RudeXJ

Hi guys,

I'd like to know if anyone can provide me the coil spec for a coil that would produce 3 inches of lift at the front of a 2000 XJ. I'm looking to get coils made up (going to do a bastard pack at the back)

Reason: Where I live there is no aftermarket XJ products and after shipping and tax any lift kit from the states will end up costing nearly triple what it already does.

Any help or advice would be appreciated

4WD4EVER

I believe there is a thread here somewhere with the specs but it should be 147lb/ in rate, 17" uncompressed and 5.25" diameter.

Search and double-check.

RudeXJ

Great I'll have a search, I'm assuming thats for a coil with 3 inch lift, not stock right?

4WD4EVER

No, those are the stock specs.

Martlor13

3 inch coils will have different rates because different companies have their own specs. You will have to do research on your own to see what rate you want.

RudeXJ

I understand that, I actually found another thread with a bunch of aftermarket manufacturers coil rates, for example RE 3.5 lift front coils have a rate of 240lb/inch and I learned the lower the number the looser the spring (more flex on the trail) the higher the number the stiffer the spring which provides better handling on the road, so I'll have to figure that out.

What I would like to know is not only the coil rates, but also the diameter and length (and any other necessary info) that would give me a coil with 3 inches of lift. Do I keep the same diameter as stock and just lengthen the spring by 3 inches?

I have to give all the correct specs to a local coil manufacturer, they're a big company doing me a favour so I want to have all my ducks in a row and dont want to mess them around.

Rogue4x4

A link I posted in another thread, but may help in your situation...there's a formula on this page to help you determine what you actually have, and where you would need to change. Spring rate may differ depending on what you want to accomplish, like what kind of offroading will you see, etc...you need to make that call...but if you like your spring rate, just increase the amount of coils to get the desired lift amount.

Also get all the stock specs you can from the original coil, talk to them, and ask what they recommend...they're the professionals, after all. If they're willing to build you custom coils, I'd bet they'd be willing to help you out, too. The other thing you can do is email some of the companies that have what you're looking for...ask them to send you the detailed specs on the spring, bet they'd do it in a second. They all have data sheets on this stuff. Can't hurt to ask them.

andrewmp6

Do you have a spring shop around you ?

RudeXJ

Thanks for the help guys, great advice @roninofako - I have a spring shop in a neighbouring city so I'm going to have to do everything over the phone, so it will be tricky, but lets see. I'll post on here as I go.

RudeXJ

Ok guys, so I've made some ground on this spring thing.

The spring manufacturers are confident they can make a 3 inch taller spring given the stock dimensions, the most important being the OD (outer dimentions) of the top and bottom, free hight and spring thickness...I've done some research on stock specs and I've found conflicting info info, I've also consulted the manual and nothing.

Top of this post @4WD4EVA mentioned springs are: 147lb/ in rate, 17" uncompressed and 5.25" diameter

From another thread:

Factory 6 cyl AT XJ Coil
Wire dia: .5"
Total Coils: 9 Active: ~8
Coil OD: 5.0"
Calc Spring Rate: 120 lb/in
Tested Spring Rate: 125 lb/in
Unloaded Height: 18.0"

Does anyone know for sure what the stock XJ dimensions are, most importantly the top and bottom OD, free hight and wire thickness?

4WD4EVER

Just a thought, but, since you're getting conflicting information, you could consult a supplier such as Moog, Omix, Crown, etc., and maybe one of their tech people would be kind enough to give you the data you're wanting.

And just my $.02, but that 120lb/in rate sounds awful low/light, even for an XJ...

4WD4EVER

Verified by someone who has
them laying around:

O.D. - 5.25"

Uncompressed/ free height - ~17.5"

Wire thickness - 1/2"

Hope it helps.

RudeXJ

Thanks so much for this, helps a whole bunch! Confirmed these dimensions with someone locally who also had a set loose, now I can build from here.

Now if we can find someone who's about to install a 3 inch lift kit that can give me their dimensions, that would save me a bunch of trouble

I was intending on winging it from here, basically just adding 3.5 inches on top of that and making the spring ever so slightly thicker for a bit more spring rate? Also looking into progressive springs, but they seem to get a bit too tech...what do you think?

The manufacturers are charging $50 per spring to make one set...not too bad I guess.

RudeXJ

So got a reply from Rough Country regarding specs of their 3" lift coils;

Free length is 19 13/16"s and the thickness is 0.562. The rate will be 720 per.

Interestingly the free length is less than 3 inches longer than the stock coil...so how does that net you 3 inches up front??

The thickness is pretty much the same as stock and the rate...well I dont understand what "720 per" is supposed to mean.

Rogue4x4

Because the wire thickness is what determines spring rate. Thicker wire=more spring rate...means less coils to achieve the desired lift. If they're truly 720 (they're not), them's some stiff coils, LMAO...I'm guessing you either got the wrong number, or that number is for something else...