Feels like bad wheel balance, but it's not

Subaru Outback '01 VDC H6

~65-75mph the steering wheel shimmies. It’s just like if the front wheels were out of balance, or the alignment was off, but it is neither. I’ve had it to a couple of dealerships, alignment checked once, wheels balanced and rotated several times, no change. There’s also no wear bias on the tires to indicate a misalignment.

Q: What ELSE might it be?

PS - the shimmy comes and goes, in-and-out-of-phase-like, while driving at constant speeds in a straight line. It goes away <60 and >75

Have you had the chassis gone over for worn o loose components?

Have you had the wheels checked on a “road force balancing” machine?
“Road Force Balancing” spins the wheel while applying a simulated road force by pressing a spinning drum against the tread. Thes machines can and do detect internal tire problems, concentricity problems, and other problems such as conicity that regular spin balancers to not. Sometimes the solution is “indexing” the tire, sometimes the tire has an internal defect.

These are the two steps I recommend from here.

A component such as a slightly loose wheel bearing or tie rod can cause something like this. Where slightly comes into play is that an osciallation can be caused which will straighten itself out temporarily.
As an analogy, think of a child’s spinning top. Touch it lightly, it will wobble briefly, and then resume spinning smoothly again.

The fact the tires were balanced doesn not necessarily mean they’re spot-on either. Electronic balancers can be contrary at times and should be calibrated ever so often. Who knows when those balancers were last calibrated.
I’ve purchased new tires many times, had a subtle shimmy, and chose to rebalance them at home with my old Micro bubble balancer.
Obsolete and out of date? No doubt, but it has never failed to correct one yet and there is no possibility of an electronic fault. The bubble never lies.

Some years back a dealer I worked for bought a Snap-On wheel balancer and that thing was nothing but a boat anchor from Day One. Within 2 weeks there was a mutiny by all of us techs and we refused to use it.
The service manager, the Snap-On salesman, and the Snap-On district rep insisted the balancer was exact and changed the PC board inside. Still garbage.
During an afternoon upheaval with the sales manager and rep who were still insisting the balancer was fine, AFTER changing the PC board yet again, the tech who worked next to me used some crude language and then pulled a new, never on the ground spare tire from a brand new VW.

He ran that wheel up 3 times and got, respectively, readings of 10 ounces, 14 ounces, and 17 ounces out of balance. These readings are beyond ludicrous of course and could only exist if someone had stashed half a brick inside the wheel.
That solved that. The balancer was history and the moral of the story is that having a name like Snap-On attached to it and the balancer being brand new does not guarantee a good result.


In no relation to the OP’s thread but where are you from if you don’t mind me asking? I havn’t heard a person use the term spot-on since I was in Bradford ;-).

Oklahoma, and still a semi-Dust Bowl.

Thanks guys - I’ll ask the dealer to check those things and look around for the road force balancer.

I’ve heard that balancers are often off cal. Even so, the problem persists through so many permutations of shops and rotation configurations that I’m now fairly convinced it’s not a balance issue - not a typical one anyway.

Thanks again.

spot on is a britishism that has infiltrated into the american language. It is kind of like when people say neech when they mean nitch. I read somewhere that empires fall when language becomes diluted. No offence, even an old curmudgeon like myself uses the term spot on on occasion, but ussually only as a witicism.