Intermittent steering shimmy

[Gatski]

Hi
About 4 or so months ago we started to get some odd behaviour driving our 2016 Leaf, which now has 118,000km on it.
You can be driving down a straight road, little or no camber and a good smooth surface. The steering will tug (mostly to the left), then settle almost immediately back to straight ahead. There is no way to predict when this may happen. It may happen every 5-10 minutes, and is more pronounced at speeds above 50km/h
When taking a corner, sometimes the front turns in normally and then part way around the corner it tugs toward the kerb before again correcting. Or it can be the other way around, vague initial turn in and then tightens part way around the corner.
All of the above behaviour is with constant steering input before the tug happens.
I took the car to our mechanic who drove it home, and it scared him! He took a left corner with adverse camber and it sent him towards the ditch.
We both suspected tires, which had 65'000km on them with tread left from 4/32 to 7/32. I went back to our tire place where they rebalanced all 4 and swapped them front to back. Their balancing machine, plus visual inspection, indicated nothing. The car still behaved the same.
I got the front end aligned - still no change.
I went back and got the 2 most worn tires replaced and stuck on the front. Still no improvement.
Our mechanic has it back in and has checked the suspension, bushings, roll bar/tie-rod ends. Nothing untoward.
We did have both front lower control arms replaced (bushings failing) and the tie-rod ends (worn and noisy) about 7 months ago.

Has anybody experienced any similar behaviour or have any clues what might be causing this? It's at the point now where we will only drive it around town and avoid highways.

Cheers
Graham

 

[Gatski]

Update from our mechanic today. The bushings on the left front control arm that was replaced 7 months ago are failing again... It is an AC Delco aftermarket part and can be replaced under warranty. After discussion we've decided to go with another aftermarket option (Beck Arnoly, same cost as AC Delco vs $600+ extra for OEM). We'll then find out if that's causing the issue.

As a side note, how many people have had lower control arms replaced, and did they go with OEM or after market?

 

[Sam66]

Same experience as you, replaced with non OEM which have failed in less than a year and now need replacing again.

 

[nlspace]

Got any photos to show the control arm and bushings in question?

Do you know if it was a thrust bushing or lateral control bushing that failed?

From the description in the op i would have guessed that a tie rod end had a loose fit in the taper or the ball, and would randomly jump between the 2 states (tight, loose).

Glad to hear that you found the culprit.

 

[Gatski]

Thanks

Same experience as you, replaced with non OEM which have failed in less than a year and now need replacing again.

Thanks Sam, good to know. Our mechanic heard from the Nissan parts dept that they supply a lot of lower control arms..... Ours is a 24kwh so 'only' 3300lbs. I wonder if they upgraded the suspension when fitting bigger/heavier batteries to later models?

 

[Gatski]

Got any photos to show the control arm and bushings in question?

Do you know if it was a thrust bushing or lateral control bushing that failed?

From the description in the op i would have guessed that a tie rod end had a loose fit in the taper or the ball, and would randomly jump between the 2 states (tight, loose).

Glad to hear that you found the culprit.

Unfortunately no photos. I'll try and get more info about which bushing failed next week when I take it back in for a wheel alignment. It makes sense thinking about the behaviour because it often happened when lifting off the throttle, so from load on the control arm to coasting.

I don't think the tie-rods were related to this particular issue, as it started after they were replaced. They made a distinct noise before they were replaced and the turn-in wasn't great but was consistent!

 

[philso]

I replaced the lower control arms on my 2011 Leaf in November 2021 with AC Delco parts. I think it had around 78k miles at the time. I have been experiencing a pulling to the left under acceleration, then straightening when backing off on the accelerator. I just checked today and the two rubber bushings that attach them to the chassis are starting to fail again.

 

[aqn]

My car is doing the same thing. It'd suddenly pull to the right while going straight on level road, often suddenly and violently enough to trigger the traction control. It'd also do it around fast-ish curves, above 50 mph or so.

I replaced both struts recently because they were 100K+ old and were essentially pogo sticks. I took it to a local Firestone to get it aligned.

The strut mount bolts' torque spec is 26 ft-lbs. I have stripped one before while tightening it with a torque wrench and had to send the strut back to be replaced. After the alignment, at home, I checked and found one bolt on the passenger side was stripped!

My theory is that with the stripped strut mount bolt, the passenger side strut's top would move enough under strain to add toe out to the passenger side front wheel, causing the darting to one side.

I'm leaning towards the funky toe out being the root cause because back when I was autocrossing a lot, a common mod especially with front heavy FWD cars is to run a small amount of toe out. That gives better steering response and less understeer, at the expense of straight line stability.

I have bought a new set of strut mounts. I will put them on, once the weather cools down enough in the fall to be working in the garage. I'll report back. In the meantime, please update if/when you find a fix.

 

[aqn]

As a side note, how many people have had lower control arms replaced, and did they go with OEM or after market?

I ran over a curb (texting while driving ) and bent the passenger side A arm:

I bought a Mevotech A arm, the next to cheapest one on rockauto.com . (Above pic, on the left.) I installed it myself. That was a bit over four years ago.