Brake Clunk

[haggisgood]

After coming to a stop.. I release the brake and 80% of the time I get a "clunk" coming from the brakes. This happens most of the time.. but not always.. gentle braking and it wont happen..
Is this a "lazy" caliper??
Just had the Abs module replaced.. same issue applies... (Module replaced due to ABS light)...
Thanks
Haggis

[etlsport]

pretty normal.. try lubing the drive shaft, that reduced my clunking quite a bit, its pretty easy to do, get a grease gun with a flexible hose, a mobil 1 grease cartridge for it, load it up, crawl under your vx and locate the 3 zerk fittings, slide the end of the hose over each fitting and pump grease in until you see it start to come out of the driveshaft near the fitting (if it comes out from the fitting, your arent connected to the fitting properly

here is a video showing where they are

http://www.youtube.com/watch?v=rzaNXz-ty34

[haggisgood]

clunk is coming from the brakes when I release them.. not when I slow to a stop..
It is certainly something to do w/ the brakes..
Just took it to jiffy lube to get all 3 lube points greased up
thanks
Haggis

[VehiGAZ]

Haggis, this infor may not be that helpful, but I had two front calipers seize up on me in the last few years, and I never got any clunk from them.

Good luck!

[haggisgood]

no one has had a clunk upon releasing their brakes? I do NOT mean when the vehicle downshifts to 0% front...
nothing seems to be damaging anything but it sure doesn't feel right

[SilverBullet75]

My '01 has the exact same symptom right now... has had it for about 3 months or more. Haven't had a chance to check into it yet. I've been following this thread, hoping someone would post something helpful.

Guys... the clunk IS coming from the brake area. Can't explain it... if I could, I'd have it fixed by now... LOL. :)

[Ldub]

no one has had a clunk upon releasing their brakes? I do NOT mean when the vehicle downshifts to 0% front...
nothing seems to be damaging anything but it sure doesn't feel right


My '01 has the exact same symptom right now... has had it for about 3 months or more. Haven't had a chance to check into it yet. I've been following this thread, hoping someone would post something helpful.

Guys... the clunk IS coming from the brake area. Can't explain it... if I could, I'd have it fixed by now... LOL. :)

Mine does this too, & it looks & feel like a motor mount to me...:sighwgray
(I hope I'm wrong)
Another possibility that keeps gnawing at my brain, (or is that a zombie?) is the possibility of front axle "wrap" or twist.

Take a look at how much your transfer case shifter moves when this happens.

You now have two cents that used to belong to me...:_wrench:

[etlsport]

Another possibility that keeps gnawing at my brain, (or is that s zombie?) is the possibility of front axle "wrap" or twist.


that would make sense.. if i brake hard where i would have that clunk on takeoff, i shift to neutral and can feel it release, sometimes feels like the entire vehicle drops 1/4-1/2 inch... sort of opposite of when you put it in drive or reverse and let off the brake before releasing the e-brake

but greasing the driveshaft did significantly reduce that clunk for me

[SilverBullet75]

Along with greasing the driveshaft, do you recommend just going through and verifying the tightness of all bolts under the VX? Reason I ask:

When I bought my first (silver '99) VX, it had a missing transmission mount bolt (according to Carmax, who found and fixed the problem). This was the first thought I had when I started trying to diagnose the problem... but with the baby, and working from home, I really haven't been driving much lately and it's become a back-burner issue.

[Ldub]

Along with greasing the driveshaft, do you recommend just going through and verifying the tightness of all bolts under the VX?

That'd be a good idea on ANY vehicle nearing ten years old...:_wrench:

After reading a post on this subject by Joe Black, I removed my transmission mount to be sure it wasn't the cause...it wasn't, as it was with Joe's.
Not being able to leave well enough alone, I through bolted the mount with some grade 8 hardware...

http://www.vehicross.info/gallery/data/500/DSC02863.JPG

http://www.vehicross.info/gallery/data/500/DSC02862.JPG

This had no effect on the clunk...:rolleyesg

[SilverBullet75]

Ok,

Issues:

1: A banging sound when I hit a bump...
- thought was bad shocks... almost bought new set!
2: Clunk when releasing brakes at stop lights.
- thought was motor mounts, after checking trans mount.

So, I went to the shop to get the banging sound looked at. Found to be my exhaust pipe hitting the crossmember/trans mount bar!
The shop that installed the Vortec Muffler did not install any muffler hanger/mounts! The only did the one at the tail pipe!
While the VX was on the lift, I asked them to give me an estimate on the motor mounts... they looked at me and asked... Why??
They showed me that the mounts were fine, and explained that all the symptoms I had could easily be caused by the exhaust not being properly hung. I was a little skeptical, and told them I'd try it and let them know...

