Minnesota Jeep spring question...

[rick90yj]

OK, I have a 90 YJ that I am building. I have a 78-79 HP Dana 44 from a Bronco/F-150 (coil spring, cast ends) Since I can't change it over to leaf spring I am going to use it with the radius arms and coils, my question is, how do I determine the spring height/rate? I need it to match the rear which has OME 3" springs. Switching to a different axle isn't an option, in this case.(already emptied every pocket) I tried PBB and a local forum, so now I'm turning to the big guns. Help a guy out here. :confused:

[goodtimes]

Spring height will depend on where you locate the upper spring buckets. You will need to mock the whole thing up (front end on jack stands at the height you want, with the axle --with tires-- located underneath it). Then you can measure the installed height of the springs. That measurement in addition to the sprung weight of the front end, will give you enough to get in the ball park for spring rate.

But unless you are having custom springs made, none of that will do you any good (because you won't have a choice of spring rate unless you go custom) I'm assuming you are going to use springs that were originally intended for some other use (like OME coils for a TJ, or something like that).

If that is the case, mock up the front end (don't actually build the spring buckets yet), get a rough measurement, find a spring that is a hair longer than your measurement (because it will compress when you load it), put the weight of the front end on the springs (to get an idea how much they will compress), then build the spring buckets to set the front end height you want.

It really isn't as bad as it probably sounds......

**edited for clarity

[rick90yj]

I should have added, I have a set of aftermarket ZJ coils I plan on using. I'm just trying to wrap my mind around how to set the bucket height. I was kinda thinking along the lines of what you said...I was just figuring I'd have to work the springs into it somehow to see where it sits. (EX: clamp the spring buckets to the frame with the coils in them, set the weight of the Jeep on them, and then determine how close it sits to level....and adjust the bucket height accordingly. I also had a suggestion to "if you run one (radius arm)on the pumpkin side and just a lower control arm on the other it will bend up good though"...comments?

[rick]

So you need to build frame side brackets for the radius arms, right? I guess I'm confused why you wouldn't use TJ brackets and just convert it to something you know will work... If you modeled it around a TJ, your ZJ springs will work and you'll have something that will flex better and maintain correct geometry unlike the radius arm setup. But, as you pointed out, if you already J.E.E.P.'ed, maybe this is too much coinage. TJ bracket kits are expensive, as are control arms, and if you already have donor stuff... I think you're on the right track, but I'm not sure I would clamp the buckets in place - maybe clamped and tack/stitch welded would be safer? I just can't imagine a clamp holding the weight of the jeep.

If you're going to use radius arms, I would use them both. I don't think one radius arm is enough to control the rotation of the axle.

my $0.02

[nagal]

Not meant to be a hi-jack or anything. But I just replaced my front control arms on my TJ. If you need/want the old stock ones you can have them just need to cover the cost of shipping is all.

[rick90yj]

Thanks for the offer, but I've been doing some research and if I use control arms, they will have Heim joints on the ends. I'm doing some checking with some Bronco sutes and hopefully will find my answer. There is one guy who runs a single radius arm on one side and a Heimed control arm on the other side. I'm looking for flex more than anything. and this seems to be the way to get the best of both worlds. I'll let you know how it works.

[rick90yj]

You will need to mock the whole thing up (front end on jack stands at the height you want, with the axle --with tires-- located underneath it). Then you can measure the installed height of the springs.

...mock up the front end (don't actually build the spring buckets yet), get a rough measurement, find a spring that is a hair longer than your measurement (because it will compress when you load it),

...put the weight of the front end on the springs (to get an idea how much they will compress),

...then build the spring buckets to set the front end height you want.

It really isn't as bad as it probably sounds......

**edited for clarity

I just read over this again, and the little light above my head should be glowing SO brightly right now. It was the "put the weight of the front end on the springs" that I missed. Now that I see it, it is SO simple...thanks.
Hey ...you guys are the best...

[rick]

Actually, I think I just got it myself... you don't need to put the weight of the vehicle on the springs *in the buckets*, just *on the springs* to get a measurement. Much simpler task than actually mocking it up with the springs where they belong. I guess my comment on clamping the bucket to the frame wouldn't apply.