Fitting head units explained - DIN vs. Double DIN vs. ISO.

[GSB]

I've been investigating a few things regarding fitting head units to the MR2, and all is not as simple as it seems.

3 years ago, I bought a single DIN Alpine Head Unit for my '2, and using the toyota fitting kit, I bolted it in into my dash. Simple...

I've recently bought a single DIN Blaupunkt sat-nav headunit, and it wont fit.  s:oops: :oops: s:oops:  (Atually, it will fit, but its just not that simple...)

Here, to save you the expense, and hassle involved in buying the wrong thing, is why...

Years ago, car radios used to have two big knobs on the front for controlling volume and tuning. The spindles of these 2 knobs were used to bolt the radio into the dashboard of the car. Then someone invented the Compact Disc, and it was found the this method didnt leace a hole big enough to get a CD into, so a new "standard" size was required...

Up stepped the German Institute for Standardization, or Deutsches Institut für Normung e. V. as they prefer to be called. The rest of the world cant pronounce that, and so knows them by thier initials, D.I.N.

DIN came up with a standard size for car radios, and thus the size of the hole that car manufacturers had to incorporate into their dashboards... 7x2 inches... Thus was born the "DIN" sized head unit...

DIN also came up with a method of mounting the radio into the dash, using the bolt on the rear of the unit, the familiar metal cage that you put into the dash and bend the little tabs to secure it, and the little wire "keys" that you stick in the holes to remove the radio again...

Radio manufacturers then developed the principle further by making radios 7x4 inches in size, and thus we have "Double DIN" sized units.

However it didnt stop there. There were still huge variations in the depths of the units, the size of the fascia's, and even the wiring configuration, so the International Organization for Standardisation (ISO) came along and sorted a few issues out for us...

They came up with the ISO plug, where all head units now have the same plug fitted to them, and as long as the car is also ISO compliant, they can be plugged straight in with no difficulty. They also came up with a more secure way of mounting the DIN head unit, that Toyota have taken up with the MR2. They used a series of screwholes in the side of the Head Unit, that were put in standard positions. This way the Head unit could be securely mounted between 2 brackets, and so now the depth of the unit didn't matter. They also brought the ISO trim ring fitted to many head units, meaning that the fascia if the unit is no bigger than the 7x2inch DIN standard until you put the trim ring on. This was done becasue a radio mounted using the ISO method, had to have the dash panel (with its 7x2" hole) put in place after the radio had been mounted. If the fascia were to big, the panel wouldn't go over it.

Unfortunatley for us, Toyota has taken the ISO mounting to its logical conclusion, and now, instead of the radio being mounted to the dash, the dash is now fixed to the radio. This means that the traditional DIN units with the cage, cant be fitted. Unless of course you use an aftermarket adapter such as the one made by Autoleads.

My new Blaupunkt has this problem, it doesnt have the ISO mounting holes in the sides, nor does it have the detachable ISO trim ring. So unlike my Alpine, it cannot be fitted using the toyota parts.

Also, the "double DIN" concept does not nessesarily mean you can stack to DIN units one on top of the other, as the fascia's tend to be bigger than DIN, so the 2 units together will be taller than "Double DIN". You can however stack to ISO mounted DIN units together, although you have to leave the trim rings off so choose ones that are pretty without them...  s:wink: :wink: s:wink:

So to spot a head unit that will fit in the MR2 without having to buy an dash adapter like the autoleads or Scosche, look for:

ISO mounting holes in the side of the head unit, and
a detatchable ISO trim on the front.

Anything else will need one of the above adaptors to fit it...