Coilover spring rates

[4PLAYZJ]

Going to order my front coiloverspring for my build I'm going to start in May. I'm planning on ordering 14" FOA 2.5" remOTE reservoir with med comp. Valve and light/med rebound valve. I was thinking of a 14" 250 over 16" 350 but I am not sure. Any ideas would be great.

It's a 98 zj 5.9l getting custom long arm lift, full internal cage, partial exo cage, prerunner style tube bumpers, AAM full width axles 37-38" tires.

[GiS]

I think that is likely a good starting rate given you will be running a partial exo, big front bumper, winch etc.

What is your planned uptravel/downtravel ratio?

I am happy to see your using a 14"/16" combo on a 14" coilover .. This will help you keep tension on your coils at full droop etc. It's a good "trick"!

[4PLAYZJ]

Not planning on a huge lift. Want a low COG. Was thinking roughly 6" of uptravel before bumpstops.  

Think I could fit a 16" without holes in the hood?

[SwampSinger]

I'll be running 275/350 on mine (if I ever get it done)... under Master Obi Wan Kenobi's advise. I think the idea was to keep the front stiffer (that's what she said) because I'm still keeping the leafs in the back. 

Loops are done and trying find my ride height/ fitting the CO.  Hopefully it wont be too much trial and error.

[GiS]

I'm not sure on a ZJ but I think you'll be hard pressed to fit a 16" without the hood cut .... ? Maybe Dom can comment on that a bit better,

I also think 16's are totally obscene hah .. I have 16" on my TJ and limit them to about 13" up front .. 16" is a TON of travel and most of your other components likely won't allow for it. Think trackbar deflection, steering components etc.

Again the spring rates sound like a great start in my opinion,

[Bnine]

Going to order my front coiloverspring for my build I'm going to start in May. I'm planning on ordering 14" FOA 2.5" remOTE reservoir with med comp. Valve and light/med rebound valve. I was thinking of a 14" 250 over 16" 350 but I am not sure. Any ideas would be great.

It's a 98 zj 5.9l getting custom long arm lift, full internal cage, partial exo cage, prerunner style tube bumpers, AAM full width axles 37-38" tires.

Unless you plan for a ton of uptravel, those rates will be a bit high. And running the 16" lower will not allow you to dial it down. You will be stuck with 7-9" of uptravel.

Combined rate on that setup is 145 lbs/inch. So even if you shot for 50/50 at 7 up and 7 down. Fully engaged springs, which when using a 14 and a 16 on a 14" shock you would have no choice but to be fully engaged, may even have to prelaod a small bit.

So 7 x 145 = 1015 lbs per side to compress the shocks 7 inch each.

Lets take a 1 ton Zj with 38's and weigh it. Even with a V8, heavy tires, 14 bolt and a 60 you will top out at about an absolute 5500lbs. And thats going heavy.

1 ton front diff with tires, rims, suspension, comes in right about 1000 lbs.
Rear 1 ton with tires, suspension, etc etc, 700 lbs.

Leaves you with about 3800lbs of sprung weight. Lets give with 60/40 front to rear weight division.

3800 x .6 = 2280 lbs
2280/2 = 1140 lbs per side
1140lbs/145 lbs/" = 7.86" of compressed shock.

6.2" of uptravel.

If this worked out it would be just great, but I dont think you will come in that heavy and if you dont you will be left with not adjustment to dial out height.

Happens all the time when people start with heavy rates.

I have have a lot of 14" springs. You could borrow some, get your weights, and get a much more accurate idea of what you will need for a final rate.

[4PLAYZJ]

That would be awsome Bill. Thanks. I will just order the shocks for now.

[Bnine]

I would also recommend getting Fox dual rate sliders instead of FOA's. FOA's sliders have no sleeve on the bottom of the their slider and it reduces your adjustability for dual rate engagement by about 3 inches.

Thats another reason they push a longer lower. So your second rate will engage two inches sooner and they can provide you with the cheaper slider.

If you run a 14/14 and a FOA slider, there's a chance you cant even get your lower rate to isolate because you are at bump before the slider hits the stop.

They are just putting the cost in your court. You pay more for a 16" spring, and they get to give you a 5$ slider instead of a 10$ one.

Personally I like the deeper slider. It gives you more adjustability for range of engagement. You can have the lower rate hit right away, or not at all.

Probably sounds confusing, but I have all the stuff at home, coil over, sliders, and springs. If you ever want to have a coffee and do a 101 on this stuff just give me a call and I'll put the coffee on.