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Insulation, Sound Deadening & Window Glass Channel - 2012

For some reason when the car was restored back in 1993 there was very little in the way of insulation fitted, hence the drive was always very noisy. A pair of earplugs left in the glove box might have given me a hint!

I believe originally there was about 25mm of underfelt type of material stuck to the body by a bituminous glue. The standard interior fitting in Aprilias were rubber mats on the front floor and carpet in the rear. Replacement mats can be bought from a number of sources including Cicognani ( I bought a set from them, which includes mats for the firewall, transmission tunnel, floor and boot. The modern reproductions are considerably thinner than the original but they’re the best we can get for now.

Some time back I’d discovered one of the window winder channels had rusted and the glass was out of the channel, luckily it was the off side rear which doesn’t get much use. After returning from the VSCC Alpine Trial that was on the list of things to do along with fitting some modern insulation/sound deadening.

The window channel was repaired using some modern aluminium channel and Sikaflex 221 to seal the glass in. Original uncured rubber was used to hold the glass in place, but I couldn’t get any at the time. The one difficulty was fitting the winder plate to the channel as the glass obviously has to sit on a flat surface. Originally Lancia had used flat head rivets but searching locally bought up a zero result. On to the net and I found some tapered flat head aluminium rivets in US. With the rivets in and a strip on thin rubber the glass seems to fit well, time will tell how successful I’ve been! In the end I only had to repair the two off-side doors, the front passenger door looked like it had been repaired in the past while the rear had had a complete new channel made when the car was restored in the UK. Why didn’t they do the others at the same time I ask myself?

Old window channel. So badly rusted the glass had pulled out.

New aluminium channel with glass held in with Sikaflex (got white by mistake but no one will see it!)

Dynamat Xtreme taped, not glued to door, for easier access in the future.

Dynamat on the floor, firewall and foot well sides. (Note the non standard gearbox cover)

For insulation I decided on Dynamat Xtreme, and where needed Dynaliner ( Again I bought it from the States as locally it was twice the price! I placed the Extreme on the doors under the trim panels. Dynamat is self adhesive but for here I left the backing on and taped it around the edges so I could get easy access to the winder and door lock mechanisms later if necessary.

A quick driving test after all four doors were done and I had a 20 - 30% reduction in internal noise, a good start.

Next was to install it on the front floors, footwell side panel and internal firewall. Again I put on a layer on the Xtreme, but glued it down this time. Then on the floors and firewall a layer of 1/2” Dynaliner. Make sure you follow the instructions and get the surface as clean as possible for good adhesion. Lastly the rubber mats were fitted. I used velcro to hold the floor mats but a spray adhesive for the firewall mat.

The next test drive was quite disappointing, there was very little further noise reduction. In the past the car did have some loose layers of carpet and underfelt on the floor and a thin piece of insulation on the firewall, which seems was doing a better job than I thought. I’m investigating some sort of removable panel to fit up under the dashboard, I think a lot of the engine noise comes through there and in the future I’ll have a look at fitting some insulation under and behind the rear seat. One positive is the interior is warmer, it’s currently the middle of winter, and hopefully there will be less engine and underfloor heat once summer arrives!

Layer of 1/2” Dynaliner on floor and firewall.

Rubber mats fitted. Autocar in 1937 described the interior as “plainly finished”.

Non standard door seal arrangement.

I also tackled the gap there was between the passenger side doors. My car doesn’t have the correct rubber sealing strips in the metal T pieces that should be on the central edge of the doors but a rubber seal fitted to the inside edge. I had bought the T rubber sections sometime back and by fixing them up against the existing seal I now have a much better noise free gap.

At the moment I’m trying fix a nasty rear brake problem so haven’t had the chance to take her on a long test drive, but I’m pretty sure the ride will be much more peaceful than before, I’ll report back soon.

And because I like to discover these things. There are two different makes of glass fitted to the car. Lancegaye, on the front door and rear windows, was a British company that were taken over by Triplex in 1939, so I guess it is original. The other, on the rear doors, I think is Italian but cannot clearly make it out. Any ideas anyone?


August 2012