Chasing steering wheel shake

Bought my '05 Mustang GT w/ 46K miles just over a year ago, it had a slight shimmy in the steering wheel coming on about 60 mph, mostly annoying tho. Research says typical Mustang problem, btw. Factory Bullit wheels, Yokohama 235 Avids had plenty of good tread, no unusual wear. No front end suspension issues at the state inspection. Could have tried rebalancing tires but I planned a suspension upgrade w/ new tires in spring '14 so I let it go. Also, I thought these tires could have flat spotted by sitting months at a time over winters.

FF to '14. Steeda Sport springs (lowered 1"/ 1.25"), D-Specs, GT500 strut mounts, new Ford front sway bar end links, poly sway bar bushings, etc. Drove over a couple hundred miles w/ stock wheels to settle the springs in, they did drop a little over 1/2". Installed 18x9 AMR wheels w/ 255 Nitto 555's mounted and balanced by AM (stick-on weights) and had alignment. .70° negative camber, zero toe, caster was 7°. Shimmy was worse, had the front wheels balanced, both were off 1 ounce w/ no sign of a thrown weight. New state inspection too, nothing irregular found in front end. Still slight shimmy in steering wheel at about 60 mph. Close, no cigar.

That is until I installed a higher tune on the motor and took it out for a good test run. On an entrance ramp under hard acceleration shimmy came on early about 50 mph, crossed a slight heaved up section of ramp, at 60-65 mph shimmy went into a mini-death wobble notorious of 4X4s. Backed off, drove normally again, still slight shimmy at 60, WTF.

Working by myself, went over the front end at home, w/ only one wheel raised 12-6 was OK, nothing visible or felt. 3-9 the same. I tried hand pressure on tie rods while raised and got no play. Set car on ground, engine off, turned steering wheel, there was a noticeable mechanical thunk in one direction, turning it back a lighter noise. Obviously RF, sounded like inner tie rod area. After immediate next try it went away and didn't repeat. Let sit a couple days w/o moving, just tried turning the steering wheel now... and there's a little RF thunk but again will not repeat.

I'll dig into this deeper time permitting. My thinking is still that the shimmy was in the car when bought. I still believe it's probably tie rod related. After two inspections specifically looking for that front end issue it somehow escaped.

How possible is it that this condition will only surface under higher load conditions or jarring road conditions? What say GRM, other possibilities?

I just wonder if the outer tie rod is partially seized and when it swings through its arc is causing the shimmy. Or a bad hub caused by excessive runout.

Just reading the title my immediate thought was Ford. Then as I typed that out it struck me that all my BMW's had similar issues.

Sorry not really helpful but consider this a free bump.

Check the runout on everything per FSM. Might also pop the tie rods off the spindles to make sure you still have good drag on the inner tie rod ends.

Have you checked the rear suspension?

Since it got worse with the tune, I would check for any play at the back end along with motor and trans mounts. Both ends may be working together to cause the shimmy, but it only is detected at the steering wheel.

Ranger50 wrote: I just wonder if the outer tie rod is partially seized and when it swings through its arc is causing the shimmy. Or a bad hub caused by excessive runout.

Going up on jack stands today for further inspection. Makes me wonder how the Ford dealer, 1st inspection mechanic and latest inspection mechanic ('06 GT fanatic guy w/ a similar 1" drop) could miss anything. They did however inspect on a lift so there's little resistance through the RnP steering. That's why I checked it w/ one wheel planted on the ground, maybe it still wasn't enough resistance tho.

While I haven't indicated the wheels, I eyeballed during latest balancing on their machine. They are round as a tire gets w/ no lateral runout. Checked again mounted on car, same. Calling hubs good here.

One problem GT owners experienced w/ aftermarket wheels was the factory stud to rotor lock tabs caused runout, factory wheels were recessed to allow for tabs, aftermarket not. My brakes were new Ford rotors and pads w/ no tabs when I bought it, not seeing a problem there.

Thanks for the input.

I had a similar issue on my e30. Turned out it was a bad ball joint on the lca to frame mount. Missed it many times. Finally showed up when I pulled off the rear lca bushing. Tension held it tight most of the time. Random bumps while in full throttle shook it loose but it jambedbsck up during the slow rides to a jack.

check for 9-6 movement on the ground, suspect possible inner tie rod knuckkle play. when jacked it would "pivot" the knuckle to a tight spot, but on the ground it is at rest in the worn spot. i hope you can understand what im trying to say

In reply to warpedredneck:

Better way of describing it, the spherical balls in the joints of the tie rods and ball joints wear in a uneven, non spherical manner, due to them rarely running their full range of travel in normal operation. So with the suspension at full droop you may not see play in loose parts due to sections with less wear taking up the slack. Ball joints on strut cars are really good at this, my car has one starting to clunk currently, feels tight on jack stands.

Best to check all suspension and steering parts for play with the car on the ground and settled.

thats what i was trying to say! thanks for a better explanation!!

Few days ago put car on stands, checked 3-9 up against the steering wheel lock, nothing on L or R side, nothing 12-6. As per the arc idea, raised lca w/ jack till chassis was coming off stand, still nothing. No play in steering rack or steering shaft. Wheels on ground: w/ lowered suspension can't see the best but again found nothing. Ramps might help, alignment rig w/ open center would prolly be the best.

I thought maybe harmonics but driving over 75, still there.

Warped and Kenny: I understand exactly what you're saying there and I can totally agree, especially on a Mustang that doesn't see the kind of suspension travel as other vehicles. It's definitely RF, thunk I heard gotta be inner tie rod from the proximity, sometimes in a left turn around my back driveway I hear the clunk on the outer side (possible ball joint too, I s'pose).

For a c-note I can get Moog inner and outer tie rods to do both sides from RA. Moog ball joints are $35 ea. My current thinking is w/ new sport springs, 255's vs stock 235's and 48K on chassis why skimp.

I consider Moog as an adequate replacement as I've been using their parts for decades. Anything a step up? Genuine Ford is kinda pricey. AA/Zone is out.

Should be a good weekend job.