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Thunking / Knocking on acceleration

63K views 67 replies 20 participants last post by  DAN.2023 
#1 · (Edited by Moderator)
I searched what I could in the forums but couldn't find anything that sounded similar. When I accelerate, I hear a thunk, thunk, thunk that gets faster until I reach 30ish mph. When the thunking gets fast enough, it is more of a vibration.

I can not hear it outside the vehicle, and it does not do it when not accelerating. I opened the door and put my head down to listen while I accelerated but nothing until I closed the door and quieted down the cabin noise. It feels like it is coming from below me. I do notice a little play in the drive line when I do a California stop at a stop sign, where it seems like there is a moment that the drive line has before everything catches up.

I have been working through many issues on this car, so I have already replaced or checked everything forward of the transfer case. I replaced the front diff because I thought it had too much play and was leaking. I replaced the front drive shaft because I thought it was the cause of the noise, and the old one was pretty rusted up. When I grab the front or rear drive shafts, there is minimal rotational play and no noticeable up-down/left-right play. I haven't removed the rear driveshaft yet. The transmission pulls hard and shifts fine. The engine runs great, idles great, and pulls hard. The rear diff input shaft leaks a little, but I notice no play.

The noise has very slowly gotten worse over the past few months. I changed the transfer case oil, and it was clean. I changed the rear diff oil, and it was clean. Could the transfer case be making this noise? Maybe the rear diff radiates the noise forward? How can I test? Thanks for any help; it's driving me nuts!

Replaced so far:
Front L/R hubs
Front L/R cv axles
Front L/R sway links
Ball joints
Upper control arms
Shocks
Front Diff w/ new bushings
Front driveshaft
 
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#2 ·
Sounds like it is probably a u-joint. You may or may not be able to check it with your hand if the drive shaft has a load on it after you stop. Jack up your rear axle with both wheels off the ground. If u-joint bad. should be able to feel by hand then.
 
#4 ·
Hoist

Jack up both front and rear of the car with jack stands or put it on a 2 post hoist make sure it is secure and check first by hand and then use the motor with someone else checking/listening, but again MAKE SURE THE XK IS SECURE.

Swanny
 
#8 ·
Jack up both front and rear of the car with jack stands or put it on a 2 post hoist make sure it is secure and check first by hand and then use the motor with someone else checking/listening, but again MAKE SURE THE XK IS SECURE.

Swanny
I did that once and it didn't appear to make the noise. It seems to only make the noise under a load like when accelerating.
 
#5 ·
Check the front differential isolator bushings. The top bushing on top of the differential housing below the driver side is a known weakness and can cause a lot of clunking when pulling away from a stop or just driving if the isolator is bad enough. If there is a noticeable clunk when engaging drive or reverse this would indicate that this isolator bushing is shot.
 
#54 ·
so after watching your video with my own car that’s been making those problems I went out and checked on my own because recently everything seem to stop working I went outside to check the CV joint and there was a lot of play and then I decided to grab the drive axle and push it towards the front and I could almost get it completely out so I think I figured out what’s wrong with my car thank you for that now my next question is how much is it going to cost me I have a jeep commander to 2008 5.7 V8 hemi in it

I have the same problem, did you know what was the problem?
I would check your CV joint I just found out today that mine is absolutely destroyed and it’s gonna cost quite a bit so I would give it a check if not read through the forums because a lot of these people have gone through the same issues and it helped me figure out multiple issues on my car
 
#13 ·
Update to an old post. I haven't messed with the Commander in a bit since I moved to Charlotte and bought a daily driver car. It's time to finish her and start driving daily again. I am purchasing a used low mileage transfer case soon and hopefully getting it swapped early January. Will update if the noise is gone. Anyone from Charlotte with recommendations on a shop that is familiar with these Commanders? I want to get my exhaust manifold bolts fixed soon too so would like to work with a shop that knows what they may be getting into.
 
#14 ·
This is a saga that doesn't want to end. For a recap the noise is a metallic/binding "click-clack" noise (no grinding) that happens with each tire rotation but ONLY when accelerating and appears to come from under the drivers feet or center console area. The harder the acceleration the louder the noise and there is a slight vibration that I think is associated with it. The noise is not RPM or gear dependent. As I accelerate with the transmission shifting and rpm's changing the noise does not change. Above 40 mph it doesn't seem really noticeable because the tires are rotating fast enough and wind noise but I can still feel the vibration when I accelerate. The noise started after the lift and has grown slightly louder over time. At this point I am literally about to attempt an action movie scene where I hang from the bottom of the car while someone accelerates so I can pin-point the noise (not really but I'm definitely frustrated).

