Has this been discussed? Engine bay sound pad Options

[rick 918-S]

I have decided to restore the Raspberry car as close to Concours as I can. I have an engine bay sound pad that is very nice. I mean really nice. One problem though. The pad is glued and held in place with plastic retainers. Over time, the pad holds moisture against the firewall and will cause rust. This actually happened to this car and the Ravenna car I have causing rust holes in the firewall. Here in MN we have cold wet winters and damp humid summers. It is very likely if I just do what the factory did to install the pad the process of rust will just start over.

My question is:

You guys that have completed a concours quality car must have thought about this. What have you done to prevent the creep of rust that starts behind the pad?

I'm working on a couple ideas that I think will work without causing the judges to freak out. I thought about trying bed liner. The stuff is near bullet proof in the bed of our Titan. I haven't even been able to scratch it. The glue that is used to secure the pad should not be able to penetrate the bed liner which is what I think is happening to the painted finish behind the pad. The glue will break down over time causing the loss of paint that it is stuck to. The moisture in the pad will start the rust process. The rest is history.

BTW: I would only be using this on the firewall and it will be completely hidden by the back pad. Cool? or Lame?

I also thought about thinning out some fibre glas resin with laquer thinner and carefully wetting the fiber that contacts the firewall. This way moisture would not be absorbed anymore. (IMG:style_emoticons/default/confused24.gif) just thinkin out loud.

[Tom_T]

Hey Rick - you saw what happened to the firewall/engine lip on my 73 in those Body shop recco topic pix that I posted, & had it happen to yours.

I'm in the same quandry as you, but won't reuse my crappy pad. (IMG:style_emoticons/default/huh.gif)

I like what George is suggesting, but I'm not sure if it passes the CdE muster, or if some judge will gig pts. for it?
... George, any experience in competition with them? (IMG:style_emoticons/default/confused24.gif)

The other idea I toyed with - similar to your fiber-glassing resin idea - was to try to adhere a sheet of polyethylene or something to the inside face where the sisal fibers are bare. I think that the resin would soak in too much & not form a solid & waterproof barrier - at least not without loading tons of resin on it!

The truck bed liner on the firewall may be a good idea & is supposed to be more waterproof than under coating, but I think that leaving the adhesive off & only using the metal clips around the perimeter (top, bottom & sides) & the plastic nuts/clips (middle area) would be preferable.

For one, you can regularly remove it & check for problems if it's loose, & another is that the slight airspace may allow any moisture to drain & dry. If it won't stay flat right, then spots of adhesive in droop areas would be preferable to the full spray-on of the entire pad.

The other critical area in this problem is to make sure that the rain tray doesn't droop/sag between the 3 forward clips/straps, thereby allowing the inner waterfall onto the pad/firewall. This is less of a problem with the late trays due to the 2 stiffening ridges added to the bottom, but the early flat ones started to sag almost immediately due to the engine bay heat.

Mark/Mikey914 is thinking of doing a repro early tray for those of us with early 914's on which that is the correct part, & I've suggested that he use both thicker plastic in the tray, as well as to add some discrete stiffener along the front lip (or a yet thicker lip).

Hope this "thinking out loud" is helpful! (IMG:style_emoticons/default/biggrin.gif)