56 replies to this topic

[Dusky]

Ok, after some more extensive testing.......Thrashing around the country side.......I have narrowed my problem down to only one thing, induction noise.
I drove, must have looked like a bloody idiot, but I was cruzing at the dreaded 4K moving my head around the cabin, trying to deduce where the sound was originating......yip from the carbs.
When I moved my head into the back seat area......thinking it would get louder from the exhaust......quite the opposite.
Guess I'm stuck with it.......not much to complain about really, at least I don't need to replace my exhaust.
I made a video and on play back you can't even hear it,

Fire retardant sound absorbing material behind the dash will absorb a lot of that noise and make things bearble (,or how do you spell it?

[Spider]

John at Mini King had some engine bay mates, cut, ready to fit, in some sort of sound deadening material a few years back. I'm sure he still has them. The son said it made a huge difference to his car for induction noise.

 

See if you can hunt down a Cooper type air filter set up, that will shut it right up.

[tiger99]

Yep! Induction noise is a pain.

 

In the early days of the single dial centre binnacle there was an acoustic lining on both sides of the bulkhead and a big round piece of insulation, with a slit in it to the centre, that was supposedly pushed over the speedo cable and into the big hole in the bulkhead. That helped.

 

I did something slightly better, although my workmanship with primitive tools was not the best. I cut a piece of thin ali sheet, dented it near one edge to make some clearance for the wiring (Mk 1 so not so many wires) and screwed it, with plenty of mastic in between, to the buklhead on the engine side. It then was covered by a thick piece if insulation. Worked reasonably well, but them I could hear transmission whine....

 

Some battles you just can;t win when you are only a poor student.

 

Later Minis with more advanced instrument clusters often have a proper sealing plate over the bulkhead hole, and that works somewhat better, or maybe it is because the A+ powerplant is quieter anyway?

[timmy850]

John at Mini King had some engine bay mates, cut, ready to fit, in some sort of sound deadening material a few years back. I'm sure he still has them. The son said it made a huge difference to his car for induction noise.

 

See if you can hunt down a Cooper type air filter set up, that will shut it right up.

I've got a similar one of them on my car, my one has a flap that lifts up to show the ID plate. You can also get some insulation on the inside of the bonnet which might help

 

Clubman

https://minikingdomo...d-clubman-mini/

Round nose

https://minikingdomo...ound-nose-mini/

Bonnet

http://minisport.com...oundnose-models

[Spider]

 

John at Mini King had some engine bay mates, cut, ready to fit, in some sort of sound deadening material a few years back. I'm sure he still has them. The son said it made a huge difference to his car for induction noise.

 

See if you can hunt down a Cooper type air filter set up, that will shut it right up.

I've got a similar one of them on my car, my one has a flap that lifts up to show the ID plate. You can also get some insulation on the inside of the bonnet which might help

 

Clubman

https://minikingdomo...d-clubman-mini/

Round nose

https://minikingdomo...ound-nose-mini/

Bonnet

http://minisport.com...oundnose-models

 

 

Yeah, that's the goods

[Chris.Williams]

I have dynamat on the inside of the firewall, behind my dashboard area and the inside of the bonnet is also done. I may just have to look at one of those insulation pads and or a cooper air filter setup.
Off for more miles this weekend so will see how I feel after a few more hours behind the wall of sound.

[Mervyn]

Have a google for "1/4 wave resonator" if the exhaust is making your brain shake

Merv

[tiger99]

Or get twin hearing aids with a notch filter at the offending frequency!

 

 

Seriously though, I wish you every success.

 

A resonator (notch filter) in the exhaust is indeed useful in certain cases.

[tiger99]

Just had a somewhat more constructive thought. Can you get an app for your mobile phone that does audio analysis? I don't know anything about Apple, except that you probably have to pay, but on Android there are many freebies including one called Sound Analyser. If you could get a spectrum and tell us the frequencies where the peaks lie, we may be able to deduce something. 4000rpm is 66.666 Hz, and engine things happen twice per rev, so 133.33 Hz base frequency, however I suspect that it is a higher harmonic that is causing you most distress.

 

 

You could maybe even make a recording and with a graphic equaliser or some processing on the phone or PC, and notch out some peaks to see which one was the worst. That may give some clue about fixing it.

 

Apologies for not thinking to suggest that sooner. I do some live audio work from time to time and ought to have suggested it right away.

[Dusky]

A guitar tuner app might work for this ^

[vx220]

Or get twin hearing aids with a notch filter at the offending frequency!
 
 
Seriously though, I wish you every success.
 
A resonator (notch filter) in the exhaust is indeed useful in certain cases.

I sat and watched a hearing aid being installed for my nan, the guy basically RTA'd my grandmother, then used a three band parametric equaliser to adjust boost and cut in each ear for her on the laptop. Very clever

[tiger99]

No, a guitar tuner will pick out only one frequency. But they have their uses. Perhaps improvised tacho?