Arch install write-up

[Hurdy]

Here's my write up in case you want to have a go 

Boot Build Part 1

Right then, I thought that it was time to change the horrible Sub box that I had stuck in the boot as it was taking up soooo much room I couldn't even get a suitcase in   


I'd had a quick scan around other forums and took the bits which I wanted from each and decided upon a wheel arch build, made from fibre-glass and MDF

STEP 1 - Stuff you need

Fibreglass kits - this contains everything you need to create a mould. You will need at least 4 packs if you use the same stuff I did (bought from Halfords)
Plenty of gloves - I bought a pack of 100 although this may be overkill, you get through a lot!
Masking tape - I bought 3 rolls at 50mm wide
Cheapo brushes - I bought 2 assorted sized packs of 5 (2" ones seemed to suit best for coverage)
Bin liners - to cover the car
A cheap glass container - to mix the resin and hardener in.


Step 2 - Removing the strap

There is a strap which needs removing.It is attached with just one scew. This is removed using a T-25 star screwdriver fitting.





Step 3 - Masking up

So as not to damage the original carpeting in the arch you will need to mask off the area you want to mould with fibre-glass. It is advised that you start masking off in horizontal strips, starting at the bottom and working your way to the top. This is to stop the resin seeping through the tape under gravity. I found that a good overlap of half the width of the tape was about right.


Part 2 coming soon.............. 

[Hurdy]

Boot Build Part 2

Step 4 - Fibre-glassing

For anyone who hasn't used fibreglass before, I'll start with a spot of safety. My advice is to:-

1. Wear eye protection to avoid splinters of fibreglass getting into your eyes.
2. Wear the gloves - the packs come with gloves. but they are poor and I advise using latex gloves and changing them regularly. Even if you wear them you can still get small slivers of fibre-glass sticking in your fingers
3. The resin stinks and the odour is quite strong, so if you are attempting it in a garage open a window or the garage door.

Before starting this part, cover the boot floor and hatch opening load lip with the bin liners that I mentioned. this will avoid marking up the boot with resin spillage and fibre-glass shards. It also protects the hatch load lip as you WILL be spending time getting in and out of the boot.

So, once you are kitted up, you need to cut the fibreglass. A sharp pair of normal scissors will do the trick. It is up to personal preference as to how large you make the strips, but I was fairly flexible in that you can use 10 x 30 cm strips most of the time and then smaller pieces for tricky edges and corners and larger pieces for the larger flat areas.


The kit gives instructions on how to mix the resin. All I can add is that the resin takes a lot longer to set when cold or if you don't put enough hardener in. Be careful though. because if you add too much hardener it can literally set in the mixing dish before you have used it all.

Once the resin is mixed, start from the bottom and piece-by-piece work your way to the top. You should cover approximately 100 mm of the boot floor and so you need to allow for this in the masking up process. Make sure you overlap each piece by at least 25mm to give the individual sheets chance to bond together with the resin. I found it best to brush a thin coat of resin directly onto the masking tape first so that the fibre-glass sheets would stick better. Stipple in the resin into the fibre-glass patches until each one loses its white colour. Also be careful to avoid bubbles of air, which weaken the mould. Once the first layer is done, stand back and admire your handywork and get some fresh air!


Repeat this procedure for at least two more layers, so that you end up with a solid mould. With each layer you build up ensure that you do not get any air between the layers.


Once the mould has had chance to set, prise the mould from the arch. It will come out, but the masking tape has a good hold and so it will need a good tug. I found that pulling from the bottom was easier to remove it.


Step 5 - trimming the mould

First, remove all the masking tape from the back of the mould.

Using a jigsaw, trim down the jagged egdes of the mould. Try to follow the outline of the hatch opening, the bottom of the parcel shelf, the back seat and the boot floor. When cutting allow for about 75mm width of the mould on the boot floor.



Once cut, refit the mould into the wheel arch and check that it fits okay.


In my case I also checked that the parcel shelf cleared the mould and had to cut out an extra piece.


The next photo shows the mould with the piece cut out to allow for the parcel shelf


Part 3 coming soon........... 

[Hurdy]

Boot Build Part 3

Step 6 - MDF front

For the purposes of this build I decided to make the front section (baffle) out of 18mm MDF. It is strong enough to take larger diameter subs too and so was a no brainer. B&Q stock this and costs less than a tenner for the size of board you will need.