SURE ENOUGH! No more clunk in the brakes! No more exhaust clunk! VX is happy again!!!

So, to those with the "brake clunk", especially if you have had your stock muffler replaced... check your exhaust mounts to see if they are THERE, and in good shape if they are! :)

Yay! Now I can go off-roading again! I haven't had this VX in the dirt YET (over a year) because of this issue. Didn't want to damage anything.

Good luck!
---JIM---

[SilverBullet75]

Oh... the reason why (theory) this fixed the clunk...

The pre-load is eliminated by mounting the exhaust, which acts like a lever.

[SilverBullet75]

Ok, same issue resurfaced again. "Brake" clunk when releasing brakes after a stop. I went under today and pushed on the exhaust near the hangers. I noticed that when I pushed hard/agressively enough, the exhaust on the TOD side hit the cross member. So, I took a heavy-duty hose clamp and clamped the rubber mount for the exhaust at both mount sites. Wah LAH! No more banging.. again. (The original remedy (2 posts up) did fix it... it's just that the rubber stretched a bit over 6 months. The clamp just rejuvinated the fix :) )
I also lubed the rear propeller-shaft zyrks.
Again.. a happy VX. :yesgray:
I'll have to keep an eye on this every few months...
Next, to replace all fluids.

[IndianaVX]

i have a post where this is discussed, because i did, and still do occasionally have that clunk, and i have a theory that i havent been able to look into yet.
when i did my front brakes, as i put things back together, i noticed some markings on the caliper bolts, and when i looked it up in the manual, of course, i had them in the wrong places. it seemed to me that there was a diameter, or some flat spots....there was something different about the two bolts, even though they fit and tightened down ok.
SO, my theory is this....that at some point, maybe the rear brakes (where i hear my clunk) were worked on, and the bolts were put in the wrong place.
this may be causing just enough friction on the wrongly placed bolts to not let the caliper release until the wheel starts to roll again.
in my thread, it was described perfectly as "unsprung energy"
just a thought, and just another thing i want to tear into to try and figure out my clunk. its been probably 2 years, but i will get around to it......:yeso:

http://vehicross.info/forums/showthread.php?t=11254&highlight=unsprung+energy

or type in the search "sticking brakes" in case i didnt do the link above correctly
the same discussion of drivetrane lubrication came into play on that thread too.

[Chopper]

I've always had one rear (pass side) that thunks on release. Like it's just a bit slow. It never affected anything, so I've never screwed with it

[Viatcheslav]

I had the same clunk when my VX was lifted by trooper springs (about 5 cm), i mounted the stock springs and the clunk gone!

[mrtew]

Mine has always clunked when I release the brakes and I thought I remembered old threads that said everyones did that and it's normal. It doesn't do it if you brake slowly or almost release the brake right before you come to a complete stop. I think it is the sound of the transmission shifting into 1st gear. If you brake right it has a chance to do it before you stop completely but if not it has to complete the shift the moment you start moving again. That's my theory anyway based on old threads I remember.

[a745035]

My 2001 does it... my brother in-law's full-size Chevy "Gladiator" conversion van does it, my GMC Yukon did it... My Avalanche now does it, and what do all these vehicles have in common? A rear AXLE. (vs. vehicles w/rear independent suspension. My theory is that during moderate to aggressive braking to an abrupt stop, the friction material grabs onto the (pad/disk or shoe/drum style) steel surface of the drum/disk during braking, hard enough to cause a slight axle "wrap" or forward roll just at the point where the last bit of forward momentum happens, causing the axle wrap amd tension it causes to be locked in place by the brakes. Once you let go of the brake, fronts just release, but that "sprung tension from the "wrapped" rear axle being released is what results in the clubk. Next time you hear it, see if you can differentiate where the sound originates, and you'll find (like people have said here) that mild subtle braking to a stop seems not to cause it, while a bit harder braking to a more abrupt or lurching stop seems to cause it.

Sorry this so long, but hopefully the theory helps a few folks have peace of mind for what this is. :happyface

Brian

[Knigh7s]

@a745035
I agree with your statement.

I have always had this problem, but I just don't know how to fix it... Does anyone have any ideas for a fix? And its kinda hard to reproduce the symptoms on jack stands.

[Ldub]

Call me a born skeptic, but due to the fact that we don't have leaf springs in the rear, I don't see "axle wrap" as being high on the list of possibilities.
I'm not saying that it isn't suspension related, I just don't think our rear axle is gonna rotate that much.

[tom4bren]

Did fixing your 'waggly rear end' help any with the clunk?

[Ldub]

Did fixing your 'waggly rear end' help any with the clunk?

No Sir...neither did the addn of HD lower links.