Another wheel shimmy solution theory

I think this is the key. The 4Runner just is extremely sensitive.

Most people who have been around cars for a long time have driven plenty of vehicles the exact opposite. Tires way out of balance, almost no steering wheel shimmy, nibble, etc. I have personally seen countless front tires on the highway bouncing like a basketball, only to see the same cars steering wheel relatively calm.

I would say what makes a vehicles steering sensitive to balance is a sum of the parts-not one item can be the culprit. Chasing down all the tiny influences that create this larger issue are costly and easier ignored than ever torn into and fixed by the engineers during production.

 

I’ve wondered about this exact thing! I thought I was crazy and seeing things. The tire bouncing around like nuts, and wheel completely completely calm, and a driver that seems to have no idea that the front wheel slapping itself down the road. I’d have to guess they must feel something, but it goes to show some types of shakes and resonances don’t necessarily manifest in obvious ways.

Agree completely. That’s why some will say the fix is a new power steering rack (or two in the case of the earlier linked video), or new tires, or clamshell bushing replacement for the needle bearing. Any of those may be a fix for one person, but not necessarily the next guy. That said, it makes most sense to work the problem starting with the cheapest possibilities, and with the thing that has the most mechanical advantage over the whole system…which is saying tires and balance are the best place to start. If known competent techs can’t get the balance right, next is suspecting the tires, and maybe even replacing them.

For mild cases, I think it maybe even appropriate to simply put some miles on the vehicle and wait it out. As rubber wears and ages, and with changing seasons, I’d suspect the natural frequency of the system will start to change slightly and maybe it could go away on it’s own. However (Obviously) that’s not an approach anyone should take with a brand new car! I’d be making a stink.

 

Interesting…I stand corrected!

Maybe that’s it! Maybe steering stabilizers could be fitted on IFS if they had a recirculating ball steering. It would be easier to mount a stabilizer on the larger/longer central tie rod on that type of system.

I think it would be challenging to mount a steering damper using only the short tiny steering tie rods found on a typical rack and pinion setup. Probably not impossible, but probably more expensive and complicated to figure something like that out.

 

The '86 Toyota pickup had a totally different setup for the front end than a rack and pinion. 1997 is the last year a "steering damper" was available for a 4Runner.. according to Rock Auto, they had rack and pinion steering, how they mated a damper(shock) with the rack is a mystery to me. Unless that was a year where up till like June they had 1 type of steering and after that was the rack era... I have no idea. 1 other example of "dampers" (shocks) on steering is my quad axle dump truck, when the shocks get 'weak', the steerable pusher axles will do what we call "the crappie flop", it is best described as violent movement of the tires/wheels, an oscillating motion. So the cause is imperfections in balance, alignment, and of course the weak shocks, upon replacement.. alignment.. no more crappie flop. So we have NO type of dampening system on our 4Runners making me believe like the other posts have stated that a bunch of things have to be "right" in order for this system to work. Another thing we are probably blessed with is the front end geometry on a 4Runner may lend itself to 'things' beyond our control (engineering anomalies).

 

Following this thread as I just recently rotated my tires (Back to front according to the manual) and still have a slight steering wheel shake at 52mph.

I assumed that my front tires just needed to be rebalanced. Well now those are on the back and I still have the vibration.
Although with 34" E rated tires a slight steering wheel wobble at a specific speed is probably not much to worry about.

 

A while back I floated the idea that difficult to solve cases (where tire balance, roundness, and pressure was more or less ruled out) might be affected by alignment. Specifically toe-in, or lack there of. In my understanding, a small amount of toe-in helps to give the steering a locked-in feeling, and to-out results in more wandering. Although it’s purely spitballing, I wondered if the frictional drag on tires at around 50mph has enough force to slightly push the the lower control arm against the bushings, with the effect of zeroing out the toe-in. When it reaches zero, the tire wont have the small amount of damping afforded by tires that are toed in and scrubbing slightly as they roll down the road. Again it’s totally a guess, but if it happened to me, I’d try having toe-in set to slightly more than spec to see if the bit of drag would constrain any side to side tire movement.

