Still searching for shimmy resolution post lift

Vermonster

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Good afternoon,
I have a set of Fox 2.0 coilovers installed. They netted me about 2.25" of lift after settling. I also installed the rear fox shocks. We did not do UCA's, but since we are at 2.25" of lift (despite Fox claiming they are set for 3"), I did not think that was an issue or concern.

Since install, I have had a very minor yet irritating shimmy in the steering wheel and cab at a number of speeds from slow (30-45) to highway (60-75). I have relentlessly tried to track this down, but without any luck. I am getting pretty frustrated overall as it was a simple change, and the only solution I can seem to come up with now is reverting it to stock. I need input, I need ideas, I need some wisdom from the masses to hopefully help me find and resolve this issues.

After the install, here is what we have done to look for resolution:
-Tires rebalanced. 2 different shops, 4 repeated visits, road forced. Almost perfect numbers (11 lbs of road force was the highest, others were at 10). The issue really felt like a balance concern but we have been exhaustive in verifying tires are not the problem.
-I replaced all 4 tires with another set, again perfectly balanced. Same exact issue. This rules out tires/wheels in my mind. Current tire is 265/65/18 BFG KO2
-Two alignments- one after install, and another a month later searching for an issue (trying to be sure it was right the first time)
-We put it back on the lift at the shop, re-torqued everything. Nothing had loosened or changed from install day.
-Checked both under power and coasting in Neutral, same issue
-Issue is NOT braking related
- Checked the driveshaft center bearing alignment, no change.
Alignments went well overall. Here are my #'s from the most recent:
Camber- left .3 right .3 (range is -.7 to .8)
Caster- left 3.2 right 3.6 (range is 1.7-3.2 right and 2.2-3.7 left)
Toe- .01 both sides (range is -.1 to positive .1)
SAI is 10.5 right and 10.4 left
Included Angle is 10.8 right 10.7 left
Cross Camber is .1 (range -.8 to .8)
Cross Caster is -.4 (range is -1.3 to .3)
Total toe is .2 (range is -.2 to .2)

I am open to any ideas or suggestions. I have run out of options to try and sort this out and have no idea where to go next. I really appreciate any insight, ideas, or experience you may be able to share. Other than tires/lift and a yakima overhaul rack, the truck is stock.

Thanks for any help!
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I would suspend the front off the ground. Loosen everything tied to the coil overs, shake and move everything you can and then retighten.

I might even lower the front to put some weight on both coil overs then tighten.

Test drive.

Next step would be to remove them and go back stock to see if you still have a shimmy.
 

Hack_Actual

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Not to go too far down a rabbit hole... were the fronts adjusted all the way to what Fox claims is a 3" lift? If so, you're saying it is only 2.25"?
 

Viator092

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Following this thread.

3-inch Ready-Lift with Nitto 285/65R18 Terra Grapplers on a Lariat FX4. Slight vibe at 65-75 MPH. Numerous balances and alignments. Mounted up some Conti 275/65R18's Terrain Contacts. Way quieter BTW but still a vibe.

Beginning to wonder if I have a coil problem. Hooking up tomorrow to figure out if I have a misfire going on..
 

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3 inch ready lift for me as well. I have a very slight vibration 35-45 and again 65-75. Nothing alarming but noticeable to me at least. Tires are bfg ko2 285/75-16. Currently running 32psi. On first alignment and wheel balance. Maybe too much angle on the front cv joints after lift/leveling?
 


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Vermonster

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Not to go too far down a rabbit hole... were the fronts adjusted all the way to what Fox claims is a 3" lift? If so, you're saying it is only 2.25"?
Yes. Fox claims they come set for 3” of lift. We did not change any preload but ended up with about 2.25 (even on both sides).
 
