Help needed - MAF 38 gal replacement rubbing drive shaft

Joined
Nov 19, 2011
Messages
108
Ok, just to get this out of the way - I know the MAF 38 gal (from Australian Long Range Automotive) hangs below the frame and sits close to the drive shaft. I'm ok with that because I want the added half tank of range (specifically, in the tank), and don't crawl a lot of rocks.

So I've just "finished" with the install, and boy was it more hassle than I expected. That's what I get for not owning a lift. Regardless, the tank is in, the straps look to be well fitted to the tank's contours (not sure if they're adequately tightened though), and my modified-to-spec fuel pump assembly is installed and working correctly. The rear hoses are connected and clamped. All the top side connections are in place. The drain has a proper M12xsomething plug in it and no leaking.

There was about an inch of space between the rear of the tank and the drive shaft, just ahead of the U joint. I added 10 gal of fuel to the tank and checked for leaks, and so far so good, BUT as soon as I started to roll out of my driveway I began to hear a loud grinding thumping sound. Rolled back into the driveway, and looked to see what the heck, and beheld the rear side corner of the tank pressed right against the driveshaft and both getting and leaving a nice rub.

I realize 10 gal is something north of 75 lbs, but I wasn't expecting the tank to shift so much that it would scoot over and hit the DS. thinking on it a bit harder, I realized that looking down through the service port under the second row seats, the tank was sitting and inch or so further back than factory. I also have the e-brake cable passing over the top of the tank in a couple spots (rear corner, front portion).


Any ideas what I screwed up? I was pretty sure I tightened the straps in thoroughly - though the rear hanger on the frame side does have some gap between the hanger bracket and the new tank's strap; I wasn't sure if that's a problem.


My thinking for tomorrow is to stick a jack back under the tank and see if I can raise it at all. If I can, then tighten the rear frame-side strap mount and see if that pulls the tank further from the DS. Second option will be to loosen the hose clamps on the hoses coming from the back of the tank, loosen the straps a bit, and try to shove the tank forward without going so far that the rear hoses can't be adequately secured. Third option is see if the e-brake cable is keeping the tank from being fully raised, and pull the cable out from on top of the tank (loosen straps, detach the rear of the cable, pull it over the top, and then route it past the tank straps - I don't want to drop the tank unless strictly necessary).

Any and all suggestions welcome!
 

LINUS

Waiting for the Great Pumpkin
 
 
Joined
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You could jackstand & shim tight the tank, loosen the straps & give it a shove, see if it finds 'home' better than where it sits now.

That tank is run by a few guys here, so not like it's a new jig & unproven product - something little like that is prob the issue. ???
 
Joined
Nov 19, 2011
Messages
108
You could jackstand & shim tight the tank, loosen the straps & give it a shove, see if it finds 'home' better than where it sits now.

That tank is run by a few guys here, so not like it's a new jig & unproven product - something little like that is prob the issue. ???
Any of those folks have input on where the e-brake line should be routed? I think that's what's giving me fitment issues - but I'm not certain.
 
Joined
Nov 19, 2011
Messages
108
Sorry for the slow delivery guys, I managed to sort this all out Monday but only just now made time to come update.

Here's the trick, and the short version is I completely overlooked something that would have been obvious from the start, but wasn't once the tank was mostly in place. There's a rib in the body right above the rear hanger. The tank has a triangular notch on top to accommodate this rib, allowing the tank to tuck in about an inch higher up. I had the tank a quarter inch too far to the rear for the rib to slot into the notch, so it didn't engage and was hanging low making everything just a little too far off where things should be.

I loosened the straps and rammed the corner with the drain bung forward a hair, using my OEM bottle jack butted against the rear axle as a press, with a wood block to help even the force out. With a very light touch on the jack. After the tank slid so the rib and the notch lined up, I put a jack under the tank and lifted it into position against the body, then the hangers tightened up nicely.

