Front end clunk pulling boat when braking--resolved! (1 Viewer)

[vjpkrmnc]

It started when heavy braking pulling the boat. It feels like something just shifting briefly in the front end. I feel it though the driver's floor. Just a quick "clunk". Then later when accelerating or sometimes hitting a bump it's like it's a reset clunk in the other direction. Multiple hard brakes don't result in repeated clunks. Something's shifting, back and forth perhaps?

I put it on a lift and put my breaker bar on all suspension bolts visible, including shock top bolts. It seems to be getting worse to the point I can duplicate it without the boat behind. Hard braking, clunk. Subsequent hard-ish acceleration, re-clunk.

I've read many of the clunk threads. My CVs and hubs are brand new. Bearings recently done.

Transmission or diff bushings? Are these DIY-able?

 

[GerLC100]

Breaker bar is one thing, not sure whether or not you can really lift your front diff with it.
I'd have someone else sitting in the car and shifting while you're laying under it. I also looked for a failure and eventually I found my diff bushings were bad and I could see movement while shifting.

 

[W03DY]

It started when heavy braking pulling the boat. It feels like something just shifting briefly in the front end. I feel it though the driver's floor. Just a quick "clunk". Then later when accelerating or sometimes hitting a bump it's like it's a reset clunk in the other direction. Multiple hard brakes don't result in repeated clunks. Something's shifting, back and forth perhaps?

I put it on a lift and put my breaker bar on all suspension bolts visible, including shock top bolts. It seems to be getting worse to the point I can duplicate it without the boat behind. Hard braking, clunk. Subsequent hard-ish acceleration, re-clunk.

I've read many of the clunk threads. My CVs and hubs are brand new. Bearings recently done.

Transmission or diff bushings? Are these DIY-able?

Sounds most likely to be your gearbox or transfer mounts

 

[MongooseGA]

Engine mounts, sway bar link bushings, control arm bushings, drive shaft u-joints, CV axle flanges, front diff bushings, trans bushing.

Pick one to start with. Testing for diff bushing play is easy like @GerLC100 said. If they haven't been done, sway links are cheap and easy and definitely in need. Do the bar bushings at the same time. Some of the rest are pretty common/infamous sources of clunks.

 

[MongooseGA]

Sounds most likely to be your gearbox or transfer mounts

We don't have transfer case mounts. They just bolt directly to the transmission.

 

[vjpkrmnc]

Engine mounts, sway bar link bushings, control arm bushings, drive shaft u-joints, CV axle flanges, front diff bushings, trans bushing.

Pick one to start with. Testing for diff bushing play is easy like @GerLC100 said. If they haven't been done, sway links are cheap and easy and definitely in need. Do the bar bushings at the same time. Some of the rest are pretty common/infamous sources of clunks.

Thanks by the way! I gave up for a few months after three separate shops including an LC "expert" couldn't solve it. That said, I am chipping away at your list. Here's the update:

- sway bar links/bushing -- almost new
- CV axle flanges -- almost new
- front diff bushings -- replaced, no effect. Local LC guy said to start here and it sure made it "feel" more like a new car.
- engine mounts -- TBD. Would that also cause the "un-clunk" when braking? Probably not, right?
- control arm bushings -- My LC guy does recommend replacing my 7-year old Nitros next.
- transmission bushing -- TBD
- sliders -- I do wonder if they're not just interacting with the frame. Obvious enough if I took them off I guess.

Anyway, thanks for thinking about it with me. My next course of action will be to borrow my buddy's gopro to see if we can catch the clunk on video.

 

[kuelblaz]

Check PS rack bushings also ...

 

[vjpkrmnc]

Thanks all. I also found the video form of this list. I'll keep y'all posted as I work through it all.

 

[vjpkrmnc]

Welp, thanks to three guys at the shop spending four hours clunking my rig, they finally determined the bolts (to frame) on the slee diff drop had worked loose over the past 7 years. The result was a clunk similar to but not fixed by diff bushing replacement. I am so stoked to get the car back. I'm out of town but will confirm on Sunday. If you need a persistent shop in Phoenix let me know! Case closed.