Insulating a defender have you done it and was it worth it?

[Pacemaker]

G'day All.
I have bought my first defender. Its a 95 110 300 tdi. I love it and the family are struggling with it. It has 285 75 16's bfg km2 and 2 tyres have not worn evenly (previous vehicle).Haha the noise at 100 is near on deafening.
Currently It has the factory vinyl covers over the tunnel and fire walls. Someone has put some grey foam under it and cut insulation out and put it on top of the seat boxes.
I can see light through the bottoms of the doors where the seals rivet on. The seals have disintegrated. There is also no insulation under the bonnet.
My current daily drive is a td5 disco with a lift and 235 85 muds. The family think its very comfy but the kids think the defender is heaps cooler.
If I could cut out half the noise that would be awesome. Please if you have insulated yours I would love to know if it was worth it or if im dreaming.
Regards.
Michael.

[BilboBoggles]

Perhaps the cheapest option would be to buy a set of second hand general grabbers and wheels, and swap the mud terrains out. That may be a lot cheaper than trying to insulate a Defender. And means you save your MT's from wearing out prematurely.

[Pacemaker]

Thanks for idea.
I have read many times that the factory fit a/c is useless. I was hoping that insulating the car including the roof would not only cut out some noise but really help the a/c do its thing.
I would also like to reduce the heat coming through the floor and fire wall from the exhaust and drive line. Its nice in winter but I can only imagine how bad it will be in summer.
Thanks.
Michael.

[ezyrama]

I lined the underside of the bonnet with 12mm sticky back insulation and the front floor and tranny tunnel with a 3mm sticky back insulation. The difference between my 110 and a mates 130 is amazing. Got the lot from from Rare Spares.

[Dervish]

Yes I have done it and yes it was worth it. The Defender is actually pretty quiet if all the holes in the body are sealed up and the factory insulation is intact.

I wouldn't say it is a difficult or expensive process, just a very long one. The two problem areas are the bulkhead and the door seals - the original grommets in the bulkhead - including the two large plastic wiring penetrations - degrade and give a poor seal. I remade the wiring penetrations in sheet aluminium, and sealed them on properly to the bulkhead. On my Defender, that was the golden bullet; on yours it will probably be something else (probably the bonnet insulation!).

The solution to the bottom door seals is to fit the door mounted ones from a post 2007 Defender. Easy job and well worth it from a noise and temp standpoint.

Go for a hunt, see where air is entering and find a way to seal it; that'll stop the noise.

[rar110]

Offender90 (Bojan) has posted the following on different occasions. I collated for future reference. It definitely helped with my 110, especially the tip about blocking any gaps or holes which allow noise in.



Offender Sound proofing advice.

Here are some notes on sound insulation that you may find useful.

Before I go into details, there are two modes of sound transmission, and one of sound "amplification" The first mode of transmission is airborne and the second structure borne. Ultimately, you must ensure that both are dealt with to get noticable noise reduction in the cabin. In addition the "sound amplification" I'm talking about is the sound reverberation buildup in the cabin, if the cabin is bare / has a lot of exposed metal / glass.

Transmission

Airborne noise is cheaper to deal with of the two, but it is more difficult, given Land Rover's superb door sealing qualities and the multitude of firewall openings behind the trim. However, it should be tackled first.

You'll find this will also help with airconditioning, for those "lucky" enough to have it.

So, before you lay out any insulation on the floor etc, make sure the cabin is well sealed from the the underside (exhaust) and from the engine compartment. This means ensuring all door seals (especially the back door) sit firmly against the door when closed, and that there are no gaps in the seal, especially at the bottom corners, where two different sections of seal meet. As a rule of thumb, if you can see the pavement , it is definately not well sealed!

Secondly, seal all wiring access holes in the firewall. When I say seal, use something like flexible mastic, which will allow movement of the wires without the seal cracking. Make sure the mastic is a skinning type, otherwise you'll end up with a mess. If you're finding that skinning mastic isn't strong enough to hold in place, you could try silicon.

Once you are certain that the cabin is well sealed, you can proceed to insulating the floor to deal with structure borne noise transmission.

Outside noise induces vibration in the floor panels, which then radiate noise into the cabin. The panels will be more efficient at radiating at certain frequencies than at others, depending on the shape, density and rigidity of the panel material. Noise transmission into the cabin will be the worst when the exciting frequency matches the resonant frequency of the panel.

For low frequency engine and exhaust noise, lead sheeting is by far the best. It has a very high density and low rigidity. The critical frequency will be well into the ultrasonic range. If you can line the underside of the car (from either inside or outside) with 1 mm or 2mm lead sheeting, you'll be doing quite well. I'd use a thin foam lining on the underside of the lead so that you don't get metal on metal rattle.

