, a vibration at that speed will generally be unevenly worn tires. A vibe that is at high speed, but goes away is tires and/or balance. A vibration that comes on around 50 and stays there is driveline related. However, it does sound like it is related to the front drive shaft and the new pinion angle.

To double check, you removed all previous bushings/plates before installing the Delta arms, correct?

If I were you, I'd do the following:
1) Rotate tires, see if there is any change
2) Engage CDL and see if there is any change at 10-15 mph.
3) Remove front drive shaft and see if it goes away
I hear you on the low speed vib, but the tires are brand new.
to answer your questions:
Yes all bushings/plates removed and delta arms come with oem bushings installed.
I will try your suggestions and report back.
thanks!
 

Surfdc

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All,
Here is the results from today’s alignment. Vib is still there.
It seems my total lift achieved was 3.25” in the front.
It also seems the caster is still in speck? Could it still be too much?
3EF171B5-F3B4-43B4-AF88-4A0A8D9A24BC.jpeg
 
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The English have similar issues.
 

Surfdc

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The English have similar issues.
Thanks. Just read. Sounds like what I’m dealing with.
 

Delta VS

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All,
Here is the results from today’s alignment. Vib is still there.
It seems my total lift achieved was 3.25” in the front.
It also seems the caster is still in speck? Could it still be too much?
View attachment 2514497
If the caster is in spec, then it is not too much, in terms of proper handling. Having proper caster at "x" inches of lift IS going to make pinion angles potentially incorrect. As many have said, this is usually seen at higher speeds though. Very good advice above to remove the front driveline (do you have CDL switch?) and drive to make sure it actually is the front drivetrain that is the issue (just because you remove the front driveline and the vibe goes away doesn't necessarily mean it's the front driveline, could be other driven parts, however unlikely).
 

Surfdc

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If the caster is in spec, then it is not too much, in terms of proper handling. Having proper caster at "x" inches of lift IS going to make pinion angles potentially incorrect. As many have said, this is usually seen at higher speeds though. Very good advice above to remove the front driveline (do you have CDL switch?) and drive to make sure it actually is the front drivetrain that is the issue (just because you remove the front driveline and the vibe goes away doesn't necessarily mean it's the front driveline, could be other driven parts, however unlikely).
Thanks for this. I will be pulling the front driveshaft this week.
Yesterday on my list of things to check related to the vibration was go check front wheel bearings. Well, the lock washer was not bent either way, one of the tabs was busted off, and another was half broke, indicating the last mechanic in there tried to reuse the old one. Both inner and outer nuts I could spin by hand! Got them back on and torqued, and the vibration is still there. HOWEVER, this did eliminate an annoying little clunk I had over every single small crack in the road!
 

Surfdc

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Update:
Tonight I pulled the front driveshaft and drove around and the vibration is gone.

any ideas/conclusions?
 
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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.

I’ll pull the driveshaft to see. Or swap back in the old arms.

Changing back to the original arms and driving with incorrect caster just to avoid a grrrr at 10 - 15 mph is plain stupid. Improper caster is dangerous for yourself and others on the road. The Grrrr isn't going to hurt anyone, but improper caster will create steering issues and could potentially lead to a bad accident. If you want 3-4" of lift than you better be willing to spring for the correct driveshaft, if that is out of your budget han sell the rig or stick with a 2" lift and 33"s. Either that or just run 37"s on a 2" lift without changing your ring a pinion gears or driveshaft, even 3fe powered 80's can supposedly run 37"S with a two inch lift and no re-gear in Cali.
 

Surfdc

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Changing back to the original arms and driving with incorrect caster just to avoid a grrrr at 10 - 15 mph is plain stupid. Improper caster is dangerous for yourself and others on the road. The Grrrr isn't going to hurt anyone, but improper caster will create steering issues and could potentially lead to a bad accident. If you want 3-4" of lift than you better be willing to spring for the correct driveshaft, if that is out of your budget han sell the rig or stick with a 2" lift and 33"s. Either that or just run 37"s on a 2" lift without changing your ring a pinion gears or driveshaft, even 3fe powered 80's can supposedly run 37"S with a two inch lift and no re-gear in Cali.
I was under the impression that a dc driveshaft would not fix this issue.

