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Discussion Starter · #101 · (Edited)
It's worth noting that the car that Rick drove (glad you liked it Rick!) has the stock front bar and the 17.0mm Prius rear bar (modified) as well as the springs and dampers as noted earlier.

That said, my other car with no front bar also feels quite nice (very balanced, no scary oversteer) albeit with more body roll.

Cornering forces are primarily handled by the springs themselves, and a key ingredient of controlling the roll of any car is sorting out the springs first. Higher rate springs result in less body roll but often a harsher ride. This is why many factory suspension setups have soft springs (to be comfortable) and anti-roll bars (to keep body roll down to reasonable levels).

In the case of the Insight, they totally missed on the spring rate and ride height, springing the car so soft that it continuously bottoms out while simultaneously setting the ride height so low that the bump stops (which can be thought of as high rate progressive springs) are always engaged. At this point, with such a poor fundamental suspension setup, they added an anti-roll bar in for good measure as pretty much all Hondas have a front bar, some for good reasons, and some simply to guarantee very safe levels of understeer in order to prevent lawsuits.

So what we are doing here is first addressing the shortcomings on front spring rate and ride height, then considering the anti-roll bar once these fundamentals are sound.

To get the car to sound fundamentals (keeping in mind that it was never even close from the factory) we do the following:
-Raise the car up 1.0" to provide additional travel above the bump stops (controlled travel = traction)
-Trim the bump stops 0.5" to allow additional travel in the linearly sprung portion of the suspension (remembering that spring rate goes non-linear and traction is upset if we transition to the bump stops too harshly ... which a stock Insight does on every single corner and bump)
-Increase spring rate so that the car actually rides up on the springs and does not blow through its now increased travel (during braking, bump impact, and under cornering)

The final result is a car that has 1.5" of newfound controlled (linearly sprung and properly damped) travel on the front suspension where before we had springs sagging into bumpers and bumpers that are so stiff that they overwhelm the dampers (effectively oversprung and underdamped).

With these fundamentals addressed, the car ends up being more comfortable despite having stiffer springs on the front due to the fact that the car is now riding up on the springs (at 200 lb/in) instead of riding on the bump stops. The initial bump stop rate, once they are engaged, is very high and very non-linear (it ramps up to keep the car from bottoming out) which is why your teeth shake out in a stock Insight. You're riding on highly non-linear springs that can't be controlled by the dampers.

Since these replacement springs are nearly twice the rate of the stock springs, body roll is tremendously reduced, so much so that the original factory anti-roll bar is no longer a necessity. If the car had a strong front or rear traction bias remaining after getting the springs and dampers right, then it would be time to consider trimming the front/rear traction bias with anti-roll bars, but it turns out that this recipe is quite balanced.

It is definitely worth noting that my car with both a front and rear anti-roll bar is the crisper handling of the two but that both of them are very well balanced and neither has a tendency to oversteer (or spin out) unless you are actively coaxing the rear end around by feathering the brakes (or similar) on corner entry. If you were to just remove the front bar and not supplement the front end with stiffer springs, you would likely end up with a rather unsafe and very poor handling (worse than stock!) Insight.

A really excellent explanation of anti-roll bars can be viewed here: https://www.youtube.com/watch?v=WhWZ57baTOw
 

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I appreciate the explanation. Very much so. Is is safe to say that one would get 90%!of the benefits you describe by addressing the springs even if one leaves the bar in place? What disadvantage (if any) would there be to this?
 

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....In the case of the Insight, they totally missed on the spring rate and ride height, springing the car so soft that it continuously bottoms out while simultaneously setting the ride height so low that the bump stops are always engaged....To get the car to sound fundamentals we do the following:
-Raise the car up 1.0" to provide additional travel above the bump stops (controlled travel = traction)
-Trim the bump stops 0.5" to allow additional travel in the linearly sprung portion of the suspension....
I didn't/don't notice the bump stop length/rate and ride height being a problem - for spirited street driving, at least... Compared to my old Miata that I used to work on, suspension-wise, seemed like the Insight had quite a bit of travel to work with at stock height... That bottom ring on the front bump stop - there's not much to it yet it's probably about 1/2 an inch. Just trimming that off doesn't seem like it'd do much... I didn't, and I didn't raise the ride height. Can't say it's posing any issues... After reading what you originally wrote I was expecting a bump stop situation much worse than it appeared once I took a look at it. There's probably like an inch and half or more of travel before the stops engage, on the front, while the first inch or so of bump stop isn't much of anything... So maybe 2 1/2 inches of travel until the stops might become an issue - seems like stiffer springs can easily handle that... As far as I can tell the ones I installed ARE handling it...

