So my xj has become kinda out of the ordinary. With the addition of a 2x4 1/4 wall tube front frame, a big block chevy engine, th350 trans and the forthcoming exo cage i am wondering about switching to some f150 lift springs in the front. Cuz i would assume the weight is getting around the same as a stock bronco in the front. The skyjacker xj front springs i got in there now are very spongy with all that weight on them( havent driven it yet but just by pushing down on the body it is easy to give).

So what should i do??

I had skyjacker springs on my ZJ (4.0) and was really unhappy with the spring rate.

I swapped to Rock Krawler springs and they were MUCH stiffer (I don't know the pound/inch difference)

F150 springs are even stiffer (even higher pound/inch springs) than that.... Hope it helps

coil overs an option?

coil overs = way out of budget. Reason i was thinking of the bronco coils was how much weight ive put on the xj springs.

i wonder what the little shoe box bronco's springs rates are???

Dont assume.....research a little and Im sure you can find Ford Spring rates. What are you intending? 3" f150 coils? stockers? What Im trying to get out and Im sure you know....rates change in spring length and diameter (material). Once you figure out the spring rates you should be able to select the rite spring according to your weight additions.

I was thinking of these-- http://broncograveyard.com/bronco/i-23210_super_flex_coils_6_inch.htm

Says 300 lbs/in spring rate.

i have a set of wild horse bronco coils (5.5 inch) and they are huge i was goint to run them but know i am not

ps there progresive rates too

well what i'm working with is what everyone on here would consider HUGE. Im using 8" skyjacker xj coils up front now. And am trying to figure out what i need now that i got a big block in there...

If you know your spring rates on the coils you have you can measure their compression with the weight on it now you know how much your junk weighs at the front corners.

Read the coilover bible section on ride frequency. Choose a spring rate that will give you the ride frequency you think you want and get a length that will give you the height you want.

The springs you have will likely give you lots of body roll and will bottom out easily so you wont be able to go fast.

Ride frequency is a seat of the pants thing for the amount of weight you have. I say run what you have first to learn more about what you really want in a set of springs.

try to get an approx corner weights of your jeep.

Subtract the wieght of the 4.0. Add the weight of the big block. This should get you in the ballpark. Then also figure the unsprung wieght. Ei axle and tires. Ten figure the desired ride height. Then figure the needed spring rate after that.

Here are my weights to help you get started. That is full of tools, spare gas etc. I'm not down about 200lbs in the rear.

LF – 1147lbs RF – 1121lbs Front total - 2268lbs 48.3%

LR – 1212lbs RR – 1214lbs Rear total – 2425lbs 51.7%

You'll have to subtract the weight of a hpd44 front and tires that weight 100lbs each and add the weight of your axle and tire combo.

Same with my 9" rear.

If you know your spring rates on the coils you have you can measure their compression with the weight on it now you know how much your junk weighs at the front corners.

Read the coilover bible section on ride frequency. Choose a spring rate that will give you the ride frequency you think you want and get a length that will give you the height you want.

The springs you have will likely give you lots of body roll and will bottom out easily so you wont be able to go fast.

Ride frequency is a seat of the pants thing for the amount of weight you have. I say run what you have first to learn more about what you really want in a set of springs.

That is what i was afraid of. them being way to soft for the weight ive added. My springs are 18" tall compressed, need to measure height un installed, but i dont know the spring rate tho...

try to get an approx corner weights of your jeep.

Subtract the wieght of the 4.0. Add the weight of the big block. This should get you in the ballpark. Then also figure the unsprung wieght. Ei axle and tires. Ten figure the desired ride height. Then figure the needed spring rate after that.

Here are my weights to help you get started. That is full of tools, spare gas etc. I'm not down about 200lbs in the rear.

LF – 1147lbs RF – 1121lbs Front total - 2268lbs 48.3%

LR – 1212lbs RR – 1214lbs Rear total – 2425lbs 51.7%

You'll have to subtract the weight of a hpd44 front and tires that weight 100lbs each and add the weight of your axle and tire combo.

Same with my 9" rear.

I wish i could go weigh my front and rear on a scale. But you have got to think that my jeep has a lot more unsprung weight than yours because of the rockwells.

I wish i could go weigh my front and rear on a scale. But you have got to think that my jeep has a lot more unsprung weight than yours because of the rockwells.


No kidding. That's why I posted mine, and told you what to do with them.

Here it is again.:shaking: You can subtract the 4.0, hpd44, 9", 100lbs for each tire add your weights.

This should at least get you in the ballpark.

Think a little man.

well so i've read the 4.0 weighed 515 lbs, big block chevy is 685 lbs, small block is 575 lbs. So im over original weight by 170 lbs on the engine.

Oh and my 8" skyjacker XJ springs are 23" tall unloaded, 18.5" loaded. So that is a 4.5" drop does that sound right??

