[tjthorson]

CLIFF NOTES - If you want a stiffer spring in the back of your TJ that nets 3-4" of lift and doesnt sag as easy - use the MOOG CC623 which is from 79-96 Chevy Caprice Wagons, instead of the crown vic coils. Disclaimer - use this info at your own risk - I am only relaying my personal experience and results - YMMV.

EDIT 5/12/2010 - I have settled in on a complete lift package. I used the Caprice Wagon coils in the rear as described, and for $100 picked up a set of 4" superlift coils from Summit. They ride nicer then stock and gives me a near flat stance after settling in (measured from the ground to the lip of the fender flare is 1/4" higher in the back). Im very happy with this setup. Also - I had to haul some cargo recently and was able to test those rear springs. over 1200lbs of cargo - all behind the back seat (50 retaining wall bricks) deflected the rear suspension about 2 inches - and it handled it all fine. I could feel it in the brakes - but there wasnt any stability or body roll issues at all.... [/EDIT]

If any of you followed any of my other threads, I have been searching and searching for some definitive answers on some better springs for the back of my TJ. Mind you - in the past I have played with springs in other vehicles with great success. Many of you use an aftermarket spring and spend $150 - $200 a pair. I just cant see spending that much for a set - when stockers through MOOG are $45.... It just doesnt sit right with me - because in most cases, those companies just look through the book and pick a spring from some other vehicle to fit that happens to lift the jeep. Some, like OME do lots of research - but still, I wanted to find something close myself.
Anyway - I wanted something that nets about 3 - 3.5" lift, and has a high (stiff) spring rate. I hate hooking up the trailers, or even having the kids in the back seat and the jeep sagging. To date, I have tried all the ones that anyone seems to talk about -

I had the typical BB pucks with stock rear springs. They were the 5AA ones that came on my 05 Unlimited Rubicon soft top. They were too soft for me - towing the camper, two teenagers and a bunch of wife stuff in the back caused me to be looking up at the sky while travelling down the highway. On my old TJ, I had put airlift bags in the back - but this time, I wanted a stiffer spring for the rear. In my past life, I used to add leafs to all my other trucks with great success - blazers, suburbans, etc.

Next I moved up to the "front spring on the back". I wasnt comfortable with the fact the both ends of the spring are not pigtailed, so the bottom tends to move around - but I ran them anyway. I figured they should be extremely stiff since there isn't and engine in the back of the jeep, right? Well, those springs did indeed net about 3" of lift, but the minute the kids jumped in the back, I was riding on bumpstops worse then with the stockers.

So then I moved up to the "crown victoria cargo coils", part # cc865
These gave me about 2.5-3" of lift, in an LJ, with the hardtop on, and some tools in the back. Again though - they seem soft to me, and hooking up the trailer, kids in the back, still resulted in the back end sagging....

I seemed to be out of options. I figured even if I spent the money on some 4" coils from OME or something - they would all have a soft spring rate and would sag anyway.... So, just like I did a long time ago with the G-body cars, I began to do some MOOG research...

These are the numbers on the CC865s I had in the jeep for the past few months:
Inside Diameter 4.540
Bar Diameter .593
Install Height 11.50
Load 620
Spring Rate 163
Free Height 15.25

I tried all i could to find numbers on the stockers - best I found was the someone stated they knew the stock rear coils (5aa?) had a spring rate of 140.

So I searched all i could for any MOOG numbers to come as close to the above specs, but with a higher spring rate (I figured about 200-225) was what I wanted.

So, in my searching I found the MOOG CC623 cargo coil. They are the coils that are OEM for the rear of a 79-96 Chevy Caprice wagon. It has a larger diameter coil - more like the stockers, just smaller then the spring buckets on the TJ - the crown vics are considerably narrower. The rate and load are higher - but not crazy high. Specs are:
Inside Diameter 5.530
Bar Diameter .671
Install Height 11.00
Load 865
Spring Rate 206
Free Height 15.13

Here is a pic of the two pairs next to each other. I no longer have the stockers to compare to. You can see they are nearly identical in height, but the 623s have a larger diameter (should be more controlled under load) and the pigtails are of sufficient size that you dont have to cut the springs like the crown vic ones...



Since these have a higher spring rate, I needed to use my harbor freight spring compressor to get the second spring in. Before I started, I measured the jeep from the ground to the tub behind the rear flare with the crown vic springs - 25.5". I no longer know how that compares to stock since I have made so many changes..... With the jeep put back on the new coils, I now measure 27.25". I figure they will settle 1/4 - 1/2" inch yet, so I expect about 1.25" over the crown vic springs - but they are much stiffer. With both kids in the back, and all the tools, the jeep moved less then 1/2". Even with me jumping on the bumper, it is much tighter then before. Now - it becomes apparent that my front stock springs with pucks are too small. Im going to start researching suitable front springs next - Ill make a separate writeup when I find a good spring for the fronts. Oh - and on my rubi LJ - no vibes, driveshaft angle looks good. Im sure a standard TJ would need all the usual stuff at this lift height, SYE, CV driveshaft, MML, etc....