 

That sounds like a solid theory. I am sure those suffering would take a life span hit on the tires to stop the vibration, I would for sure.

 

The HD Fords still are prone to death wobble…..the 4R shimmy pales in comparison.

 

Back to the steering stabilizer topic, because I find all this stuff fascinating lol, not because I’m making any counterpoint. You’re probably right, maybe the last steering dampers went out with a midyear change to rack and pinion. I have a suspicion the 4runner’s vulnerability to “nibble”/low-amplitude steering oscilltions is basically the result of a whole bunch of design compromises.

I did a bit of research on death wobble with regard to jeeps when I was helping my buddy out with his jeep. More than a few times I saw it mentioned that violent (high amplitude) death wobble is a sign that suspension bushings, drag link bushings, steering tie rods, etc need to be looked at. Replacing a stabilizer damper when worn components exist is a temporary band aid. There a whole ton more connections on solid axles that, when worn, cause a lot of more slop/free-play than on a an IFS vehicle. The slop is essentially the cause of high amplitude wobble, because out-of-tolerance components collectively add up to a lot of “space” for unrestrained movement that’s perfect for a harmonic to develop and amplify very quickly to a violent level.

I think 4runners have a smaller version of that space caused by stacked tolerances. Except that space is somewhat and lightly damped by rubber bushings, not free-lash, so it never develops to a violent event.

I’ve actually checked for free slop by having someone turn the wheel about half an inch in either direction. The tie rods moved immediately/directly with the steering wheel, but my 265/70 K02s (at the time) did not move until you added a bit more steering angle. That makes me suspect the tie rods don’t move the tire until the collective soft initial take-up stage of flex of the bushings is complete. There was no actual lash between any parts I could observe/hear/feel, as the wheel had an immediate effect on the tie rods, and there was not clicking/clunking suggesting that hard parts had reached each other after taking up free lash (not sure if that makes sense lol).

I think the design compromise was creating a comfortable, soft ride, that isolates the vehicle from rough terrain, with the effect of longer component life, against increasing the probability that small variations in tires, rubber compounds, air pressure, alignment etc could incite low amplitude steering wheel oscillations.

Is it worth the trade? I guess it depends on what the driver wants out of it, and how persistent the oscillations are. Personally, in my situation it’s worked out, but I also don’t have to deal with the shake. I drove for a week and hundreds of miles over some very rough roads this summer in colorado, and was absolutely amazed at how smooth around the edges it felt. There was only one road coming off cinammon pass into Silverton that made the 4runner shake and vibrate to a point of actual concern. Absolutely horrible and godforsaken road lol. It was made up purely of football sized pointy jagged granite, and I could not make more than 4 or 5 miles per hour before my mechanical sympathy forced me to slow down. Horrible!!!! I thought for sure I was wrecking my 4runner, and after 3 hours on that road I fully expected it would sound like a clapped out hooptie for the rest of its natural life. But yet, it still drives as smooth as the day it was born. I thought it was pretty amazing.

 

2 different things. F150s had the nibble that was uncurbable. Death wobble totally different and of course leagues worse.

 

Well, enough ideas and theories posted to at least give a few things a try. Going to replace needle bushing with clam shell. Not too hard or expensive. Play around with another set of tires, balance and alignment. Don’t mind another set more aggressive than the michelins on the stock wheels in the storage shed anyway for the winter. And they look cooler. And ride it out for now. Will not sell it unless something else comes out that I like better overall. Done the wrangler thing already. Enjoyed it, but wife hated driving it, and canceled a 1st gen Bronco order when I bought the 4runner. No regrets at all there on hindsight. And I don’t see anything else on the lots that there would not be something else to deal with that I don’t like.
Oh well. Always something…

 

I get the steering wheel "nibbles" at 58-63mph. But not all the time! Michelin Defenders. It kinda cracks me up at this point. I'll go days without any shaking. And then all of the sudden it shakes like crazy on one outting. Really a LOT. So strange! The next day it's fine. WTF.

