General sound deadening and dash noise issue.

[fm.illuminatus]

I really need some sound deadening material in the Mini. I finally got my iphone hooked into the car, but frankly, at freeway speeds, I have to blast the stereo just to hear.

I recently drove the new 1 & 3 and one of the things that struck me is how quiet they are compared to the Mini. Is there any way I can reach that level of quietness with the Mini? I don't care if I have to add a truckload of sound deading material, I just want to hear my music at 95 mph.

What do you guys recommend? How much would this cost me? Is this a DIY project someone with moderate vehicle repair / mod ability could handle? Can we have a sticky about the basics of sound deadening?

Also, while I'm at it, I have a rattle in the dash and a strange high pitched howling noise when I get north of 100 mph. The dealer replaced the dash 3 times and it didn't fix it. Anyone else had this problem, any thoughts on what I should do?

[Robin Casady]

Here is something modified from a post in another thread, but I don't think many saw it, and this is a more appropriate thread for it.

I started with Dynamat. I did a rear-seat-delete, so considerable soundproofing was called for.

I learned later that this was over-kill with Dynamat. It stops a panel from vibrating, but doesn't block much sound. So, you don't need to cover every inch.

Now I'm in the middle of a DIY install of an amp and higher grade speakers (all from Image Dynamics). I've also learned more about soundproofing and will be doing some additional work on that. I found this site useful for soundproofing material:
Sound Deadener Showdown

Since access to the doors is difficult, I'm using this: Dynamat DynaXorb Speaker Kit

If you remove the battery in the MINI you will see a big port for the fresh air filter. I read somewhere that this was designed to let a certain amount of engine noise into the cabin for a "sporty" feel. Unfortunately, it also lets in significant road/tire noise. I'm going to attemp to reduce this noise by applying a mass loaded viny & closed cel foam barrier (MLV/CCF) to the plastic wall between the fresh air intake area (houses the battery and windshield wipers) and the engine bay. I'm hopeful, but not certain this will help.

The wheel wells seem to be one of the significant areas to deal with. I've put Dynamat there, but may add some MLV later. There is a thread here about putting Dynamat in the wheel wells.

Another thing that helped was creating mats of MLV that go under the floor mats. I made mine extend beyond the floor mats to cover some of the firewall, and go under the front seats (from rear mats).

MLV is heavy stuff (that's why it stops sound) so you will be adding weight to the car. Dynamat is also heavy, but much thinner. Dynamat stops a panel from ringing, but it doesn't block much sound. A traditional method was to use multiple layers of Dynamat to try and block sound, but this isn't very cost-effective. I suspect it would take many layers to be effective. Several sites recommend Dynamat (or equivalent) topped with CCF and then MLV. The CCF isolates the MLV from the panel. The MLV absorbs much of the energy from the sound waves.

[cmcveay]

Thanks for the pics and the info. I've got a rear seat delete as well but never really took exception to the noise - even when using the BT phone. Last week, I put the Borla "Sport" exhaust in and I found that I'd acquired some irritating resonance/vibration. Last night, I pulled out the RSD and put down dynamat just in the area where the rear seat was (cutting the heck out of my thumb on the dynamat's aluminum cover) and I also covered most of the underside of the RSD piece and I reglued the interior matching carpet. On my drive to work this morning, I noticed a difference but I'll take it out on the highway this evening to see how it does "at speed". I'm also waiting on a delivery of Thermo-Tec exhaust wrap and I'm going to wrap the exhaust from the flex coupling to the twin mufflers in the rear and verify that none of the exhaust is touching the underside of the car.

For the original post, I wonder if the good old fashioned spray on undercoating would help? Either that or try to stay off the phone when the speedo goes above 90?

[fm.illuminatus]

Originally Posted by cmcveay

For the original post, I wonder if the good old fashioned spray on undercoating would help? Either that or try to stay off the phone when the speedo goes above 90?

The iphone is for music (it's an ipod), I try to avoid talk & drive at any speed, too distracting.

What's spray / undercoating?

[Robin Casady]

Originally Posted by fm.illuminatus

What's spray / undercoating?

The stuff some car dealers would try to sell you as you were in the final ordering process of a new car.

Perhaps Spectrum Sludge would be more effective. However, it looks like this would be a mod that was difficult to undo.

[fm.illuminatus]

Originally Posted by Robin Casady

The stuff some car dealers would try to sell you as you were in the final ordering process of a new car.

Perhaps Spectrum Sludge would be more effective. However, it looks like this would be a mod that was difficult to undo.

So I would coat the frame with spectrum sludge... this would reduce noise?

[Robin Casady]

Originally Posted by fm.illuminatus

So I would coat the frame with spectrum sludge... this would reduce noise?

Maybe. I've never used the stuff. I have no idea how effective it is.

I' going with the CCF and MLV method. If I were going to try the sludge, I'd probably start with the wheel wells. Remove the "felt" liners and apply it to the steel underneath, where it seemed appropriate. There is a thread on doing the wheel wells with Dynamat. Good instructions and photos for opening them up.

I'm going to go with the reversible sound deadening techniques before I apply something that wont easily come off.