New coil installed, with axle hanging - note the larger diameter - about the same as the stockers were.


Here is how it sits now. Quite a rake, but the front are stock springs with 2.25 pucks and my snow plow frame, winch, aftermarket bumper, etc. Now I can work on some front springs....

[95yj_bstick]

awesome!__

[tjthorson]

Originally Posted by 95yj_bstick

pics aren't showing up for me, problem on my end?

Sorry - my dynamic DNS account had expired - all renewed for another year.... Should see them now.

[cheapjeep06]

Try a zj v-8 front spring... I gained 1 1/2" over stock, but may not be stiif enough for you. I bought mine for $40 at a junkyard.



PS: has anyone ever tried an F-150 front coil?

[tjthorson]

Update - I found another rear spring option, which should sit 1 - 1.25 inches lower then the springs I installed - it would be another good one to try....

MOOG CC805 - mercury Maurauder rear springs.

Numbers on the ones I installed above:
Load 865
Spring Rate 206
Free Height 15.13

on the CC805
Load 770
Spring Rate 187
Free Height 14.00

This one might have been a better choice for me - I expect it to sit 1 - 1.25 inches lower then it does now.
I do have a little "shudder" at 30mph. I have some currie adjustable upper control arms on the way to dial in the pinion angle.....

[krawlerjeep]

did you ever find any moog spring to work in the front to level things out

[tjthorson]

Originally Posted by krawlerjeep

did you ever find any moog spring to work in the front to level things out

I havent - mostly because its snowing and im plowing like crazy with the jeep now. I WILL be finding front springs as soon as the snow melts and will report one I like. I wont be going as stiff over stock in the front, because I still want it to ride decent AND you typically dont load any cargo in the front. I will of course have my aftermarket front bumper and winch, so be sure to include that. I will be looking for a net 4" lift front spring, so the jeep should sit level. Sorry I cant do it now, and I dont want to just recommend something I havent installed.... As always, I figure I can go through 3-4 sets of experimental springs before I would have even paid for one set of aftermarket springs (which I may not like anyway).

I will report back my findings in the spring... Sorry for the wait!

[jeepinmichguy_]

good info

[Dog Man]

Great info thanks , I have been looking for a fix for my rear springs (to soft 180 spring rate) 206 spring rate should help out .

[timritchieblue]

just install some alcos in the front, and be done

[nfunlimited]

Is Moog a brand?? Can I just call my local parts supplier and give them the make model and year?? Just want to be sure to get the right springs. THis seems like the fix I am looking for, plus I can get it locally in Canada.

[tjthorson]

MOOG is an aftermarket company that makes replacement suspension parts for all types of vehicles in the US.... If you go to your local parts store and order a ball joint, tie rod, spring, etc - it can be from MOOG - or others.... I trust the MOOG name - and its fairly easy to cross reference specs to other springs to do what I did here with the jeep. (in the past , I successfully used IROC and S-10 springs in G-body cars (Grand nationals, etc) to lower the front 1" and make them handle like a slot car compared to the plush stockers.

In this case - if you cant directly order MOOG up there - you are looking for one of two vehicles to order springs for. The taller ones (look at my pictures carefully, I have 33s and the lift may be too high for you) or the other ones I would have tried had I found them first.. Right now, to not have any vibes, I have a TC drop and a MML. I will be getting the CV driveshaft and control arms in the spring, so it wont be an issue.

To recap:
10" from spring perch to spring perch on the backside of the axle (3.5" lift?)

1979 - 1996 Chevrolet Caprice Classic Wagon rear springs (MOOG Part# CC863)
specs:
Load Rating - 865
Spring Rate - 206
Free Height - 15.13

Estimed 9" from perch to perch
Mercury Maurauder rear springs. (2004?) - MOOG Part #CC805
Load 770
Spring Rate 187
Free Height 14.00

Note - I order all my springs right off the Amazon.com site - you might be able to do that in Canada, eh?

[nfunlimited]

You've definately done your research. I think the Marauder springs are for me as I have a bout 3" lift in the front, and a 1.25" BL. I'm happy with a 2.5" - 3" lift, I just want some load capacity, plus I don't have an SYE.

Thanks again.......ordering from Amazon sounds like a good idea, but I usually get nailed on duties. I think there is a local auto supplier that can help me.

I'm from Newfoundland.....so "right on by!" LOL!

[nfunlimited]

Does anyone know the spring rate on the 6AA oem jeep springs? That's what I had in my unlimited before the RC springs, and they were stiffer. Just trying to compare that to the mercury springs with the 187 spring rate.

[tjthorson]

I have heard that the 5aa/6aa are around 140.....