Wednesday, April 18, 2018

Sound Deadening Step 2 - Bulkhead Insulation.

After chatting with a good friend and fellow Mini owner about the EVO Mini Run UK camping weekend in North Wales, somehow before I had chance to think about it, I was online and had the tickets booked. But as the consequences set in, I had the realisation that two adults, two kids and all the required camping equipment had to be somehow stuffed into the smallest car we owned and reliably driven a total round trip of about 400 miles. Gulp!! Best get busy making the Mini the best it can be.

In the previous post, I mentioned that one thing that would for sure spoil some of the fun would be the skull numbing drone of the engine at motorway speeds. It's like being locked in a small metal shed with somebody drilling out the concrete floor, and all the while, you have to concentrate on driving. So you can imagine, not exactly the most conducive background for a pleasant jolly around the Welsh countryside with your family.

Something had to be done! And indeed something has already been done, which you can read about here in the previous post as I've already reinstalled the factory air filter box in favour of the much louder cone style filter. This alone has had a dramatic improvement to overall auditory comfort, but there's more that can be done to make it even better and today I'll be reinstalling some bulkhead soundproofing insulation.

Thankfully, it's still something that can be bought today and I picked some up that was advertised as fire retardant and specific to Mk3 onward carbureted only models for just under £20. On inspection, it seems to be made from a jute mat about 1.5cm thick with a plastic film bonded to one side for aesthetic purposes.

Offering it up to the bulkhead, I soon found the first issue: I didn't know which way up to fit it as none of the cutouts seemed to align with anything on the car. But after closer inspection, I guessed that the best way was probably like this...

I'm not sure if there's a specific procedure for doing this properly, so this is by no means a 'how to'; it's more of a 'This is what I had to do to get the job done - and here are my ramblings on the subject!!'.

After removing the stock air filter I'd just installed recently, I tucked the soundproofing material down behind the carb and for no logical reason whatsoever, decided to tackle the left hand side of the bulkhead first, meaning that I somehow have to get it behind all this stuff shown below...

The first thing I decided was to detach the fusebox from the bulkhead as there're only two screws holding it in place... simple enough. Now the soundproofing can be tucked/stuffed down behind the two master cylinders and wiggled into place.

As the soundproofing was advertised for Mk3 onwards, it's obviously designed to fit a good number of cars so I wasn't surprised that a little trimming would be required to fit in and around the specifics of my car and the first thing I came up against was the heater hose and some wiring.

After cutting the necessary holes, the soundproofing material was basically shoved where it needed to be and a little black duct tape was used around the hole to secure it in place. For now I left the fusebox unattached and danging as I soon realised that the screws I took out, were now too short to reuse through the thickness of the soundproofing so I'll have to have a look in my tray of assorted screws for some suitable replacements when I'm finished.

Moving on to the right hand side, I can only see two things in the way. One is the small silver cylindrical case that houses the hazard light controller and the other is the windscreen wiper motor. Both are simply held in with screws so they are both easy to undo.

With the hazard light unit lifted out of the way, the soundproofing can be brought up to and fed behind the wiper motor and again just sort of pushed into the place it best seemed to fit. It's not really an exact science.

In order to refit the wiper strap back to the bulkhead, I chose to cut a small square hole out of the material rather than playing 'find the hole with the screw through the material', a great game I'm sure, but not one I fancy playing at the moment!

Once the wiper was secured, it seemed that, although I didn't fancy it, the mini really wanted a game of  'find the hole with the screw through the material', so I obliged as I tried to re-screw the hazard unit mount back to the bulkhead. I suppose I could've cut a hole for it, but it seemed overkill for such a small thing.

So the game consists of feeling about with one hand behind the soundproofing for the hole and then guessing where to stab the screw through in order to line it up. It takes a while and is a little annoying, but once you realise that the original screw is now too short and go find a longer one, it makes the game a lot easier to win!!

The same game also had to be played when I reattach the fusebox. Again the original screws were too short to go through the soundproofing which forced me to have a scrat through my box of random screws that I guess we all have, to find suitable replacements. Of course the old ones were left in the box for future searches as they may just get used elsewhere, you never know!!

At this point, you could pretty much consider the job done, but as there was a slight cavity behind the carb, I decided to pad it out with a little more insulation before I taped the soundproofing shut. Luckily I had some cold water pipe lagging in the shed which looks suspiciously like it's also made from jute. So a little cutting and sticking later (all those years at school weren't wasted), I had my extra bit of insulation to stuff in behind the carb.

Once in place, a bit of duct tape was stuck over the slit in the soundproofing behind the carb to finish the job off.

One thing to check though is that the air filter box still fits and although it's certainly snug, it poses no real issues.

And that's that as I like to say, standing back and looking at the engine bay, I don't think that the addition of the old air filter box and soundproofing have made it look any worse at all, just different. As long as it's clean and tidy, I don't mind.

But the big question is: how does it sound? Well I have to say that after a finding a road where I could reach 50mph, I was very happy. Sure the drone is still there, but at a much, much more tolerable level, meaning that when chatting inside the car, we don't need to yell at each other and I'm sure that will make our little trip much more pleasant.

EVO Triange Mini Run, here we come!!!....

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