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[Brynjaminjones]

Hi Birties 

I've been trying to track down a clunking noise over bumps from the rear of my XJ for about a year now, with no luck whatsoever.

I finally found yesterday that there seems to be a lot of end play (in and out) on both sides of the rear axle (Dana 35). Pulling the wheel, it makes a loud clunking noise.

I know that some end play is normal with a C-clip axle, but does this seem excessive? I've got new wheel bearings and seals waiting to go in, but I'm not sure if that's the issue or not.

Video:

[wildwood]

Believe me they clunk a lot and the c clip is quite loose when jacked up and you pull the wheel towards and push against it….
Mine on the YJ before ‘1 Tonne Build ‘ clunked a lot and then the rise in tyre size from 30” to 31” to 33” and finally 35” made it worse….then it finally let go in the rocks at tong and I got a scrapper 44 from a TJ….end of probs…..

[Dave69]

Correct if wrong, but the movement inline with the shaft has no criteria for MOT failure, but vertical and forward and aft has due this movement being attributed to bearing wear.

You could remove the diff cover and get someone to move the wheel in and out while observing the 'C' clip if possible. Yo may have a a worn clip or its stating to dish allowing for more movement than intended.

[Brynjaminjones]

Thank you Jez and Dave. To be honest I'm not convinced it's a problem, but something back there clunks over bumps and this is the only thing I've been able to find that makes noise over the last year or so of searching.
I even sent it to Peak Jeep in Chesterfield a few months back, and they couldn't find anything wrong with the damned thing!

I need to change the rear axle seals anyway, so I've torn it down to inspect. The gears all look great and the noise is barely audible with the drums removed.

Here's how that play looks inside the diff - I assume this is completely normal?

https://youtube.com/watch?v=Y42aFWSogRE

[JamesH]

For a clunk sound some things you’ve probably checked but that spring to mind are: gearbox mount (sounded like a rear clunk to me), rear diff backlash (I’d be surprised if it was this), rear anti roll bar bushes including links. There are plenty more but I remember having issues with these things.

I have a rear clunk/click on the patrol and diagnosing it with a static vehicle is a nightmare but on the road it is consistently there. I’m going with cheapest replacement parts first as everything is worn out. Hopefully the noise will go before the parts get too expensive!

[Hillbilly]

Hi, Bryn. Your clunking noise over bumps reminds me of a similar problem I had with my XJ. Turned out to be broken cat ceramics. No issues on the flat but every time over a speed bump, for example, it sounded like the clunk was coming from the rear suspension. Just a thought.

[Brynjaminjones]

Thanks both, I've tried a few things with this now.
James, good luck with sorting the noise on the Patrol!

My noise sounds exactly how I'd imagine a worn shock bushing would sound, and my original shocks were in terrible shape (leaking, broken covers, cracked bushings) so I replaced them. That made no difference at all.
There is no anti-roll bar on mine, so I can rule that out!
The cat is new and not rattling. The noise has also remained present with two different cat-back exhaust systems.
Nothing inside the Jeep makes any noise - it's unusually rattle free!
I've now replaced the rear wheel bearings and seals (the seals have been leaking for ages) which has had no effect. The differential appears to be in great shape (rebuilt 3 years ago).


I must have a look at the gearbox mount, as that seems like it could create this kind of noise. The only doubt I have about that though is that this noise definitely comes from under the floor in the cargo area. When I've sat in the back you can hear it clearly behind you.

The search continues!

[wildwood]

Another maybe is the prop….

I’ve mullared a few in my rime …
 

[gazjeep]

Another maybe is the prop….

I’ve mullared a few in my rime …
 

Bloody thug 

[donk498]

What about exhaust hitting gearbox cross member? I had that years ago, changed gearbox mount first and the realised it was the exhaust bracket bent and the cat knocking on the cross member.

[wildwood]

Thanks Gaz… .I was sometimes a bit lead footed…..

Now it’s trying to control the “whiskey throttle syndrome “ on the KTM…. :hysterical:had a few blasts shy-wards recently…..so far KTMs seem to crash well.

[gazjeep]

Hope the Merlot & the mushrooms ease your bruises mate 

[wildwood]

Off to Spain next week for some Enduro fun in the sun…..flying in to Marbella area and abusing somebody else’s stuff for once….

 

[gazjeep]

Enjoy & come back in one piece hippy 

[Brynjaminjones]

Another maybe is the prop….

I’ve mullared a few in my rime …
 

Prop seems good. I got under there last night and I couldn't find any play in it at all, plus I recently greased the slip-yoke so I don't think that's banging in and out either.

What about exhaust hitting gearbox cross member? I had that years ago, changed gearbox mount first and the realised it was the exhaust bracket bent and the cat knocking on the cross member.

I also had a look at this - mine has loads of clearance and the exhaust itself is very solid. For once I think the exhaust on this XJ is actually tight, rattle and leak free!


I am now suspicious of the transmission mount though. I grabbed the prop/transfer case and found that I could push them both upwards by hand about an inch. The first time I did that I'm pretty sure it might have made a noise, but I couldn't repeat it.
Is it normal to be able to lift it all up that far?

[Brynjaminjones]

New transmission mount ordered. Lately I've been trying to only buy Mopar where possible, so it's cost me a small fortune from the dealer. I have noticed an occasional thump when pulling away, so let's hope this helps.

[gazjeep]

Fingers crossed that sorts your issue young Bryn 

[Brynjaminjones]

I've now replaced the transmission mount. What a surprisingly easy job, which was a relief as it started snowing halfway through! 



Unfortunately it hasn't fixed the problem, although I do think I have slightly fewer vibrations at speed now which is good.