Clunk (1 Viewer)

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It's a 2007 lx470 and when it goes in gear or changing direction let's out a loud clunk. Thinking broken motor or transmission mount but sounds like front drive line or transfer case. Rear shaft firm but front looks like it has some play creating the noise. Could it be as easy as a u-joint. Any thoughts?
 
I have the same. Feels like it’s beneath my seat. I’m guessing a trans mount or something.
 
This is a long discussed topic.
>>The OFFICIAL clunk/thunk driveshaft thread - https://forum.ih8mud.com/threads/the-official-clunk-thunk-driveshaft-thread.401590/page-21
The long short of it all, is these big heavy AWD vehicles have a lot of moving parts. A clunk when shifting through gears or if it's felt when coasting and then back on the pedal can relate to a lot of different things.

As noted above, front diff bushing could be a culprit. Another likely cause is where your front axle meets the hub flange. Don't start throwing money at parts until you can narrow it down. I lived with the clunk for a few years and eventually swapped my axles and flanges to solve the problem but there are steps you can take to troubleshoot.


OK try this first
  • In park, foot firmly on the brake, safely have someone go down under the front of the truck ( or just prop up your phone camera towards this area ) and look up at the axles. Shift through the gears with your foot on brake and see if you can watch where the axle meets the hub moving. >> There is a video floating around somewhere on that thread showing this. It'll be obvious
  • While you at it, foot FIRMLY on the brake. Have someone stand off to the SIDE of the truck, out of harms way.
    >> Put it into drive and give the gas pedal a quick rev. Have your monkey who is watching the engine tell you if it moved alot or if you felt the clunk. That is your test for motor mounts. It's probably not your mounts.
  • Grease your drive shaft, make sure you hit the slip joints and the spiders. There are tips on these forums on how to do that.


    Don't lose sleep over this one unless you feel it's so bad there is a safety issue.. A lot of our trucks are plagued with this. You can soften the blow by shifting into neutral and slightly rolling before your shift.. Same for when coasting on the highway, just ease back on to the throttle, any quick throttle you'll surely feel the clunk


Heres that video, thanks 2001lc..... If you have this symptom it's very likely this is the main cause of the clunk.
>> If you lock the center diff , and then shift through gears, does the clunk go away?

 
I went through hub flanges, diff bushings, new CVs, transmission mount, and rear control arms before I eliminated my clunk. They all have it in some form, some more than others.
 
Is the backlash excessive in this video clip? You can see both the front and rear drive shafts and the rotational play, which I have been told is normal. Thanks eh!

1F4BEBDC-3228-4924-9B71-7F96888622A3-2396-000002BD0DF84EDA.gif
 
Prob diff bushings, but go grease your CV’s and check.
 

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