But then again, I'm not the expert, the suspension connoisseur, that you seem to be; I'm just trying to get a good street ride without unsightly fender gap...
 

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Given the reports that the Camry springs raised the front end 1.5" and the ebay springs that eq1 used lower it by 1/4", I still don't think we have arrived at an easy drop in solution if you want to maintain the stock height. My rear did come up a little with the addition of the new springs from Hybridrevolt, but I personally am not interested in raising the front very much, but also disagree with dropping it at all. I am torn!
 

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Discussion Starter · #105 ·
You can easily cut the Camry springs to whatever length you like to achieve stock ride height. Just run the numbers from the calculations on page 1 until you get the ride height you want. Spring rate will go up slightly as you trim the springs more.

The increase in height on my car was 1.125", just a fuzz over 1".

eq1's experiment with keeping things low but going to stiffer springs is great as he also got very positive results, showing that the car is no longer blowing through its suspended travel when on higher rate springs and that the fundamental issue is the low stock spring rate.

The two cars I did, perhaps on account of the bad road conditions they've seen most of their life, showed a lot of fatigue on the first and second sections of the stops, which indicates frequent engagement (I'm pretty sure this is why the ABS is always engaging and kicking re-gen off under braking ... loss of traction from the car riding down on the stops under braking). Having additional compression travel available was therefore something I found desirable, but I did not have the opportunity to set things lower to see how that worked out. Overall, it's really really sorted and never harsh anymore, so I can't say I have any desire to change it, but if you have smoother roads and/or want the aero efficiency, it sounds like setting it lower isn't a problem at all.

Lastly, I would say that going to the stiffer springs and leaving the front bar in would be fine. The car will have a ton of understeer (as you've increased roll stiffness on the front end with the springs), but it will still be driveable. I was able to remove my front bar without doing anything special. I just put the car up on jackstands, removed both front wheels, removed the end links and bar to chassis mounts, and snaked the thing out in a couple minutes. It's pretty easy to snake it back in to do an A-B comparison if you feel like it.
 

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....the ebay springs that eq1 used lower it by 1/4", I still don't think we have arrived at an easy drop in solution if you want to maintain the stock height.
The 1/4 inch hardly seems noticeable. You can stick a polyurethane spring riser under the springs or something like that if you wanted that 1/4 inch back. But I feel for you on us not quite being at the drop-in replacement point yet. That's one thing I was really trying to nail. I still might try the rear springs from that set - just grind a bit off the bottom coil to make the diameter a bit smaller. If that worked - i.e. made the spring fit - and then the springs turned out to be a good length and rate, we'd be pretty close to a drop-in replacement. Of course, there's still the issue of needing two right side front springs not the right hand and left hand springs that come in that set. That's a hassle to deal with...

Quick note on my setup: it does have a bit of understeer. I pushed it hard the other day and felt the front wheels/tires giving first... I don't think I really mind that, though I still might try a rear bar of some sort at some point... The rear is a bit under-dampened, too - at some point I'll have to go for GAZ or GAZ-like shocks...
 

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The mod has me glued to the screen. I am very tempted by the handling you two have reported.
Ditto! But my situation is a bit unusual. Our 2000 Insight is a young pup (in terms of use) having been driven only 50,000 miles. So its suspension parts should be in quite good shape. My wife and I use our Insight primarily for long road trips carrying luggage for both of us, so our Insight spends much of its time bouncing harshly off its bump stops. One of these days if we decide to vacate Sweden, we might repatriate our Insight to use for a couple of years visiting National Parks throughout the western U.S. and Canada. Riding on actual springs instead of bump stops sounds great!