I'm not happy with the mounting of the front hanger bracket that shipped with the tank, so I've got some additional work to do there - it has a hole that the factory bolt goes through to pull it onto a body rib up front, a stud to hang the new strap on, and holes in the sides to cross-drill the body rib and run a couple carriage bolts through. The problem is that the fuel lines run right along the back of the rib in the same place this mounts, so you'll have to reroute or flex them away from the rib to make room for the bolt heads and avoid rubbing (which turns into cracked fuel lines in no time). You also have to do some fiddling to move them out of the way to cross-drill the holes. I only managed to cross drill for one of the two carriage bolts, and I think it's probably plenty strong, but I suppose I may find myself regretting it later down the line if I don't go back and fix it.

Modding the pump assembly was relatively simple, but my kit a) didn't come with any fasteners for extending the spine, and b) included 1/4" tube rather than the 5/16" that the factory assembly uses. I managed to muscle it on with a bit of hydrocarbon lubricant, but it strikes me as something I ought to go back and replace sometime sooner or later - not having that extra 1/16" might increase pressure on the pump or something. Modifying the pump wiring requires extending 2 wires, and the kit only came with 1 butt splice connector, when I'd expect 4 to be needed, but maybe I just missed a clever trick - being that this wasn't in the instructions at all, that wouldn't be a shocker, but frankly I didn't see a shortcut. (The kit didn't include brazing supplies for the float arm either, but that's to be expected)

Also, FYI, the instructions that come with the tank are best viewed as rough guideposts. It would be nice if there was a hair more detail, like where the heck does the e-brake line go so it's not (literally) pressed between the tank and the exhaust? That's something I'm still trying to work out - I see you can take the rear strap mount and the e-brake line bracket and mount that bit up together, but the line is too short to then not be up against the exhaust... a mystery I'll ponder later on. For now my line is some 1" from the exhaust but loosely held in place, so it won't be able to live that way forever.

The tank, by the way, has a second wall on the bottom which makes the bottom surface quite stout. It does hang below the frame, but no further than the muffler & t-case shield, and the leading edge is tapered up above the cross member it nearly touches, so in all it's probably not going to take a lot of hits with my driving. I try to avoid drops onto things that could smash my t-case anyway, so this just means I have a slightly wider area to apply the same caution to. I'll take some pix and post them here soon.


In the end, the tank is in and it holds a lot of gas. It may only be 13 gal over factory, but that's near enough to 3 jerry cans worth, and I'm happy to have the extra capacity along with the weight of all that gas moved down low. I'm feeling a lot more confident in my range with this sucker - took a test drive for 140 miles after I got it in, and didn't even knock the fuel gauge down 1/3rd. Maybe it's reading weird because of the mods, or maybe I'm just hitting a bit over 10mpg for the time being.


So, the tank is awesome, the kit is marginal, the instructions are garbage, and the whole process of installation is a PITA, and the thing cost a whole darn lot. I'd do it again, but not without a shop with a lift and these notes. :)
 
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Joined
Nov 19, 2011
Messages
108
Here are a few pics of my install - Any tips on improving the fit of the inner strap mount up front would be welcome - I had to shim under the strap with 3 or 4 fender washers for about 1/4-3/8" thickness, and it's still oddly tweaked. I think the tank is sitting on the c-channel bracket when it should be next to it, but I don't see a good way to get it shifted further toward the frame since it's rubbing on the body above on the frame side already, where the body slants downward toward the frame. I could drop that side 1/4" to make some room to scoot the tank that direction, but then I'd just be left shimming the outside hanger joint, I think.

The rear inner (and outer) mount is nice and solid - the fender washer and nut you see on there is just holding the e-brake cable in place to keep it away from the exhaust. The strap itself has a nut holding it on above that. If you look closely, you can see the burnt rubber residue on the inside edge of the upward turn of the exhaust pipe from prior to doing so. Melted a patch flat on the cable's outer sheathing.

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Joined
Nov 19, 2011
Messages
108
Second set of pics - I included a shot of the proximity of the rear of the tank to the drive shaft with my fingers for reference. It's over an inch.

Bonus - you can see where my initial bad fit rubbed a nice ring on the DS

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