Brake Clunk

[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...

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...





This had no effect on the clunk...

[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.
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......

http://vehicross.info/forums/showthr...nsprung+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.