A few weeks ago, I had the Brown Davis 68 litre reserve diesel fuel tank fitted. Prior to that, I’d already installed a set of King shocks from Expedition HQ. When the shop installed the tank, they said it was a nightmare to fit—but they got it in eventually.
The other day, while checking the tyre pressures, I noticed the exhaust pipe was pressed hard up against the shock absorber. I’m no expert, but even I knew that wasn’t right. I booked in with a local exhaust shop and dropped in this morning. They put it up on the lift so we could get a proper look.
Turns out, it wasn’t just touching the shock—it was also hard up against part of the suspension linkage and something else I can’t remember the name of. While the contact with the shock was the only thing obvious when the vehicle was on the ground, lifting it by the chassis and letting the suspension hang (which, according to the exhaust guy, is how you should check exhaust clearance on a 4x4) revealed multiple contact points.
The fix? Slide the Brown Davis exhaust extender further over the existing pipe. To do that, he had to remove the extender and extend the expanded section to allow it to slip on further. Not a huge deal if you have the right tools, but it took him a couple of hours and cost me $350.
In my opinion, the original 4x4 shop didn’t cut the exhaust in quite the right spot—leaving it a little too long. They probably realised this after the tank was installed, and instead of removing the tank to correct it, they just left it. The proper fix would’ve meant taking the tank back out, trimming the pipe, and reassembling everything.
I also noticed that the fuel filler tube is jammed up against the right rear shock. The exhaust guy didn’t want to take that on, so it’s still like that for now. My overall conclusion? The Brown Davis fuel tank needs special consideration if installing it with King shocks. Get a shop that is meticulous with detail and one that has exhaust fitting equipment to do the job properly
On a related note, the Brown Davis exhaust extension is just a hollow pipe—not a muffler. That said, I haven’t noticed much change in noise. My partner reckons there’s no difference at all. Personally, I think it sounds slightly more like a tractor—which I love! It does make me wonder why the stock muffler is even necessary when removing it makes so little difference. If anyone needs a spare muffler, let me know. I’ve also got four OEM shock absorbers and the factory front steering dampener lying around. I'm in Sydney, AUS. Oh, and swapping out that front steering dampener has been the best mod I’ve done so far.
As for filling the tank—when I put diesel in, it seemed to fill both tanks together. I’m not sure if one fills before the other, but I did have to ease off the pump to avoid it backing up and cutting out. Transferring fuel from the Brown Davis tank to the main one took around 30 minutes. A bit slower than I expected, but honestly, not a big deal.
Consider the weights if you do any towing. I recently purchased a hybrid camping trailer and it had me in nearly panic mode when I hooked it up at the dealer to tow it away. Lowering it onto the towbar squatted the back end of the Grenadier right down. The steering was really light and a tad scary. The manufacturer's specified ball weight is 280kg but I'm guessing it was way over. The Brown Davis fuel tank is quite heavy, maybe 50kg (my best guess trying to pick up the box). Filling the tank adds another 56kg, with the weight right at the very back, behind the rear axle. I fixed the sagging back end by adding air bags to the rear suspension but it's still pretty heavy back there. I don't know if the Grenadier 350kg max towbar weight is impacted by adding weight with the reserve fuel tank. It's just worth considering the weights of the reserve fuel tank if you do any towing.
