[rjack]

Anyone know the use for the 3 adhesive pads on the interior ceiling of cargo van mid roof just behind slider? Thanks!

 

[sb930]

Sound deadening. The pads reduce resonance.

 

[rjack]

Doesn't seem like 3 small 8" x 12" pads would do anything on a huge ceiling -- buy what do I know!

 

[ultane]

It must be true. It's on the Internet.

 

[sb930]

My van has three on the ceiling and two on each rear wall. They appear to be asphalt based pads which I think is what the original Dynamat products where made from. The front doors also have small triangle shaped pads that are butyl instead of asphalt and aren't much bigger than a Dorito chip. Butyl caulk or tape is also what's used to secure the plastic dust shields inside the doors.

The pads work on the premise that securing to even a small area on a body panel can greatly reduce the resonance which makes the vehicle quieter. You can test the effect yourself by tapping on a panel without the pad and then tapping on a panel that includes one.

The Sprinter vans I've seen use a lot more and basically have a pad stuck to every section of the roof.

 

[garandman]

It must be true. It's on the Internet.

The pads tune the panels so they don't resonate at typical speeds and use conditions. Some is caused by driveline vibration, some by wind loads, and the exhaust system can also contribute.

You don't need to coat a tuning fork with rubber to keep it from vibrating. A little dab of chewing gum will do it.

I've purchased nearly 180 sf of sound/temp insulation, Ford gives you enough to dampen the noise to a reasonable level, I'd guess 70-something dB at highway speeds. Good enough for most.