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Sound deadening removal, floor panal rust, POR-15 question


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So my z sat outside, semi-neglected, in the driveway for 10 years. I've recently driven it across canada, and figure that it could use a rust check.

It will be another two years before I graduate, recieve a rather large promotion, and am able to afford some nice sound deadening and insulation. I figure if this is going to be my daily driver in the summer, we better stop thinking about weight. I can buy a 240z to SCAA modify at a later date, and worry about fibre-junk and drilling my alumimum blots out at a later date.

I have more important things to spend my $ on while in college (electrical, gas, and food [in that order]). But I can't leave what I know is certain to be rust, untreated and wet under the floor below me... so I decided to strip the interior to bare metal, then POR-15 it and live with a noisy interior for a couple years.

The seat's can't come out until the new ones get here, but I got eager today and ripped the drivers side carpeting out, from in front of the seat to the firewall. The floor panal had two well-rusted grooves which facilitated easy removal of the bottom layer of sound deadening. Where it was not rusted below, I tried a drill with a wire head on it. I was using it to remove rust, but instead of melting, all the deadening came off in tiny plastic flakes. If you're having a hard time removing non-tacky deadening, the drill worked wonders for me.

The rust is all surface (so far), and it's all going to be gone by the time I POR-15 it. I am wondering what to use overtop of the POR. It should be cheap, glossy, and preferably clear. I know the POR is supposed to be good by itself, but for some reason, I think a clear coat (or gloss finish) will prevent moisture more than the matte POR finish. What do you think?

Edited by fiveleaf
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These guys sell cheap and ship fast. Great price too.

100 squae feet of 50 mil FatMat. 2 rolls of 18"x 33 feet and the shipping weight is only 33 pounds and shipping is FREE!!! Just $129.95? total.

You've seen my 260Z page and this is what I used.


Real sticky, easily forms and easily cut to form. Wipe down everything with alcohol or brake cleaner, let dry and go for it. 100 sq. ft is more than enough.

Edited by Zs-ondabrain
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Then it would be +insulation and +carpets (thanks for that ebay carpet seller tip).

I really don't mind waiting until I can do the job to what I believe will be absoutely top-notch. I also enjoy learning about it, and have many more tech articles to go through about the acoustics of a car.

I'll admit, sometimes, part of me want's to say screw car audio... but the wife and I disagree in our music tastes. I can't stand club hits. Can't stand them.

She won't let the hip be played in the house anymore. This means headphones. You think I should drill holes under the taillights? She doesn't like the way it smells. :finger: I know.

Right, sound deadening... I was thinking of this. Seems overpriced, but I'm still looking for "the one", really.

For now, "Second Skin Audio" makes many products, and is regarded as one of the best... as pricy as it is, it's not as bad as Dynamat Xtreme.


Edit for pictures. Anyone know a way to seal this plastic cover? Or where I can find one that is actually aftermarket? I tried to make a new one about 4 months ago, and it's coming apart already (picture 6)

Also, what wires are supposed to go in the harness clamp on pic 8?










Edited by fiveleaf
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POR15 should be all you need on the interior. As long as the prep work is done correctly before the POR15 is applied, you shouldnt have to worry about it again. Also, there is no need for anything else since it wont be exposed to UV after the carpets/vinyl/sound deadening is put in. (I believe it dis-colors after long exposure to sunlight)

And I dont understand the drilling holes under the tail lights? Is that to minimize gas/exhaust fumes? Expandable foam might be an option near the rear tail light seals.

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My oldest son is in college and has a 72 and he did what you are planning. Clean the rust off as best you can then follow with the Por15. We found it works best to use the Metal Ready. I have some Por15 that I put on my 1970 FJ55 Landcruiser 15 years ago and it has held back rust very well. I would not put anything over the Por15. Be sure the surface is dry, if there is any moisture the Por15 will dry with a matte finish instead of a gloss. I found this out. It can take quite awhile for a rough pitted surface to dry.

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Preparation is the key when you use POR-15. Follow the instructions. Marine Clean, then the Metal Ready. Then brush on the POR. You need to flush the panel with water in between the M Clean and the M Ready. Once the panel is COMPLETELY dry , this is critical because moisture will cause the POR to foam and cure too fast, then brush on the POR paint. Metal Ready will leave residue when the moisture is gone, leave it . I used black gloss . Once POR is cured completely no paint will adhere to it properly. It will just peal off. If you must cover the POR with another color for some reason. You have three options. 1. apply the color of choice while the POR is still tacky. 2. wait until the POR is cured and sand it to dull and scratch the surface, not easy POR is a hard finish, then you can paint your color choice. 3. Apply Tie-Coat primer , a POR product, right over the cured POR . It is the only stuff that will stick without a lot of sanding. Then paint with any finish you like.

I did all my floors and allot of other areas on my 240, and just stuck the sound deadening material right over the POR. I also prepped the under side and PORed it as well. I have had zero rusting on any metal so treated and it has been 8+ years and I drive my Z. It is true that the UV light will effect the finish of POR . In time it gets a slight hazy looking. I painted my gas tank with it at the same time I was doing the rest of the project and it is starting to be visible now, Incidentally the black glossy applied with a brush right from the can. Will flow out and look like you sprayed it. Do not buy any larger cans of paint than 1 QT, otherwise you will waist a lot of paint. It goes a long way. I painted the complete underside of both front fenders the inner finders the floors up front. Hatch area was rust free. I shot it into the rockers and cowl , doglegs and on the inside of the doors. Inside the rear fenders and inside the hatch, actually I poured some inside the hatch and tipped it around so it ran all through the hatch . The glass was out. I also did the gas tank, and front suspension and under the cabin floor. Total I used only 2Qts. The stuff is not cheap but it goes along way and it is the best I have ever used for this purpose. Been doing this stuff a lot of years.


