LJ Rear springs solution

glockman

I hate Jeeps
Location
Pleasant Grove
#1
My wife's LJ has had a saggy floppy rear end the entire time I have owned it. It had Teraflex 3" coils all around with 9550 shocks for the first couple years. The rear would bottom over just about any bump over 10mph.

I replaced the coils with Teraflex's 4" coils. At the time I called Teraflex and asked if they had a coil with a spring rate to compensate for the added weight of an LJ. They said the 4" coils had a higher rate (245lb I think) than the 3' coils. So I went that route and replaced the leaking 9550's. The bottoming resistance was significantly better but degraded over time an I didn't realize it.

Now that I am running the almighty Falcons, the ride is WAY better than with the 9550 shocks. The rear shocks had 25k miles on them and were again leaking. I still have the bottoming issue but it is significantly better. It takes washouts at 20mph to bottom the rear.

The LJ has 35's with a full size spare and Poison spider rear crusher corners in steel. Does anyone know of a better spring for the rear of a heavy LJ?

I have been leaning towards aluminum rear corners and gas tank skid to reduce weight but I think I am putting the cart before the horse. Maybe progressive rate springs are the answer. Metal cloak makes some decent looking units.
 

pkrfctr

Registered User
Location
Spanish Fork, UT
#2
I really liked my AEV springs in the LJ. I had hundreds of pounds of weight back (tools, spares) there plus the tank shifted back and never had any issues. You can still get the springs from nth degree.
 

DAA

Premium Member
Premium Member
#3
AEV progressive rate springs on mine too, all around. I bet I have bottomed out the bumps less than five times total, ever. Very rare thing for that to happen. It actually seems like it wants to bottom more now with the Falcons than it did with the ten year old Bilstein 5100's, to be honest. But it damps out way faster. Loaded with gear or empty, the AEV springs ride nicer than the OME HD springs I had on it for awhile before the AEV. Those OME's were harsh empty and over powered when loaded down - they sucked. The front AEV's are awesome too. First couple inches are pillowy soft but firm up very nicely.

Almost everyone who rides in my LJ, even before the Falcons, comments on how surprisingly nice it rides.

- DAA
 

DAA

Premium Member
Premium Member
#5
Double PS... They are AEV now. They were Nth when I bought them and at that time they had both TJ and LJ rate 3" springs. I of course have the LJ. They were corner specific too. Ten years before that became a thing :D.

- DAA
 

pkrfctr

Registered User
Location
Spanish Fork, UT
#6
Double PS... They are AEV now. They were Nth when I bought them and at that time they had both TJ and LJ rate 3" springs. I of course have the LJ. They were corner specific too. Ten years before that became a thing :D.

- DAA
AEV sold the Nth line a few years back to knowwheretojeep, they now run nthdegree.com. I dont think AEV is doing anything TJ/LJ related anymore.
 

Gravy

Edd China of Dirtbikes
Premium Member
#7
I've used ZJ rear lift springs in the rear of my stretched TJ. I couldn't find a TJ spring with a high enough rate to damp my much heaver unsprung weight from that Dana 60 and super heaver steel beadlocks and swampers...... and I liked to jump my TJ. They were Clayton Offroad 4" V8 ZJ springs (on the front too) and I netted maybe 0.5" more lift. But the coils are a thicker guage.
 
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DAA

Premium Member
Premium Member
#10
Bummer... I have heard several guys with the Currie's say they sag pretty bad pretty quick. But they also say they do ride nice and if you want 3", that sagging might work out :D.

I don't know anyone running the Metal Cloak.

- DAA
 
#12
Do you have a belly up? If so that angle could be affecting your coil rate. If that’s the case, relocating the upper coil mount to the top of the arch may help. I did that with some improvement, but I’m still not super happy with my RK 2.5” coils. I used the Artec coil correction kit, but I’m kinda wishing I would have used the Teraflex speed bump to do the same thing as well as add a softer bottom out.
 

glockman

I hate Jeeps
Location
Pleasant Grove
#13
I do have a belly up. My lift is a Tera LCG kit. I don't know how that affects the coil rate? I moved the upper rear coil mount to center over the axle to straighten the rear coils. I cut the stock buckets off and moved them back and rewelded them. It improved the bottoming slightly but I went to the 4" coils at the same time so it's hard to say what part the coils vs the bucket relocation played. It still bottomed very easily, baby steps though lol. I am also considering the Tera Speed bumps. However, I feel like I should correct the spring issue vs put a speed bump in to absorb the bottoming caused by improper coil rates.

Edit: I see what you mean. The belly up rotates the axle and turns the rear coils more if I hadn't relocated the upper spring mount.
 
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DAA

Premium Member
Premium Member
#15
Edit: I see what you mean. The belly up rotates the axle and turns the rear coils more if I hadn't relocated the upper spring mount.
Are you still running the stock rear drive shaft or did you change to a CV? I'm still using the factory rear drive shaft, so with belly up and lift, I just needed to rotate my pinion down a bit. Opposite of what usually happens when running a CV shaft where you have to rotate the pinion up. Anyway, my coils aren't bowed much at all, in the factory position. Nothing anyone would ever go to the trouble of trying to correct.

But the frequent bottoming you are experiencing has me wondering. Mine, literally, I'm not exaggerating, it almost never bottoms out. I mean, very, very rarely. I have to hit something pretty big at pretty high speed, like didn't see it coming oh shit hold on type stuff. Put it this way, if my rear is bottoming out, there is some air under the tires. So I'm not too sure why yours is bottoming out so easily.