 

Ya, that's it, one day good, the other day not so good. Did you ever try different tire pressures? If everything else is within spec., try a pound or 2 each direction. It's alot of pissing around, but cheaper than a new set of tires or worse.. getting rid of the truck. We had issues when we 1st put on our Coopers, tried the air press. thing, and they have a "sweet" spot no doubt.

 

Toyota surely knows about it , and knows exactly what the issue is. But will never admit it due to the cost or ability to fix on a recall and no real pressure because its not a safety issue. And why bother since they cant keep them on the lot, nibbling or not. Frustrating! But No point in getting too angry about it. Money is the ONLY loyal customer these companies care about these days.

 

I will say this.... after extensive research, my aftermarket wheels were not the correct bore size. After multiple trips to the dealer about this issue, it was determined that when the wheel is mounted, there is play around the bore. I needed to get bore rings to close up this radius but went with OEM wheels and now my shakes and shimmy's are gone. The wheel has to be the correct bore size or you will have shaking issues.

 

Yep I've been playing with pressures. And I agree- there's a sweet spot. But I think that shake is different than the other shake? Dunno.

I've also wondered if road crown and fuel volume plays into this. Or maybe in combination with tire pressure.

 

Something that should be mentioned in this thread is the proper road force balance protocol and identifying if your tires are the culprit in the first place. Some shops don't know (or care) that Toyota trucks require a certain protocol. Just getting a standard RFB will not solve the issue. Ask your tech to follow this protocol for the best results:

1) Find a shop with a Hunter's Road Force Balance Machine.
2) Tell them you would like your wheels and tires match mounted.
3) Tell them to use adapter plates (aka finger plates or spider plates) instead of cone adapters.
4) Tell them to turn off "Smart Weight" before running the balance.
5) Ask for the run out numbers for every tire.
6) If a tire shows a run out above 20, that tire is going to create a shimmy. If it's a brand new tire ask them to redo the balance to get it under 20. If they can't, then reject that tire and inform them you want a new one. If it's an old tire that you can't get below 20 then have them put it in the back and leave it there until you get new tires.

 

I don't know how one could even mount a steering stabilizer on a 4R. They were on all the solid axle Jeeps I used to own, but they were mounted on the axle on one end, and the other end to a single tie rod that went from one wheel to the other, independent of the axle, which was also connected to the steering box via a pitman arm.

 

YES! I own both vehicles, a 2019 Ford F250 & a 2019 4Runner TRD. The 4runner steering wheel shimmy/nibble is different and yes pales in comparison.
Im not saying anyone was insinuating death wobble in this thread, but just wanted to quickly comment that when my F250 went into death wobble at 75MPH it had approx 45000 miles, and it was COMPLETELY uncontrollable! I could barely even grip the steering wheel as it oscillated left & right so quickly! The truck changed 1 1/2 lanes over before I was able to slow it down enough to stop the oscillations (approx 25mph) Ive done A LOT of dumb sh*t in vehicles over the years (intentionally) but that situation scared the crap outta me!
Anyways sorry back on topic...

 

Yes same for me too! My shimmy is intermittent but always happens around 50-60-ish. Which is why I didnt think wheels/tires out of balance is the issue. and Ive had them re-balanced twice by Discount Tire. I will, whenever our schedules allow have a mechanic buddy in a Porsche dealer (top notch Hunter machines) do a thorough match mount and balance and will definitely follow the procedure that "Nimby" outlined above (thanks for that!)
- I am just now starting to play with tire pressures, so we'll see on that.
- I will also do a alignment when Im at Porsche getting the re-balance to see about the toe theory.
- Lastly I will do the ECGS carrier bushing swap

Of course I will also verify all the basics are inspected & checked in the suspension & steering (bushings, ball joints, anything bent, slop, loose etc.. too)

 

Please report back. People would love a definitive solution.

 

The 5th gen being a derivative of 4th gen may be a contributing factor - 4th gen OEM wheels were +32mm offset; 5th gen OEM wheels are +15mm. The increased scrub radius affects aligning torque and steering feel. TRD Pros with +4mm wheels might have it worse.

 

The hardcore wheeling crowd has been trying to come up with an assist ram installation, as the OEM rack becomes inadequate with >35" tires, to no avail. There's no room.