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Holes near the taillights are to suck the fumes in, which has the effect of freeing up the passenger space of anything female.

I just ordered 4 quarts of POR-15, for $160, two silver and 2 black.

I also found some paint-over gloss black POT-15 topcoat. The two products should have a nice effect when I'm done. The inside of the dash, passenger dogleg, and eventually the rear hatch will also need to be done.

Reccomendations on the hole? cut out a patch and weld it back in? I've never done any of this before, just seen pictures.

Here's after some sanding... or cheap $30 drill + zapstrap "ON" + wire brush

Also, starting pictures have been added to my second post.








Edited by fiveleaf
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There must be a faster way to do this. I'm searching for a tool that does this job better than a drill and wire brush attachment. You can see it in picture #5 (above).

The wire brush also wear's down faster than I would imagine. Especially in the non-smooth areas (under the pedals).

I tried to dremel it with a wire attachment and wore that little brush out in about 120 seconds.

Edited by fiveleaf
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Do yourself a favor and look into Zero Rust before you commit to POR15. I know the Z illuminati all love POR, but Zero Rust has some advantages.

Anyway, if you have a really limited budget for sound deadening, you can go to Home Depot or Lowes and get some mobile home roof patching material that it cheap and works pretty well. It is the same principal of asphalt sandwiched between aluminum . Keep to horizontal surfaces only though if you live in a hot climate as it may slide down over time if its really hot.

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Money is not an object for rust-proofing.

I'm still going to wait on the sound deadening until I graduate. There are more important things to do than sound deadening anyways.

My order for POR-15 had already been paypaled, but was just refunded because of spelling on the street name. I'll look into the Zero Rust; thanks.

Until then, I could really use something more effective than a wire wheel for saning. I'm thinking a grinder attachment...

It also looks like the floor panels were at one time painted with a really tough topcoat, which looks good until you grind it hard for about 15-20sec, when it reveals the rust below.

Another issue is the hard-but-tacky sound deadening on the firewall and centre console to the floorpanels. Too soft for the wire brush (gums it up), too hard for a scraper. About 1/4 to 1/2 inch thick.

I will need to remove the pedals to repair to weld over the rust hole on the driver's side. I couldn't find any screws or bolts, looking with a mirror. I have new pedals coming. Is there a trick to getting these off?

This carpet kit is cheap, and not what I will end up using. For $150, I think I'm going to temp install it with minimal ammounts of glue for the next couple years, then give it away when the time comes for another interior job.

hmmm... Need to pick up the new seats/dash cap/anti-rust before taking eveything apart. I don't want my seats and dash out while waiting for parts. I still need to daily drive it!

Edited by fiveleaf
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It sounds like somebody else already tried to treat the floor pans. My car had old, brittle factory sound deadening (asphalt sheet, basically) that I had to chip away before I could remove what was underneath- primer! The lack of protection is the leading cause of Z rusty floors... anyway, wire wheels have their uses (i.e tight spots) but they can be a pain to work with, and dangerous (little pieces of the wire flying off as light speed). Go to an autobody supply store and ask about Norton Speed-Lok discs. They are little "sanding" discs (not sandpaper, similar to scotch-brite) that attach to a hand drill via their proprietary chuck/backing plate. 80-grit discs will work for paint and rust removal. You won't need a whole box, so see if they'll sell them to you piece-meal. I used them not only on my floorboards, but when I was prepping my car for the paint job I gave it, removing paint and primer in the door jambs and other areas that I couldn't hit with my big sander/polisher.

Do NOT use the speed-loks with anything faster than a had drill. No angle grinder! It will melt them LOL. They last for quite a good size area, too. You can probably do around a square foot or so with a single disc depending on what you are stripping.

I tried POR-15r and Metal Prep a long time ago, and then I tried Zero Rust and Picklex 20. They are far easier to work with and give better results IMHO. Picklex 20 is a terrific single-product rust disolver, metal prep, and anti-rust coating all in one. It is a little expensive, but worth it. You could use a single bottle for your floor pans, but I ended up buying that and a whole gallon ($100 +) when doing my car. The awesome thing was that I could leave stripped sheet metal un-primed for MONTHS and there was no flash rust. All I had to do before priming it was scuff it. It is incompatible with epoxy primers, so be aware of that fact. I used it on the whole car because I had to strip things one at a time over a period of about a year. It works really well to convert rust, and when you wipe away the excess after a few minutes of letting it work, it leaves behind a zinc coating on the bare metal - hence no flash rust :-)

Anyway, I don't want to sound like a shill so I'll stop here. Good luck to you though, and I hope you don't wind up with any gaping holes in your floor pan like I did :-)


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  • 4 weeks later...

I'm going with POR-15, with a glossy black POR topcoat to go overtop.

I've been sanding for the last week now, and am almost finished the entire passenger's side.

Seats/dash/console are all out, I'm mostly using an angle grinder. I picked up a 7" giant makita grinder to make the drivers side go faster. This grinder with a wire wheel attachment (and no guard) can remove sound deadening like no tomorrow.

Most of the work is being done with the smaller shop angle grinders, and a 4.5" sanding disc. The kind that are thick, with layered sandpaper. Those things last forever.

The transmission tunnel and firewall had some crazy spray-on stuff that proved impossible to sand off. It was thick, like tar, and would melt before flinging off the angle grinder. I was in a t-shirt the first day and got a large piece of the molten stuff, which lit on fire mid-flight, on my forearm. Never again.

I was actually about to give up on it... until a hammer and chisel worked their wonders. FAR faster than the sanding method. And a good thing -- the front of the tunnel came off with chunks of rust on the bottom. All surface.

Pictures to follow!

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