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I think I was actually picturing the grill of an older Mazda 3 - it's the first thing that comes to mind with 'modern' styling. But that's actually kind of old now. I should have said 'Darth Vader-like' grills - that seems to be the 'face' most modern cars are trying to capture these days... Or how about the Prius C? I generally like that car, the idea - but the front has a nasty scowl while the rear has an insipid smile. It's the manic-depressive car... I could never own one...
 

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Yet it seems like all we can adjust is toe - so having pretty thoroughly tested my toe options (from toe-in to a bit of toe-out) and not having any luck, not sure how I could have messed up anything else and not sure where to go from here...
Have you tried swapping your tires front to rear to eliminate anything going on with the front tires? Or swapping them side to side to change the direction of rotation?

Sam
 

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I rotated the tires just before my first drive with the new front springs... Tire wear is very even across all the tires, so I don't think it's the tires. Unless there's some defect rearing its head now, if the front suspension is now more sensitive for some reason... It reminds me of the way my Miata had a slight shimmy - something that was supposed to be common and demanded a super-accurate balancing. I seem to recall one of my wheels was slightly out of round and after getting a new one the shimmy went away. It's been a while since then though, can't remember exactly...

hmm, I just re-read a couple things I have about that Miata shimmy and road-force balancing. The shimmy in the Miata is a 'resonant shimmy' at around 65 mph, something about the chassis's resonant frequency. I wonder if removing the Insight front bar changes some 'resonant frequency' of its chassis?... Perhaps coincidentally, this shimmy is happening at around 65 mph (between about 63 mph and 70 mph)...
 

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When I bought my last Insight from that guy in El Paso, it didn't have any of the tires balanced and one of the rear tires was separating from its tread. Around 65 MPH is where I noticed the car shaking the most, tapering off a bit if I sped up to 70 MPH. I don't think I went over 70 with them like that. I got the one replaced and them all balanced before I left El Paso and everything was smooth.

I'm not saying there's anything wrong with your tires, but near 65 MPH being a resonating frequency for our cars sounds plausible to me.
 

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I think I'm going to have to swap the rear wheels back to the front and try that. I mentioned that I had just rotated the tires - but that was after I replaced the front springs, which means I actually haven't tried different tires (wheels) on the front. It wasn't doing the shimmy before the spring replacement and front bar removal, not sure if it was doing it with only the front bar removed, stock front springs - as I don't recall driving at highway speeds with that setup...

I tried one other thing and it didn't make a difference. I cut some thin, ~3mm thick washers out of microcellular urethane foam (from some old bump stops I had) and stuck them between the strut top nut/retaining washer and the stock rubber bushing/damper rod boss thing at the strut tower... There's a little space there, meant to provide some wiggle room when the strut flexes or leans. I thought maybe tightening that up a bit might help, but no...

Two or three things I'm thinking now: one is that there IS some natural resonant frequency to whatever - the chassis, the control arm assemblies, stuff. In stock form it's kept in check, but with the mods I did it's now out of whack somewhat. The replacement springs I installed are quite a bit heavier than stock. That probably makes a difference. Having the front bar attached to the strut probably makes some difference as well (or rather, removing it does something to upset the 'balance', for lack of better terminology). Both of these things combined - the extra weight plus less bracing, I guess, might make any wheel/tire imperfections set-off that resonant frequency...

The few other things I'll try: change tire pressure - I bumped up pressure to about 45 psi cold, 48 psi warm; I'll bump it down to see if it changes anything. I'm thinking softer tires might absorb some vibration, though that wouldn't seem like a permanent solution, as one thing I was hoping for from front bar removal and different springs was to be able to run higher tire pressures yet with similar or even less NVH...

Swap rear tires to front. I noticed there's a couple little dents in the edge of one of the current front wheels. Maybe the rim is slightly misshapen...

I was thinking I'd try to bolt a weight or something to where the front bar used to attach to the strut. Seems counter-intuitive, since heavier springs might be part of the problem, yet maybe the added weight might 'balance' stuff again. I'm mainly thinking it might change something - like the speed at which the shimmy occurs (seems to occur between 64 mph and 74 mph, but it's not exactly the same all the time, which is weird) - and thus might provide a clue as to what the solution might be...

Does anyone know if camber and caster can actually change (enough to make a difference) when you take suspension stuff apart? None of that is adjustable, yet maybe there's wiggle room in the bolt/hole tolerances that can add up to changes if you don't measure, mark, and put everything back exactly the way it was??
 

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You could try putting the front bar back on just to see if it stops or worsens the shimmy. If it needs to be there for stability, maybe you can modify or replaced it for more flexibility rather than removing it entirely.
 

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yeah, but I actually found removing the bar to be kind of a pain in the ***. So I expect it to be a pain in the *** to put back. I had to pop the wheel hub nut and pull the axle shaft from hub to make room to move the bar out - and I hate dealing with the shaft key/nut flange thing, where you have to bend the nut flange out to remove it, and bend it back in to secure. All that bending and banging - I'm sure to screw something up... Oh, and one of the bolts that secures the bar to the car, where the bushings go, got buggered-up (it's aluminum). I chased the threads with a good bolt, so it does screw in fine, but I think it's slightly cross-threaded. If I try to put the bar back and tighten that bolt, and then try to remove it again - I'm sure I'd end up having to buy the right-sized tap, a new bolt, and spend another whole afternoon just dealing with all that... Yeah, I don't think putting the bar back in is at the top of my list at the moment...
 