Initially I replaced the front CV axles with Cardon Select reman's and when that didn't work I installed a new front driveshaft but it also made no difference. So next I thought maybe transfer case chain or internal bearing/bushing so I swapped the transfer case for one with only 84k miles. The noise persisted un-changed! Next I thought maybe the original 12 year old rear drive shaft had a bad u-joint I couldn't feel so I replaced it with a new steel driveshaft with serviceable u-joints. The noise persists but slightly louder now!! Finally I thought maybe rear diff ring gear issue because two things 1) now that the noise is slightly louder maybe the new steel shaft is resonating noise from the rear diff more than the aluminum and 2) the noise occurs with each tire rotation, not driveshaft rotation. But since I don't have any differential experience I decided to take it to a 4x4 professional for a diagnosis. He blew away my theory and said front CV axles, even though i replaced them 5k miles ago (I told him this but he persisted). Sooooo I went out and bought new not reman front CV's and dug into replacing them along with my LCA's since the bushings were looking a little old. The noise persists but even louder now!!!

The transfer case and front differential changes didn't change the noise level or frequency at all. The only things that have affected the noise (by making it louder) was the rear driveshaft and new front CV axles, otherwise everything I have done hasn't affected the noise at all. At this point the noise is louder than my new Magnaflow exhaust.

So far I have done the following:

2" RR lift w/ Bilstein shocks (21.5 hub center to flare)
1.25" spacers
255/70R17 tires
JBA UCA's
OEM LCA's w/ new bushings
OEM sway bar links
Moog Sway bar bushings
Timkin front L/R hubs
NEW Carquest front L/R CV axles
Low mileage front differential w/ new bushings (Amsoil fluid+mopar additive)
New front driveshaft
Low mileage transfer case (Mopar fluid)
New rear steel driveshaft
Rear differential Amsoil fluid+mopar additive
 
#22 ·
This is a saga that doesn't want to end. For a recap the noise is a metallic/binding "click-clack" noise (no grinding) that happens with each tire rotation but ONLY when accelerating and appears to come from under the drivers feet or center console area. The harder the acceleration the louder the noise and there is a slight vibration that I think is associated with it. The noise is not RPM or gear dependent. As I accelerate with the transmission shifting and rpm's changing the noise does not change. Above 40 mph it doesn't seem really noticeable because the tires are rotating fast enough and wind noise but I can still feel the vibration when I accelerate. The noise started after the lift and has grown slightly louder over time. At this point I am literally about to attempt an action movie scene where I hang from the bottom of the car while someone accelerates so I can pin-point the noise (not really but I'm definitely frustrated).

Initially I replaced the front CV axles with Cardon Select reman's and when that didn't work I installed a new front driveshaft but it also made no difference. So next I thought maybe transfer case chain or internal bearing/bushing so I swapped the transfer case for one with only 84k miles. The noise persisted un-changed! Next I thought maybe the original 12 year old rear drive shaft had a bad u-joint I couldn't feel so I replaced it with a new steel driveshaft with serviceable u-joints. The noise persists but slightly louder now!! Finally I thought maybe rear diff ring gear issue because two things 1) now that the noise is slightly louder maybe the new steel shaft is resonating noise from the rear diff more than the aluminum and 2) the noise occurs with each tire rotation, not driveshaft rotation. But since I don't have any differential experience I decided to take it to a 4x4 professional for a diagnosis. He blew away my theory and said front CV axles, even though i replaced them 5k miles ago (I told him this but he persisted). Sooooo I went out and bought new not reman front CV's and dug into replacing them along with my LCA's since the bushings were looking a little old. The noise persists but even louder now!!!

The transfer case and front differential changes didn't change the noise level or frequency at all. The only things that have affected the noise (by making it louder) was the rear driveshaft and new front CV axles, otherwise everything I have done hasn't affected the noise at all. At this point the noise is louder than my new Magnaflow exhaust.

