Forgot to ever update this at the time but I did eventually get round to welding up the A post:
With the car solid again I moved my attention to the ICE. I've always liked loud music when I'm driving and really wanted to improve the standard Manta system. I had a Kenwood USB head unit already, it was the awful little speakers and total lack of bass that was getting me down.
So, I decided to make a snug fitting and relatively discreet ICE install. The metal part of the parcel shelf was creaking and groaning like mad which was getting really annoying, so it was an ideal excuse to get rid of it!
Most of you will recognise the ICE from my Volvo Lowrider
Started off by marking up and cutting a basic sub box from 18mm MDF. I used long wood screws to fix it all together and then sealed it from the inside. The box is designed to be exactly the depth of the boot (including the original shelf) and the top panel is exactly the same width as the original metal half of the shelf (albeit not as deep)
This means that in effect the new sub box will be the first half of the shelf.
Then I covered it in acoustic cloth using Dunelm's excellent heavy duty spray adhesive:
And fitted my cheap and nasty Ebay subs. "MAXIMUM BASS" apparently! At £16 for the pair I couldn't really argue:
Then I mounted my amp - another Ebay cheapskate purchase. But amps are relatively simple pieces of kit so I thought economising here would be fine. I had this setup in my old Volvo and it worked brilliantly. I know you aren't really supposed to mount amps to the sub box but killing a £35 amp isn't really the end of the world so I did it anyway:
After this I thought I'd better check the box would actually fit. Bingo! Doesn't slide an inch side to side which is exactly what I wanted, and the depth is perfect:
This is where I discovered I'd made a mistake. When I measured up I forgot to take into account the amount of space the amp takes, preventing my sub box from mounting flush against the back seats. So instead, I cut a spacer bar from MDF, carpeted it up and wedged it between the seats and the sub box. It doesn't move a millimeter because it's such a snug fit and fits the bill perfectly.
I then cut the rear parcel shelf using the old fibreboard one as a partial template. Smoothed all the edges off with an orbital sander which made a hell of a mess in the garden. I test fitted it along with the spacer bar and tried to shut the boot. SPOT ON!
Here it is in place:
Now I needed something to stop the sub box from sliding backwards. Using the old boot carpet as a template, I cut a sheet of hardboard, and fixed a small strip of wood to butt up against the sub box. The whole lot got carpeted and slotted in. The sheet of hardboard is wedged against the rear panel, so it can't move, and the strip of wood stops the sub box from sliding back. I need to make the small infill panel that goes on the left side but I was running out of carpet:
I didn't want the rear shelf to be a featureless plain sheet so I considered a few options and decided to go with 2 raised sections, just to break it up a bit. So first I marked out:
Then cut up some wooden strips with the mitre saw:
All screwed down and the edges sanded smooth. It gives the shelf a bit more rigidity and some contours:
Went with 8" JBL GTO speakers. I've always used JBL in the past and been happy with them. I'll amp these shortly but for now they will run off the head unit. The Manta has a lot of parcel shelf hence I chose such big units:
Fitted the speakers to the shelf. Even though this will be carpeted over the I thought the grilles would give the speakers some protection:
And started the carpeting. I tested what effect the carpet would have over the speakers. Almost none. If anything some of the tinnier treble is a little muted. Happy with that, I stretched the carpet tight over the raised sections and glued it down.
One of many test fits! When I was happy I screwed the shelf to the sub box with some small piano hinges:
I still need to stretch the carpet tight around that corner but the install is basically done.
Looks relatively stock which is what I was aiming for:
Same from the inside:
And subtle from the outside:
Now I need to wire up the rear speakers, finish off that boot floor panel, and then I can start thinking about how to get some sound into the front. The original design leaves a lot to be desired! Thinking of making some footwell pods but not sure at the moment.