My first guess, might have been that your old shocks were too long for your lift, which would certainly do it and if not bump stopped all to hell would cause your leaking shocks too. But the Falcons are definitely not too long for the rear.

Are you bottoming on your bumpstops as I would hope, not the shocks? Is it just a case of just having a ton of bump stop and very little uptravel?. I really don't know. Something is weird though. Mine has to be at least as heavy as yours and I would bet even heavier. But like I said, it just almost never bottoms out the rear. I setup the bump stops with the rubber bumpers and the coil springs out, so using a floor jack to put each side at full bump, metal to metal, the original Bilsteins were just 1/4" short of full compression. So I was getting as much uptravel out of the shocks as possible without danger of over compressing and causing them to leak. I would suspect you just have a ton of bump and not much uptravel if it weren't for the old shocks leaking - indicating they were over compressing. But, again, possibly they were just too long for the lift?

Guess maybe it is the springs, like you are thinking? I really don't know. But it's something and I bet you can figure it out and correct it.

- DAA
 

glockman

I hate Jeeps
Location
Pleasant Grove
#17
Those are really good points Dave. I have never pulled both springs out and verified where my bumps are in relation to every thing else. I've just measured up travel sitting flat and measured the shock exposed rod length. I've flexed it and made sure it's hitting the bumps, but that isn't the same as a flat hit where both sides compress. I get dark marks on the rubber so I know they are hitting but when and before what is a great question. My rear track bar sometimes makes contact with the cross member in the frame above it (where the front of the gas tank skid mounts). I'm running the stock track bar with the bracket on the axle that raises it. I have been thinking about lowering the hole on that bracket, getting an adjustable rear or going with triangulated uppers and ditching the rear track bar.

This has me thinking.
1. Maybe it's not actually bottoming and it's always the track bar hitting that I hear/feel not the bump stops. I assumed it was the other way around.
2. Shocks where too long and were bottoming but aren't now, that's why it improved with the Falcons.

Looks like I've got some springs to pull and some measuring to do.
 

DAA

Premium Member
Premium Member
#18
FWIW... I just put some wheel spacers on today. Looked at my rear bump stops while I had the tires off. Did not actually measure, but they are only extended about 1.25" from factory. The rear Falcons are exactly the same compressed length as my old Bilsteins (for 3" lift) so I left those bump stops alone when changing shocks. When fully stuffed, my 35" KM2's do just barely, barely kiss the rear fender. But so barely, that they stop rubbing after they get worn down a bit, after 11 years, the paint hasn't even worn all the way through. So I have never worried about that very light contact. Like I said, using all the uptravel the setup can give on 35's. The only way to get more would be even less bump stop and trimming the fenders but I'm happy with how it works as is.

- DAA
 

glockman

I hate Jeeps
Location
Pleasant Grove
#19
FWIW... I just put some wheel spacers on today. Looked at my rear bump stops while I had the tires off. Did not actually measure, but they are only extended about 1.25" from factory. The rear Falcons are exactly the same compressed length as my old Bilsteins (for 3" lift) so I left those bump stops alone when changing shocks. When fully stuffed, my 35" KM2's do just barely, barely kiss the rear fender. But so barely, that they stop rubbing after they get worn down a bit, after 11 years, the paint hasn't even worn all the way through. So I have never worried about that very light contact. Like I said, using all the uptravel the setup can give on 35's. The only way to get more would be even less bump stop and trimming the fenders but I'm happy with how it works as is.

- DAA
What rear track bar setup are you running Dave?
I pulled the springs and indeed I am bottoming the track bar on the cross member. It is making contact just before my bump stops touch. The bolt on the tank has worn a groove into the track bar and the bar may even be slightly bent. Hard to see but here is the track bar about 1/2" prior to the bump stops touching. I'm sure when the rubber on the bumps compresses the track bar is hard into the crossmember and deflecting.
20190104_160456 (640x480).jpg
20190104_160310 (640x480).jpg


I have plenty of tire clearance with 4" of lift and 35's. This is at full bump.


20190104_155807 (480x640).jpg



I found a couple other issues too. The track bar is obviously rubbing the gas tank skid and my Falcons are really close to bottomed out at full compression, as in 1/4" from bottomed. I was running upper bar pin eliminators on the 9550s but didn't press the bar pins out on the Falcons. This puts the top of the shock about 1" lower than the 9550's were. So I will be moving the eliminators over to the Falcons. The passenger side upper coil bucket was also slightly bent causing the bump stops to not line up perfectly but they were still making contact.

Option 1. Add more bump stop, which will correct my shock bottoming and the track bar hitting. This would be easy and cheap but I'd still have to deal with the upper coil bracket and I'd have up travel really limited for the tire size I am running. This also doesn't resolve the rear end blowing through the travel so fast and so often either.

Option 2 Cut the upper buckets off, install Teraflex speed bumps. This resolves the springs blowing through their travel and bottoming. With my current lower bumps and the speed bumps I should have slightly less up travel than I have now but it will be more usable.

I called up Mesha and had him order the speed bumps. I'll have them next week and report back.

I am going to try and lower the axle side track bar bolt slightly or put it back in the stock bracket and lengthen the bar. One of those two should help get me some more clearance on the cross member. I can't lower the frame side due to exhaust clearance.
 

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DAA

Premium Member
Premium Member
#20
I'm using a JKS adjustable rear track bar, the non CV one. It clears everything. But just barely. Speed bumps would be way cool but I'm petty sure they are too long for my 3 inch lift. I think I'd have to give up some uptravel to use them and I don't want to do that.

- DAA
 
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