Another potential problem for me is that our Insight is in Sweden. I'm really on my own here. I did meet the Swedish Insight owner a couple of years ago. He told me that mine was one of only 4 (I believe) registered in Sweden, the others having been imported from Germany. In 2009, the local Honda dealer told me that he could get Insight parts from Honda's European parts center ($$$), but by now, I'm guessing that parts availability isn't so good. So I don't have a local support group of any sort and am not familiar with local machine shops, parts suppliers, wrecking yards, etc., because I haven't needed them. Fortunately, our Insight has been totally reliable since shipping it from the U.S. to Sweden in 2009, so I've just performed the usual periodic maintenance by carting 0W-20 synthetic oil (not available here as far as I can tell and likely $20/qt. if it were), oil and air filters, and even 4 RE-92's from the U.S. in checked luggage. So I could cart springs and bump stops back from the U.S. next spring if I decided to do so. With so many more small cars in Sweden, I could probably find suitable springs and bump stops here, but it would be difficult and I could screw up :)

I do have an enclosed garage where I could perform the modifications, I have the Service Manual and basic tools including a torque wrench and jack stands, and I have enough mechanical ability to be dangerous :) I'm guessing that some special tools would be required (e.g., a spring compressor) which I could probably rent here. I don't have the ability to cut and grind springs, etc., and paying someone to do such things is quite expensive in Sweden. So drop-in replacements would be ideal for me.

I would probably keep the stock rear shocks and front struts which should be in pretty good condition, replace the front and rear springs with those having higher spring rates but with lengths that maintain the standard ride height, replace and/or modify the bump stops, and remove the front anti-roll bar. Maybe I could complete any necessary modifications in Honolulu before bringing the parts back to Sweden. I think I could create a list of parts and tasks to complete these modifications based on recommendations in this thread.

Thanks to those who have posted their suggestions and experiences!
 

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Ditto! But my situation is a bit unusual. Our 2000 Insight is a young pup (in terms of use) having been driven only 50,000 miles. So its suspension parts should be in quite good shape. My wife and I use our Insight primarily for long road trips carrying luggage for both of us, so our Insight spends much of its time bouncing harshly off its bump stops.
Hi, Art. I was exactly where you are. Low mileage car that lived on the bump stops with two people and luggage. Scott's rear springs completely cured it. No more bouncing off of the bump stops!

I didn't change the shocks at first, but later got the GAZs. The springs made more of a difference than the shocks, probably because my stock shocks were still good. I now also have a set of the springs on my wife's CVT, with the stock shocks. It's fine.

The installation is quick and easy, and no special tools are required. You don't even have to remove the rear tires. Scott has a video of the installation here: https://www.youtube.com/watch?v=UC7VYTnGrig

Try the springs first and then move on to more complicated changes if you think you need to. I'm happy with mine the way it is and don't see any need to fool with the front.

Sam
 

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Very interesting suspensions mods and options. I am reading my way into it via these posts and have a couple of questions.

Rear upgrade seems a clear drop in matiz job, I have just collected them and they look to be 110 to 115 p/inch.

Regarding the Corolla front springs:
are these 160 ish or 200 ish pound/inch when cut to around 280mm?
[I see different numbers on different posts. As I do have a set of springs that are 200 pound/inch at 280mm free length from a former project, it would be nice to know if I need to source other springs or not]

Regarding the 160 figure, if that is the number to aim for:
If the Corolla's are 162 p/inch when cut, are the NA Miata front springs an option to? [Miata: 164 or 153 p/inch, 282 or 292 mm, 105 overall diameter, 10.9 mm wire, compared to Corolla cut? 162 p/inch, 280 mm, 100.5 mm overall diameter, 11 mm wire][as mentioned before, these are a lot easier to find ;) ]

for more Miata dimensions:
https://www.mx5oc.co.uk/forum/yaf_postst35747_Coil-spring-dimensions.aspx
 

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Oh and for good measures

Does someone have the dimensions of the outer diameter of the oem front spring ends where they sit in the strut cups? As they seem to be a little tighter, looking at the posted pictures. Just to estimate if my 200 pounders can [be made to] actualy fit.
 

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I don't know if it's the top or bottom, but the end that is flattened off is 4 1/4 inches. The other end (round) is about 4 5/8. The center is about 5 1/2. The length is 11 1/2.

I temporarily have uncut Miata springs in the back of one of my cars. They are way too tall and way too stiff. It is unacceptable. If I cut them down they would be even stiffer. The front might be different.

