Knocking sound underneath

G

Grak

New member
Maybe someone here has an idea. Driving relatively slowly over washboard there was a random bang from the rear.. wasn’t vibration in time with the ruts but a random whack. Maybe several times over 10 seconds. I’m not near washboards to recreate it but it was really odd at the time. Anyone familiar with such a thing?
2 door Rubicon JL with less than 4k mi at the time. Maybe the lack of lift and 315s was part of it?
 

WiscoHR

WiscoHR

Member
Grak said:
Maybe someone here has an idea. Driving relatively slowly over washboard there was a random bang from the rear.. wasn’t vibration in time with the ruts but a random whack. Maybe several times over 10 seconds. I’m not near washboards to recreate it but it was really odd at the time. Anyone familiar with such a thing?
2 door Rubicon JL with less than 4k mi at the time. Maybe the lack of lift and 315s was part of it?
Click to expand...


Bumpstops?


Sent from my iPhone using JL Wrangler Jeep Forum mobile app
 

JTCO

JTCO

Meme King
Grak said:
Maybe someone here has an idea. Driving relatively slowly over washboard there was a random bang from the rear.. wasn’t vibration in time with the ruts but a random whack. Maybe several times over 10 seconds. I’m not near washboards to recreate it but it was really odd at the time. Anyone familiar with such a thing?
2 door Rubicon JL with less than 4k mi at the time. Maybe the lack of lift and 315s was part of it?
Click to expand...

Any chance something inside the Jeep is loose and rolling around?
 

G

Grak

New member
Muffler is snug, as is spare.. bump stops, would they make a hard knock like that? Doesn’t seem to fit since a previous 10 hour off-road journey never produced that sound. These ruts were little, on the main scenic loop of white sands nat’l monument where passenger cars travel. Very strange.

There was a lot of gear in the rear, but couldn’t find what may have made that thumping. I will just try to find some washboard ruts for more research. Thanks.
 

wayoflife

wayoflife

Administrator
Staff member
Grak said:
Maybe someone here has an idea. Driving relatively slowly over washboard there was a random bang from the rear.. wasn’t vibration in time with the ruts but a random whack. Maybe several times over 10 seconds. I’m not near washboards to recreate it but it was really odd at the time. Anyone familiar with such a thing?
2 door Rubicon JL with less than 4k mi at the time. Maybe the lack of lift and 315s was part of it?
Click to expand...

Is your JL lifted? Do you have any modifications that you've installed recently?
 

WiscoHR

WiscoHR

Member
Grak said:
Muffler is snug, as is spare.. bump stops, would they make a hard knock like that? Doesn’t seem to fit since a previous 10 hour off-road journey never produced that sound. These ruts were little, on the main scenic loop of white sands nat’l monument where passenger cars travel. Very strange.

There was a lot of gear in the rear, but couldn’t find what may have made that thumping. I will just try to find some washboard ruts for more research. Thanks.
Click to expand...

I’m still going to guess bumpstops. I bet stock shocks got hot from the weight of the 315s and you hit the bumpstops a couple of times.


Sent from my iPhone using JL Wrangler Jeep Forum mobile app
 

G

Grak

New member
No lift, just the bigger tires and new wheels. Was on a lot of washboard again yesterday, Death Valley on way to Racetrack Playa. Four people in the car, all heard it coming from left rear underside. Wouldn’t all bumpstops bang, not just one? Almost like something’s loose.
No idea what it could be.
 

Last edited:
G

Grak

New member
Been looking for a video of bump stops being hit, wondering if the sound is similar. Just looked under the Jeep again and nothing obvious stands out.
 

G

Grak

New member
Checked, all solid. I have a theory of what it may be. There’s flexible plastic between the bumper and wheel well that moves up and down. I felt a very slight rubbed texture on the edge where maybe the tire clipped it and sent it upward enough to go whack. It’s just plastic trim but may have made the knock at speed on washboard... other than that, I’ve got nothin, and am going to shrug it off and just hope it doesn’t happen again after lift/new rear bumper etc.

Thanks all.
 

Last edited:
You must log in or register to reply here.
Top