Knock in rear end after 4" JBA lift

Natidog · **Joined:** Tue Oct 19, 2010 10:22 pm **Posts:** 23

I have a knock in the rear end when I rock the Jeep from side to side or grab the stabilizer bar links under the Jeep and pull side to side. I've retorqued everything including the sway bar brackets after some light wheeling. I've only had the lift on for about 100 mile.

The noise doesn't actually seem to be coming from the suspension, and I have retorqued every bolt that holds the rear axle onto the vehicle. The noise actually sounds like it's coming from above the spare tire. I have taken everything out of my cargo compartments and have dropped and reseated the spare tire several times, but the noise is still there. Also, the noise is not muffled like it is inside the vehicle.

It takes very little side to side movement to make the noise, but it doesn't sound damaging. No problems in the way it drives and the alignment came out fine.

Any insight would be awesome.

Jeepin_it_real · **Posted:** Sun Dec 11, 2011 8:57 pm

check your drive shaft and the gas tank skid

DirtyKK · **Posted:** Sun Dec 11, 2011 10:19 pm

put money on it being the axle shafts moving slightly side to side in the axle. it probably wasnt noticeable before the lift because the track bar had bushings, now its solid making it more noticeable. the axle shafts are held in with c-clips and a little bit of in and out play is normal.

Natidog · **Joined:** Tue Oct 19, 2010 10:22 pm **Posts:** 23

Very much appreciate the input. Double checked the axle, it clears at full extension and compression.

I over-torqued the rear sway bar mounts to 90ft-lbs and double checked it with a second torque wrench. The original noise is gone and all there is now is a very slight knock which I think is the axle shaft. It's not noticable from the cab.

Thanks again. Runs like a champ through all the nasty, mud/ice/slush holes we have right now. It was -20F degrees here two weeks ago, now it's December in Alaska and 37F...

hislop · **Posted:** Thu Dec 15, 2011 8:02 pm

i have the same knock with mine, my friends are afraid to ride in the back cause they think my jeep will fall apart

JL Rockies · **Posted:** Thu Dec 15, 2011 10:32 pm

Just Be Aware that it won't be fixed until people complain about it. It's the root of in-field R&D. Welcome to the team.

musclezmarinara · **Posted:** Fri Dec 16, 2011 10:28 am

I might put money on the rear shocks moving left to right because the bushing is to big for the OEM Bolt.

clacker · **Posted:** Fri Dec 16, 2011 10:46 pm

some of my knocking noises were coming from the new rear tracbar floating around on the joints. Since those are hiem joints with no rubber bushings, as the bar rotates, the joints bump into the bracket on the body side

Natidog · **Joined:** Tue Oct 19, 2010 10:22 pm **Posts:** 23

clacker wrote:

some of my knocking noises were coming from the new rear tracbar floating around on the joints. Since those are hiem joints with no rubber bushings, as the bar rotates, the joints bump into the bracket on the body side

This sounds promising too. I may try mounting some rubber on the brackets where the tracbar balls hit when I get home from work in a week.

Texasrugby911 · **Joined:** Thu Feb 04, 2010 3:18 pm **Posts:** 196

Natidog wrote:

clacker wrote:

some of my knocking noises were coming from the new rear tracbar floating around on the joints. Since those are hiem joints with no rubber bushings, as the bar rotates, the joints bump into the bracket on the body side

This sounds promising too. I may try mounting some rubber on the brackets where the tracbar balls hit when I get home from work in a week.

I would almost guarantee this is the problem. While installing the rear of the lift a bolt on the swag bar snapped. I then made the executive decision to leave the swag bar off for good. I have no noises while on flat road, since the track bar is not torquing or flexing, but as soon as I hit the trails or any rough roads I hear the thing all the time. It doesn't really bother me but I also wouldn't mind it gone. Let me know if you fix the noise and how you did it.

jezza · **Joined:** Fri Mar 25, 2011 9:16 pm **Posts:** 4

Hi all,

I've got the same noise and it's driving me mad.

Did anyone work out what it was?

Cheers

hislop · **Posted:** Mon Jun 18, 2012 7:12 pm

hey guys, update, Jeepin by al put up the heim joints to buy now. So i bought a new pair (they are different) and now i have no more noise from the rear.

http://jeepinbyal.com/cat-Ball_Joints_a ... K-128.aspx

Texasrugby911 · **Joined:** Thu Feb 04, 2010 3:18 pm **Posts:** 196

Bump

Hey hislop,
Are you still experiencing no noise from the rear? I bought a set but had to deploy before I could install them. That knocking was driving me up a wall!!

lfhoward · **Posted:** Sat Jan 26, 2013 10:51 am

Hi Texasrugby911,
Hislop traded in his KK on another vehicle, but before he did he put it back to stock. He sold me his 4" JBA lift kit :BANANA:

, but I won't be able to get it installed on my KK until March. JeepNCrowd is the most recent LOST member to install a JBA 4" lift on his KK. He has a thread about banging in the rear end, but I think he and Diggerfreek have narrowed it down to the driveshaft hitting the gas tank skid at full extension. Here is JeepNCrowd's thread. http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=88&t=73878&p=772800#p772800

Diggerfreek · **Posted:** Sat Jan 26, 2013 5:55 pm

It's either the drive shaft or I know on my KK I also have a noisy track bar that bangs a little when i hit a small bump in the road...

27tubguy · **Joined:** Sun Dec 30, 2012 10:45 pm **Posts:** 8

musclezmarinara wrote:

I might put money on the rear shocks moving left to right because the bushing is to big for the OEM Bolt.

he sent me a set of roller bushings for that exact bolt.

Knock in rear end after 4" JBA lift

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