Stick the fibre-glass mould over the MDF and copy the outline using a marker pen


Using the jigsaw cut out the shape for front baffle.


In the previous photo you will also see that I have drawn a circle in marker pen. This is for the cut out to put the speaker through. I measured across the inner rim of the speaker so that once the hole had been cut the speaker would sit flush on top of the rim of the hole.

To start the hole select a 1/2 inch wood hole cutter


Drill a hole as shown in the pic below, so that you can get the jigsaw blade a starting point


Cut the hole for the speaker using the jigsaw and then offer up the speaker to the hole to test that it sits correctly.


NOTE:- At this point you could use a router to cut the hole to the size you want AND recess the hole so that the speaker sits flush inside the MDF. I decided against this, deciding insted to mould on top of the MDF to give a less flat finish and still achieve a flush fit with the speaker.

The speaker I have has writing on it and therefore I want the writing to be the right way up when the install is complete. I pre-drilled small holes in the MDF through the mounting holes in the speaker to ensure that I would get the writing the correct way up on completion.


Step 7 - Enclosure Volume

Once the front was done I measured the volume inside the fibre-glass mould. I needed at least 17 litres of volume to give a decent response, but you can go larger if needed. The mould was very slightly under 17 litres and so I opeted to cut out a piece of MDF to fill out the volume a little. I copied the outline from the baffle and cut the piece out approx 20mm wide. I glued it using No More Nails Ultra for a good seal.


At this point I decided to round off the edges of the front baffle. This would give a softer edged finish to the install when covered in the fabric. To do this I used a manual plane, followed by a coarse sanding block.


Part 4 coming soon..........   

[Hurdy]

Boot Build Part 4

Step 8 - Access for wiring

There are a couple of ways to do this:-
1. You can drill a hole in the rear of the moulding and feed the wire through...or..
2. You can fit a proper connector at the front.

I decided on option 2 as it meant that I could disconnect the sub box and remove it whenever I needed to. If you think you will not need to remove the box at any point then drilling into the rear would give a smoother finish at the front.

The connector I had came with the original sub box and so I used this. You can buy them from any audio dealer though.

The connector needed to have another hole made in the front baffle for it to sit flush. Again, I marked out the hole and piloted a start point for the jigsaw.



In the next photo you can see the back of the connector has a round section and so this was the size of the hole needed. I cut the hole slightly larger to allow for when the fabric was put on the baffle.


Once cut, offer up the connector to ensure it sits flush in the baffle.


Step 8 - Flush fitting the speaker

I wanted the face of the speaker to sit flush and so the way I decided to tackle this was to build up the front of the baffle with polymer. There are plenty of other ways to do this (polystyrene, another MDF layer, recessing in the original MDF layer etc), but using sandable polymer is reasonably quick.
I bought a 750ml tin of sandable polymer from Halfords, which needs mixing with hardener and sets in around 20mins - so speed is the word here.

Firstly, I took off the rubber surround to the speaker (if your speaker doesn't have a detachable edge, then use the full speaker) and covered the edge in around 8 layers of masking tape. The reason I used so many layers of tape is that you need to allow room for the fabric to fold over the edges of the polymer mould. Screw the rubber trim/speaker into place


Empty the entire contents onto a flat board and mix with the hardener.
Build the polymer up around the speaker adging until it is flush with it and has a decent slope running up to it. smoothing it off with the applicator as best you can.


Once dry, remove the speaker/edging and trim the top so that it is smooth. To trim the top I used a Stanley knife and medium sanding block.


Sand off the rough face of the polymer. The finish doesnt have to be super smooth as you will be covering it up with fabric which will cover minor blemishes.

Part 5 coming up soon..............   

[Hurdy]

Boot Build Part 5

Step 9 - Fitting the front baffle to the rear mould.

This is probably the trickiest part of the build.

Tape the front to the rear of the box using masking tape. I found that the best way is to go around the perimiter twice with one strip of tape and then use strips of overlapping tape across the join to reinforce the seal. It needs to be leakproof as if it isn't the resin will find a way through.


