HUmmer H2 Owners, lend us your ears / cameras, seeking info on fuel tank protection

[rayra]

GMT800 Suburban guys have been talking about solutions for some fuel tank bottom protection. Talking about plates and such. Member geronracing spotted an H2 that seems promising - http://forum.expeditionportal.com/t...g-Suburban-Build-Thread?p=2282799#post2282799

http://www.factoryoemparts.com/03-09-hummer-h2-fuel-gas-tank-skid-plate-25884456-25884456

Problem is the tanks look differently shaped, H2 vs GMT800 Sub, so we're wondering how it might fit, looking for some image details of the tank cover, if you have it. So if you could comment here or take and post some pictures of the fuel tank and its cover, mounting locations, it would be appreciated.

Also have yet to find a definitive source of info about the commonalities between our vehicles. H2 vs Tahoe etc



That big expanse of poly tank is just worry-making. Would like to shield it somehow.

 

[e60ral]

Is that plastic? That looks plastic

 

[rayra]

Yes, the fiber-impregnated plastic they use for lots of parts. The chin "plate" on Tahoes and Suburbans appears to be made of the same stuff. Certainly not very strong, but better than nothing. And at the low price point, not terrible either.

I've been looking at fabricating a plate from 1/8" steel or 3/16" aluminum. Part of the issue on the Sub / Tahoe setup is that the bottom of the tank is practically flush with the bottom of the frame rails. So it's a bit of a catch-22. Build a sturdy cage / plate and you lose ground clearance and end up making contact more than it is. With the Sub / Tahoe, the transfer case and its factory plate are about the only thing that hangs below the frame (besides the usual drive shaft, rear diff, rear trailing arms, rear shock bottom mounts).

Mostly looking for something that will act as a double hull for the tank, not something sturdy enough to high-center on. I've been looking to fabricate something that uses the factory saddle straps to hang a plate. So the Hummer tank cover schematic is very interesting, as that cover seems to use the saddle strap attachment points.

 

[Burb One]

Is that plastic? That looks plastic

Yep, Really just interested in something that'll stop scrapes/ gouging. As Rayra said, more like a double hull.

 

[rayra]

All the big auto makers are notorious for using same parts across multiple vehicle models / lines. It's very likely that the H2 and Tahoe fuel tank parts are the same, looking into that too. And the saddle straps for the tank look very much the same. So I / we're digging into parts number references looking for that commonality.


Our Sub tanks' front ends tuck over a cross member in such a way that mounting a flat plate to that cross member and the adjacent frame rail with rivnuts and cap-head allen bolts is a very tempting idea. But there's no readily available way to mount the inboard edge. So I'm thinking to use the tank straps. It won't be structural / support the vehicle weight, but it will give good added protection against sharp objects and road / highway debris. And do it without reducing clearance to any significant degree.

Our tanks also have a thin sheetmetal guard on the inboard side, facing the exhaust and the driveshaft. A bottom plate could be hanged from that, but again it's not structural. But it would do for a 'second skin' sort of solution.

Might just wind up adapting the design idea of the Hummer tub and adding vertical brackets that attach to the tank strap mounts and just suspend a metal plate below the tank. Maybe an 'H' sort of bracket fore and aft, so it has some lateral rigidity. Or even a cage framework from 3/4" or 1" square tubing that again attaches to the tank strap mounting locations and serves as an attachment frame for a skin that is also attached to the frame bottoms. That might just be the trick if I can't find a ready-made solution.

 

[rayra]

The more I think about it the more I like the simple idea of a flat plate with the inboard edge turned up to overlap the metal skin on the inboard side of the tank. Then it's just drill holes in the bottom edge of that skin and into the underside of the frame rails. Use those sheetmetal flange nuts that slip over fender flanges as attachments on the inboard skin. And either self-tapping bolts or rivnuts on the frame rails.

I'm going to get under there with some big flat cardboard later this week and look at clearances.

 

[DanCooper]

Any H2's with that tub in a local salvage yard that would allow you to photograph, measure, etc?

 

[rayra]

Possible, planning a wrecking yard run in the near future. But the best one in my area recently closed and cleaned out. But now that I think about it I actually have a Hummer dealer in my town, so I might go by their parts department and see what I can find out. Have to take a strap spacing measurement on my Burb (and Tahoe too, what the hell) and see if the H2 tub is sized the same. Probably go pick up an empty 'wardrobe' moving box too while I'm out and about, and start the 'Cardboard Aided Design for making a plate. And a couple other protective plate ideas I'm doodling.

The Sub and Tahoe have a long trailing arm setup, so the tail 1/3? 40% of the tank plate is unsupported. But the last crossmember forward of the rear axle can also serve as an attachment for that end of the plate. so both ends on the crossmember, the forward 60% of the driver side on the frame rail and the inboard 100% on an added tubular frame, ought to give a good amount of support for a flat panel.

Just went out and put a tape on the Tahoe fuel tank. The straps are 28" apart, on center. Tank is ~48"L by ~20" wide. And only 20" of it are forward of the trailing arm pivot, with no good plate attachment on the rear outboard 60% of the tank. So it will have to have a metal frame depending from the tank strap attachments to support a protective plate for nearly 70% of its perimeter.
I'll get measurements on the Sub tomorrow. Or find the notes I've already made, I think I measured it already.

scratch that, found some notes. The Sub tank is ~62"L. Straps are ~42" on centers. The same ~20" width. Wth about 12" forwad of the front strap and 13" trailing by the axle.

Given how flat the tank area is on a Sub it might be possible to rig a support frame from square or round tubing. An 'L' that completes the perimeter for the plate, attaching one end to the crossmember on the long inboard side of the L and to the outboard frame rail on the base leg. Then borrow the H2 tub attachment design and run some vertical supports to the tank strap attachment areas. It won't bear the weight of a high center but it's more than enough to support a second skin.

Have to get under it again adn do a good photo-survey of the tank attachment framing and figure out a mounting that won't just spike thru the floor if you put the vehicle weight on the plate.

 

[rayra]

Doh. Failed to notice that Hummer brand has gone away. Local Chevy dealer wanted $402 for the H2 tank cover ($250ish on eBay), couldn't or wouldn't do a comparative lookup of the H2 and Tahoe tanks to see if they are the same. But I'm fairly certain it's not going to fit a Sub. Although the H2 tub mounting hardware for the tank strap locations would be useful in a custom build for the Suburbans.