Chassis sound insulation

[richardw]

I've wondered for a while whether chassis resonance contributes to exhaust noise inside the car. I have the LB 2.5" stainless system which has a sometimes pleasing but sometimes irritating resonance at 2400-2600rpm (corresponds to normal cruising speed.) The chassis is made from quite thin sheet steel and does resonate when you tap it. So I bought some self adhesive padded heat insulation and fixed a piece to the nearside chassis leg from the engine mounting back to the front of the gearbox - basically, adjacent to where the manifold runs. It should also help minimise heat soak into the cabin.

Result - the drone is sill there of course but now is only noisy under acceleration and well damped at light throttle cruising, so my theory seems to have been correct

ATB Richard

[Pete Boole]

That's really interesting Richard - I've been thinking about the best places to put sound insulation as I rebuild the car. Exactly what type of material did you use?

Pete

[richardw]

That's really interesting Richard - I've been thinking about the best places to put sound insulation as I rebuild the car. Exactly what type of material did you use?

Pete

Hi Pete, it's this reflective heat shield for motorbikes from Alchemy Parts: https://www.alchemyparts.co.uk/search.p ... on=content

Richard

[richardw]

That's really interesting Richard - I've been thinking about the best places to put sound insulation as I rebuild the car. Exactly what type of material did you use?

Pete

Hi Pete, it's this reflective heat shield for motorbikes from Alchemy Parts: https://www.alchemyparts.co.uk/search.p ... on=content

Richard

Sorry, that link doesnt work well - just type 'heat' in the search bar on their website and you'll see it!

[richardw]

More tinkering this morning!

I've attached more of the reflective padded heat insulation along the chassis tunnel above the centre silencer. After another test drive, the car seems quieter again.

Pete, if I were you I'd definitely put this insulation material on the chassis where the exhaust system runs; I do believe that it's a bit like a large tuning fork and resonance is transmitted to the body via the mountings as well as being transmitted normally. This insulation reduces the resonance and acts as a sound barrier as well. It will also reduce heat soak I'd imagine (as this is what it's sold to do on motorbikes!), although I've not tested that yet.

ATB Richard

[bash]

My wife complains about a drone in the car.......

[Pete Boole]

My wife complains about a drone in the car.......

You should concentrate on driving and not flying your drone!!

Pete

[Pete Boole]

While the body is off the chassis I could also put some inside the chassis itself to reduce the resonance further, although there are fewer access holes on the underside of the Elite chassis.

Pete