I was always going to have a go at an under-tub water tank after seeing this thread some time back
Subi's water tankI certainly didn’t have a new idea; I just copied Subi’s with my own changes.
I did make quite a number of mistakes & would change a few things if I was doing it again. That’s why I’m writing this up, so you don’t have to design from scratch.
If you have any other options/designs please add them to Subi’s thread for easy search in the future.
You will need just under 2 mts of 100mm PVC sewer pipe (more for an MN)
2 x ‘y’ junctions (screw cap type) –you could use just 90deg bends but it would have less volume
2 x 30deg bends
2 x 90deg bends
2 x end caps
Sleeve/joiner to reinforce outlet
4 x clamp style brackets
90deg fitting for outlet –I used a fitting from an underground sprinkler system
Hose clamps
PVC primer & glue
Tap (I got mine from Bunnings-it is brass & has a ball valve with a small leaver
Assorted flat steel –I also used 4 x galvanised stand-off brackets
Paint for brackets & any holes drilled in tub
A nipple to suit your hose for the outlet
About 1 mtr of hose to suit your fittings
Bolts, flat washers & Nyloc nuts to suit
Fittings & hose for breather.
Rubber grommets for breather
Breather – I used a small air filter type from our local AutoPro.
I don’t know how this will hold up long term. A diff breather style would be good. Do Not connect it to a spare diff breather inlet on you current diff breather- when you fill the tank you will probably get some water going back down the pipe to your diff.
I will not go into measurements as it is different depending on your model & probably which towbar you have.
Just measure twice & cut once.
The BuildThe pictures show most bits so I won’t go into too much description.
I probably did things the hard way as I built the tank first & then had to find a way to support it.
After lying on my back under the car for quite some time the ideas started to come. There is a reinforcing rib above the towbar & I drilled & tapped that. The metal wasn’t quite thick enough & would strip if done up tight, so I also drilled & tapped a piece of a gal standoff bracket. This was used to add some thickness to the thread. I later drilled in some Tek screws to add more strength.
The pipe was measured to fit without touching the chassis directly to avoid vibration stress cracks.
The front brackets also had me thinking for a while, the spare wheel support beam had some holes on the top so I decided to use them, with large flat washers both sides & Nyloc nuts this should be fine.
The tap was fitted to a piece of flat that I cut with a holesaw, heated & bent then screwed up on an existing hole under the rear panel. I used some rubber stip to help take up any vibration.
The breather system was another problem. Initially I used 2 in-line fuel filters as Subi had done. I just got it all fitted up as the wife went past & I said ‘here have a look at this’, turned on the tap & got a dribble out.
Too much resistance to the airflow when they are wet so not enough flow. Back to the drawing board
I went to our local auto spares shop & found a breather & thought what the heck, lets try this one.
A trip to the fitting/hose shop on Sat morning & I picked up some nylon hose & fittings to suit.
I mounted the breather up under the LH rear of the tub behind the wheel –big empty space
All fitted up & it works a treat.
Where I went wrong.Fit the outlet into the pipe before assembly-I had to cut it in half after I built it.
Make sure which part goes where & in what order before gluing
derrrrr
If possible, fit the breather outlet to the top of the pipe-use 90deg fittings if you have to. This will allow you to fill it to capacity.
When I assembled the pipe I could get 17lts. When it’s fitted I get just over 15lts. This is due partly to a small amount of water staying in the low end of the pipe & not filling fully due to the breather location.
All up it took considerable time to nut this out (just ask the MOWF
) much of it starring & waiting for inspiration to hit. (I would estimate about 10 hrs total
)
As for the cost I have to wait until my hardware account comes next month & I will add up the parts used
I hope this helps someone else to build & improve on my version & a whole lot faster too.