Clunk Going In Reverse

Hey all,
I’m new to the forum, but very happy to be here. I tried the search function, but can’t find the answer to my question. I hope this is the right forum. If not, my apologies!

2007 JK automatic 2.5” lift. No other major mods.

When I first start the Jeep, it doesn’t want to shift out of P. Then, after a second, I get it into R, but there is a big clunk when I do. Here is a video of the DS and rear diff when it happens. Thanks in advance if you can help!

https://youtu.be/wEpfH-tlkYY

 

Hello Chris,
That is interesting. Seems like something is binding and the deflection in the rear pinion can't be good on the bearing.
Unfortunately, I have no answers though if it were me I would probably disconnect the driveshaft from the transfer case and see if it still binds and makes a clunking sound.

 

Are you parking on a hill? The way automatics work the parking brake is a dog that goes up against a gear if it's on a hill it puts extra pressure on the dog and gear. My LJ does when I park on a hill. Ok after watching the video n/m everything I just said. Welcome from Texas .

 

Seems so obvious to remove the ds to isolate transmission from Drive components. But, I never would have thought about it! I’ll give it a try

Thanks for the idea. Not a hill isssue for sure. Hope it is cooler in TX than it is here. 5 minute intervals working on it before it gets too hot to continue!

 

Hot and humid today feels like the tropics without the breeze. Sweat sitting in the shade today.

 

Cooler in Texas? Where are you from Chris?
I forgot to say, welcome from Oklahoma.

 

I heard it's raining there again and the dam at Tulsa is being over taxed

 

Only place hotter than here is Arizona in the low desert. 120 with no humidity.

 

Yeah we had some pretty bad flash flooding again, so saturated at this point it doesn't take much. We've got to dry out soon, I have some work to do on the driveway now.

 

I'm in Phoenix. We've had a cool spring, so now that its warmed up, the middle of the day is no good for working on the Jeep!

Quick thought...since it takes an extra second to shift out of P, is it possibly a shift linkage? Seems like it wouldn't be the DS or Gears since the initial issue is getting it out of park. Also, it comes out of park easily after the initial start up. I did get the diff cover off, and all seems well in there. No gears ground down, broken teeth, etc... A very little play in the pinion gear (I think that's what it's called...the one that goes in the back of the diff), but it seems within what would be normal to me.

Thanks again for the help!

 

Ok, one more note: the clunking sound is coming from the pinion/rear diff. Jeep got a 2.5” lift a couple weeks ago and now has 33” MTs. Any adjustment to the angle/pinion depth required? I guess I’m still not sure why it only clunks when going into reverse.

Oh, and one more! Haha. Noise goes away when I put it in 4wd.

Hmmm... no more time to mess with it today, but I can’t stop thinking about it! Lol

 

Where is @OFFGRID when we need him. He's our best at these issues..
Does any one have his Bat Signal? Or in this case....OFFGRID signal......

 

Clunking only in reverse I would imagine is from gear slack I know ring and pinion will do that when they are worn out . I've worn a few out and they always started making a noise I put 33's on my Dana 44 and it didn't start clunking in reverse

 

Anyone smarter than me see anything obvious here? Thanks in advance! I appreciate any help!

 

I am by far the furthest thing from a diff expert but those side spider gears look ate up to me.

 

I see no locker ..... Good enough excuse to take it in and have it inspected and a locker installed.....lol easy to say when it's someone else's money .... Yep Jon those spider gears have mushrooming on the ends of the teeth it looks like.

 

The wear pattern don't look very good either

 

The worn spider gears may make some noise but the clunk occurs when shifted in reverse / hard to disengage PARK might be something else.

 

Ok, finally getting around to looking at this again today. I watched the video again, and I notice that the first time the clunk happens, I can see the Pinion Yoke move outward just a bit. I'm suspecting that maybe the pinion nut was removed at some point and not torqued back down to speck. Maybe the crush save didn't crush or the bolt is coming loose. I'm going to remove the DS, but wanted to see if anyone has opinions on my suspicions. I'm not versed in gears at all, so kind of grasping at straws here before I charge up a bill at the mechanic.

Thanks again!