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MG MGF Technical - Noise reduction
|Using the hard top recently I noticed a lot of wind noise coming from the leading edge. Using a piece of black duct tape to join the leading edge of the hard top to the windscreen leads to a dramatic reduction in noise.|
Anyone have a more elegant solution to this problem?
Also has anyone experimented with sound deadening material in the rear bulkhead (behind the seats) or in the doors themselves?
Raj. P58 NVF
|Hi Raj, i've fitted foil backed bitumen sheet (Dynamat or 'Brown Bread' as obtained from most car hifi shops) to the inner and outer skins of the doors and to the engine cover. The work in the doors was done to improve the sound of the speakers but does also block a little noise and vibration, the doors also shut with more of a heavier 'thunk' now too. |
The double sheet on the engine cover was done to reduce engine drone and does work quite well...don't expect too much though. I do a fair amount of motorway miles and recently experimented throwing it into neutral at 75mph or so, about half the noise dies away, so engine noise is a fair proportion of the engine/tyres/wind noise total. I think i might have a go at putting in some sheet and additional felt on the back bulkhead and engine cover at some point, means taking off the T-bar to do a good job. At least in an F is an easier job to do than a front engine car as you have a flat bulkhead between you and the engine.
In view of the cloth hood and plastic window (though different if you have the hard top on) i think you can only go so far with noise reduction. One worthwhile thing might be to improve the fit of the seals between the hood and body at the rear of the side windows, this is where the majority of the wind noise on my car comes from. However i sometimes think that the air flow into the cabin around these seals is the reason i never get a steamed up back window!. I had a TVR before and the motorway drone and wind noise in that was way worse than the F, and the back window would steam up at will...*grin*.
|Other ideas to reduce noise include to get MOSS to line your cloth hood, or get thicker mats!.|
|TBQH Raj, I haven't had this kind of problem with my OE MG Hardtop- is yours an MG item or one of the body coloured 'Heritage' items?|
I have tried additional sound deadening on the engine cover using the acoustic sound deadening material 'Brown Bread'. Works a treat at reducing the decibels from a combination fo Trevor Taylor exhaust and K&N filter- I can now hold a conversation without having to raise my voice (too much!).
Sound proofing in the doors works a treat too- makes the doors 'thunk' close with a real quality sound!
Looks as though we are following one another again!
I too had thought of removing the T-bar to fit more sound deadening on the bulkhead- but it is big area to cover! The material would weigh a tonne!
I think that most of the sound one can hear- especially in softtop up/down mode is comming out through the boot lid over the engine compartment. Not sure what one can do about this really- blocking off the hot air vents would have an unfortunate side effect... But maybe some sound deadening material in the 'lid would help? Worth a go?
|Hi Rob, i think that basically you're right about the noise coming through the hood and back window. I think sticking in more sound proofing to the bulkhead and engine cover might reduce overall noise by say 5-10% probably a lot less than the difference with a different type of tyre. (Though that still might not stop me trying it!)|
How do those new Bridgestone of yours compare regarding road noise with the original NCTs? I remember the Bridgestone tech who comes on here now and again saying the SO2s and F1s were noiser. I fancy the RE720s when i come to change, just for lower noise. I had F1s on a previous car and they were a fair bit noiser than the standard Michelins.
I try not to mention car noise in this house as i get that look from the wife which says 'why the hell did you get another soft-top then'...*grin*.
Sound proofing felt can be heavy. I got some stuff for a previous car, (do you get the impression i'm obsessed...*grin*), from a place at Rochdale that still advertises in classic car motor magazines. Not only was it heavy and pretty crappy (but cheap!) it smelt really bad for ages (gluey smell). It wasn't too bad once under the carpets but there was still a faint wiff when i sold the car 2 years later. You have been warned....if anyone ever gets in sound deadening felt by mail order ask if it smells first!.
I've seen better quality, lighter, more expensive felt in car hifi shops which looks ok for the limited area you would need for the F.
|Thanks Paul & Rob,|
Funny how like minds gravitate to the same solution!
I have a heritage Hardtop cover, hence the difference in fit at the front end.
When you mention the engine cover, do you mean the section into which the soft top folds when the hood is down?
I went to a local car audio specialist who suggested a custom fit enclosure made of MDF and lined with sound deadening material which could be 'dropped' into this space. Of course you wouldn't then be able to drop the hood, but it would act as both noise reduction from the engine and improve sound quality. What do you think?
Raj P58 NVF
|Hi Raj, great minds didn't gravitate to the same solution!....i copied Rob...*grin*.|
Yes the engine cover is the bit where the hood drops into. If you unclip the back of the hood, lift it forward, then lift out the carpet and existing Rover sound proofing felt you will see a grey coloured hatch almost the full width of the car. This is unbolted to get to the engine (dead easy). If you hit the panel with your knuckle it makes a clanging sound, if you cover it with two sheet of Dynamat if makes a dull sound thus hopefuly damping noise and vibration when re-fitted. If you want to see how much difference sound proofing makes to an F, then replace the hood and have a run in the car without the engine cover, Rover sound-proofing and carpet...its a bit loud!. The diference in sound the standard stuff blocks makes me think that a bit more felt on the engine cover and back bulkhead would still make a difference.
As regards the custom made enclosure, this sort of thing has been talked about before for mounting rear speakers, but of course it means that there are problems lowering the hood....defeats the object of having a soft-top i guess. If you want to fit rear speakers there are various discussions on this subject accessible in the archives. I've fitted rear speakers into the T-bar behind the seats and they sound very good. There are pictures of the speakers on Robs site, i'm sure he'll give you the link if you ask.
This thread was discussed between 29/05/2000 and 30/05/2000
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