As pointed out earlier, it may be difficult to secure in place - This may have been the reason for lead sheeting with foam on either side mentioned in one of the other threads. I have not gone through the process myself yet, so unfortunately I can't give you too many practical tips. I am an acoustic engineer, however, and have come accross many similar problems in building applications.

Reverberation

Many of the older Defenders / countys and series vehicles have a lot of bare metal within the cabin (in addition to all the glass), so the cabin is highly reverberant (sound bouncing around for a long time, because there is little to absorb it). This results in significant increase in noise levels inside the cabin. I recently bought a Defender 90 panelvan with a stright-through exhaust, and next to no floor coverings - I should know!

This is what I've done so far, and what I plan to do.
I've used high density short pile marine carpet with a rubber backing to line the back area, with noticeably improved results. I also plan to line the rear panels with 50mm polyester batting behind a perforated metal sheet, to help with sound absorption wintin the cabin even more. (admittedly this may be a bit of overkill, but I also think it will improve the looks / practicability of the cargo area.

When I get time, I'll look at sealing the doors and firewall, and then I plan to line the cargo area with 1mm lead sheeting with a very thin underlay. I still have to think about what the impacts of lead in direct contact with aluminium have on corrosion.

Anyone with a son or daughter doing Yr 12 chemistry??


Also, to dispel a common myth, the foil has no effect on noise transmission. It is acoustically transparent, as it has no weight. Silver foil is a great heat reflector, and it is often found on insulating materials because they serve a dual purpose for insulation of both noise and heat.

ANOTHER

It's supposed to dampen out high frequency vibration, which is regenerated by the body panels to cause some of the high speed "hum" noise. In discos, (which are better insulated from noise), I'm guessing this is a significant component of overall cabin noise, and therefore worth eliminating.

Unfortunately, it doesn't do much on the defenders (that one I know). The defender rear tub is made from very thin aluminium panel which has very poor transmission loss characteristics. Defender in-cab noise is dominated by tyre/road interaction transmitting through the floor, so eliminating vibration regenerated noise will make no difference in overall internal levels.

Vibration and Harshness are both due to lower frequency vibration from the wheels and the engine / drivetrain, which go straight through the rubberised ring "isolator" so once again, don't expect much.

To cut a long story short, the ruberised ring is great as a 10mm spacer in a Defender, but don't expect any improvement in NVH (I should know, I have them in my 90). If you're serious about noise insulation there is a thread on it here. Keep in mind it is practically difficult to achieve, given the defender's bolt on construction. Ultimately, if you want a quiet(er) 4WD, buy a disco or a rangie.

As an aside, next time you drive your defender, have a listen to what's causing the noise. At low speeds, it should be the diesel clacking away, while at higher speeds, especially > 70 km/h (less if you have muddies), the noise should be dominated by the road/tyre interaction "hum". In order to cut it out, follow the link above before you worry about fitting a ruberised spacer.

If you have an Isuzu county, forget all of the above, there is just no hope. Just get rid of it, buy a disco!...

FROM ISUZU FORUM

I'll get back to this once I have a bit more time, however a brief summary of "quietening" a vehicle:

Noise in the cabin is the sum of:

- noise generated by the engine, drivetrain and wheels being transmitted into the cabin through the panels,
- vibration from both mechanical and aerodynamic sources transmitted into the body panels and re-radiated into the cabin as noise, and
- noise reverberating (bouncing around) inside the cabin, amplifying as it does (can add up to 4dB in a bare defender interior with only seats to absorb reverberated noise).

To effectively reduce noise in the cabin you need to reduce both modes of transmission as well as amplification.

Dynamat type products are effective at "deadening" the panels so they reduce vibration re-radiating as noise. For this to be effective you DON'T need to line the entire panel with Dynamat. It won't hurt (other than damage to the wallet and added weight in the car), but it won't really help either. Dynamat is most cost-effective when placed in patches, where each patch occupies 30% to 40% of the area generally placed in the centre of each flat panel. It is a viscoelastic material that works primarily by dissipating vibration energy into heat. It also adds some mass to the panel which shifts the panel resonant frequencies higher up the spectrum (but generally not high enough to be out of the audible range). I would use it in strips on roofs (several 10cm wide strips placed lengthwise between the stiffening ribs), with perhaps one widthwise strip across the centre, and on door sections (covering approx 40% of the centre of the flat area between the rounded section and bottom of the door). If in a wagon, a thin strip may also be placed on the rear quarter panel, below the rounded fold in the sheet.

