Steering vibration = bad REAR UCA?

[DEF4Runner]

Guys, I'm REALLY not trying to add to the myriad of vibration posts out here, but I've been chasing a mild (shakes my wrist watch a little) steering wheel vibration occasionally occurring between 50-65MPH for quite some time now and I'm left scratching my head. It's managed to remain throughout what's been a total front-end suspension refresh and through two incremental lifts...just can't find it.

For the record, I've performed the following in the past year/year and a half:
1) Front shocks (5100's, 0 setting)
2) Front springs: saggy OEM to FJ to Wheeler's T1 (net 2.5" lift)
3) Driver's wheel bearing
4) Front diff pinion bearing
5) New OEM LCAs
6) New OEM alignment cams
7) SPC UCAs
8) OEM outer tie rods
9) OEM front axle repack/reboot (both sides)
10) Front sway bar bushings, to poly
11) Both front calipers and pads
12) Rear shocks (5100's)
13) Rear sway bar bushings (OEM)
14) Rear springs: saggy OEM to FJ (with Daystar 1.5) to Wheeler's T12 (net 2.5" lift)
15) From stock tires to 265/70/17...including multiple balances (trusted dealer included)
16) Pass rear axle seal replacement (Dealer performed)
17) Two alignments...all 'green'
18) Complete fluid exchange, wherever fluid may reside

Despite the 'refresh', the steering vibration remains. Not one of the mods listed above changed it in any measure. The only other thing I've read about is the driveline, and recently, the rear control arms.

In terms of the driveline, I've moly greased it religiously. Thinking I might have OVER greased it, I removed the zerk and bounced over a curb a few times...nada. Pumped a few more ounces of grease into the fittings and pressed on.

In looking at the REAR of the vehicle, the only control arm that looks bad is the upper control arm, near the gas tank. Damn thing is rusting skin like a birch tree and the rubber...I was going to make a comment about an old high school condom...is REALLY dry and cracking.

SO...my question...what's the likelihood that a bad upper REAR control arm could refer 'pain' to the steering wheel? I understand the need to maintain proper pinion alignment (I haven't measured yet), but could THAT be the gremlin causing my steering wheel vibration?

Thanks!

 

[dkyleb]

In looking at the REAR of the vehicle, the only control arm that looks bad is the upper control arm, near the gas tank. Damn thing is rusting skin like a birch tree and the rubber...I was going to make a comment about an old high school condom...is REALLY dry and cracking.

SO...my question...what's the likelihood that a bad upper REAR control arm could refer 'pain' to the steering wheel? I understand the need to maintain proper pinion alignment (I haven't measured yet), but could THAT be the gremlin causing my steering wheel vibration?

Thanks!

Just because it's rusting, doesn't mean it's bad.

Mine had literally no bushing in it for a couple months. No vibrations.

Here's some things off the top of my head:

1. Are wheels/tires balanced and properly inflated?
2. If so, try rotating wheels.
3. Check tightness in steering joint and interior rag joint
4. Was the driveshaft installed in the same position after the front pinion bearing was replaced? An out of phase driveshaft may cause this.
5. Were the rotors checked for warpage when the calipers were replaced?

 

[DEF4Runner]

1-2) Yes. Toyota recently aligned and did a balance/rotate and it's still there
3) I can't feel any play in the steering joint. I had someone twist the wheel back and forth and I didn't see any play in the rack either.
4) As for the driveshaft, I didn't have to remove it to replace the pinion bearing. I just had to pull the front driver's axle for access.
5) No warpage in the calipers. I don't get any cavitations when I apply the brake...nice and smooth.

One other important thing. It doesn't do it all the time. There are times it goes just fine without vibrations, but others it makes my watch dance.

To that end, the only things I was thinking at this point were possibly the rear UCA (since it's in pretty bad shape) or the CVs possibly??

As for the CVs, I've heard the inner joints can get loose after a while and cause vibrations.

 

[usuarioxyz]

I have the same problem and a Toyota mechanic told me that it is the steering wheel shaft that sometime has "play" and the only way to fix it is to replace it. So eventially I will do that and post back.