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Back Box ... noise?

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Old 02 December 1999, 11:36 AM
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Mike Owen
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Just had a MAGNEX back box fitted (3.5 in round). Looks good, sounds good etc. The car even seems to "spin up" sharper (pysocological?). But (there always has to be a but)... it is slightly intrusive at steady speed driving. Nothing I suspect that I can not live with and the dealer did comment "that once they Soot Up, they mute slightly).

I as wondering though. If putting some sound deadening on the boot floor (as the carpet only appears to be a quarter of an inch thick), would make any difference. Anyone tried this? My car is an MY99 turbo saloon.
Old 02 December 1999, 11:41 AM
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Orville
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Carpet!
I seem to have recycled toilet paper for my boot lining. Since when have Subaru fitted carpet?
Old 02 December 1999, 06:34 PM
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Sam Elassar
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mark
I have got the same problem. I have been thinking about that. I have not done any thing yet though. I was thinking about maybe some of the sound deadening material you get from damon tweeks. Dynamat ( self adhesive noise control ???). may be in the boot and the door panels. I think the main problem is behind the back seats ? if you do any thing in there you can't fold them ??

as you see it will take a lot of experimenting. I have asked a similar question before but no body suggested anything.

what do you think. any ideas?
Old 02 December 1999, 09:14 PM
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MarkF
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Mike, I had this problem with my Nova especially on long runs. The magnex backboxes get really boomy when hot don't they!!
Old 03 December 1999, 07:36 AM
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Bajie
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I haven't looked into costings but I was 'told' you could use a good underlay instead of dynamat with good results.
Has anyone out there tried this?
Old 03 December 1999, 08:27 AM
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robski
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Exclamation

Didnt put it in the boot but in the foot wells, but I used the bitumen coated thick felt underlay from Wilco (I think this is a local cahin). It smells nasty, but once that goes, it really worked well.

I guess this was the bitumen stopping the low frequencys (its dense), and the felt stopping the higher frequencys (trapped air).
Anyway at approx £10 a roll why not try it, its easy to cut to shape, and light, not like dynamat and equivalents.

robski
Old 03 December 1999, 09:16 AM
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Sam Elassar
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are you talking here about normal underlay used under floorings from your local homebase? i might give that a shot this weekend.

thanks for the tip

Robski. what else did you cover with it ?
(that did not sound right but u know what i mean
Old 03 December 1999, 10:35 AM
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robski
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Sam,

nope it is not normal underlay that I know of. But that may work, I just used in footwells since most of my boot was filled with MDF!

It definately worked in the footwells, so can see no reason why wouldnt work in the boot.

robski
Old 04 December 1999, 12:33 PM
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Mike Owen
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Sam,

Small world. I bought my car from Melvilles on the Perth to Dundee road. Damn, finished working up in Perth today. Otherwise could have met up! Think I will have a wander round the loacal Homebase and places like that tomorrow. Got plenty of time, as my next contract don't start until the 6th Jan! Got to do something though, as I tend to end up doing silly miles in the car. Next job in Edinburgh, so that's a nice once a week run up the Devils Beef tub and on up to Edinburgh (got to be one of the best drivers roads!).

Will keep you informed of progress on the noise front.

CU....
Old 04 December 1999, 12:38 PM
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Stef
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I'm sorry, but NOTHING sounds as good as a Scorpion system....I'm slightly biased though!

Stef.
Old 04 December 1999, 01:10 PM
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MorayMackenzie
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Stef,

So when are you going to organise an exhaust system "sound-off" ? ( )

Moray
Old 04 December 1999, 01:53 PM
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Stef
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Absolutely whenever Mr Moray Man!
I guess it would be difficult to judge though, what with everyone's differing tastes and all.
I'm basing my judgement on the number of people that have approached me that were already owners of 'other' systems .
To be honest though, I don't think most people would like the intrusiveness of my system, although I do 1,000 miles a week and I love it!

Stef.
Old 04 December 1999, 06:58 PM
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Doug
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Dynamat has told me that the Dynamat from your local ICE dealer is for sound deadening and not soundproofing - there is a difference.

I am currently waiting for some Dynaliner sound proofing material that I have ordered for the good ol’ US of A. I’ve spoken to several ICE dealers who say this is the only thing that works, I’ll have to wait and see.

Cheers

Doug
Old 05 December 1999, 12:28 PM
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AndyMc
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Hi everybody

I have a tip that may be worth a try.My dad used to have a mk 5 escort (company car honest!)I noticed that the boot carpet had a thick sound deadening backing to it,I also noticed that the boot looked about the same size as mine (4 door).
It turns out that it fits almost perfectly under the original crappy carpet.I only have the standard exhaust at present but even so it made a worthwhile improvement.It may be even better for you guys with noiser exhausts.

Andy
Old 05 December 1999, 01:29 PM
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david
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Sorry guys, (flame suit most definately on), but it puzzles me why anyone should buy a performance exhaust and then complain about the noise?

Personally, I wish I could drive my car from the outside to hear what it really sounds like (SS System).

Dave
Old 05 December 1999, 01:42 PM
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Bajie
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David.
Get a dump valve and change the air filter.
Drive with the windows open and you'll be in heaven ...
Old 05 December 1999, 07:53 PM
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WAYSIDERS
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Wink

Look guys,

I just spoke to an acoustical engineer about your problem and he is confident that mass is the solution. Apparently concrete is the ideal material.

So go down to your local Readimix depot. Two cubic metres should do nicely. Provided you adjust tyre pressures suitably, handling should change only marginally, although fast driving should be postponed for 12 hours, to ensure it has set properly.

I hope you find this tip helpful. All donations and letters of thanks please to The Treasurer, RS Owners' Club.
Old 05 December 1999, 08:45 PM
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MorayMackenzie
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Waysiders,

Good one!

As an aside, adding weight over the rear axle would affect the handling badly. The car would hold-on for a little longer (extra weight holding tyres down) and then loose grip and go wide faster with less chance of catching it (extra weight giving greater lateral momentum).

Moray
(Who has been wrong before, but did own up to it!)
Old 05 December 1999, 10:48 PM
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Mike Owen
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O'well... at least it looks like I've promoted a healthy? thread for once.

Starting to get used to the new "aural feast" (????). Maybe I'll drill some holes in it and really see how she blows....

Now all I need is my driving lights to turn up from ScoobySport. Strange... I thought they said they would turn up last Thursday! (color "hint of sarcasm"). Then I'll be able to see those sheep, before I deafen them.

David... maybe I'm just a frustrated wanabe Sti owner! or I just like the look of a 3.5 incher!

Enjoy.
Old 06 December 1999, 06:19 PM
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Sam Elassar
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Mike
It would have been nice to meet up. We can still meet when you are in Edinburgh to see if have done anything regarding the noise.

As for funny blokes out there I really love the looks and sound of my blitz + downpipe. Sometime though I would like it to be as quiet as a BMW in the inside ( dream on I keep reminding myself).

Andy
Performance exhausts are for performance. ( noise is just a by-product )
Old 08 December 1999, 08:50 PM
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Mike Owen
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Sam,

CU in the next Century (scary, or what!).
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