Next we need to do something about airborne noise transmission through the panels & into the cabin. Dynamat is a REALLY EXPENSIVE sound barrier material IMHO. Sound barrier performance at low frequencies (i.e. the hardest to block out & therefore controlling) is determined by the WEIGHT of the barrier material. "Dynamat Extreme" weighs approx 2.2kg/sqm - Barium loaded vinyls come in sheet weights of up to 8kg/sqm, and at prices comparable to, if not better than, Dynamat. If you do a search for Sorberflex on here, you should find several of my earlier posts on what I would use, why, and where to buy it. On all panels that are between an airborne noise source and the cabin (e.g. firewall, footwells, transmission tunnel, seat boxes and load area) you need to ensure full coverage and use a heavy (4 to 8kg/sqm) vinyl. I would look for an 6mm to 10mm closed cell foam backed loaded vinyl (that dampens panel vibration and decouples the vinyl from the vibrating panel). Alternatively, strategically located Dynamat strips could be used under the loaded vinyl (wouldn't be my preferred choice).

Noise absorption inside the cabin. - Any "soft" surface will provide some absorption. Seats, people, carpet, roof lining... all help absorb some of the reverberating sound. Noise that's transmitted out from the cabin (through the roof and sides) also reduces the amount of noise that's left inside. Unfortunately, closed cell foam does virtually nothing to absorb sound in our cars, especially the high density type of foam that cheap sleeping mats are made out of. It will help with heat, and may provide reasonable panel dampening if surface glued to panels, but that's about all it's useful for (that I can think of). Noise absorption would probably be the last thing I would "get to", as we can hope to gain at most a 2 to 3 dB reduction.

to give an idea of perceptive differences of the decibel scale, a reduction of:

1 dB - not noticeable by over 90% of the population
2 dB - barely noticeable
3 dB - noticeable
5 dB - clearly noticeable
10 dB - noise perceptively halved

In order for the above measures to reduce noise, we first need to ensure effective sealing of doors, windows and vent flaps. By effective sealing, I mean reasonably airtight. In addition, all firewall penetrations should either have rubber grommets in good condition, or if these have perished, or for large openings with multiple wires running through them, you can tightly pack a "ball" of fibreglass or polyester insulation wrapped in a durable cloth or similar permeable membrane to prevent it from disintegrating and spewing out fibres everywhere, but allowing air to get through. Unless the cabin is effectively sealed, any additional measures are a waste of money.

Note - I'm not convinced that a "noise barrier" type material is helpful under the bonnet - if anything, I'd use an absorptive type foam or fluff to reduce the buildup of sound within the engine bay. (EDIT: Unless driving with windows / flaps open)

Firewall is a different story - I'd use a composite material comprising a thin layer of closed cell foam, a layer of loaded vinyl, with a thick layer of open cell foam, placed closed cell foam against the firewall. A range of manufacturers make it for noise control of firewalls and engine rooms. I've posted details of products I'd use in previous posts

As for quietening the engine itself, I wouldn't have a clue where to start, but have heard that later engines are quieter than earlier ones, and some are definitely quieter than others.

Isuzu appear to have had a reasonable go at insulating the engine itself, fitting an acoustic rocker cover (the outer steel skin's only purpose is to reduce noise), as well as decoupling the oil pan from the engine by using a double rubber seal with special rubber clad studs to isolate it from the engine. I'm led to believe the pump and injectors themselves make quite a racket and, if that is the case, don't understand why they were never dressed with a cover of some sort. There may have been an operational reason - I don't know.

Lastly, fitting a turbo will also reduce exhaust noise emissions by approx 6dB from memory.

HTH

Bojan

[noyakfat]

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[Cracka]

If you search the topic you will find a LOT of info. Yes, I've done quite a bit and its worth it in my opinion.

[VicDisco00]

My 2000 Discovery S2 is really quiet except for the right front tire . untill you get above 55mph. my wife has a Silver Isuzu Rodeo. Here in fl we have 97 degree days. I put a temp gauge in both cars. hers reads 114' and the Disco reads 87 degrees. I have no sunroofs. nor does she. So I was Impressed with my LR.. and Heat and noise effects..

[Jode]

I removed the headling from our 110 300TDI and glued 25mm thick acoustic insulation batts, for two reasons - noise first and heat second. These batts are denser than roof insulation batts, but denser still would have improved the sound reduction quality of the result. Also I didn't cover the roof rails in order to avoid reducing the head height under the roof, which meant thermal bridges from outside to inside and increased heat gain within the vehicle.