It took 2 tins of 500ml resin and several strips of fibre-glass to seal the front to the back and make it air tight. I did this in four stages. as the box has basically four sides. I did the narrowest side first and pushed in a strip of fibreglass and then poured in around half the contents of one tin of resin (mixed with the herdener). The only way to do this is to lift the box and angle it so the resin runs into all the cracks and covers the fibreglass in the process. Lay the box down on the floor with the freshly resinned side to the floor and let it settle and set for around half an hour. Repeat this process for the other four sides until you have a good set seal. Once done. remove the tape, sand down lightly with a medium sanding block and offer up the box into the wheel arch to see if it fits okay. Remove and sand, offer up, remove and sand etc etc etc until it fits like this:-


Step 10 - Fitting the fabric

I managed to find some fabric that was a good match for the OEM fabric already in the boot and also bought some professional spray glue at the same time. I bought it from my local Audio dealer who was happy to give me some extra advice. The fabric I bought stretches in all directions if needed and is perfect for pulling into position. I cut the fabric with the front of the box laid on it and allowed about 150mm of overlap so that the fabric would go around the sides of the box. Once I'd done this I sprayed glue onto the bottom of the box and onto the inner side of the fabric which would overlap the base. I let the solvent in the glue evapourate and then pressed the fabric carefully against the box base.
Next I turned over the box and fabric so that the box front was facing upwards. I sprayed the glue onto the rest of the inner side of the fabric and all around the front and sides of the box.
When the solvent had evapourate i lifted the fabric over the box, stretched it ever so slightly and laid it down over the box. You have to be careful as the glue is contact adhesive and make sure that you lay it down level. Once this was done I pressed and stretche the fabric into the moulded section and worked my way around the edges.

Once the fabric is in place quickly cut holes where the speaker and the cable connector go, leaving around 15mm overlap so that you can fold the fabric into the hole edges.

Fit the connector and feed the cable through and out of the speaker hole and connect up the speaker (ensuring correct polarity!)

Screw the speaker and connector in place.

At this stage I fitted strips of velcro to the back of the sub box and to the wheel arch.

Fit the sub box in place and connect the amp at the connector point

Sit back and enjoy your handy work  O0




I'm sorry about the slight lack of photo's at the end, but I got a little carried away as it was 6pm on Saturday, the wife wanted to go out and The Elsecar mega meet was the following day, so I was a bit rushed!!

Anyway, I hope this write-up helps

Cheers

Hurdy 

[WhiteGTI]

Great write-up Hurdy!!

Wish I'd asked you if i could see/hear this at the last meet!

At the pod I shall be askinggggggggggggg!! 

[Top Cat]

Nice one Hurdy.

And Chris i had a couple of minutes in his car and the sound was amazing.   

[JPC]

nice mod mate, i really need to do this for mine after christmas

[joesgti]

nice one john, read it about a year ago and was very impressed, id do this my self, if i could be arsed. 

[JPC]

nice one john, read it about a year ago and was very impressed, id do this my self, if i could be arsed. 

lasy b@stard! haha!

[VC]

Luvin your work there 

definatley going to do this. questions though

hows it held in place? i know you said velcro but how exactly? does it shift on hard cornering?

also, what if something slides into the speaker as it isn't protected

finally, is there a reason the connectors are on show? is this something that could be hidden away as well?

cheers dude 

[WhiteGTI]

Great write-up Hurdy!!

Wish I'd asked you if i could see/hear this at the last meet!

At the pod I shall be askinggggggggggggg!! 

I bl00dy forgot AGAIN!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[Hurdy]

Luvin your work there 

definatley going to do this. questions though

hows it held in place? i know you said velcro but how exactly? does it shift on hard cornering?

Velcro strips attached to the wall of the car and the hooked part of the velcro attached to the back of the enclosure. The main holding part is built up underneath the plastic trim at the top (the bit that the parcel shelf sits on) , the enclosure is pushed into place with the top end first under the trim and then pushed hard into place. It doesn't move at all, no matter what you do with the car.

also, what if something slides into the speaker as it isn't protected

I thought about protectors, but the speaker is reasonably high up and if I want to put something bulky in the back that could damage the speaker (quite rare) I tend to remove the enclosure.

finally, is there a reason the connectors are on show? is this something that could be hidden away as well?

I put the connectors on the front for ease of removal as it is much easier than drilling into the back. It means I can disconnect first and not have to worry about lifting the enclosure out and then having to think about disconnecting. If you look at my build thread I did mention that either could be done

cheers dude 

[Hurdy]

Great write-up Hurdy!!

Wish I'd asked you if i could see/hear this at the last meet!

At the pod I shall be askinggggggggggggg!! 

I bl00dy forgot AGAIN!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I took the sub enclosure out for the Pod meet

[WhiteGTI]

Ahh ok, that makes me feel slightly better! Next time I'm looking forward to hearing it!