Fitting Front 6.5 speakers to a Skyline GTST

Now we are all aware that the standard size in the front door housing is 5.7 inches or 13cm and that the standard speakers as fitted are wonderous items made from tissue and good intentions. So the simplist way of upgrading is buy some more 5.7 speakers, plop them in and job done!

However being Skyline owners we don't do things the easy way, especially considering that with induction, blow off valves and daft exhausts, it can get a tad noisy in the car. So you may want to squeeze in a 6.5inch or 15.5cm speaker for that extra notch on your radio dial. Additional to that, most cars generate bass (exhaust, engine etc.) this has the effect of cancelling out bass sounds from your stereo. So you want to generate as 'warm' a feel as possible.

To make this modification we will need some MDF (Medium Density Fiber Board) some hot glue sticks, a glue gun and cross headed screwdrivers.

Note: Alraldite can take the place of a hot glue gun but is messy and you will not get such a polished finish!

Here is an idea on how I upgraded my speakers.

Standard R33 Speaker Housing

The pictures I have included are on the drivers side door, the passenger side housing is slightly different, although the basic principals remain the same. I am fitting Alpine SXE-1725S which are widely available at time of posting.

Firstly remove the plastic speaker housing (duh!)

Apologies for the shakey hand picture!

You can see that in principal the housing is quite a good idea and that the flange on the end forms part of the door pocket, stopping all those essential items such as sweet wrappers disappearing behind the door card!

Now it's time to bite the bullet and chop up the housing! Cutting around the inside edge of the speaker opening, remove the inside of the speaker housing. I used a Dremel and cutting disk to do this. It half cuts, half melts it's way but does clean up well.
It's good to try and keep a straight edge, ignoring the exciting curve of the housing front, remember we are fitting a flat plate to the inside here.

Separate the back of the housing by cutting around the inside edge of the flange

Great so you have ruined your housing.. What's next? So we have a big hole, now to the cardboard and MDF!

Cardbard Template

Trace around the inner and outer parts of your housing onto cardboard to make a template.

Get it nicely sized so it fits snug and using the template that usually comes with the speakers on the box, place the speaker hole central to your template.
When your happy with the fit you can transfer this to the MDF and cut out. For this I used 9mm thick MDF, cutting out the speaker hole first and then the shape.

Cutting out the shape from 9mm MDF


At this point I attached my mdf shape into the housing with a hot glue gun, these are available quite cheaply for around £10, to save on time I also used black glue sticks.


On the back side you will find that where we used 9mm MDF there is a nice 'channel' created between the housing and the MDF, fill this with glue and run a bead around the inside.

MDF Insert, ready for bead of hot glue.

Ready for mounting

On the front, again fill the channel with glue and clean up with a sharp knife, you should be able to get a quite acceptable finish (that no one will ever see!). There will be some slight material removal left to do on the front of the housing for speaker clearance although this is minimal.

Clean up your new housing and give it a lick of spray paint, I went with a satin black on mine (very tasteful).

Mounted to car door, ready for door card to be put back on

The easy bit now is to drop in your speaker, drill some small guide holes and mount them up.



So there you have it, I fitted some pretty standard Alpline units to mine which were ridiculously cheap at £29 (34 euro's or $46 USD) a pair and claim to pump out 40 Watts RMS. They certainly sound the business and I can merrily crank my stereo upto a level without distortion or vibration that is enough for me!

For the real 'power users' out there I would also suggest possibly some sound deadening material, although I find the MDF is man enough for that job already. You may also want to use components and mount tweeters etc. to create that 'front sound stage' feel. As this is my car I didn't want to ruin the original asthetics of the interior... Well that's my excuse!

I hope you have enjoyed my little 'howto' and found it at least entertaining!

Has to start somewhere - so it may as well be here

Hi there!

Why am I here and what do I want to post? Well primarily it is my aim to keep a track of my car and the evolution of a modern day classic. Including all the trials and tribulations associated with it. As I have decided to start this, especially when I consider that I am more than half way through the renovation/modification, is all down to bad planning… You will see a lot of that as we journey together on this adventure of 1001 surprises. So, hello and welcome to my blog!

How she started out when she first came home!