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ZJ coil spring question

PacificEd

NAXJA Member
NAXJA Member
Location
Middle Tennessee
I got in our 1998 Grand ZJ and noticed something was wrong. The rear passenger coil had almost completely collapsed with maybe a .25 inch of down travel left in the shock. The entire rear looks like it's sagging pretty bad now. The ZJ only has 167,000 miles on it. This thing is a DD so I'm surprised that it fatigued at such low (to me) mileage. Anyone ever had this happen?
 
Messed up pic.
 
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Here is the passenger rear spring.




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This sounds nuts but this morning it was still sagging. I went outside at 2:30 pm to tinker with it and it’s back up at ride height. What the.......? I took it for a drive and it was fine. I’m thinking the shocks were frozen? Is that possible? The shocks are of unknown age and are mounted piston up which I’m guessing has allowed moisture in.
 
Since the shocks were of questionable age and brand, I pulled the trigger and ordered a set of Bilstein 5100 shocks for the ZJ. My future plans are to go to OME HD 2.5" lift coils down the road, so the shocks are ordered to work with the future coils. The Jeep currently has a 2" BB lift puck in there now so everything should be good until the future mods begin.
 
This sounds nuts but this morning it was still sagging. I went outside at 2:30 pm to tinker with it and it’s back up at ride height. What the.......? I took it for a drive and it was fine. I’m thinking the shocks were frozen? Is that possible? The shocks are of unknown age and are mounted piston up which I’m guessing has allowed moisture in.

Well that's bizarre. Definitely seems like a shock issue tho like you said. I've seen some struts totally lock up before so doesn't seem totally out of the question.
 
The shock issue does make sense. Especially since you don't get as hard of cold weather as others...and it's been cold lately.

mac 'it is odd' gyvr
 
I asked the guys at O'Reilly's that I do a lot of business with about frozen shocks and what could have caused what happened. They said they have never seen shocks freeze and were really at a loss as to what could have happened.

Hopefully the shocks will be here soon so I can check this off my list of things to do.
 
I got the Bilstein shocks but I'm worried that since the coil compressed once, it might do it again. I'd sure hate to ruin a new shock.

What do you guys think?
 
I got the Bilstein shocks but I'm worried that since the coil compressed once, it might do it again. I'd sure hate to ruin a new shock.

What do you guys think?



Im not sure what you are worried about exactly?

mac ‘more deets pls’ gyvr
 
I've made the assumption that the compressed coil issue was solely shock related. If a coil collapses like mine did and then comes back to normal, can it be ruled out as the cause of the ZJ sagging? If I install the new shocks and it turns out the coil is weakened, and the coil fails again, the shock will beat itself since it becomes the part that limits travel.
 
lol i think you are over thinking this

i'd put the shocks on it and call it a day...

mac 'not your dads leaf springs' gyvr
 
lol i think you are over thinking this

i'd put the shocks on it and call it a day...

mac 'not your dads leaf springs' gyvr

I have a tendency to do that. Thanks for the input.
 
Agreed. It would be the first instance I've ever heard of a coil intermittently sagging. I think you'll be fine.

That is what I wanted to hear.
 
My 2.2 cents, cause I've seen similar things before.

The ZJ rear coils are fairly soft. My money is on how the vehicle was parked causing the rear suspension to get loaded up and the ride height is what happens due to the geometry. Think squat/anti-squat.

--Matt
 
I got the Bilstein shocks installed Saturday and they seem to have made a nice improvement in ride quality. I'm really happy with them.
 
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