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Sad to hear the anti roll bar removal was that difficult.
Was the repair manual removal method followed in sway bar removal?
Is there another way it could go back on than it was taken off. i.e. car body supported on stands, manipulate control arm height with hydraulic jack. [nb. good chocks at rear] [would spring compressors help?]
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Any chance the improper torque was applied to that wheel hub nut on reassembly? How many ft-lbs? <<<<< maybe there's your shimmy
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The stripped bolt* issue as reason for not putting the bar back on [if that's the problem] appears as a false dilemma.
Simply replace the bolt with an original in good condition or get a new one from the dealer/specialty bolt house/online. How much could the bolt cost? fwiw: With a different R&R technique, replacement could be much easier than removal.
Bolt coatings are discussed in the body section of the manual iirc.
nb. Dielectric welding of dissimilar metals, esp. with lots of road salt.
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[*Lacking tap and dye kit, I'd try chasing mildly stripped threads on a bolt with an appropriate nut with a filed groove cut inside the threads to catch any cuttings.
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EDIT: almost forgot to say adding extra unsprung wt is not desirable imho.
 

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Sad to hear the anti roll bar removal was that difficult. Was the repair manual removal method followed in sway bar removal? Is there another way it could go back on than it was taken off. i.e. car body supported on stands, manipulate control arm height with hydraulic jack. [nb. good chocks at rear] [would spring compressors help?]
I didn't use the repair manual. I just try to remove as few things as possible while getting the job done... I don't think the bar can come out without removing the axle shaft from one of the hubs, but I could be wrong. That seemed like the easiest way to do it. Tycho wrote above somewhere that he thought anti-roll bar removal was easy... I wouldn't say it's "hard," it's not hard. But like I said, I don't like banging on the axle nut, and screwing bolts in and out of aluminum threads always seems like a risky thing to me...

Any chance the improper torque was applied to that wheel hub nut on reassembly? How many ft-lbs? <<<<< maybe there's your shimmy
I generally don't use torque wrenches. And I didn't for the hub nut. I just put it on tight and so the keyway lined up with where the nut was bashed in before...
 

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fyi, I tried dropping the front tire pressure but that didn't change anything. I tried the added weight idea: I put a bolt through the hole where the front bar attaches to the struts, plus a thick ~1 inch long spacer, washer, and nut, maybe 4 ounces? not a lot of weight at all. I took one trip up and down the highway where I had been testing before, no shimmy... Varied speed between 60 mph and 80 mph - no shimmy. It had been happening without fail between 63 mph and 73 mph (seemed like 67 mph was the worst)... So it's either some massive fluke or it's actually fixed. I'll have to drive some more to be sure, yet I'm pretty hopeful... If it is fixed - if that little bit of weight makes the difference - it's just really hard to believe...
 

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I doubt the ascription, it being insignificant in light of changes made from stock and the aforementioned issues.

Considering the unsprung wt. independent of the rotational mass, adding wt generally decreases the suspensions ability to react to road conditions [inertia]. This will affect the geometry assumed by the suspension. If it's working, it's all grins, but 4oz unsprung isn't significant imho.

[If you were adding 4oz to the rotational mass all in one spot, there would likely be a quite perceivable difference.]
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Personally, I really think torque wrenches keep us all on the same page and should be used where practicable. Having replaced hubs on my track cars I realize torque matters and can be adjusted within reason.
 

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The shimmy is definitely gone now - took it on a trip for many miles so that's that. Maybe I'll take the weights off to see if it comes back...
 

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The shimmy is definitely gone now - took it on a trip for many miles so that's that. Maybe I'll take the weights off to see if it comes back...
The Scientific Method demands it. :)

Let us know.
 

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eq1........Never say "MAY" say "WILL"....Without that you can only assume. You know what "Assume" is?
Like Paul said.

Eager to know.
Willie
 

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I took the weights off. The shimmy didn't come back... No clue why it disappeared in the first place...

Is there any reason changes in caster might cause a shimmy? Seems like just after I filled the tank there was a slight slight shimmy (whereas just before that, with an empty tank, I couldn't feel anything). I'm thinking maybe my caster is just on the edge. Before I installed the different front springs, my car had a slightly negative rake - because my rear springs, cut Miatas, dropped the rear a bit. But then the new front springs dropped the front a bit. In any event, before I installed those front springs and dropped the front, the steering felt a bit heavier with more central tendency. I thought it might be due to that negative rake and the extra caster it imposed...
 

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Zowie!

I had the opportunity to drive Tycho's car this weekend. It's a revelation. I had no idea an Insight could handle like that. He was in my Miata and I chased him through some twisties- just a short ride. It handled almost like a track car (but then I'm not that experienced in that). Understeer was minor, body roll minimal, cornering was predictable. The car was confidence inspiring! You would definitely have a higher average speed with this setup.

I have badmouthed the Bridgestone RE92s here on the board but on Tycho's car they were great. The Bumblebee battery helped too I'm sure. By the way, that car has more than 500,000 miles on it and it was as quiet and solid as an Insight with a third the miles.
 

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The mod has me glued to the screen. I am very tempted by the handling you two have reported. It may be something that We try on the Citrus.
But
I'm wondering if there are any safety concerns regarding the removal of the bar. Let's here from some of you hot rodders and mechanical engineers. What might break if there is no bar? Where does the stress and torsion go when the bar is missing? It has to go somewhere.
 
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