I've always had an issue with how bulky the heater/blower box is in the classic Mini Clubman and in my previous Mini I found it easy to kick and damage the flexible duct (leading from the heater to the windscreen demister) that is right next to your feet.
To solve this issue, I decided to fabricate a compact heater box so after laying up some fibreglass on some sheets of glass (to get a series of fibreglass sheets approx 2mm thick), a series of pieces were cut to shape and temporarily superglued together to make a box of two halves. I then laid in a layer or two of fibreglass on the inside to strengthen everything. I replaced the bulky squirrel cage fan in the factory heater box with a high flow 120mm computer case fan in the new heater box. The fan I chose flows a hefty 138CFM at 12V and with a noise level of 48dB, it's not intrusively loud.
With some foam glued around the perimeter of the core, the factory Mini heater core was used and fits snugly into the box.
The factory heater box has an air direction flap to adjust the air flow between the windscreen or footwell but I deleted this function to make the custom heater box smaller again. The second half of the custom box was designed with some baffles so the airflow would be fixed and evenly split between the demister vents and the footwells.
Some M4 screws with captive nuts were fitted to the perimeter to hold the two halves of the box together. A good idea to hold the captive nuts in place is to use a combination of superglue, and bicarbonate of soda (aka baking soda) as a catalyst. After scoring the surfaces, I simply placed some superglue on the parts and sprinkled some bi-carb soda on the glue and it sets within seconds. Repeating the glue/soda combo to build up the thickness results in a very hard setting material. For example :
I made the duct on the underside (leading to the passenger footwell) removable so it would be easier to sand and paint later. This photo is of the heater box upside-down :
The size difference between the factory Mini heater box and my custom heater box is substantial.
Factory heater box :
Compact custom heater box :
With the demister outlets to the windscreen at the top of the custom box, the tubes are no longer exposed to contact from your feet.
The Toyota Starlet engine cooling system has 16mm outlets and the Mini heater core has 1/2" outlets so I've previously made an 16mm-1/2" adapter that bolts through to the bulkhead (https://mearcat.blogspot.com/2018/03/cabin-heater-hose-connections.html)
I had to remake this adapter to include some bends to get the rubber hoses to clear the box section under the dash. Note : The bends are not parallel as they point towards different outlets on the heater core in the custom heater box below it.
I was going to use a new right angle 1/2" heater tap under the dash but after some discussion with some local Mini guys, I was advised that a lot of the new 1/2" Mini taps are of average quality so I fitted 1/2" hose between the bulkhead adapter & the heater core under the dash without a tap.
... and purchased a universal 16mm (5/8") heater tap instead.
This heater tap was fitted in the engine bay coolant line, between the engine block and the bulkhead adapter (inlet to the heater core)
To solve this issue, I decided to fabricate a compact heater box so after laying up some fibreglass on some sheets of glass (to get a series of fibreglass sheets approx 2mm thick), a series of pieces were cut to shape and temporarily superglued together to make a box of two halves. I then laid in a layer or two of fibreglass on the inside to strengthen everything. I replaced the bulky squirrel cage fan in the factory heater box with a high flow 120mm computer case fan in the new heater box. The fan I chose flows a hefty 138CFM at 12V and with a noise level of 48dB, it's not intrusively loud.
With some foam glued around the perimeter of the core, the factory Mini heater core was used and fits snugly into the box.
The factory heater box has an air direction flap to adjust the air flow between the windscreen or footwell but I deleted this function to make the custom heater box smaller again. The second half of the custom box was designed with some baffles so the airflow would be fixed and evenly split between the demister vents and the footwells.
Some M4 screws with captive nuts were fitted to the perimeter to hold the two halves of the box together. A good idea to hold the captive nuts in place is to use a combination of superglue, and bicarbonate of soda (aka baking soda) as a catalyst. After scoring the surfaces, I simply placed some superglue on the parts and sprinkled some bi-carb soda on the glue and it sets within seconds. Repeating the glue/soda combo to build up the thickness results in a very hard setting material. For example :
I then made some simple angle brackets to mount the box to the three factory points under the dash. The baffled box section was then modified to include two hand made 50mm tubular bends to feed air to the two windscreen demisters, and then two rectangular outlets to blow air into the footwell areas.
I made the duct on the underside (leading to the passenger footwell) removable so it would be easier to sand and paint later. This photo is of the heater box upside-down :
The size difference between the factory Mini heater box and my custom heater box is substantial.
Factory heater box :
Compact custom heater box :
With the demister outlets to the windscreen at the top of the custom box, the tubes are no longer exposed to contact from your feet.
The Toyota Starlet engine cooling system has 16mm outlets and the Mini heater core has 1/2" outlets so I've previously made an 16mm-1/2" adapter that bolts through to the bulkhead (https://mearcat.blogspot.com/2018/03/cabin-heater-hose-connections.html)
I had to remake this adapter to include some bends to get the rubber hoses to clear the box section under the dash. Note : The bends are not parallel as they point towards different outlets on the heater core in the custom heater box below it.
I was going to use a new right angle 1/2" heater tap under the dash but after some discussion with some local Mini guys, I was advised that a lot of the new 1/2" Mini taps are of average quality so I fitted 1/2" hose between the bulkhead adapter & the heater core under the dash without a tap.
... and purchased a universal 16mm (5/8") heater tap instead.
This heater tap was fitted in the engine bay coolant line, between the engine block and the bulkhead adapter (inlet to the heater core)
Beautiful work Mate!!!
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