[hiren.mistry]

Originally Posted by dinu2506

Got mine installed today at the rear. Was a 15 min job followed up with alignment. Alignment showed no variation from stock. Did not drive much for a full experience, just back home from the garage with only me in the car. The rear feels a lot more planted, and from first looks, the car has a more tipped forward and purposeful stance. The bounciness of the rear has reduced and I'm urged to take on speedbreakers without worry. Tried over couple of humps and there was no scraping or bottoming. Need to try with a full load and over some notorious speedbreakers in the coming days. Will keep you updated. Attaching some snaps of the installation.

Congrats dinu! Another installation where it defies all the collected wisdom on this thread.
My car did have some variation during alignment, will put up the report tomorrow.

[zulfi hansi]

you are right Ananth, I do not have bottoming issue. Time to overhaul I guess.

[zulfi hansi]

Sounds like you need to overhaul your suspension, and not an after-market cheap fix.

That was spot on. Yes I need a suspension overhaul, but its good for another 20K I guess, I am saying that since it bounces a lot but does not bottom out. It is wobbly at highway speeds. And I feel it has a lot of spring travel. Does not inspire confidence.

[vina]

Originally Posted by ananthkamath

Hi Rehaan,

From rough calculations and GTO's "12 mm higher ride height, fully loaded" number, it appears to me that the rear wheel center stiffness (not the spring stiffness) has increased about 32%. This is a drastic change if not anything else, but according to the driving impression, it appears that this car is not very sensitive to a rear spring change. This happens sometimes, depending on the tire, bushing stiffnesses and suspension kinematics.

Again, what this also means is that the same 32% change may cause some other vehicle to be so completely screwed up as to be almost undriveable.

Hi Ananth

I have been trying to find some references to "rear wheel center stiffness" you have mentioned above (my technical curiosity) but unable to find any reference.

Can you let me know any book or (better still) web link where I can get a definition for the term?

[patron]

Had these inserted yesterday. My primary aim was to get a slight lift (Posted on other threads as to why). I think this solved my problem. Not only did it solve the problem but now the car definitely feels more sprightly and I feel more confident on the speed humps.
See the pictures for a comparison on the height gain.

Don't mind the dirty car, just back from a 1500 km road trip and could not get a chance to clean it yet and the rains...

[msupercool]

hey guys would the coil spring adjusters be of any help in my Accent? I heard it makes the ride better and smoother, is that true?

[dhanushs]

Originally Posted by msupercool

hey guys would the coil spring adjusters be of any help in my Accent? I heard it makes the ride better and smoother, is that true?

As far as the results posted here, the coil spring adjuster only increases ride height. Of course, the effects should vary from car to car, but then, it certainly wouldn't increase ride quality, as it stiffens the spring.

Well, it might improve the ride over bouncy roads (reduce bounciness) to certain extent, but, IMO, that's the max you can expect from it in the ride department.

[dinu2506]

Originally Posted by patron

Had these inserted yesterday. My primary aim was to get a slight lift (Posted on other threads as to why). I think this solved my problem.

Seems to have really raised the height. My ride height does not seem to have increased much, however the bounciness has reduced and I hardly scrape any speed breakers now.
Yours seem to have lifted the car a bit too much (from the pics). Did you use a taller donut than the 1" recommended?
Also, it will be good if some Civic owners can measure and report the height from the ground to the tallest point in the rear wheel arch. I did for mine after the installation, it was 67cm. I measured a stock Civic of a friend and it was 66cm. Will be good if others could report this.

[patron]

Originally Posted by dinu2506

Yours seem to have lifted the car a bit too much (from the pics). Did you use a taller donut than the 1" recommended?

I have used the 1" ones. I have not measured the increase in height but it is just perfect.

[vina]

Originally Posted by patron

I have used the 1" ones. I have not measured the increase in height but it is just perfect.

I think increase in ride height will also depend on whether you measure it for loaded car and for unloaded car.

Since loaded car would have already compressed the spring (and the donut will resist that) it should get a better increase. The loading can come from passangers and/or any stuff in the back (like GTO's music system)

[dinu2506]

I see a lot of posts asking whether this can be used in other cars. I thought I will share this excel that I got from the distributor when I bought mine. This could be useful for others.
Disclaimer: I have no commercial dealings with the distributor. For further details please get in touch with the distributor directly.

[vina]

Originally Posted by dinu2506

I see a lot of posts asking whether this can be used in other cars. I thought I will share this excel that I got from the distributor when I bought mine. This could be useful for others.
Disclaimer: I have no commercial dealings with the distributor. For further details please get in touch with the distributor directly.

Interesting to see that on some cars (Mercedes included !) he recommends a taller donut on front that on the rear.

[ananthkamath]

Originally Posted by vina

Hi Ananth

I have been trying to find some references to "rear wheel center stiffness" you have mentioned above (my technical curiosity) but unable to find any reference.

Can you let me know any book or (better still) web link where I can get a definition for the term?

Its a term we use in the industry. It is a measure of how much the wheel center moves up (or alternatively, vehicle body moves down) in reaction to a vertical load placed upon it. Also known as wheel rate, different from the "ride rate" because it does not include tire deflection.

Obviously the wheel rate or wheel center stiffness is dependent on the spring rate and the installation ratio (where the spring is installed with respect to the wheel, i.e. a measure of the lever arm ratio on the spring).

[mukeshgoel]

I got it installed in my Civic (rear) on Sunday but could not check it with full load yet.

Yesterday, I did Gurgaon-Delhi-Gurgaon on NH8 expressway around 100 kms with usual 100-120 kmph and I did not feel any change in car dynamics. It handled well as usual.

So, my observation is, if you drive single (or less load), these Coil spring adjusters do not make any change which is a good thing. They start functioning when there are passengers in rear / other load in boot.

[vina]

Originally Posted by ananthkamath

Its a term we use in the industry. It is a measure of how much the wheel center moves up (or alternatively, vehicle body moves down) in reaction to a vertical load placed upon it. Also known as wheel rate, different from the "ride rate" because it does not include tire deflection.

Obviously the wheel rate or wheel center stiffness is dependent on the spring rate and the installation ratio (where the spring is installed with respect to the wheel, i.e. a measure of the lever arm ratio on the spring).

Got it, thanks.

In that case, the wheel-rate is roughly equal to (spring rate)/cos2(theta) where theta=angle the spring makes from the vertical, and cos2 means "cos squared" I we consider symmetric loads.

(I'm defining spring rate as spring stiffness here, force in numerator, deflection in denominator).

For a constant angle theta, the percentage change in spring rate and the percentage change in wheel-rate wouldn't be very different.

Since the angle will change as the spring gets compressed, the wheel rate can increase faster than spring rate (e.g. if initially the spring was vertical, but eventually ends up at 45deg from vertical, the wheel rate would become double of spring rate - don't know whether that much deflection is possible or even likely though).

However if the angle of the spring doesn't change much then the percentage change in spring rate and wheel rate should be same.

Let me know if the above calculation makes any sense

I must be missing something here because you said effective change in wheel rate is 32% and not 20% (or 25%, depending on whether you take initial value or final value as the base) - this is a pretty big difference and calls for a big chnage in theta above (25deg if the spring was vertical to begin with).