RE 7.5" and Skyjacker 8" coils

Was there ever a consensus on what the spring rate was of the RE 7.5" XJ coil? How about the rate of the Skyjacker 8" coil"?

Does anyone have the spring length (bottom seat to top seat) of either of these coils at ride height?

Any hard comparisons between either of these and the RE 4.5" ZJ coil, which I guess now is the same as the 5.5" XJ coil?

I'm running the 4.5" ZJ coil, and I'd like to go stiffer, but I'd also like to not get any more lift. I'm getting 5-5.5" out of the current coil, with one extra isolator on top and the lower spring seats raised 2". Six inches of lift would be OK, then I'd remove the extra isolator. I'm considering the feasibility of cutting a little off one of the longer coils to both give me the ride height I want and to stiffen the spring to what I want. Any of you math guru's want to take a shot at figuring how much to cut off to give 6" of lift and what the resulting spring rate would be?

I figure cut a little at a time until I get what I want. I'd try the Currie Jeepspeed coil, which should be just the right spring rate for what I want, but they're not long enough. I'd have to add another spacer or two, which I'd rather not do.

I ordered my RE springs etc. yesterday from Richard and will be installing next week. I'll post back with anything you might want to know.

Rich, the RE 7.5" are goingt o be softer thanthe RE ZJ's, contrary to what I was told when I bought the springs. They are the same wire diameter as the RE ZJ's, but taller, so that equates to a softer rate.

I'm going to run them and see how they feel with the 255/70 7100's.

The SkyCrackers are definately stiffer, the wire diameter is larger by a good amount.

CRASH

Crash what shocks would you recommend with the 7.5's i had planned on 5100's because of the deal i can get on them but I would be open to anything.

Depends on the kind of wheeling you do. 5100's are great shocks. The newer 5150's with 255/70 valving would probably be a bit better for high speed stuff, as they have more compression control.

CRASH

It will be my DD as well as weekend toy. I live in the NW so alot of forest-bying and dune running I plan on doing anything i can as often as i can.

CRASH said:

Rich, the RE 7.5" are goingt o be softer thanthe RE ZJ's, contrary to what I was told when I bought the springs. They are the same wire diameter as the RE ZJ's, but taller, so that equates to a softer rate.

I'm going to run them and see how they feel with the 255/70 7100's.

The SkyCrackers are definately stiffer, the wire diameter is larger by a good amount.

CRASH

Click to expand...

Sort a delemma here. To get more travel out of the spring, it needs to be softer and longer so it compresses more at ride height, leaving more room to extend in droop, so the suspesion can drop more without the coil unseating. Sounds like the RE 7.5" coil will be good in this situation.

I want the best of both worlds, more spring rate but also more doop......what to do? Coilovers with dual rate springs?

I like the idea of the Currie 250/300 springs, but they advertise 4.5" of lift, which would likely be less for me with a winch and heavy bumper....not enough without spacers. A custom Deaver dual rate spring? Maybe......but I wonder how much they are.

The 7.5" TJ coils (the part description is TJ coil, not XJ coil) net ~1.5" of lift over the 4.5" ZJ coils. I wanted an extra 1/2" to 3/4" up front, so I removed the ZJ coils plus 3/4" poly spacer and added the 7.5" TJ coils, which was perfect. My compressed (loaded) height on the 7.5" coils is 19 5/8" - 19 3/4". It was 18 1/4" with the ZJ coils.

With no winch bumper (just a light prerunner), it's 8" of lift with a stock coil isolator and 10mm OME poly spacer. The 7.5" spec seems accurate to me, and 4.5" ZJ coils have always netted me exactly 6" of lift.

To the qualitative aspects: I like these coils better than the ZJ coils plus spacer. I run them in combo with Bilstein 5100's (255/70), which were also in place with the ZJ coils. They don't so much feel stiffer as just better optimized for 8" of lift. My XJ *feels* more balanced. Definitely not a quantitative view, but then the numbers never tell the entire story. Keep in mind I wanted to lift the front a bit more to match the back, and that may be part of my positive impression, i.e. my "ass-high" previous setup may have had it's own minor issues.

Can't give you any impressions on your desired "high speed" usage, as I haven't been hauling down any backroads yet, but you'd definitely get more lift than you have now so you'd have to cut them. My guess is that your setup is already the best "off the shelf" application for your usage, and it's either custom coils or coilovers at this point, although I'd like to see the results of a shortened 7.5" coil.

Nay

A shortened RE 7.5" is called and RE ZJ.

CRASH

CRASH said:

A shortened RE 7.5" is called and RE ZJ.

CRASH

Click to expand...