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Vermonster

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3 inch ready lift for me as well. I have a very slight vibration 35-45 and again 65-75. Nothing alarming but noticeable to me at least. Tires are bfg ko2 285/75-16. Currently running 32psi. On first alignment and wheel balance. Maybe too much angle on the front cv joints after lift/leveling?
I was wondering if it might be a cv issue as well. Seems odd I am getting it at 2.25”, especially when ford is offering the same kit at 2” as an option. Maybe I’ll drop it to 2” and see if that helps. Otherwise, stock stuff is standing by and can be reinstalled if need be, but I really would prefer to keep the fox set up if I can get it right!
 
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Vermonster

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I would suspend the front off the ground. Loosen everything tied to the coil overs, shake and move everything you can and then retighten.

I might even lower the front to put some weight on both coil overs then tighten.

Test drive.

Next step would be to remove them and go back stock to see if you still have a shimmy.
doing this today (minus the stock re-install). Will keep you posted.
 

P. A. Schilke

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Good afternoon,
I have a set of Fox 2.0 coilovers installed. They netted me about 2.25" of lift after settling. I also installed the rear fox shocks. We did not do UCA's, but since we are at 2.25" of lift (despite Fox claiming they are set for 3"), I did not think that was an issue or concern.

Since install, I have had a very minor yet irritating shimmy in the steering wheel and cab at a number of speeds from slow (30-45) to highway (60-75). I have relentlessly tried to track this down, but without any luck. I am getting pretty frustrated overall as it was a simple change, and the only solution I can seem to come up with now is reverting it to stock. I need input, I need ideas, I need some wisdom from the masses to hopefully help me find and resolve this issues.

After the install, here is what we have done to look for resolution:
-Tires rebalanced. 2 different shops, 4 repeated visits, road forced. Almost perfect numbers (11 lbs of road force was the highest, others were at 10). The issue really felt like a balance concern but we have been exhaustive in verifying tires are not the problem.
-I replaced all 4 tires with another set, again perfectly balanced. Same exact issue. This rules out tires/wheels in my mind. Current tire is 265/65/18 BFG KO2
-Two alignments- one after install, and another a month later searching for an issue (trying to be sure it was right the first time)
-We put it back on the lift at the shop, re-torqued everything. Nothing had loosened or changed from install day.
-Checked both under power and coasting in Neutral, same issue
-Issue is NOT braking related
- Checked the driveshaft center bearing alignment, no change.
Alignments went well overall. Here are my #'s from the most recent:
Camber- left .3 right .3 (range is -.7 to .8)
Caster- left 3.2 right 3.6 (range is 1.7-3.2 right and 2.2-3.7 left)
Toe- .01 both sides (range is -.1 to positive .1)
SAI is 10.5 right and 10.4 left
Included Angle is 10.8 right 10.7 left
Cross Camber is .1 (range -.8 to .8)
Cross Caster is -.4 (range is -1.3 to .3)
Total toe is .2 (range is -.2 to .2)

I am open to any ideas or suggestions. I have run out of options to try and sort this out and have no idea where to go next. I really appreciate any insight, ideas, or experience you may be able to share. Other than tires/lift and a yakima overhaul rack, the truck is stock.

Thanks for any help!
Hi VM,

Okay..I said I would not comment on any mods, but here is an opportunity to make folks aware of something related to these aftermarket tires. It is called pneumatic trail. It is the natural caster trail of a tire in that the tire footprint on the ground follows the caster intersection of the caster setting and the tire footprint centerline. When you change tires, if the pneumatic trail is not known, you can exerbate shimmy induced caster by not having enough caster. So in this case, if the condition is not tire balance or aftermarket rim runout, then my recommendation is to increase the caster setting by between 1° to 1.5° positive. In addition, set the toe to 1/16 of an inch inwards. If that does not work try 1/32" out. I know this sounds crazy, but short of dismantling the leveling kit, it is a simple thing to try.

On the old Ranger we set the toe to 1/8" out because it improves the ackermann of the of the steering and promoted increased ability to turn in to a corner. Poor on tire wear but made the Saleen racetrucks so much faster.

Again, when you modify your vehicle you must expect such as above and maybe in this case it may allow you to adjust your vehicle after the mods are in place.

Good luck with solving your shimmy!

