Rear Axle Clunk: Brake Caliper or Axle?

CMD Z

CMD Z

Member
Joined
Nov 16, 2019
Messages
47
Location
West
Been chasing a "clunk" for some time now. It only happens the first time braking after changing direction from forward<->reverse. Getting out of parking spaces is a great example of the conditions for the clunk. Threw a couple of GoPros under the chassis and saw that the brake caliper jumps right when the "clunk" happens (see video below). Even the dust shield and the parking brake cable moves, but everything else is smooth. The caliper mounting bolts are properly torqued. Took off the wheel and rotor and there is a little bit of rotational play in the axle (not side-to-side though). With enough force, I can get a soft "clunk".

Any suggestions for what to try next, or educated guesses on the cause/solution?


Here's some background on the Jeep:
  • 2005 Jeep Wrangler Unlimited (LJ)
  • 65,000 miles
  • Bought last fall
  • Pristine frame, lived in SoCal it's entire life (kept in a garage for the last 5 years)
  • No signs of previous off roading or abuse
Replaced:
  • Shocks
  • Rear upper and lower control arms
  • Sway bar links
  • Drag link
  • Tie rod
  • Stabilizer
Inspected, and found good:
  • Track bar
  • Sway bar bushings
  • Torque settings on the caliper mounting bolts
 
Could it be an outer wheel bearing? This is more of a question than a possible fix. I'm getting a rear clunk every direction change or when up-shifting. So watching with interest.
 
Great video. I would think it's where the brake pads ride on the bracket. Are the small stainless clips in place for the pads to slide in and out? Are the brake pads the correct size or worn out? it sounds like they have vertical play that allow them to move up and down rather than just slide side to side...
 
The stainless clips appear to be in place:

tabs_in_place.jpg
 
The brake pads have a partial notch (one tab) on one side and a full notch on the other (two tabs). Which should be on top / bottom?

Brake_pads.jpg
 
Picked up new set of brake pads. There's plenty to choose from, most are without the spring. Made sure I got a set that had the spring and fresh "caliper slippers". Checked out a few videos and it looks like the full notch goes on the bottom, though no one explicitly stated this. The wheel where the "clunk" is happening has the full notch at the top. Hoping it's as simple as this.
 
The rear pads on my ‘06 Unlimited has those funky springs. I just recently Started getting a clunking sound when applying the brakes while in reverse too.
 
The Service Manual mentions putting the "positioning notches" on the bottom for the front brakes. Assuming this is the same for the rear (not mentioned in that section). Gonna give it a try this afternoon. 🤞

Caliper_Installation.jpg
 
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Replaced the pads. Nice and snug fit with that spring clip. Lubed everything and torqued accordingly...

Same. Freakin'. Clunk.

Also did a test in 4H, 4L and neutral (on a hill). Same. Freakin'. Clunk. :poop::poop::poop:

I asked a co-worker and gear head about the issue before posting here... he said:
"Sometimes, a vehicle is just built like crap."

🤦‍♂️
 
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Mine doesn't do it all the time though. I need to try your go pro idea and see if I see anything moving anywhere.
 
I think I found the culprit: a loose or damaged brake backing plate / support plate (depending on the Service Manual's name or the Parts List name, part #5017 760AA).

New video comparing the right side (the "clunker") and the left side:


I'm too green to tackle removing the axle shaft. Gonna take it to a shop for further analysis.
 
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