King / OME / coil spacer vibes issues

[hamishpotter]

Pardon everyone for posting this on the Compiled Suspension spec thread earlier.

I recently picked up a set of King 2.5 resi adjustable shocks for 0-2" lift for my 80 as well as 2.5" caster plates from Wits' End and new OEM bushings for the control arms. I'm on OME medium springs (~ 2.5" lift). I checked measurements compressed and extended compared to my OME Nitrocharger shocks that came with the OME springs, the Kings are about an inch longer compressed and extended. As an experiment I purchased 30MM front and rear spacers from Slee and installed those along with the springs...

While driving around town, I prefer the added height and the shocks are SMOOTH - noticeably smoother than anything I've driven (a handful o 80s). However at highway speeds I was quickly given a physics lesson: the driveline hummed, vibrated on load and deceleration, and the whole thing wandered. It did not consistently track straight as it had before. And I noticed a burned rubber smell when stopped after driving for a while.

I'm about to remove the spacers, will drive it, check for vibes, if they persist remove the front driveshaft for re-balancing. Since it's a DC shaft I thought I had more margin for lift. I suspect the spacers exceeded the range of the caster plates, and possibly the sway bar mounts, and I'm not sure what else...

Should I get an alignment job as well? I'm in the weeds. Out of frustration I'm not thinking clearly so I'm posting here in case anyone has a solution / suggestion within arm's reach or sees a glaring oversight. Thank you

 

[graham5david]

I had the same issue but once I replaced rims and tires most of the vibes were gone. I then replaced my differential fluids and sway bar bushings and all was better.

 

[Qball]

So the springs are 2.5 inch or 50mm lift, spacers are 30mm that put you right at 80mm. Most of the time if you have anything at or over 75mm lift you will have vibration from front drive shaft and the easy fix is a DC front drive shaft or remove the 30mm spacer. Some reported vibration even before 75mm. Another way to tell is per our suspension guru @landtank, measure center of hub to un-modified fender and if it’s too much over 23 inches then You will have vibration and need DC drive shaft.

However you have DC so it’s most likely your caster is off, I had stock height lift and was wondering all over the road and down right scary even though everyone says I don’t need caster correction at stock height......but boy did I need it.

First step is to remove spacer like you said and then do an alignment if that doesn’t work. These are the reasons that I won’t go pass 70mm of lift.

 

[-Spike-]

At 4" of lift, you may need 4" lift components.

 

[koifish]

@hamishpotter what ever happen with this? Been wondering how this combo worked out? Anyone else have king 2.5 bypass 0-2” shocks with OME 2.5” coils?

 

[Delta VS]

@hamishpotter what ever happen with this? Been wondering how this combo worked out? Anyone else have king 2.5 bypass 0-2” shocks with OME 2.5” coils?

Have installed this setup on a client rig. No spacers, OME mediums were already on the vehicle, we added the King components. Guy can’t get enough of driving it. He’s loaded fairly heavy (has roof tent) and it’s an LX, so ride height isn’t super high. He’s on General X3 35s too. Any particulars you’re looking for?

 

[koifish]

Thanks @Delta VS! Looking to upgrade my ome NitroChargers soon and keep my ome heavies. Just trying to see if others have gone with king bypass/ome coil combo like the OP.

 

[Delta VS]

Thanks @Delta VS! Looking to upgrade my ome NitroChargers soon and keep my ome heavies. Just trying to see if others have gone with king bypass/ome coil combo like the OP.

Ok, well reach out if you have any specific questions or anything, happy to answer best I can.

 

[Qball]

@hamishpotter what ever happen with this? Been wondering how this combo worked out? Anyone else have king 2.5 bypass 0-2” shocks with OME 2.5” coils?

I have OME heavies and Kings’s 2.5 but mine is 3-5(4) inch shocks to get some more droop, only two things I had to do were longer brake lines and bump stop extension which I was planning on doing anyways.

What do you want to know? I love the ride and handling but they are a little overkill for most people’s application.

 

[Box Rocket]

A few things come to mind that should be checked. First, at ~4" you're probably needing more caster than you can get with the 2.5" lift caster plates. That should help with the wandering. Additionally, if you haven't installed swaybar spacers that could also be contributing to the wandering. But more important is that it will put undue stress on the swaybars and link and could break either one or both. It's also possible that the front driveshaft is contacting the front swaybar without proper spacers. So you should check the driveshaft/swaybar for any signs of contact.

The vibes and noises could be a number of things. It's possible that even though you have a DC shaft, the ujoints could be dry or worn out and need to be replaced. You should check the angles of your pinion flanges. In the front, the pinion should point directly at the tcase (or as close to it as possible) if you're using a DC shaft. If that isn't the case, the you could have vibrations. In the rear, the pinion flange needs to be parallel to the tcase output flange. If those are not parallel you can have vibrations. When installing a lift the rear axle will get rotated slightly (points the pinion up more) and the flanges will not be aligned. This is the reason many use adjustable upper control arms to correct pinion angle. It could also be addressed with longer lower control arms that will rotate the pinion back down and into proper alignment.

Dry or worn out wheel/trunion bearings and dry spindle bushings can also be a cause of noise and vibration. A little less common, but also a possibility is a worn t-case output bearing that can make noise. All of these things can show up after a change in lift height even if they weren't noticeable before. The change in angle and load on the parts could be the difference in noise or no noise.

If you haven't extended your brake lines, you should. That probably isn't a factor in the noises or vibes but should still be addressed.

Lastly, it's probably a good idea to get your wheels rebalanced to rule that out as a factor and also get an alignment. Lifting a solid axle truck is less problematic to alignment than it is on an IFS rig. Caster is changed which you've addressed (but might need more caster) and the only other thing that can really be adjusted is toe-in. If the toe is out of alignment it can definitely cause wandering and vibrations felt in the steering wheel. But it will also cause bad tread wear on the front tires.