Best,
Phil Schilke
Ranger Vehicle Engineering
Ford Motor Co. Retired
 

I_smell_like_diesel

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I have noticed that I can feel the vibration from the engine, throughout the drivetrain, after moving to larger tires. Recalibrated my tire size with a Hypertech speedometer tuner and it seems to help a bit. Most noticeably when the trans tries to hold gear, under light load and low rpm.

BFG All Terrians are a pretty heavy tire. I run a load slight larger load E tire and I've pretty much come to accepting that they will never ride like a cloud.
 
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Vermonster

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Hi VM,

Okay..I said I would not comment on any mods, but here is an opportunity to make folks aware of something related to these aftermarket tires. It is called pneumatic trail. It is the natural caster trail of a tire in that the tire footprint on the ground follows the caster intersection of the caster setting and the tire footprint centerline. When you change tires, if the pneumatic trail is not known, you can exerbate shimmy induced caster by not having enough caster. So in this case, if the condition is not tire balance or aftermarket rim runout, then my recommendation is to increase the caster setting by between 1° to 1.5° positive. In addition, set the toe to 1/16 of an inch inwards. If that does not work try 1/32" out. I know this sounds crazy, but short of dismantling the leveling kit, it is a simple thing to try.

On the old Ranger we set the toe to 1/8" out because it improves the ackermann of the of the steering and promoted increased ability to turn in to a corner. Poor on tire wear but made the Saleen racetrucks so much faster.

Again, when you modify your vehicle you must expect such as above and maybe in this case it may allow you to adjust your vehicle after the mods are in place.

Good luck with solving your shimmy!

Best,
Phil Schilke
Ranger Vehicle Engineering
Ford Motor Co. Retired
thanks so much Phil for the detailed reply. I will definitely try the alignment adjustments as you noted above. My caster is already really close the the max allowable range on the factory specs. Are you suggesting I try another degree beyond that (about 4.5 degrees?)

We did put it up on the lift again in the shop, and basically reinstalled in, re torqued everything. Nothing seemed to change at that point. We did loosen the uca bolts which was not done originally, then retourqued then once the suspension was weighted. Slight improvement overall, and somehow with the work today my lift is up to 2.75” now. Wondering if the UCA bushings/bolts were part of the issue.

Either way, making some progress and a few more things to try with your suggestions. Thanks for all the info you bring to the forum!
 

P. A. Schilke

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thanks so much Phil for the detailed reply. I will definitely try the alignment adjustments as you noted above. My caster is already really close the the max allowable range on the factory specs. Are you suggesting I try another degree beyond that (about 4.5 degrees?)

We did put it up on the lift again in the shop, and basically reinstalled in, re torqued everything. Nothing seemed to change at that point. We did loosen the uca bolts which was not done originally, then retourqued then once the suspension was weighted. Slight improvement overall, and somehow with the work today my lift is up to 2.75” now. Wondering if the UCA bushings/bolts were part of the issue.

Either way, making some progress and a few more things to try with your suggestions. Thanks for all the info you bring to the forum!
Hi VM,

Yes...go beyond the factory spec by 1°. Sort of a long shot, but if it makes it better, then another half degree and see if it again improves or stays the same. Again...this is for a suspension shimmy, not for tire/wheel balance..


Best,
Phil Schilke
Ranger Vehicle Engineering
Ford Motor Co. Retired
 

SN13

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I know you said that the shimmy happens even when coasting so you discounted the brakes as an issue. And maybe it's not.

BUT I will chime in with a bit of experience I had long ago on my 2004 Jeep GC.

Terrible wheel shimmy while driving, worse when I broke but there all the time.

Turns out ONE side of the Caliper had "locked up" and kept the brake pad resting on the face of the brake disc. This caused the disc to eventually overheat and warp slightly to one side and caused a shimmy like crazy.

So while it MAY not have anything to do with your issue. It's just something I will always check when I get a front shimmy. Make sure the calipers are releasing properly and not dragging one side and warping the disc.

Experience teaches us to look at problems in multiple ways. That's why I'm glad Phil ( @P. A. Schilke ) is on board.
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