Hummer Forums - Enthusiast Forum for Hummer Owners - Hummer H3 Rear Door Thump/Thud

BOTTOM LINE UP FRONT: Have the dreaded *THUMP!* coming from the rear door when going over even mild, or perhaps even the smallest of bumps? Here a couple small things to look for in the rear passenger door, and how I fixed the problem (at least in my case). By no means a "perfect" fix, but it has held up for the time being (and hopefully will for much longer).

Vehicle: 2007 Hummer H3 Base, 35" BFG Goodrich KO2, Manual Transmission.

I purchased this vehicle in February of this year, and the problem was there even when I first purchased the vehicle. While I accepted this at first, as simply a perk of having an older vehicle (I initially suspected something in the rear suspension), the problem got worse over time, especially once I pumped up my tires to 38 psi resulting in a slightly rougher ride. Additionally, I would get this god awful thumping sound even when simply going over the tiniest of bumps (think of going from land to hitting a bridge on an interstate; something to that effect).

Today I decided to take a look and see if I could narrow down the problem.

TROUBLESHOOTING

1. TEST DRIVE WITHOUT SPARE TIRE - I first removed the spare tire and took a test drive just to help narrow down if this was in fact the rear door being loose (and not something in the rear suspension). A 35" tire by itself weighs ~65 lbs, so I'm guessing it's closer to 85-90 lbs (maybe even more) once it's mounted on a rim and inflated, which is a lot of additional weight on the rear door. If your rear door is in fact loose, removing the spare tire and going for a test drive should lessen the violent thumping sound from the rear, which is exactly what happened in my case. In my case, when driving around without the spare tire and hitting the same bumps in my neighborhood that I normally hit during daily driving, I could still "hear" the thumping from the rear door area, however the magnitude was much, much less than usual.

Convinced that this truly was something with my rear cargo door (and not suspension), now it was time to take a closer look.

2. LOOK FOR LOOSE BOLTS - Really nothing crazy here; I simply looked for loose bolts in the following areas:

i) Latch mechanism on the rear door (3x Torx Screws)
ii) Rubber Tapered Piece on the Rear Door itself (2x Torx screws)
iii) Rubber Piece inside the rear cargo door area (that fits into the rubber tapered piece on the door itself, 2x torx screws)
iv) Latch Piece inside the rear cargo door area (2x torx screws)
v) 8x bolts on the opposite side of the rear door (where it bolts/mounts onto the vehicles body).

While some of these were in fact just a hair loose, they were ultimately not the cause of my thumping, however I tightened them up anyways.

3. CHECK FOR UP/DOWN PLAY IN THE DOOR ITSELF - You can do this with or without the spare tire installed, but I feel it is a little easier without it installed (and if you test drive without the spare tire installed, it will be off anyways). Now you want to look for some up/down play in the door itself in the latch area when the door is closed and latched shut. Even if the door is slightly loose when closed and latched, it will still feel relatively tight and you may swear that there is no play in the rear door, however to truly test this (this is where having the spare tire removed comes into play), grab the spare tire mount and push UP on the rear door. Look very closely at the area where the latch and the rubber tapered pieces meet (basically just to the right of the door handle itself near where the metal meets the rear glass....to the right of that). Use a pretty decent amount of force to push up from the spare tire mount, then use some force to also push down. It may take multiple iterations of this "up-down" force to see any motion, and it may not be a whole lot either (you won't see something like an inch, instead it will be something in the realm of 1/8-1/4 of an inch, if that). It is especially tough to see this movement since the suspension will be rocking the vehicle as well, however really try to lock your eyes just to the right of the door handle at the edge of the rear door, and look for up/down motion. If there is any play in the door, this is where you will see it.

In my case, I noticed a small amount of up/down play in the rear door. Now I started looking into the metal tapered piece and the rubber pieces inside the vehicle. Turns out, the rubber pieces (inside the vehicle) that meet the metal tapered piece (on the door itself) were not meshing up quite as they should (it appears that the rubber pieces inside the vehicle are slightly worn out from age/wear). I'm going to go out on a limb and say that if there is any play in your rear door, it's probably because of this exact reason.

