Coil spring questions

gosborne

gosborne

TJ Enthusiast
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Nov 22, 2020
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Columbia Falls, Montana
Ok I've got a few of questions. I've been building my 99' Tj for a couple of years now. I put a 4" rough country short arm lift on it and within a few weeks the only thing left on it RC was the coil springs & windshield banner. It now has Core 4x4 adj. upper and lower control arms, Core 4x4 adjustable front track bar, Advance adapter slip yoke and Adams driveshafts front and rear. Rancho 5000x shocks & 33x12.50x15 ( run at 26psi) I'm happy with the setup BUT winters coming and my shop is empty. Question one: Are the RC coil springs any good ? Looking to fine tune the ride on the washboard roads I travel. Question two: I've been looking at Metalcloak dual rate 4.5" coil springs. Will the extra 1/2" change the geometry enough to get me in any trouble? Or am I just wasting my time and money ? I also tow a 4x6 trailer I built. Rear track bar relocation bracket is still on it. Also looking at Rusty's off road long arm upgrade

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Coil springs mainly provide lift. If you are getting the amount of lift you want, there is no reason to change your RC springs. It won't change your ride quality. What could change your ride quality would relate to your shocks. You are aiming for riding in the middle of your travel (50:50 up/down travel bias). If you are trying to fine tune your shock performance over washboard roads, you will need to buy some tunable shocks. They are about $500/shock.

Going to a spring that is 1/2" taller will not dramatically affect everything. Essentially what you will need to do is adjust your control arms and trackbars. If you are happy with your current lift height, it is a waste of money. If your'e not happy with the lift height, a 1/2" spacer is a much cheaper and effectively the same as a 4.5" MC spring since the spring rate up top is so low on those that the coils are already touching under the sprung weight of a TJ, effectively functioning as a spacer.
 
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JMT said:
Coil springs mainly provide lift. If you are getting the amount of lift you want, there is no reason to change your RC springs. It won't change your ride quality. What could change your ride quality would relate to your shocks. You are aiming for riding in the middle of your travel (50:50 up/down travel bias). If you are trying to fine tune your shock performance over washboard roads, you will need to buy some tunable shocks. They are about $500/shock.

Going to a spring that is 1/2" taller will not dramatically affect everything. Essentially what you will need to do is adjust your control arms and trackbars. If you are happy with your current lift height, it is a waste of money. If your'e not happy with the lift height, a 1/2" spacer is a much cheaper and effectively the same as a 4.5" MC spring since the spring rate up top is so low on those that the coils are already touching under the sprung weight of a TJ, effectively functioning as a spacer.
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Rancho® RS9000™XL 9-position adjustable series. Any good?
 
gosborne said:
Rancho® RS9000™XL 9-position adjustable series. Any good?
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According to @Jerry Bransford, the 9000XL in the lowest setting was still firmer than the Rancho 5000X. I'll let him explain more if he wants to. Personally, if I were you, I'd stay with the Rancho 5000X. My experience is with stock shocks, Monroe, Bilstein 5100's and the Fox 2.0's Savvy Tuned. I was most unhappy with the Fox shocks. Some have liked the Skyjacker BlackMax, so you might look into those.
 
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Don’t get dual rate or even triple rate springs. Go for something linear. Everyone around here loves anything made by Currie. I happen to have teraflex springs and combined with a fox 2.0 shock it rides and flexes great. The fox 2.0 isn’t an adjustable shock just an FYI. If you want adjustable you’re going to need to pony up a good bit more cheddar.
 
TRE3TOP said:
Don’t get dual rate or even triple rate springs. Go for something linear. Everyone around here loves anything made by Currie. I happen to have teraflex springs and combined with a fox 2.0 shock it rides and flexes great. The fox 2.0 isn’t an adjustable shock just an FYI. If you want adjustable you’re going to need to pony up a good bit more cheddar.
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LOL! Not worried about the cheddar. But thanks for the input.
 
JMT said:
According to @Jerry Bransford, the 9000XL in the lowest setting was still firmer than the Rancho 5000X. I'll let him explain more if he wants to. Personally, if I were you, I'd stay with the Rancho 5000X. My experience is with stock shocks, Monroe, Bilstein 5100's and the Fox 2.0's Savvy Tuned. I was most unhappy with the Fox shocks. Some have liked the Skyjacker BlackMax, so you might look into those.
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Thank You!
 
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Springs don't have any affect on the ride quality. That is what the shocks do. If you are happy with the ride height, leave the springs alone.
 
gosborne said:
I guess I was thinking there would be different "spring rates" / that may be better or worse.
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What are you trying to accomplish?

If you have some very specific goals there are some reasons to get a longer spring with a lower spring rate. It doesn't affect ride quality though.

If you want better ride quality you'll look to shocks, travel bias, tire load, and tire pressure.
 
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gosborne said:
I guess I was thinking there would be different "spring rates" / that may be better or worse.
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This is a pretty hotly argued topic in the forum. Personally I really Iike my dual rate JKS coils. I did notice a very slight improvement in ride quality. However, most people will never notice the difference. Infact, if you argued it was a placebo effect or due to a 1" taller spring, I can't prove its not just that. The difference between spring rates is very slight. I would not go down the rabbit hole of chasing spring rates unless you have issues with your current height or have a specific coil issue you need to address. Shocks will make a bigger difference.

Shocks can also be a very personal issue. I love my BIlsteins, they provide the precision and control I want. I did not like my Rancho 9000xls at all. I felt they did not control the rebound movement very well. I'm sure you have seen comments on the forum from very respected builders complaining that Bilstiens are so stiff you can tell if a quarter is heads or tails when you drive over it. Its an exaggeration to be sure, but although the Bilstiens provide much better control, I will admit they can be harsher than a twin tube shock on some small events.

I'm not sure why you mentioned the rear trackbar relocation bracket. You will need to keep that. The flatter you can keep the trackbar the flatter your jeep will handle in corners. As far as long arms go, they have been pretty well debunked and are considered a poor choice. If you want longer arms most people will recommend the Savvy mid arm setup. But its not cheap and not typically recommended unless you are trying to address specific issues that a mid-arm will address.

So as JMT asked above, what are you trying to accomplish? The better you understand your needs and can describe what you are trying to achieve, the better every one will be able to help. If your just looking for a winter project and fine tuning for washboard roads, then I would suggest starting with making sure all your control arm joints and steering joings are tight. Check any body mounts for visible degradation as well. If your joints are all tight and good. Then experiment with different shocks to most dramatically change your ride and handling.
 
The biggest improvement to handle washboards roads in my case was to ditch the stock front sway bar. The factory bar is too stiff. I went with an anti rock, roads that would throw me all over at 20mph with the factory bar, was able to hit them at 40 and way smoother with the anti rock.
 
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Superjay5 said:
The biggest improvement to handle washboards roads in my case was to ditch the stock front sway bar. The factory bar is too stiff. I went with an anti rock, roads that would throw me all over at 20mph with the factory bar, was able to hit them at 40 and way smoother with the anti rock.
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I thought Michigan only has pot holes? Grin
 
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