OEM Coil Spring tech: Tuning for ride, not height - JKowners.com : Jeep Wrangler JK Forum
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post #1 of 4 Old 03-21-2013, 03:18 PM Thread Starter
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OEM Coil Spring tech: Tuning for ride, not height

I started a thread in "General" regarding my upcoming JKU build. 2013 JK unlimited sport.


It's going to be simple, cheap and very effective. I read through that dumb ass JK-Forum thread about the stock spring part numbers and was losing my mind. It's the same question or statements 200 times. I am posting this here because I only want to go over this exact topic.

So I want to fine tune, or dial in my suspension using different spring rates. I am going to use OEM coils from whole sale mopar. They are significantly cheaper than other springs. I will fine tune the height with coil spacers from either Teraflex or Synergy.

I am looking for a very good offroad ride for spirited trail riding and mild desert-almost prerunner wannabe, based on the stock suspension.

My stock front springs are 17's and rears are 58's. Typically people are just going to the stiffest part numbers, 19's front and 60's rear just for a slight lift. I want to select them based on my suspension performance, not height. Like I said, height (whether it sits level or not) will be fixed with spacers.

So it's my understanding for this, you want softer rear spring rates and stiffer front spring rates so the ass squats when you hit a jump or whoops. (not going to actually jump it)

In the Front I was thinking about going from the stock 17's to stiffer 19's. And in the rear, going from stock 58's to softer 56's. I can't find any info on what the numbers mean or if they actually represent anything at all, other than just being a part number. I also can't find info on how big a difference there is in spring rate (or perceived ride quality) from spring to spring. Such as front 17's to front 18's. How much difference?

I am not running any aftermarket bumpers or winch, and removing the spare tire/carrier. Jeep has a hardtop. My other concern is all the info I found was 90% 3.8L Jeeps and the 3.6L is slightly lighter. So perhaps I don't want to step up to a 19?

Shocks will be Bilstein 5100's with 255/70 valving all around. Unsprung weight will only increase due to larger/heavier tires. Going to run either 33" x 10" KM2's or 32" treadwrights. Stock 16" steelies.

I will be running Teraflex 2.5" Speed Bump kit. I am trying to do this on the cheap while coming out with a unique and effective build.

Can anyone help?
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post #2 of 4 Old 03-21-2013, 08:14 PM Thread Starter
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Anyone have input?
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post #3 of 4 Old 03-21-2013, 11:19 PM
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Sorry im not familiar with the spring part numbers or what they mean but how do u like the current spring rate that came stock?

I've always felt the stock spring rate was too soft especially the rear. Theres also too much body roll on the road and its constantly bouncing off the bump stop when it got rough. It gets way worse when u start adding weight to the jeep. On long outings with the jeep fully loaded, it would ride on the bump stops. Only nice thing it was smooth on even dirt roads with no load.

Factory shocks fades pretty quick and the 5100's isn't too far behind.

The TF Speedbumps are awesome but will need a minimum of 2.5" of lift.

09' White JKU Rubicon with some stuff
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post #4 of 4 Old 03-21-2013, 11:27 PM Thread Starter
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The ride you're talking about could mean you had softer coils. It has been shown that there is no rhyme or reason to what coils are put on what JK.

People were under the impression that it had to do with rubicon or non, soft top, hard top or trailer package. None of that seems to matter. Not even the HD suspension. Those things only seem to consistently affect what shocks come on the JK.

I could just step up the front coils at first.
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