Lift Coil Spring Rates

[feerocknok]

Does anyone know how to find out the spring rates of coils from different manufacturers without calling every one?

I checked RE, Rancho, and Rusty's sites and saw nothing.

 

I know Rusty's uses stiff springs, and my friend's ProComp springs are stiff, but I'm looking for some cushy soft, almost rolling on-road, 5.5"ish lift coils.

Any suggestions on that maybe?

[Twisty]

I think Skyjacker springs are softer.

[Eagle]

I know Rusty's uses stiff springs, and my friend's ProComp springs are stiff, but I'm looking for some cushy soft, almost rolling on-road, 5.5"ish lift coils.

Any suggestions on that maybe?

What changed? Rusty used to have a reputation for very mushy springs, softer than factory.

[feerocknok]

It's just been the hear-say that I've been getting lately. I've heard it on this board probably twice in the past 2 months, and spring rates don't come up often.

[Duner]

My rusty's 6.5" are rated at #150, the stock comanche springs are #142 for most and #146 for the eliminator package. My 3.5" tomkens seemed relatively soft as well. I can't imagine what the ride is like when they use the ford f-150 springs which are closer to #250-#275 range I bet they don't compress at all.

 

My dad had 4" lift soft ride leaf springs on his 1978 scout from skyjacker so their reputation of being a little softer might be true.

[jared]

rustys also offers a stiffer spring pack too i belive that at 180pounds

[feerocknok]

I'll give Skyjacker a call on Tuesday and see what they say. Thank you guys for the recommendation.

[Eagle]

My rusty's 6.5" are rated at #150, the stock comanche springs are #142 for most and #146 for the eliminator package.

Not saying you're wrong, because I have never seen any spring rates given by the factory, but what's the source of these numbers? I know that stock Cherokee rear springs are much heavier than that, and usually the front springs are stiffer than the rear because they carry the engine. I thought factory fronts would be around 180 to 200+ pounds-per-inch.

[jeepthing07]

I have Rustys 3" HD 180# coils they are stiffer than the stock ones

[comancheman]

ive got the re 5.5 inch coils and they flex like a highschool cheerleader id deffinetly recommend them not sure on the spring rate though

[DirtyComanche]

My rusty's 6.5" are rated at #150, the stock comanche springs are #142 for most and #146 for the eliminator package.

Not saying you're wrong, because I have never seen any spring rates given by the factory, but what's the source of these numbers? I know that stock Cherokee rear springs are much heavier than that, and usually the front springs are stiffer than the rear because they carry the engine. I thought factory fronts would be around 180 to 200+ pounds-per-inch.

 

 

I'm not sure, spring rate confuses me as nobody 'knows' for sure and the lift companies don't answer anything truthfully. And the calculation is just a PITA.

 

 

 

But, I can tell you this. My 6.5" rusty's XJ coils (apparently 150, but maybe 180?) were STIFFER than my stock springs. Which seemed reasonable just eyeballing the thickness and number of coils and putting my weight on them (I did not bother to work it out).

 

I have always said that stock springs are 138~ lbs per in. Barring that you have two front coils, so that's 276lbs per inch on the front. (Which is also why I think the guys with 'heavy bumpers' buying longer springs are whack)

[ryno1121]

Just FYI,

 

If you have the spring you can determine the spring rate by measuring the length of the spring with no weight on it. Then place a know amount of weight on the spring and measure the lenght of it again. The spring rate is the weight placed on the spring divided by the difference in the lengths. If you measure in inches the units of the spring rate will be lbs/in. As you guys said before it will probably take well over a 100 lbs to get the spring to deflect enough to even get a measurement.

[Pete M]

I bought Rusty's 180 lb coils and find them to be reasonably soft and very compliant. :dunno: Might have something to do with the big bumper though. :D

[87manche]

I've got skyjackers 3" coils in the front. They seem plenty soft. The springs will outflex my short arms.

[pingpong]

Poly performance is real good about helping with spring rates as is Rock buggy supply

[Duner]

Sorry for getting back to this one so late.

The #150 spring rate is what Rusty's advertised during my purchase so I don't know exactly what they are. They seem relatively compliant in their movement and the ride is not harsh.

 

The rates for the stock springs were obtained from partsamerica.com on their TRW replacement springs select the year and model of your truck then click on the TRW springs and on the details page they provide the free height, installed height, spring rate and total load compression. I did not check rear spring rates since they do not carry them. I think the 2wd springs are lighter.

 

Where is the best place to get replacement factory leaf spring (4wd)? I need to gain about 1" of rear lift over my current 2wd leaf springs.

[Pete M]

Junkyards. Try car-part.com

[Eagle]

Where is the best place to get replacement factory leaf spring (4wd)? I need to gain about 1" of rear lift over my current 2wd leaf springs.

I'm going to make my own. I have three 2WD MJs here at the moment. One runs and drives just fine but I'm not interested in upgrading it. The other two I regard as keepers. Whether or not I ultimately convert one or both to 4WD, I want to improve the rear spring capacity.

 

The plan is to take old XJ main leaves, cut off the eyes, and stick them into the MJ spring packs as AALs. I'm actually hoping this will increasse the spring rate without adding much lift, but there will probably be some net increase in ride height.

 

For those wanting some lift, doing the same thing but using old MJ, S-10, or older Dakota main leaves should generate some lift. When you add a second main leaf to an XJ leaf pack, it generates about 1-1/2" of lift. I would expect a similar result adding a second main leaf into an MJ leaf pack, but I haven't done it (yet).

 

Or just buy the Rancho XJ/MJ AAL set for around $50. The Rancho catalog says it produces 2-1/2" of lift. But ... it says the same thing for the XJ and, since one is SOA and the other is SUA, thats clearly impossible. I called Rancho awhile back to clarify that, and the nice engineer gal I spoke with went off and checked with some other engineer type, then came back and said that should be 2-1/2" for the XJ and 1" to 1-1/2" for the MJ.

 

IMHO the Rancho kit is the cleanest way to go. No junkyards to slog around in, you don't use up $25 worth of cutoff wheels or sawzall blades chopping the eyes off old leaves, just buy it and go. The kit includes new center pins and a couple of spring clips, although I would probably add a couple more clips for security (unless I was looking for a lot of flex).