So far I have done the following:

2" RR lift w/ Bilstein shocks (21.5 hub center to flare)
1.25" spacers
255/70R17 tires
JBA UCA's
OEM LCA's w/ new bushings
OEM sway bar links
Moog Sway bar bushings
Timkin front L/R hubs
NEW Carquest front L/R CV axles
Low mileage front differential w/ new bushings (Amsoil fluid+mopar additive)
New front driveshaft
Low mileage transfer case (Mopar fluid)
New rear steel driveshaft
Rear differential Amsoil fluid+mopar additive
Silly question but did you check and/or replace the front/rear differential bushings?
 
#16 ·
I don't think so. It doesn't change with engine RPM and it is directly related to the axle tire rotation (1 click/clack per revolution).

On a positive note I think I have isolated the noise to the front passenger hub. I decided that hanging from the bottom of the Jeep wasn't save ;-P so I went out and bought a cheap wifi action camera that I attached really close to different areas of the car. After lots of recording and driving around like a drunk lunatic I finally recorded the noise loud and clear! Bought a new front hub and will be installing this evening. Here is a video of the noise.

 
#17 ·
thats a great idea. i have a voice recorder and gonna do the same thing this weekend. i have a howling noise 50-70mph that i can not isolate. must be front diff or xfer case as i have replaced everything else!
 
#20 ·
Front hub was not it!! Sound is still there.

Today I went and tried to get the noise to change, just to get a reaction out of it so I can pinpoint the source. I tightened and loosened both front half shaft nuts at different torques, even as far and backing off 1/4 inch so the splines can slide in and out a little and tightening them to 300+ ft/lbs. Did a lap around my parking garage but the noise didn't change with any combination of loosening or tightening. I even went and popped the passenger half shaft out a little at the differential so the snap ring wasn't holding. My goal was to allow the half shaft to free up some just in case it was to tight or loose for some reason but no change. I even loosened the lower diff bracket so it could shift a little but no change in the noise at all.

At this point I am thinking maybe an issue with my front diff and maybe the noise is loud at the hub because it is resonating down the half shaft to the hub area where it is being amplified.

If someone can pinpoint this I will for ever be indebted to you and you might save a human being from going insane!
 
#21 ·
Mickey - I did computer support for 40+ years and so many times I just jumped in to the hard stuff to fix and completely skipped past the easy stuff like is it plugged in? or is it turned on? Have you tried to just jack that wheel off the ground and turned it to hear/feel. Removed the wheel and inspected it for foreign debris, brake pads. Since it happens every wheel rotation I'd start there. All the parts replaced is good for regular maintenance.
 
#23 ·
I come from a computer support background to so I totally understand your comment about skipping the easy stuff. But I have jacked it up and spun the wheels and everything feels fine, it also only makes the noise when accelerating ie. under some level of load/torque. As for debris everything is clean, I've quadruple checked that 10 times over. I thought maybe brake calipers so I even pulled the caliper and pads then hung the caliper with something stuffed in them so my brakes would work and drove around my parking garage. The noise didn't change so I know it isn't a rotor/caliper/pad issue. Thanks for the reply.
 
#30 ·
This weekend I tried another fix. I found several TSB's for 2011+ Jeep Grand Cherokee's, Chrysler Pacificia's, and Ford Explorer/Taurus's about the CV axles causing a click/clack noise. Their solution was a metal washer between the CV axle face and wheel hub. So I ordered the washers for the Grand Cherokee and installed them along with my extra front diff. The noise didn't change. Still there in all its annoying glory. However, my front diff now has new seals, fluid and Creative Steel Daily Driver poly bushings. I guess the bright side to all of this is that each time I do something I am making it that much more reliable.

At this point I am about to leave the noise since it doesn't appear to be serious or I would have found it by now. I will update if one day I find the source. If anyone knows an amazing vehicle sound diagnoser let me know and I might indulge their expertise.

Thank you for the help so far.
 
#31 ·
Bought a remote vibration microphone off Amazon and used it around the problem areas. The noise is definitely coming form the front passenger spindle. This only leaves the CV axle and/or Front Hub and/or Brake Rotor/pads as possible causes. Since there is no vibration when braking and the noise stayed on the passenger side when I swapped my rotor/pads side to side this only leaves the CV axle or Hub. If the issue was with the hub then one of the 3 hubs I put in should have fixed this. So this really leaves just the CV axle as the culprit. I have had 2 aftermarket reman CV axles and 1 aftermarket new CV axle so I am hoping the issue is with using aftermarket CV axles. I ordered a NEW OEM Mopar CV axle today and will install this week. Hoping for something!!
 