Sam
 

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From AutoSpeed - Budget FWD suspension upgrade, Part 2

Front springs, standard Macpherson strut


Spring rate

2.0 kg/mm


Free length

280mm


Weight acting through spring

255kg


Compressed length with weight of car

152mm


Natural frequency

1.6Hz


Front spring requirement:

•45 per cent stiffer – therefore, 2.9 kg/mm


•25mm increase in ride height (car was too near bump stops in standard form)


Car weight acting through spring divided by spring rate = 255 divided by 2.9 = 88mm spring compression.

New free length calculation:

Required compressed length = 152 plus 25mm (ride height increase) = 177mm.

88 (spring compression with static load) plus 177 (required compressed spring length) = 265mm required free spring length. That is, a free length 15mm shorter than standard.

New spring actually used:

Toyota Corolla rear spring, 1.5 coils removed and end heated, closed up and ground flat.

New front springs:


Spring rate

2.9 kg/mm


Free length

265mm


Weight acting through spring

255kg


Compressed length with weight of car

177mm


Natural frequency

1.9Hz


Rear springs, torsion beam rear axle


Standard:

Spring rate

1.4 kg/mm

Natural frequency

1.7Hz


Modified (+25mm ride height):



Spring rate

2.1 kg/mm


Natural frequency

1.8Hz


New spring actually used:

Standard Daewoo Matiz rear springs
 

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After lamenting both my stock Insight and K24 swapped version's ride quality I stumbled upon this thread. Surprisingly, both cars have similar ride heights despite vastly different engines. The K in particular is front biased, what with no IMA battery in the rear. The 12v battery was relocated to the rear to offset some of this. The front Corolla/rear Scott's spring combo should alleviate the stocker, with trimmed bumps up front and GM rears. Probably go with a disconnected front bar as it's the daily with less spirited aspirations. For the K I may cobble together an EM2/Insight hybrid front with Civic springs and add the Corolla bar to the rear with the other additions. Thank you for all the R & D! I'll update eventually but don't mark your calendar, my pace is turtle.

Mak
 

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Scott sells ~30% stiffer springs in stock height.

That math should bring it to about a 145 lb or so. Apparently it's a very good spring for stock use.

It is good to see that ep3 springs should fit as it's a sporty native k series chassis.
 

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I'm aware of Scott's front and rear springs and I'd agree a higher rate is a necessity and one part of the full equation. I believe it was originally Julian Edgar that theorized the stock Insight was riding the front bump stops and both a higher spring rate (~200#), raising the height one inch and cutting .5" off the bump stop would solve most of the deficiencies up front.

As for the EP3 spring/shock combo, it makes sense since the K swap utilizes that era spindle and bolts up, some parts are a mix of both to mate to the tower's original bolt pattern.

If you were set on upgrading the front beyond what's available on a stock Insight the factory spindle would have to be milled down as it is wider than EP3/EM2. Beyond that is past my research.

Mak
 

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I've been studying through and picked up an extra set of worn out stock front shocks. Going to (eventually when time/money) is available to try and fit koni sport inserts into them. Will post back with a thread update in the appropriate threads.

I'm very likely just going to go the ground control route but this thread will allow me to get a decently closet spring rate off the bat. Not that crazy spine compressing stuff the want to sell you.
 

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Shoot for post #260 concerning the insert. Keep in mind he has EP3 spindles.

Yes, I've heard the off the shelf rates are far too stiff for street use. Luckily, they accept any standard ERS spring (to my knowledge).

Mak
 
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Yup, I remembered seeing the information somewhere but I wasn't sure where. Too many threads that melt together over all the forums I'm on.
 

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Adding in this very well written paper on stock s2000 coil springs (and anti roll bars, but that isnt exactly needed) On paper at least they look to be quite close to fitting without any modifications. Plus lots of options. I am just not sure if the springs are large enough in diameter to fit in the perches correctly.
 

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Took a shot in the dark and bought a set of used 250 lb s2000 front springs, long story short, they fit on the shock. Waiting for the upper bearing and perches to come in to verify 100% fitment. Went with that rate since I will be going k in the future. Picture is next to Scotts front spring. Stock spring should raise the front about an inch.
 

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