Because this lift kit kept everything including castor in spec I was told a dc driveshaft was not needed.

Swappping the arms back was to be done as an experiment to conclude that there was too much castor. If this, then yes I agree with you. I would have to lower the rig. Or live with the vibration.
 
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I was under the impression that a dc driveshaft would not fix this issue.

Because this lift kit kept everything including castor in spec I was told a dc driveshaft was not needed.

Swappping the arms back was to be done as an experiment to conclude that there was too much castor. If this, then yes I agree with you. I would have to lower the rig. Or live with the vibration.

That makes more sense, sorry if I came off as a dick in my post, I think I misread your intentions.

That being said I think it would be hard to have to much caster on a lifted 80 series with oversized tires. The only negative consequences of too much caster would be driveline vibes from driveshaft angles and issues with steering linkage contacting the radius arms. (Hence the need for aftermarket arms)

The OEM spec for caster was 2-3 degrees if I remember correctly. That being said it is important to remember that the 2-3 degree spec was for OEM sized tires. With bigger tires you have more weight and a larger contact area between the tire and road than compared to OEM tire sizes. That means the larger tires will put more force on the steering system when hitting bumps, ruts, uneven surfaces or crowned pavement when compared to an OEM tire size. This will cause the rig to change course much easier. For me this was very noticeable on crappy old highways and the worst on dry dirt roads with ruts formed in the road. Anytime you hit a rut the larger tire creates more force compared to OEM size and it will pull the vehicle nto the rut or off the side off the road because the extra weight of the tire and the increased tread to road surface contact area. This is the best way I can describe the physics involved. Basically 3 degrees of caster is correct for an OEM tire, but if Mr T had designed the 80 series to run 35's than the stock caster would have been more than 3 degrees to compensate for the increased forces seen with the larger tire.

It sounds like you have put a lot of thought and planning into the set up that you want. I really hope you can figure it out and don't hesitate to spend a little extra to get it right. I can tell you from experience that driving with incorrect caster is sketchy, dangerous, and no fun.


Good luck, if your ever in southern utah send me a pm and I will send you to some cool areas.
 

Surfdc

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That makes more sense, sorry if I came off as a dick in my post, I think I misread your intentions.

That being said I think it would be hard to have to much caster on a lifted 80 series with oversized tires. The only negative consequences of too much caster would be driveline vibes from driveshaft angles and issues with steering linkage contacting the radius arms. (Hence the need for aftermarket arms)

The OEM spec for caster was 2-3 degrees if I remember correctly. That being said it is important to remember that the 2-3 degree spec was for OEM sized tires. With bigger tires you have more weight and a larger contact area between the tire and road than compared to OEM tire sizes. That means the larger tires will put more force on the steering system when hitting bumps, ruts, uneven surfaces or crowned pavement when compared to an OEM tire size. This will cause the rig to change course much easier. For me this was very noticeable on crappy old highways and the worst on dry dirt roads with ruts formed in the road. Anytime you hit a rut the larger tire creates more force compared to OEM size and it will pull the vehicle nto the rut or off the side off the road because the extra weight of the tire and the increased tread to road surface contact area. This is the best way I can describe the physics involved. Basically 3 degrees of caster is correct for an OEM tire, but if Mr T had designed the 80 series to run 35's than the stock caster would have been more than 3 degrees to compensate for the increased forces seen with the larger tire.

It sounds like you have put a lot of thought and planning into the set up that you want. I really hope you can figure it out and don't hesitate to spend a little extra to get it right. I can tell you from experience that driving with incorrect caster is sketchy, dangerous, and no fun.


Good luck, if your ever in southern utah send me a pm and I will send you to some cool areas.
Great knowledge there. In light of that I think I will try to make the new arms work because the more castor they provide is too good. Not to mention it is my dd.
For sure ill contact you for a tour of UT! Thank you🤙
 

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