Front suspension question

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broku-hachi
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Front suspension question

Postby broku-hachi » Wed May 08, 2019 7:58 pm

whats up, was wondering if some one could help me out with a question regarding spring rates.

So in hawaii, if you modify your car you have to get a reconstruction permit in order to pass safety inspections and such.

The inspectors do a jounce test to see if you have acceptable suspension travel. Right now I have 8 kg front and 6 kg rear spring rates. The rear of the car will pass the jounce test, but the front is too stiff.

My question is if anyone with 7 kg up front has 1" to 2 " suspension travel if they try to bounce it?

Thanks for any input.

Nick94tt
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Re: Front suspension question

Postby Nick94tt » Wed May 08, 2019 8:13 pm

Do they apply the weight at the corner or the center of the bumper?

If it's the corner removing the sway bar might help. Easy to disconnect at home and test.

Definitely hold back on the canyon carving before you experience the ultimate in steering vagueness beyond disconnecting the steering wheel though. :lol: (have my front bar removed while sorting things out - was hitting the rcas. )

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broku-hachi
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Re: Front suspension question

Postby broku-hachi » Wed May 08, 2019 8:17 pm

Corner i believe, but i could be wrong.

Ill keep your tip in mind hahaha.

Nick94tt
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Re: Front suspension question

Postby Nick94tt » Wed May 08, 2019 9:06 pm

Looks like it is a corner test, though this is still all second hand...

http://www.scionlife.com/forums/viewtopic.php?t=181752

"Are coilovers/lowering springs legal?
That depends. Any time you have suspension work done to your car, you will have to get recon. You will need to have an alignment done within 30 days prior to your recon inspection. Make sure you bring a copy of the alignment sheet with you. Your suspension must be able to be aligned within stock specifications. Your car will also be subjected to a "bounce test" to check for adequate suspension travel. They typically test this at a front corner by pushing down on the bumper. You need to have VISIBLE (not necessarily 2 inches) of suspension travel. If your springs are too stiff, you will likely not pass."

So, fresh alignment, pull sway bar, acquire recon sticker, reinstall sway bar...

This assumes you understand eventually a cop will probably try and bounce a corner of the car if they're feeling bored or you give them a reason... :lol:

Otherwise it's back to the search for a softer spring or progressive style/dual spring setup vs the linear rate springs most folks run that'll allow proper travel with the swaybar attached.

UNLIMITED 86
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Re: Front suspension question

Postby UNLIMITED 86 » Fri May 10, 2019 4:33 am

This actually law exists? This is worse than California, which I didn't believe was possible! Several parts of this sound super subjective as well. How is it conducted, by a random person? What's the pass/fail criteria, whatever 'random person' feels is acceptable at any given time? What if that person wasnt feeling cute that morning and decided he might fail a few jounce tests later... but he dont know.
What if they dent your car when they test it, who pays to have it removed?

If you want to get technical, having enough suspension travel cannot be always be determined by the test you're describing, or at least the way I under it is conducted.

Spring rate, or spring constant, is the mass (kg or lb) required to compress the spring a unit of distance (mm or inch). These are linear rate springs which make this calculation simple: front spring rate is 8kg/mm or 447 lb/in and rear spring rate is 6kg/mm or 335 lb/in. (1inch = 25.4 mm, 1lb = 2.2kg).

In other words, you're not running out of suspension travel (hitting bump stops) but your spring rate too high for this type of test (anyone under 200lb likely can't overcome the physics).

Can you supply the person who does the jouncing? If so, you're gonna want to bring the guy from the Kona beer commercials.
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totta crolla
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Re: Front suspension question

Postby totta crolla » Fri May 10, 2019 9:43 am

It's what adjustable dampers are for, surely?

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Re: Front suspension question

Postby Nick94tt » Sat May 11, 2019 2:15 pm

UNLIMITED 86 wrote:This actually law exists? This is worse than California, which I didn't believe was possible


Quiet, they'll hear you. :lol:

I've honestly wondered when they'd just cut and paste part of the codes.

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Re: Front suspension question

Postby UNLIMITED 86 » Sat May 11, 2019 9:30 pm

California tries to but they do it differently.

In CA your headlight must be XX inches from ground level. I think that number is 21 inches but dont quote me on it.
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davew7
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Re: Front suspension question

Postby davew7 » Sun May 12, 2019 3:58 am

J565c-4.17 Mounting height- The center of the device lens shall be mounted no less the 24 in. (610mm) above the road surface.
But there has to be a lot of vehicles on the road with lites lower then 24". My guess, there is not to many states actually look at enforcement? When my vehicle was inspected, they did not check the front or rear lite height, just function.

And now back to our regularly scheduled front spring rate program!!!
DaveW7

Nick94tt
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Re: Front suspension question

Postby Nick94tt » Sun May 12, 2019 2:26 pm

UNLIMITED 86 wrote:California tries to but they do it differently.

In CA your headlight must be XX inches from ground level. I think that number is 21 inches but dont quote me on it.


Was similar in Detroit, NY, and here in MD as well. They flat out ignore the crazy lifted trucks, despite having light and bumper minimums and maximums though.

Friend's mom near Detroit got run over in a Camry by what I think was an actual monster truck with tags - literally straight over the roof... The lawsuits weren't pretty, nor was her spine thereafter.

UNLIMITED 86
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Re: Front suspension question

Postby UNLIMITED 86 » Sun May 12, 2019 4:01 pm

Nick94tt wrote: They flat out ignore the crazy lifted trucks, despite having light and bumper minimums and maximums though.


Same in California. These trucks are also required to have mud flaps but most of them do not. This pisses me off cuz they have the potential to damage other vehicles but yet the law does not seem to be enforced. Instead, they go after me with my 'loud' and 'modified' exhaust that hurts no one.
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