Rob's GBS Zero Project: Bonnet & Nose Cone

The manual advises that the bonnet and scuttle is a two person job. Unfortunately there's only me so that will have to do.

The nose cone fixings were very simple. Stainless m6 rivnuts in the handy upper holes. Then under the radiator there are some pre drilled holes. I used some m6 chimney nuts and positioned them accordingly.

Offering up the nose cone, I clamped it at the bottom with some adjustable clamps. I centred it laterally first and then set it longitudinally so that it was very close but not touching the upright mounts where the top rivnuts were located. I then realised I had to remove the radiator assembly to get to the lower rivnuts..... grrr.

Nose cone in rough position

After following the same process again I then offered up the pre rolled bonnet. It was a country mile off the right shape! So before I was confident to fix the nose cone position I set about the bonnet.

Bonnet a mile off!

First off was to fix the bonnet pins. I chose black. I wrapped them in tape to give some (but not enough) protections. I installed some M6 rivnuts into the side chassis rails. Then i needed to enlarge the bonnet pin holes in the bonnet to allow the bonnet a chance to match the side panels. I also temporarily installed the bonnet catches (pre drilled holes that were actually in the right place!) and protected the nose cone and scuttle with tape.

Next job was to bend the bonnet. I removed the VVT housing and pipe from the top of the engine and cut a small hole in the bonnet to deal with what's left that will clash. Eventually there will be a scoop so not worried about the hole. With some heavy liquid filled plastic containers and a large roll of plastic carpet protector (the only solid cylindrical object of large enough radius in the house) I set about some large adjustments to the bonnet.

I first flattened it as much as possible and then rolled the bonnet around the cylinder to try and get the shape. The bonnet must have gone on / off 50 times and I flattened / deformed so many times but eventually I got it about right. I temporarily installed the edge trim and I think the result is acceptable. Need some more bonnet pins as they are so scratched up they are no longer black!

The final bonnet shape

A few minor dents (will be cut out by the scoop) and minor scratches (will be prepped out for paint) and I was happy enough with the result. So I drilled pilot holes in the nose cone through the chassis fixings and firmed things up.

Next step are cut outs for the exhaust manifold and scoop!

The exhaust cut out worried me the most as there is no room for error. Measure a million times and cut once.... Time for a bit of CAD (cardboard aided design). I installed the exhaust manifold and measured the approx centre of each of the pipes as they passed across the outer chassis rail. I drew the centres on a piece of cardboard (coco pops I packet I think) and used a french curve to make a nice shape to aim for a 10mm clearance to the manifold. A quick cut out later and I had a template.

Template in place

I transferred the pattern onto the bonnet and then set about it with a Dremel 38mm cutting disk for a rough cut out, and then a file to finish. I cut inside of the curve to ensure I didn't stray outside the line. This left me with a lot to file off but better that way. I reinstalled the manifold, measured and finished the job. A bit of trim around the cut out and it will look good.

View from the front

View from the rear

Next step was the scoop. The VVT housing and oil pipe on the engine clash with the bonnet. I considered a few different options. A formed bulge, lowered engine mounts were thoughts, but I decided on the scoop. I like the look and it offers flexibility in case I want to do something else under the bonnet later.

The scoop itself is a GRP one from GBS. At £90 it felt good value against other options. Since the bonnet will be painted i thought going for a carbon one a waste of money.

I centered the scoop on the bonnet and straight away realised the shape of it is not a great match to the bonnet curve. Only bonding it would be difficult to achieve so I decided to use a few countersunk rivets when installing it. That made it even more important that the cut out was well sized but not too over sized as I will want the filler to cover the rivets.

Big hole!

I used a cutting disk on the Dremel again to to the hole. I went through two discs but it was generally easy to keep steady. I finished the cut out with a file.