#34 · (Edited)
Bought a remote vibration microphone off Amazon and used it around the problem areas. The noise is definitely coming form the front passenger spindle. This only leaves the CV axle and/or Front Hub and/or Brake Rotor/pads as possible causes. Since there is no vibration when braking and the noise stayed on the passenger side when I swapped my rotor/pads side to side this only leaves the CV axle or Hub. If the issue was with the hub then one of the 3 hubs I put in should have fixed this. So this really leaves just the CV axle as the culprit. I have had 2 aftermarket reman CV axles and 1 aftermarket new CV axle so I am hoping the issue is with using aftermarket CV axles. I ordered a NEW OEM Mopar CV axle today and will install this week. Hoping for something!!
@mickeyoneil;

Please keep us posted with your results.
 
#35 ·
Yes, please keep us posted. I developed a click/clack after thanksgiving that sounded like the rear brakes or drive shaft. I've jacked up the rear end a dozen times and can't replicate it when stationary. The click/clack is now gone but a vibration develops around 25-30 mph and the vehicle feels like its dragging. if I shift it into neutral the vibration goes away. Is the driveshaft under load in neutral? I'm pulling my hair out. Both Diffs and transfer case got new fluids last June.
 
#39 ·
The noise is fixed!!!!

Lesson learned about OEM vs Aftermarket. After using the microphone and honing in on the passenger spindle area I decided to try for a 4th time replacing the CV half shaft but this time I bit the bullet and bought OEM at $275 (vs $80 for 'new' Advance Auto). A friend talked me off the ledge of buying the RCV Ultimate axles with my credit card and convinced me to do the OEM first.

So don't cheap out on drive train parts, spend the extra bucks and be happy it is fixed the first time.

Time to bask in my Magnaflow exhaust tones and only those tones.
 
#40 ·
The noise is fixed!!!!

Lesson learned about OEM vs Aftermarket. After using the microphone and honing in on the passenger spindle area I decided to try for a 4th time replacing the CV half shaft but this time I bit the bullet and bought OEM at $275 (vs $80 for 'new' Advance Auto). A friend talked me off the ledge of buying the RCV Ultimate axles with my credit card and convinced me to do the OEM first.

So don't cheap out on drive train parts, spend the extra bucks and be happy it is fixed the first time.
-
Time to bask in my Magnaflow exhaust tones and only those tones.
Thanks for following up Mickey; I find this to be true with a lot of parts for Commanders - like the OEM factory spark plugs for example.

You might pay more for OEM replacement parts, but, more often than not, you'll have less headaches down the road using them.
 
#42 ·
Sorry for the pause... had to take a break after getting it fixed. I posted the link to another user on page 4 for the electronic microphone/stethoscope. As for the CV axle I bought that off of RockAuto.com which is an amazing place to get parts pretty cheap.
 
#44 ·
Update on my version of vibration while accelerating. After replacing front driveshaft and front diff passenger side half shaft bushing it turned out to be the rear driveshaft. The rear u joint was BAD. Strange thing is that while the shaft was in place it had no discernible movement. When I unbolted it to check I was shocked at how bad the rear joint was and how the front joint was loose/sloppy. I initially thought it was the rear shaft. Lesson learned, follow your gut.
 
#50 ·
The OEM rear driveshaft is made of aluminum. The u-joints are staked in so are very difficult to rebuild. Most driveshaft shops won't touch them, so it's either spend a lot for OEM, $900-$1305, or replace with steel for $275-$400. The steel shafts usually can be greased and rebuilt. Interesting thing is if you buy a new one from jeep/mopar they have a $100 core charge. So someone is rebuilding these things. One dealer I called told me they can get reconditioned shafts every so often. They use to to have them consistently but not any more. I would guess less and less people are buying OEM so less cores to rebuild. I kept my old OEM with the hope of finding a shop that can rebuild it.
 
#51 ·
That's pretty interesting, so the OEM driveshafts are made from aluminum and they are basically toast once they wear out;

The steel drive shafts are about 1/3 the cost of the OEM aluminum drive shafts and they are easily serviced and rebuilt meaning they should, in theory, last much longer.

Thanks for the information Al.
 
#52 ·
Hi my jeep commander has an ugly knocking noise coming from under the center console, it’s mostly when I start accelerating and i have to let off the gas so it’ll stop then accelerate again. I was told it was a chain from inside the transmission or something wrong with the 4x4. Can anyone give me any ideas of what it might be?
 
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