Clunk in rear end

daytona701 · **Joined:** Sat Oct 20, 2012 11:32 pm **Posts:** 99

Heavy loud clunk coming from rear end when going from park to reverse or drive. Lots of gear oil flung out of pinion seal across floor pan and frame. Replaced driver side outer wheel bearing and axle some time ago. Filled with 90# gear oil and level was holding between oil changes. It’s a 2005. Questions are how much allowance for pinion gear to move back and forth is considered normal? Is the gear ratio 3.73? Is it a Chrysler 8.25 rear end? If the rear end needs to be opened and rebuilt may install Detroit TruTrack as others have done.

DieselJeepLuvr · **Posted:** Thu Aug 31, 2023 12:02 pm

Mines been doing that for the last 100,000 miles.

daytona701 · **Joined:** Sat Oct 20, 2012 11:32 pm **Posts:** 99

Jeep has 196,500 and is running well.

WWDiesel · **Posted:** Thu Aug 31, 2023 12:36 pm

If your pinion seal is leaking, you should replace it. 0.003-0.006 is the normal allowable pinion to ring gear backlash measured inside the differential with a dial indicator. When testing pinion backlash from the outside with the driveshaft, keep in mind you are also feeling all the slop in the spider side gears and axle gears and it adds up. Only true way is to open up differential and inspect everything closely.

Clunk you hear is most likely the weak factory upper rear control arm bushings, at the body mounting location up right under the rear seat, are worn out and allowing a lot of movement of the control arm when going from F to R. It will actually allow the metal control arm to make contact with the metal body making a loud clunking noise even when the transmission upshifts or downshifts or goes from F to R.

Best solution is to replace the crappy weak OEM control arm with a IronRock control arm. Bushings are much stiffer and are replaceable if they ever get weak which they will not. The IronRock control arm also has an adjustable HEIM joint on the differential end mount that is greaseable and rebuildable. This allows for adjusting and setting pinion angle correctly when installing a lift kit.
This arm was designed for the much larger and heavier Jeep Grand Cherokee (WJ) so it is super heavy duty for the smaller Jeep Liberty.
Control Arms - Iron Rock Off Road

daytona701 · **Joined:** Sat Oct 20, 2012 11:32 pm **Posts:** 99

I replaced the upper rear end control arm not long ago. Is the rear end a Chrysler 8.25 with 3.73 ratio? If so what Detroit TruTrack part# will work? When throttling the Jeep changes direction. I’m thinking the TruTrack would apply torque evenly to both rear wheels and keep the Jeep straight going down the road in dry conditions. Change of direction is most noticeable when cruising on the interstate and lifting my foot off the throttle. Currently have front driveshaft on bench to rebuild not that it pertains to this discussion.

CATCRD · **Posted:** Fri Sep 08, 2023 9:25 am

The rear is an 8.25, 3.73 from the factory but I forget what spline. I can't find the part number of the trutrack I used in the rear. But I see they have the elocker available for the 8.25 now. That could be cool. I love mine in the front but it wasn't available for the rear 10 years ago.

The directional change you describe really sounds like a control arm bushing issue. I have the iron rock lowers installed. Still getting around to putting the top one in. My replacement Mevotech upper only lasted a year, so it's not out of the question for you.

03black · **Posted:** Fri Sep 08, 2023 10:48 am

The "dancing" the rear end does when going off and on the throttle (as I call it) is definitely the rear lower control arms. There was a recall from jeep to have the arms replaced due to the arms rusting out and the possible breakage when driving...bad things will happen if that occurs. Call up your local Jeep dealership and see if your had the recall done and you might get a them replaced for free.

As for what axle you have, yes it is a Chrysler 8.25 and if memory serves me right, only the gasser 2.5L came with a different gear set ratio (the coveted 4:10s) so your would be 3:73 gear ratio set for those with automatic transmissions (same gear ratio for the gasser 3.7L). I think the manual transmissions came with a 3:55 gear sets but don't quote me on that as I am not 100% sure, beside those are rare in the US.

The clunk in the rear end can be caused by either the upper control arm, the ring and pinon gear set backlash is out of tolerance, or the lower control arms being bad and about to break. All of it can be fixed if you have the knowledge and follow the service manual which can be found/download link if you do a search on here.

WWDiesel · **Posted:** Fri Sep 08, 2023 1:45 pm

Replace all the weak factory junk with adjustable super heavy duty IronRock rear upper and lower control arms and your will never have any issues with the rear axle making clunking noises again and the rear suspension will be rock solid. Jeep will handle and ride better as well.

daytona701 · **Joined:** Sat Oct 20, 2012 11:32 pm **Posts:** 99

Iron Rock Off-road parts look good. Clunk was from worn out driver side lower control arm bushing. Replaced both lower control arms with parts from Detroit Axle. Filled the voids in the control arm bushings with silicone before installing. Also rebuilt both ends of front driveshaft. I’ve got 4 vehicles with over a million miles combined that are all running well today. With all the parts needed to maintain the vehicles it’s hard to justify putting high end components sometimes. At this point I have about $4,500 in upgrades to the Liberty since I bought it with 90,000 miles for $9000. It has 198,000 miles now and hoping to get at least 400,000 miles with the upgrades that have been done. It’s a lot of fun to drive. On a different note I lost my cell phone some months ago and searched my shop at least 20 times because that was where I remembered having the phone the last time I used it. Ended up getting a new phone after a couple of weeks and luckily was able to retrieve my old contacts. Working on the Liberty recently I found the lost phone sitting on top of the battery. Lesson is if you lose your phone don’t forget to check the engine compartment. Thanks for the advice WW Diesel.

taroo · **Joined:** Sun Apr 27, 2008 2:14 pm **Posts:** 278

Had the clunk in the worst way. Pulled the rear upper and replaced the bushings. The problem went away. That said, the Iron Rock solution looks interesting

Clunk in rear end

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