Yea, that's what I was going to say. Spend money to convert a 7.5" RE TJ coil to a 4.5" RE ZJ coil that you already have .

Nay

I sold my 4.5" re zj coils with 1-3/4" spacer on 35" mtrs for 8" skyjackers without any spacers. The 8" skyjacker coils are very stiff and have a wider coil. They are almost identical side to side, unsprung weight of a used 4.5" re zj coil comp compared to a new 8" skyjacker coil which seems surprising to me at 1st. Now I think that I have gotten about 7" of lift or so, a tad less than my 4.5" re zj coils and spacers by the look of them. I have a re 5.5" lift bumped up 2" with lift blocks in the back. The skyjacker coils are very stiff and ride much firmer than the 4.5" re zj coils on the street. I haven't had them off the pavement, but I should have a better idea this weekend on the con.
Troy

hey goat,

i have the RE 7.5 coils and they are a little softer than the ZJ coils. mine netted at 7.25" with a BPI bumper and XD9000I winch, so i added some coil spacers to even out the front and rear height. now i have about 8.25 front and rear

brandon
:cheers:

Richard,

If you ever need to calc out spring rate for either leafs or coils, this should come in handy. You may need to right click / save to blow it up a bit to read better...

Ivan

Thanks guys. Ivan, thanks for the formula. BTW, just using the dimensions of the example in the formula, if one coil was cut off the spring rate would increase from 271 to 296.

I measured my current spring length at ride height and I'm at 17.25", with the RE 4.5" ZJ coils. It looks like the Skyjacker coil will be more than that, but I can cut it down some. I'd like to figure out what spring rate they are, anybody know?

Still need to call Deaver.

The reason I couldn't use the Skyjackers was that their overall spring diameter was too large. My springs are tight up aginst my inner knuckles, so I can't use any springs that are larger in overall diameter. Something to keep in mind if you are fairly tight on clearance.

CRASH

I just put my 7.5 Rubicon Express coils on and the over all diameter was much larger than the Skyjacker 8" coils I just pulled off. I wound up having to trim a little off of some sway bar mounts and some bracing that I had added to the mounts. The R.E.'s Have two less coils than the Skyjackers did. I too am in hopes of a little stiffer spring. And I can't imagin these could posssibly be any softer than the Skyjackers I was running. I am also adding an Anti-Rock sway bar to help with my efforts to force flex to my rear leaves. Goatman, are you going on the Rubicon trip in Aug? If so I will be there with my new setup and you can see how you like it. I hope to have everything done to hear in a couple of weeks and get some wheeling in before we hed out to Cali.
:cheers: Mike

Well, we have 100% different experiences with Skyjacker springs, which is just odd.

See SteinJeeps post above.

In order of stiffness (from softer to stiffer):

RE 7.5"
RE ZJ
Skyjacker 8".

Have you plugged your dimensions into the spring calculator above?

CRASH

BTW, got you registration for the 'Con.

I'll be on the 'Con in August, so I'll see you then. Whatever I do with springs will be done by then.

I called Skyjacker and they don't have (or couldn't give me) specs on their 8" coils, other than total height (unloaded) of 22 7/8". The SJ coils can be had for about $150, so it could be worth trying. I also called Deaver, and they have a spring like the Currie 250/300 Jeepspeed coil that gives an additional inch of lift, 5.5" where the Currie is 4.5". That's just about where I'm at now with my RE 4.5" ZJ spring, but with my bumper and winch their spring should give 5" or a little less........the Jeepspeed guys run lighter bumpers and no winch. These coils are $338, and should be a good choice for some. They will make a custom set with similar specs tweeked a little for my application for the same price of $338. He said his coil spring guy is pretty good and they've come to understand the XJ requirements with their Jeepspeed experience. I'll probably give them a go, especially since it seems hard to figure out exactly what the Skyjacker springs will do. I like the idea of dual rate since it will provide more spring compression at ride height and so more droop without the coil unseating.

I haven't tried plugging the specs of my new springs in the calculator yet. I do know that Skyjacker has a way of changing there product as they go with out telling anyone. It is possible they have modified there 8' coils scence I bought mine 3 or 4 years ago. I have already sold them or I would give you some specs off of them. Looks like I am stuck with what I've got for a while, I have been cut off for a while. The wife says "if you want to go do the Rubicon you have to stop buying parts". So looks like we will see you guys in Aug.

my 8 inch sj's have been awesone and i had zj 4.5's before, both flexed like hell, and yeas the sj's are a little wider but they have been awesome with 2 inch spacers and a mutt kit. But after review i think they are like a 1/2 short of 8 inches, doea anyone know why?