Rear UCA Clunk (Accel / Brake / Bumps) - Solution Methodology

elafilos

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Hi Guys - been lurking on this forum for quite a while -got a KJ 3.7 renegade with almost 200.000 KM (124.000 miles) which has been through some serious abuse during it's lifetime.

Long story short - My car has been long overdue for a rear bushings overhaul so I decided to replace everything last week. Was running short of time so I had it done by a shop locally.

Bought new LCA (assembled with bushing) and the bushings / BJ to be pressed on the tri link. Note that I am running stock wheels with 235 / 70 / 16 BFG MT and OME 2.5 Lift (shocks / springs).

Immediately after getting my car back and driving it I noticed the dreaded rear clunk. I had to travel with the car since we were filming through the weekend in some remote locations where the problem became WAY more evident. Anyhow - got some time tomorrow evening to work on the car, since I have read almost everything concerning my issue - I am pretty sure (!) - that my issue is going to be on the UCA area and not the LCA. So that are the steps I am going to follow - please fill free to chip in if I am missing anything.

1. Check LCA assembly for play
2. Check LCA torque specs / bolts

If both are OK move to UCA

3. Make sure that the BJ bolt is in place and there is no evident play
4. Jack the vehicle and loosen the 2 bushing bolts
5. Lower the vehicle and tighten according to specs

At this point should test if the issue is remedied - if not move to step 6

6. Remove the whole tri-link assembly
7. Tack weld the BJ + Bushings
8. Follow step 4 and 5 again

If still it's not fixed - I should either order a new one or fabricate one since the issue would be deformation.

Any other ideas / suggestions? The car was "fine" before working on my Rear CAs, so there must be related.
 

tommudd

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It is really hard to press in new ball joint and new bushings into the Tri link
Many have tried and failed as the tri link will bend/ crush some and not worth the hassle
Check the bolts holding the bracket to the diff as well
Had a customer have work done at a 4X4 shop, they left bolts loose and almost fell out

also check the upper bolts on the rear shocks , just in case they removed them for some unknown reason
They clunk at times just slightly loose
 

elafilos

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Thanks for the reply Tom.

I would check those out too just in case they forgot (!) to torque something. Can't really explain how hard it is to find a specialized shop in Greece right now - that's why most of the times I am working on my own fixing random things clueless mechanics have done to my car.

Quick update on the issue - just got off the phone with the shop which failed the job and their answer was hilarious. They claimed that the issue is caused by bad alignment of the new Tri-link due to my lift, and that the clunking comes from the Tri-link binding at it's upper mount points. I could prove with math that this is not even remotely possible but not even worth the hassle.

In case they bended / crushed the Tri Link do you thing that tack welding it would remedy the issue? Looking for a spot fix right now - since next weekend we'll be filming again and would need to use the car for a couple of days.

@tommudd Any chance you are travelling to Greece this summer? Lot's of KJs here being neglected / fitted by clueless mechanics.
 

elafilos

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Quick update.

The bushing popped off the Tri Link.

Got the car back to the shop since it was under their "10 day warranty" to fix it. They kept insisting that the Tri-Link angle was too steep blah blah blah.

Anyways - told them to weld it once for good and in the meantime I am going to either order a new tri-link with a custom diff mount - or just work on designing my own.

Thanks for all the help.


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hvacmrm

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Hi Guys - been lurking on this forum for quite a while -got a KJ 3.7 renegade with almost 200.000 KM (124.000 miles) which has been through some serious abuse during it's lifetime.

Long story short - My car has been long overdue for a rear bushings overhaul so I decided to replace everything last week. Was running short of time so I had it done by a shop locally.

Bought new LCA (assembled with bushing) and the bushings / BJ to be pressed on the tri link. Note that I am running stock wheels with 235 / 70 / 16 BFG MT and OME 2.5 Lift (shocks / springs).

Immediately after getting my car back and driving it I noticed the dreaded rear clunk. I had to travel with the car since we were filming through the weekend in some remote locations where the problem became WAY more evident. Anyhow - got some time tomorrow evening to work on the car, since I have read almost everything concerning my issue - I am pretty sure (!) - that my issue is going to be on the UCA area and not the LCA. So that are the steps I am going to follow - please fill free to chip in if I am missing anything.

1. Check LCA assembly for play
2. Check LCA torque specs / bolts

If both are OK move to UCA

3. Make sure that the BJ bolt is in place and there is no evident play
4. Jack the vehicle and loosen the 2 bushing bolts
5. Lower the vehicle and tighten according to specs

At this point should test if the issue is remedied - if not move to step 6

6. Remove the whole tri-link assembly
7. Tack weld the BJ + Bushings
8. Follow step 4 and 5 again

If still it's not fixed - I should either order a new one or fabricate one since the issue would be deformation.

Any other ideas / suggestions? The car was "fine" before working on my Rear CAs, so there must be related.
Hey Elafilos,
I noticed on both mine,(02 and 03) when LCA bushing was cracked I had no noise but on and of the gas was like having a rear stear vehicle and whe upper went,, I had the clunk and a lot of side to side sway..
That ball joint on the UCA takes a lot of abuse and wears out quick for the cost of the UCA.
Just throwing in my experience with both of my liberty rear control arm issues.
 

elafilos

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Hey hvacmrm,

Was having the exact same issue. Anyways - did it myself last night. Jacked the car and removed the tri-link , pressed the bushings with a vice and stick welded them in place.

Already ordered a new tri-link to redo it ASAP. Can't stand having parts ready to fail under my car.
 
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