This will be my first time messing around with a 4-link and I think I have a basic grasp of the process based off of what I've read on here and watched on TV. The thing that seems like it would be real simple to figure out and for what ever reason I haven't found yet..... Is what size of spring do I get for the rear.

I'm going with TJ rear coils vs. Coil Overs based solely off of not having the funds for the Coil overs.

The jeep right now is sprung over and when converting to the 4-Link I'm planning on pushing the rear axle back and relocating the gas tank into the bed. The springs I have on the jeep right now are flat and I'd like to keep the same (or close to it) ride height when done.

So when picking out springs, considering that the spring over gave me about 5 1/2" of lift (figuring in the flat springs) do I order Stock TJ rear Springs, or a TJ 5-6" lift spring for the rear?????? The axles are wider than stock so it looks like I will be able to place the springs on the outside of the frame if that makes a difference (have to double check width of the spring).

First figure out were you want your wheelbase length or how much you intend to stretch the rear. Mark that spot and measure the diiffrences in height from the ground for the front to the rea. Whatever the diffrence is, is eqaul to the amount of spring lift height you need. Example....Your top front sping mounts are 38" off the ground with a 5.5" spring. To where you want your rear springs mounted it 35". So if you wanna use (typical) front springs out back, then you need ones that are for a 3" lift. Got it? Try and shoot for a matching spring rate. Ex...175 front with 180 rear would be a good setup.

First figure out were you want your wheelbase length or how much you intend to stretch the rear. Mark that spot and measure the diiffrences in height from the ground for the front to the rea. Whatever the diffrence is, is eqaul to the amount of spring lift height you need. Example....Your top front sping mounts are 38" off the ground with a 5.5" spring. To where you want your rear springs mounted it 35". So if you wanna use (typical) front springs out back, then you need ones that are for a 3" lift. Got it? Try and shoot for a matching spring rate. Ex...175 front with 180 rear would be a good setup.

THX for the reply. I don't quite get why the spring would be longer if the measurement is shorter. Let me preface that by telling you I have not looked at a TJ suspension and I have no idea what the difference in springs (in length and size) are to begin with. Are the front springs shorter than the rears?

I think you misunderstrood me. The rear spring is not longer. Let me try again. Ok so looking at your front springs....at the very top of the spring lets say the measurment is 38". That using a 5.5 lift spring.

Now the back lets say the mount is at 35" to where the top of the spring would be. So to get a correct ride height you would need (if using front TJ coils) a spring thats for a 2.5" lift. Not 3", I was wrong there.

I think you misunderstrood me. The rear spring is not longer. Let me try again. Ok so looking at your front springs....at the very top of the spring lets say the measurment is 38". That using a 5.5 lift spring.

Now the back lets say the mount is at 35" to where the top of the spring would be. So to get a correct ride height you would need (if using front TJ coils) a spring thats for a 2.5" lift. Not 3", I was wrong there.


I get how your telling me to measure. I think I needed to clarify a litte more. I don't have coil springs anywhere on the jeep right now, it's all leaf sprung. When I converted form spring under (stock) to spring over (still with stock leaf springs) it gave me about 5 1/2" s of lift. As it sits now, I'm still sticking with front leafs for a bit so I don't have anywhere to measure the difference between where the top of a front coil would sit and where I would be mounting the rear coil. Does that make sense?

To make it even easier.... Do you or does anybody know off the top of their head the height and diameter of a stock rear and front TJ coil? I'm not sure which I will use yet. The jeep is all fiberglass and the only real weight in the rear is the spare tire and fuel tank. Not sure if a spring set up for a front end carrying the weight of an engine would be too stiff, or if it's even enough of a difference to worry about. I do know from paying attention to what they look like now that the rear coils seem to have a larger diameter and I'm guessing people use the front on the rear to help with clearance issues. Is there another reason why front are used more frequently on these types of conversions?

Along those lines, It appears I have plenty of room between the inside of the tire and the outside of the frame to mount either a front of rear coil. I'm also guessing since I am basically starting this from scratch, as far as a coil set up, I can pretty much buy what's needed just based off of standard stock coil height and place my mounts on the frame accordingly. I just don't to take away from the articulation I have now buy screwing up and buying either to small or too still of springs.

I have no idea what my weight is at each tire and don't know of anywhere local I could go to find that out.

your ride height is going to depend on where you mount your coil buckets, so the answer your looking for is really, it depends... if you want it taller move the top of the spring mounts down, for a lower ride move them up.

Yeah..... google works wonders and I'm figureing out that some of the assumptions I had regarding spring and weight displacement were not correct. Oh well, that's what questions are for right???

I will more than likely end up using TJ fronts, or Early Bronco Fronts since I have a couple laying around and save a litte on space department between the tire and spring.

Search here for my postings or threads started. About 3 yrs ago or so I did the same type swap with a CJ7 and have all the info listed in that thread for TJ ride height and compressed / extended lengths of TJ front adn rear coils. the rest is veh specific when you start doing what you are. get your susp setup and at your ride height and then figure out mount locations and then you have a close idea as to what compressed spring you need.

OK nevermind above... I got all my info from another site and its posted there...

http://www.jeepaholics.com/support/topic.asp?TOPIC_ID=47366&SearchTerms=coil

Thanks for the link. That answered most of questions.