Composite Fuel Tank #4 – trial part fitted

and I’m a happy bunny. The finish is a little rough, and I can do a little mould polishing to get that, but once the part is in, it will never be seen again, so I’m not going to get all artistic about it.

Prepare to swoon at the fitment …

trial fitting 7 trial fitting 6 trial fitting 5 trial fitting 4 trial fitting 3 Top Down – here it is, fitting nicely, stopping about 100mm from the gear lever. There’s a good 10mm clearance all round between the tank and the rest of the transmission tunnel.


trial fitting 1



Open Wide for the Doctor

This is the view right down the tank into the sump.




Bolt Recess

Here you can see the cut-away area of the part I made to allow me to get a socket in to first insert and then secondly tighten the 1/2″ bolt for the top of the diff cradle.



Tank and Chassis fail to meet

The tank nicely runs under the chassis rail. This is just shy of 10mm. The tank isn’t going anywhere once it’s in, so I’m not stressing this.


Diff Clearance

Again, loads of room here. The diff cradle is held in place with 1/2 inch bushes, so there’s no way can it ever touch. I’ll also be making prop-catchers, so I won’t worry about the prop hitting it. And the tank will be in aramid, so i’m not fussing that.


Topping Out

Here’s the tank the whole area behind it is where the old MG Midget tank used to sit. The black brackets are temporary. I’ll made something rigid out of CF that spans the top of the tank between the cross-members. The tank itself will have m6 male fasteners bonded on to it, so it can be fitted from below.

The last picture demonstrates just how far I’ll be able to move the mass of the tank. It’s forward by 300-400 mm, to the point where it’s now inside the axle line. The aramid tank will have better impact resistance properties than the steel one it replaced, and being in the new place it is in the chassis, will benefit from greater impact resistance. The area behind (at the top of the picture) where the old tank used to hang from will be replaced by a crumple-zone.

trial fitting 10And  … Attach

These are Big Head fasteners. You basically put a big dollop of the special 2-part epoxy glue no the part (after keying it), push the fastener through, let it set and trust it.

I don’t have a solution for the front of the tank yet – I think I may take a bracket off the prop-catcher I haven’t made yet, or make a top-hat shape, cut a hole in the tank and stick the top-hat to it, but inverted so the top hat makes a recess. Then I can stick a big-head to it (I have some female ones) and bolt through from the other side of the transmission tunnel. It’s going to be … specific.


Composite Fuel Tank #3 – prototype part pulled

Or – Transformers – Fuel Tanks in Disguise!

So, before I make the part out of lovely aramid and carbon I thought I’d do the sensible thing and crack a part out of chopped strand mat first. I wanted to do this for three reasons:

  • check the part for fit in the car – if the mould needed a tweak or two, now is the time.
  • check the part for fit for the ATL fuel sender – I’d gone to a huge amount of effort to site this so that it reaches to the bottom of the tank.
  • fill it full of water to see what the capacity is

tank bag of partsHere we have the entire set of parts pulled and trimmed from the mould. As I went along, my trimming got a lot better a lot quicker. I realised it was far easier to scribe the part in the mould for where the trim-line should be, and then to pop it out and trim it. As such, I have a few gaps which have been sorted with how I’m bonding it together (30mm strips of glass, wet laid on).




prototype tankNow the part is pulled and bonded together, hopefully you get a sense of the size and shape of it.

I managed to bond the whole of the top tank (the top bar of the T shape) internally, but the lower part needs to be bonded externally. I did a reasonable job, but it’s not watertight. It was good practice for when I do the aramid/carbon part.

The entire part weighs just over 2kg, which gives me a saving of 3.7kg over the standard midget tank. It’s a great weight saving, before I even take into account moving the mass about.