Fortunately, without replacing the part, this is actually a super easy (although jerry-rigged) fix.

https://cimg7.ibsrv.net/gimg/www.hum...27887e6771.jpg
Much easier to perform with the Spare Tire removed, however the idea is to push upwards from either the bottom of the spare tire, or from the bottom of the spare tire mount (tire removed). Don't be afraid to give it a considerable amount of force; even a "loose" door will still feel fairly tight.
https://cimg8.ibsrv.net/gimg/www.hum...ae5c6e1055.jpg
Look just to the right of the door handle to where metal meets the rear glass. When pushing upwards & downwards from either the spare tire or the tire mount, you should be able to see any up/down motion, indicating that the door is loose. You won't see a lot of movement, but even the smallest amount is enough to cause the violent thumps from the back of the vehicle

4. "THICKEN" UP THE RUBBER PIECES INSIDE THE VEHICLE BY APPLYING ELECTRICAL TAPE OVER THEM - Pretty much says it all; I applied a generous amount of electrical tape over the two rubber pieces. If either one of the rubber pieces are initially too "slick" for the electrical tape to stick, (which happened to me on the lower piece, but not the upper), I simply applied a small layer of scotch tape first (more gritty than electrical tape), then followed with electrical tape afterwards.

https://cimg2.ibsrv.net/gimg/www.hum...5db9b84d79.jpg
Upper rubber piece with electrical tape applied. The lower piece was very slick, so I applied some scotch tape first, then followed with more electrical tape after.

Once you've applied a generous amount of tape, TEST to make sure the door is not too hard to close. Give the rear door a pretty hard close and take note of how difficult it is to re-open the door with the door handle. You'll know you're on the right track if the door handle has more resistance than usual to re-open the door, but it shouldn't be so difficult that you risk feeling like you're going to pull the door handle out of the door to open it. If you put too much electrical tape on at first (like I did), simply remove a little bit at a time until the door handle becomes more loose, and easier to open. To re-iterate, if done properly, the rear door should be harder (than before) to open, but not so much that it takes a considerable amount of effort (risk damaging the door handle).

Lastly, when you think you have it right, re-perform the forceful push up/down test on the spare tire mount. If you applied the proper amount of tape, the previous up/down motion you saw should be gone.

https://cimg5.ibsrv.net/gimg/www.hum...390736c4ec.jpg
Finished product.

5. TEST DRIVE AGAIN WITH THE SPARE TIRE INSTALLED - the moment of truth. Give it a go. In my case.....wow, WAY smoother than before. Now that the door is nice and tight, all those little bumps that I previously drove over no longer seemed as bad as they were before. Furthermore, there is one particular bump/divot in my neighborhood road that (without fail), ALWAYS induced the violent rear door thump, even at a measly 30-35 mph. This time, I took the bump a lot faster than usual (40-45 mph), and.....nothing. Absolutely nothing, except a nice predictable "bump" the way the car is supposed to perform.

6. ENJOY YOUR NEW RIDE.

As mentioned, this obviously is not a perfect fix, and it does look rather crude with a whole bunch of electrical tape over the rubber tapered pieces, however it worked for me and hopefully will for you if you're experiencing this same issue.

Tomorrow I am getting a new set of tires for the H3 (decided to go with Toyo Open Country 285/75R16 H/T II, as my vehicle hardly ever leaves the pavement and 285s were the biggest HT tire I could find), and I'll be doing a real-world MPG test between the two tires (35" BFG KO2 AT vs 33" Toyo HT II). I play to drive the vehicle ~90 miles before the new tires, and then immediately after the tires are installed, drive (the same) ~90 miles to see the effect on fuel economy. Definitely not quite apples to apples since it will be an AT vs. HT tire, however it will hopefully provide some a data point for those out there in a similar situation who are deciding between 33s and 35s.

Hope this helped; spears welcome. Have a great day ahead!