Here are some spring rates straight from the makers. rock krawler 8" 190#,6" 170#. RE 7.5 230#. sky jacker 6" 230#,8" 235# bds 3" 240# 4.5 240#.takin from threads on naxja where people have called, including myself. sky jackers always were highest rate but bds makes theres a little higher. didnt look up bds # rates on there 6 and 8" spring. but i would say it's even higher since they prefer all there coil rates higher.it's on there web site.and bds is warrantied for life.with the added weight you have in the front of your xj 300# coils don't sound out of line at all. just a matter of if you like the progressive coil.maybe find out what a bronco's weight is? and go from there.maybe bds 6 or 8 " is heavier than the sky jackers your running now, havnt looked.but your running one of the heaviest you can buy with the sky jackers. hope this helps

So my xj has become kinda out of the ordinary. With the addition of a 2x4 1/4 wall tube front frame, a big block chevy engine, th350 trans and the forthcoming exo cage i am wondering about switching to some f150 lift springs in the front. Cuz i would assume the weight is getting around the same as a stock bronco in the front. The skyjacker xj front springs i got in there now are very spongy with all that weight on them( havent driven it yet but just by pushing down on the body it is easy to give).

So what should i do??


Are your shocks hooked up? or are they still hanging from the upper mount?

Are your shocks hooked up? or are they still hanging from the upper mount?

they are still just hanging there. havent gotten around to making mounts for them on the radius arms. That could affect my spongyness too.

So do ya'll think some 300 lb/in coils would be stiff enough to hold up the weight ive added but yet still flex?

they are still just hanging there. havent gotten around to making mounts for them on the radius arms. That could affect my spongyness too.

yeah - maybe just a little bit... :shaking:

Unless youve sudenly got a front end loader I some how get the feelin 300 is WAY to stiff. With your weight additions I wouldnt look any further than like 240.

The skyjacker xj springs i got on there now want to bow all over the place with the weight on them. So i just ordered some superflex full size springs that are 300 lb/in. They should be fine and give me the lift i want. http://broncograveyard.com/bronco/i-23210_super_flex_coils_6_inch_made_in_the_usa_.htm

Xjtony, how about taking some measurements off those F150 springs before you install them:
OD of coil=
OD of wire=
Height, unloaded=
Number of active coils=

Xjtony, how about taking some measurements off those F150 springs before you install them:
OD of coil=
OD of wire=
Height, unloaded=
Number of active coils=

sure, i'll help somebody out. Since i will be trying these springs. Will measure everything when they get here. This is all i know as of now=

Height unloaded is 26"
300 lb/inch spring rate

My skyjacker 8" xj springs are
23" unloaded, 18.5" loaded, and somewhere near 230 lb/inch..

Looking forward to more details:)

Couldnt remember if i updated this thread or not...

SuperFlex 6" Full size bronco springs=
25.5" tall unloaded
0.75" coil diameter
15 coils
300 lb per inch

Skyjacker 8" XJ springs=
23" Tall unloaded
0.68" Diameter coils
14 coils
230??ish lb per inch

http://i284.photobucket.com/albums/ll26/brizag/100_0955.jpg
http://i284.photobucket.com/albums/ll26/brizag/100_0956.jpg

Holy Jebus! That things huge! Just got em mocked in or have you tested em out yet?

Is that with all the weight on it?

Those look like a good coil for the weight you have but I would mount them higher on your frame to lower the body. Set it up so you only have like 5in of vertical up travel and it will feel alot more stable and less massie:massey:

Holy Jebus! That things huge! Just got em mocked in or have you tested em out yet?

Yep its huge, compared to rock crawlers low as possible motto, but there arent any rocks in MS and i wanted it tall! And they are mocked in there, with the weight all on them in the pic. Still have to make something to hold the coils in place. I cant really test them until i get the rear suspension built then i could grab a tire with the cherry picker and see what happens.

Maybe it wont fall over.

So months down the road ive finally gotten some progress on this experiment. Bronco coils in the front are pretty stiff, the Skyjacker 8" front coils in the rear are working tho. I guess i really need a softer spring in the back to work more since the front aint doin much...
http://i284.photobucket.com/albums/ll26/brizag/100_1148.jpg
Not impressive by any means. But i'm gonna work with this for a while and when i get everything working i will get some ride time and change up after i see how it acts.

So months down the road ive finally gotten some progress on this experiment. Bronco coils in the front are pretty stiff, the Skyjacker 8" front coils in the rear are working tho. I guess i really need a softer spring in the back to work more since the front aint doin much...


Making the rear softer is not going to help you. If anything, get a sway bar in the rear to make the front work harder. Did you ever cycle the front suspension before the springs were in to see if it bound at all?

No i didnt but i did take one upper arm off and flexed it again and it did give a little more but not enough for me to redo my upper links. I will buy some kind of antirock swaybar for the rear if i can find one for sale on here or something.