Monday, April 16, 2018

Sound Deadening Step 1 - Air Filter Downgrade!

Holy 'tempus fugit' Batman, where did the last year go!! Yeah, time certainly can fly if you let it and it has. Anyway for a variety of reasons (some good, some not so good), it's been a whole since we last spoke. As for progress, well I have to confess, not a vast amount except for two small tasks which were to remount the exhaust as I wasn't quite happy with it and to service the engine back in November 2017. That said, I have driven the Mini quite a lot so it's not all bad.

Well it's time to dig myself out of the rut I've become stuck in and what better way than to go on a Mini run weekend. For one reason or another this seems very daunting, but it's just the antidote I need for getting progress moving along once more. So somehow, thanks to the persuasion of a friend, I found myself booked on the EVO Mini Run UK in the beautiful open countryside of North Wales, but before that can happen, I need to make sure the Mini is up for the job, so time to prep...

Apart from checking the usual things, like fluids and general maintenance that you would normally do before any big trip, by far the biggest issue is the noise. It's not too bad when pootling to and from work were I rarely get above 30mph, but take it on the motorway and do anything above 45mph and the drone becomes very unbearable, very quickly. If it was just me, I might be tempted to put up with it, but as this trip is a family affair, there might just be a complaint or two before we get even half way there.

Most of the problem comes from the fact that I moved away from the standard 'frying pan' style air filter, in favour of a cone style filter. Apart from looking a bit more natty and outlasting paper filters, cone filters don't really boast a huge set of benefits. Some argue that it provides better flow, but for the day to day driving I do, I don't think I'd ever noticed a difference. One of the main reasons I and other people go for a cone filter though is the noise it makes, which is quite nice in small doses, but just doesn't suit motorway speeds, so it has to go.

Along with downgrading the air filter, I'll be adding back in the bulkhead soundproofing that I took out some years ago. Again this was mainly for aesthetic reasons, but also due to the fact that the old soundproofing was falling to pieces. Anyway, the past is the past and now it's going back in regardless of how it looks.


Thankfully I'm the kind of person that never really throws anything away, which can be as much a curse as it is a blessing. This time though, it was a blessing as I still had all the parts necessary to perform the downgrade and after a quick search around the shed, all the old parts were dug out and dusted off.

 And after a quick trip to the shop for a new filter element, everything was ready to start the job...

... which starts with the removal of the cone filter and after undoing the small nut at the rear, the main part of the filter is removed leaving the plate which is simply unbolted from the carburettor.

At this point, the next step would normally be to just bolt on the stock elbow joint, however, I also need to swap the abutment plate as the current one is missing an essential threaded shaft which is needed to hold the air box in place. So to swap these plates over, I'll have to disconnect and remove the carburettor.

Getting the carburettor off is just a matter of undoing the accelerator and choke cables on the right hand side and sliding the whole thing backwards off the studs.

Once the abutment plate was out, you can see the difference.

After the accelerator return spring was attached to the hole at the bottom of the new abutment plate it was mounted back on the studs followed by the carburettor and new gaskets, and all bolted back up...

... and the cables were reattached.

After a quick clean up and ensuring the rubber gasket was the right way up, the 90 degree elbow joint could now be bolted to the back of the carburettor.

With all that done, the old air box could now be put into it's place, however I soon realised that something was missing as it wasn't sitting at all well. After a bit of research, I discovered that there was supposed to be a rubber seal between the air box and the elbow joint. Maybe it was lost in storage or maybe it was never there in the first place, either way I needed to get a new one. Thankfully they still sell them and a quick trip to Mini Spares later, I had my new seal which stretched into place pretty easily.

Not forgetting the nice new filter element of course!!

Now when put in place, the air box felt like it was sitting properly and once the two retaining thumbscrews were screwed down, it was job done.

And a quick peep underneath with the camera shows that the seal is doing its job nicely.

So that's that - Step 1 of my two step plan ticked off the list and after a blast down the motorway, I can already hear a big difference on wide open throttle. No longer can I hear the engine slurping the fuel through the carburettor and most importantly the aircraft-like engine drone is almost bearable now. Let's hope it'll get even better when I unleash step 2 - reinstalling the bulkhead insulation.

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