Knocking noise on takeoff only

[Paco1210TJ]

2002 Jeep Wrangler TJ x

Good day folks! Hoping to get some insight on an issue. It’s my first time posting so bear with me if I don’t have this down yet lol .

I have a knocking noise only on take off. Goes away after 10mph. I just recently put a 4inch rough country lift kit. (No SYE installed)
New sway bar end links and new upper and Lower control arms.
Everything was just tightened down the other day. I also inpected ALL UJoints and everything checks out on those. Checked driveshaft for an play and nothing out of the ordinary.

Knocking noise is just on take off for a few seconds then goes away. Next step would be carrier bearing?
Not too savy on knowledge and this is my first Jeep. Thanks a bunch on any advice! I put a video also but not too good. Thanks again!

 

[TJBob]

Couldn’t make out the sound your talking about in your video... Have you checked your transmission, and motor mounts... if those check out, remove one driveshaft at a time to see if you can isolate the issue. If those check out, go Back over all the newly installed parts and check torque. Control arms should be torqued with the vehicle on the ground.

 

[06lj]

I couldn't hear anything in the audio either. Did the knocking start immediately after you installed the lift?

 

[Gollywomper]

Did you install a skid plate drop? Can barely hear it. Sounds maybe driveline related.

 

[astjp2]

Well what ever it is, it sounds expensive! Haha just kidding, just start with the advice above.

 

[Paco1210TJ]

Couldn’t make out the sound your talking about in your video... Have you checked your transmission, and motor mounts... if those check out, remove one driveshaft at a time to see if you can isolate the issue. If those check out, go Back over all the newly installed parts and check torque. Control arms should be torqued with the vehicle on the ground.

What’s up!
Thanks for your reply!
I have checked motor mounts and transmission. I took it for a drive today again and the sound is most definitely coming from underneath the shifter (automatic). I took a look at the driveshaft and as of now no wear and tear on the ujoints that I can see. There isn’t any play with the drive shaft either. This issue don’t not happen in 4H or 4L. Also when I put it in Nuetral and rev the engine it does not happen. Maybe the carrier bearing?

 

[EzPeezy]

It sounds like you're looking for a reason to check your carrier bearings

Pull the diff cover, pull the axles, crank the carrier out and see how the bearings spin.

 

[Leakey]

2002 Jeep Wrangler TJ x

Good day folks! Hoping to get some insight on an issue. It’s my first time posting so bear with me if I don’t have this down yet lol .

I have a knocking noise only on take off. Goes away after 10mph. I just recently put a 4inch rough country lift kit. (No SYE installed)
New sway bar end links and new upper and Lower control arms.
Everything was just tightened down the other day. I also inpected ALL UJoints and everything checks out on those. Checked driveshaft for an play and nothing out of the ordinary.

Knocking noise is just on take off for a few seconds then goes away. Next step would be carrier bearing?
Not too savy on knowledge and this is my first Jeep. Thanks a bunch on any advice! I put a video also but not too good. Thanks again!

View attachment 106193

So I think this is an issue with Rough Country control arms. I have a set of their long arms and experience (what I assume) the same noise. The noise started right after I installed the arm's, I believe it is coming from their X flex joints. I'm replacing them with Savvy arms.

 

[06lj]

Have you checked your transfer case linkage to ensure was adjusted properly after the lift. When accelerating the engine torque can pull on the linkage and slightly engage the transfer case. If it is not adjusted right it will sound like something is hitting the floorboard right underneath the transmission tunnel.

 

[TJBob]

Did you physically remove the transmission mount and inspect it? I had a similar issue, and didn’t realize the mount was bad until I removed it. The rubber isolator was rotted, and torn. Couldn’t tell it was bad by just looking at it while it was installed. Mine is a 5 speed though.

Did you drop each drive shaft, one at a time, and take a drive to see if the sound was still there? Sometimes it’s hard to tell when a U-joint is the issue if it’s just starting to go. Or a bad CV socket.

Is there any vibration with said knocking noise? If so, where do you feel it? In the steering wheel, or more in your feet and butt?

Did you loosen all the control arms and retorque them?

It’s a possibility it’s your carrier bearings, but before I would crack the diff open, I’d go through the checklist first. Maybe check your 4x4 linkage to the t-case like mentioned above. Pop the arm off and go for a drive.

Edit: To me it wouldn’t make much sense to be a carrier related with the sound coming from directly beneath the shifter... I would think it would be pretty obvious if the sound was coming from one end, or the other (front/back).

 

[Leakey]

Since I have a similiar issue and have changed axle shaft U-joints and have the novak T-case shifter I can tell you it is neither of those. Good Idea on the transmission mount but from where the sound comes from (in my case at least) it is most likely not that.

 

[cmactj]

Hard to hear in video but check to make sure your exhaust isn’t hitting the shock. That happened on mine and after a few adjustments it went away.

 

[Paco1210TJ]

Have you checked your transfer case linkage to ensure was adjusted properly after the lift. When accelerating the engine torque can pull on the linkage and slightly engage the transfer case. If it is not adjusted right it will sound like something is hitting the floorboard right underneath the transmission tunnel.

Thanks for your reply!
I just got a second diagnosis from an auto shop here in Denver. They said it was coming from the transfer case. It’s such a minute sound at this point that they wouldn’t be able to identify the problem if they stripped the the T-case. Weird I think.

 

[Paco1210TJ]

Have you checked your transfer case linkage to ensure was adjusted properly after the lift. When accelerating the engine torque can pull on the linkage and slightly engage the transfer case. If it is not adjusted right it will sound like something is hitting the floorboard right underneath the transmission tunnel.

Just got a diagnosis today at the auto shop here in Denver. They said it was coming from the T-case “for sure”.
They also said they wouldn’t be able to indentify the issue “stripping the T-case” exactly because the sound is not bad enough yet. Weird! I don’t have the ability to work on it myself because I travel for work. I’m interested in your response about the transfer case linkage. That was never adjusted after the lift. Hope to hear more from ya! Thanks so much!

 

[06lj]

If the linkage is your problem then it is an easy fix. All you need is a 13mm wrench or socket. Here is a decent video showing the adjustment. You don't need to worry about getting it perfectly adjusted. You just want to make sure you are firmly in 2-hi. After you are locked into 2-hi take it for a test drive. If this solves your problem then you can set about finding the sweet spot for the adjuster to make sure it engages all the gear selections. The stock linkage is a common problem and there are options to replace it with a better system.

 

[LieutenantJohnson]

If it is a load clunk, check all your suspension components. Especially check the CA bushings and torque on the bolts. When you installed the arms were the tires on the ground when you torqued them?

Also check transmission mount as it can make a clunk like that with load

 

[Camdenst]

I had clunking upon take off and i traced it to the tranny mount.

 

[Jeepers~Creepers00]

I have the same type of issue in my 2000 Tj. The sound seems real faint outside but pretty loud in the cab, especially with the enclosure. If I press down on the handle for the 4wd it doesn’t make the noise. There is also a little bit of play in it as well. The sound is only there at take off. I’m going to check the linkage to see if that’s the problem.

 

[APM]

Having the same problem.
When taking off, I put my hand on the side of the auto box in the footwell and can feel the knocking.
Happens is 2wd but only often 4x4 mode.

I have on the way a transmission mount to see if it fixes the problem

 

[apacheredleg]

I've got the same noise on take off. I though it was the exhaust but it's in the wrong spot for it. I'm going to check my linkage and mounts later today as well.