Rear upper control arm.

Kevin.womacks · Aug 9, 2024

I am not terribly mechanically inclined for starts.
I have a 2004 manual Liberty.
Just wondering if a bad rear upper control arm could cause a horrible clunk sound when accelerating after a shift.
My mechanic suggested drive shaft, but everything seems tight there.

Thanks in advance.

duderz7 · Aug 10, 2024

Certainly could. The ball joint on top of the diff is usually to blame.

KJowner · Aug 10, 2024

Mine clunked on overrun and acceleration, one of the bushes had disinterested so the arm was hitting the mount.
The a frame is a well known weak point.

DadOSix · Aug 10, 2024

Usually it is the rear upper control arm. Ball joint first suspect, bushings second suspect.
My 04 had a new upper sometime ago and i was driving her home from Baltimore and we were all over the road on throttle changes - gas on, sway right, gas off, sway left.
Turns out it was the lower control arm bushings this time, even tho they had been replaced under the recall program way back. Nothing rubber lasts forever. Check them all.

The upper can be DIY if you think it thru. And it does not involve dropping the whole rear down for access. Just a few jack stands and enough room is available to sneak it out the left side of the jeep. Many threads on here discuss. I admit, it is easier in the air with a proper lift, but it can be done on the floor. Same with the lowers. Worst part of that one is the muffler is in the way of removing the front bolt on the right side.

seafish · Aug 10, 2024

Replacing the rear UCA is not really a difficult job.
IMO, there are really only two problems

1) The dirt that will be falling all over your face as you work to remove it

2) Finding the OEM balljoint or even another high quality aftermarket BJ

The former can be dealt with by pressure washing under the Jeep before you attempt the replacement
Unfortunately the latter is a difficult situation as the OEM upper balljoint is no longer being made even if you had the $300 to buy it and AFAICT the replacement aftermarket ones are generally made from shoddy materials, no matter which one you choose.

Kevin.womacks · Aug 10, 2024

DadOSix said:
Usually it is the rear upper control arm. Ball joint first suspect, bushings second suspect.
My 04 had a new upper sometime ago and i was driving her home from Baltimore and we were all over the road on throttle changes - gas on, sway right, gas off, sway left.
Turns out it was the lower control arm bushings this time, even tho they had been replaced under the recall program way back. Nothing rubber lasts forever. Check them all.

The upper can be DIY if you think it thru. And it does not involve dropping the whole rear down for access. Just a few jack stands and enough room is available to sneak it out the left side of the jeep. Many threads on here discuss. I admit, it is easier in the air with a proper lift, but it can be done on the floor. Same with the lowers. Worst part of that one is the muffler is in the way of removing the front bolt on the right side.

Thanks for the detailed reply.
I saw a video that did it the way you describe. Better than taking everything apart as manual would suggest.

Kevin.womacks · Aug 10, 2024

seafish said:
Replacing the rear UCA is not really a difficult job.
IMO, there are really only two problems

1) The dirt that will be falling all over your face as you work to remove it

2) Finding the OEM balljoint or even another high quality aftermarket BJ

The former can be dealt with by pressure washing under the Jeep before you attempt the replacement
Unfortunately the latter is a difficult situation as the OEM upper balljoint is no longer being made even if you had the $300 to buy it and AFAICT the replacement aftermarket ones are generally made from shoddy materials, no matter which one you choose.

Thanks.
I figure even a crappy aftermarket has got to be better than a broken OEM.
Haha.
I actually found a brand new upper control arm in the back of a Liberty in the salvage yard. Still in plastic.
Hopefully it is decent enough.

vlad588 · Aug 10, 2024

Do yourself a favour and buy iron rock upper control arm. They are much better quality and will last way longer.

seafish · Aug 10, 2024

vlad588 said:
Do yourself a favour and buy iron rock upper control arm.

Do they work with a stock height KJ??

Ramstrez · Aug 11, 2024

2nd the iron rock, i have one and they are amazing quality
not sure if they work with a stock liberty or not, they are adjustable so i would think they could.

JeepinSteve · Aug 12, 2024

There is a Recall on the Rear Lower Control Arms.

https://static.nhtsa.gov/odi/rcl/2018/RCRIT-18V278-7810.pdf

DadOSix · Aug 12, 2024

JeepinSteve said:
There is a Recall on the Rear Lower Control Arms.

https://static.nhtsa.gov/odi/rcl/2018/RCRIT-18V278-7810.pdf

True - they will replace once per vehicle.

seafish · Aug 12, 2024

Yes I had to replace the UCA to get rid of the shift point clunk, but when Jeep replaced the LCAs under recall, Giddyup was once again able to ride without swerving both when full out galloping or slowing down.

Deb'nKJ · Aug 13, 2024

Mine failed inspection, which came as a total surprise as even when removed I couldn't find anything really wrong, although the bushings were showing their age.
An interesting job, I consider it an achievement but it's not one I'm anxious to repeat. Would I have started, knowing what I learned in the course of adding to my experience? No, I would have saved the cost of the part & weighed the KJ in for scrap, as it couldn't possibly be worth the cost of having it done professionally.

KJowner · Aug 13, 2024

Yours must have been well stuck for some reason, I've done them on both of mine and they weren't that bad, a bit of jiggling with jacks and a chisel to open the clamp a bit and they pop off.

vlad588 · Aug 14, 2024

seafish said:
Do they work with a stock height KJ??

Yeah they do

Deb'nKJ · Aug 15, 2024

KJowner said:
Yours must have been well stuck for some reason, I've done them on both of mine and they weren't that bad, a bit of jiggling with jacks and a chisel to open the clamp a bit and they pop off.

I suspect we exchanged views/experiences over the month (i.e.4 or 5 consecutive weekends) it took me. I was thwarted by no line of sight on the clamp, no possible way of inserting anything into it - or applying enough effort to the stud to push it out. Reassembly was almost as bad, I think that only took 3 days.
I do remember the MoT tester, who had some experience of KJ's, saying, when I suggested I might simply replace the whole thing (rather than re-bushing), "If you can, without dropping the axle"

Rear upper control arm.

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