Clunk Under Floor During Hard Turns?

[Sundown94]

Hi Everyone!
For the first time ever, tonight on the way home from work I started to feel a clunk through the floor of my 2003 H2 when I make hard left or right turns. It almost seems like something is loose under the truck because if I make a right turn and feel the clunk, it won't happen again during a right turn until AFTER I make a hard left turn (and feel the clunk on the left turn). So it is like when I turn hard left, something slides to the right of the vehicle and then when I turn hard right, it slides back to the left. I can't be positive about what is really going on under the truck, but what I do know is that I can easily feel it through the floor and into my foot (especially my left foot when it is resting flat on the floor in front of the seat while I'm driving). Unfortunately it is also raining heavily tonight (and it is dark), so I am unable to crawl under the truck until tomorrow. In the meantime, does anyone have any ideas on what is clunking -- or thunking or whatedver you want to call it -- under my H2???

Thanks!
Sun-

[Agriv8r]

dont know how often i make hard turns, but it there possibly anything in the back of the truck sliding???

[H2R]

Sounds like an axle shaft is gone. I would check them.

[Sundown94]

Agr thanks for the response. Just to clarify, the hard right and left turns are not tire squeelers, but more like if I am coming up to a left or right turn and the traffic light is about to turn red, so you go a little faster through the turn to make the light. If stop first and then make a slow turn, no clunk. Also, there is nothing inside the vehicle to slide around (because I am so anal about keeping the truck clean and empty).

H2R, thank for your reply as well. Are you serious about an axle shaft going??? Is that common and, more importantly, dangerous???? I have never done any off-roading or done anything that might put extreme pressure on the axles to cause them to fail prematurely. I can say though that I have 80,000 miles of normal local and highway driving. Could it be a CV joint?

Thanks in advance for any additional feedback!!
Sun-

[MattRoberts123]

IMO, this is the SAME problem I and many others on the forum have had. Try going fast from a dead stop and hitting the brakes hard.... does it happen again?

I have taken it to the dealer, and they have told me it is defective body mounts. They have no fix for it and GM doesn't really seem to care to fix it. I am BEYOND furious about the problem in mine, and nothing seems to fix the problem. There are a few posts on this forum about it and quite a few other people have had the same problems. THe only solution that was offered to me by another forum member was to get some silicone spray and spray the body mount areas on all 4 corners of the vehicle.

This did seem to temporarily fix my problem, but it always seems to come back. I hope this helps, and if you find anything else out let me know...

[Sundown94]

Matt, that sounds extremely logical and -- so far -- the most likely cause of the clunk. It's funny that you say body mounts because one of the possibilities that I came up with last night while I was driving was body mounts (maybe the whole cab was moving on the frame), but then I thought "how could that be?". It would also make sense that I felt it for the first time last night because it has been raining hard up here in the Northeast for the whole week and last night was the first time I drove the H2 since Monday (when it was dry out), so the body mounts might have been wet and more prone to "slip". I will see if it stops today or tomorrow now that we have dry weather here. If it does stop "clunking", then I think this comes close to proving that it is the body mounts.

Thanks again, and if anybody else disagrees and/or has any other ideas, I would certainly still welcome them.
Sun-

[mikejr]

Originally Posted by Sundown94

Matt, that sounds extremely logical and -- so far -- the most likely cause of the clunk. It's funny that you say body mounts because one of the possibilities that I came up with last night while I was driving was body mounts (maybe the whole cab was moving on the frame), but then I thought "how could that be?". It would also make sense that I felt it for the first time last night because it has been raining hard up here in the Northeast for the whole week and last night was the first time I drove the H2 since Monday (when it was dry out), so the body mounts might have been wet and more prone to "slip". I will see if it stops today or tomorrow now that we have dry weather here. If it does stop "clunking", then I think this comes close to proving that it is the body mounts.

Thanks again, and if anybody else disagrees and/or has any other ideas, I would certainly still welcome them.
Sun-

I had the same issue in my 2006....dealer couldnt find the source since it was so intermittent. So i fixed it myself and bought a 2008...lets hope i doesnt happen with the new one. I recall someone posting on here that if you torque the body mount bolts a bit it will stop the clunk/creak.

[Vettster]

Had the same thing happen on my 06.
Dealer replaced the right rear body mount and all is well.

[tower]

Do you bowl?

[3Hummer]

sounds like you guys need an H3

[RippSpeed]

I have kinda same problem except only happens during stop and go traffic or coming to a stop... Where the my rig is rolling at 10 to 15mph ( rolling to a stop ) and then traffic starts to move and give it just enough gas just to get it moving again... I hear a loud clunk under my rig... Sounds like a axle or a motor mount or even a transmission mount gone bad...

[3Hummer]

might be the transmission downshifting

[H2Finally]

Mine is prob not related, but a couple of times I felt a really major-sounding "CLUNK!" that shook the entire rig, it was because I forgot to secure the rear-tire carrier! And before y'all laugh, it wasn't an easy prob to find because the louder "THUMP!" was when it swung CLOSE! So each time that happened, I'd look everywhere and everything looks ok!

[Aich Tew]

Originally Posted by 3Hummer

sounds like you guys need an H3

I'd buy an H1 if it would fit in the garage.

[Sundown94]

RippSpeed, the clunk you are talking about is another totally different clunk that also happens to me at the same time (rolling 10-15MPH and hitting the gas). I believe 3Hummer is correct in that this problem is related to the transmission downshifting. I personally can't stand it, but have no idea how to fix it.

And just to provide an update to the original issue that prompted me to start this thread, the clunk that I felt through the floor seems to have gone away after the weather dried up. I am waiting for more rainy/humid weather to see if it comes back, at which point I think I would be able to conclude that the clunk is in-fact caused by the body mounts and is directly correlated with rainy weather (and therefore nothing to worry about).

Thanks for all of the responses guys!!

[jaxtrip]

Just got back from the dealer to check out the exact same problem and it ended up being the body mounts. They fixed the problem by installing what is listed on the paperwork as "Body Mount Insulator Kit". The service advisor explained that it is basically a set of washers they install at the mounts. Problem fixed! I don't know what this costs as I am still under warranty.

[iccon]

Are the mounts rubber or urethane?

[porschett]

Originally Posted by 3Hummer

sounds like you guys need an H3

Funny you should say that, I just pulled out a H3 that flooded in 2' of water.

[jaxtrip]

Originally Posted by iccon

Are the mounts rubber or urethane?

I don't know as I didn't see the parts being installed.

[iccon]

Should use urethane, rubber just don't last and it has no memory so over time they will compress down urethane will last about 50 times longer, better ride and no squeaks.

I am just starting to manufacture them will be on the market late winter or spring