240Z interior restoration: Jute or DynaMat?

[Warty]

Hi Folks,

I have a 1970 I've been tinkering with as time allows. The car originally had a blue interior, but then some nice person screwed down brown carpet, and another nice person after that installed black carpet and black vinyl in back. I am restoring to the original blue. I still have most of the interior bare, but I'm close to being ready to re-assembly everything. Just finished cleaning out the heater core and blower, should be able to get that reassembled by end of this week. 

I can't decide if I should try to do jute padding for trans tunnel and under seats and on rear deck, or DynaPad + Dynamat Xtreme. I have a new set of jute I cut myself, and I have a repro carpet kit, and a repro blue vinyl set to go over. I am generally trying to get this car to be MORE original than it was when I bought it, but OTOH... I really hated removing all the hairy jute crap, and I hate to think of the next owner (yes, the wife tells me there WILL be a next owner) having to go through that removal process if they want to go a different way. 

I don't have any experience with the Dynamat stuff, but it looks pretty straightforward to work with (and I have paper and jute patterns for the cutouts anyway). I'm not going to make this a daily driver, but seems like Dynamat would be quieter (and cooler) and easier to "undo". I haven't made up my mind, but I'll probably sell the car a year or two after I finish it so I do have the next owner on my mind.

Any recommendations one way or the other? 

[grannyknot]

Have you chipped off all the original tar mat that was installed on the assembly line? Those tar mats were laid down on to of bare metal and very often when they are chipped up and removed you can find rust that has started underneath.

That rust needs to be addressed first before sealing the metal up with primer/paint, then you could go ahead the a Dynamat type product and jute on top of that.

Dynamat will take away some of the originality of the car but as you say will make the car quieter and reflect some heat from the engine bay and exhaust.

Edited May 29, 2023 by grannyknot

[HusseinHolland]

I would not add dynamat. Having made the mistake of doing so on my X1/9, it is a royal PITA to remove should you need to do so. It can be applied judiciously to act a panel damper, but that's a different goal from what you are proposing. I'm sticking with the original matting on my 75, I just added a layer of batting to the original undermatting to help keep it's integrity 

Edited June 5, 2023 by HusseinHolland

[Warty]

On 5/29/2023 at 4:23 PM, grannyknot said:

Have you chipped off all the original tar mat that was installed on the assembly line? Those tar mats were laid down on to of bare metal and very often when they are chipped up and removed you can find rust that has started underneath.

I chipped up a tiny amount of it, but have decided to leave it in place. This car had a fair amount of un-originality when I bought it, thanks to PO doing a restoration in something like 1990, and switching interior from blue to black, with carpet all up the tunnel, etc. However, maybe because of that restoration, maybe luck (Colorado car helped a little maybe), it is remarkably rust-free for a 1970 Z. 

[Warty]

19 minutes ago, HusseinHolland said:

I would not add dynamat. Having made the mistake of doing so on my X1/9, it is a royal PITA to remove should you need to do so. It can be applied judiciously to act a panel damper, but that's a different goal from what you are proposing. I'm sticking with the original matting on my 75, I just added a layer of batting to the original undermatting to help keep it's integrity 

Thanks for that vote. 

I spent the weekend working on the car, and did some soul searching and decided I think it would be better to keep moving back towards original condition, not "better" condition. So, no dynamat. I also did an experiment this weekend that another poster suggested, spraying the jute with clear PlastiDip. I thought this would produce a rubbery effect, but it didn't. Maybe it would if you put on 40 coats, but I just did 4. It definitely seems to cut down the "dust" effect though, so I'm going to spray the jute under the carpet with it, when I get that far. 

Off to hunt for snaps for the carpet & firewall...

[Warty]

So… I spoke too soon about rust under the tar. For whatever reason in this car the driver side has less rust than the passenger side. On the right side, in the seat riser area, there is some rust. I trimmed away the edges of the tar along the front seat riser and for the most part the rust only extends back 1/8 inch into the tar. Deeper around the hump. I also chipped some more off near the outer rear seat attachment and there was more rust under that (all light surface rust). I suspect more under there somewhere. 

Recommendations?

Strip off ALL the tar on the car, assuming there is more? Strip just this right side tar?  After sealing the rust, would you try to remake tar as replacement? Just lay down some kind of rubber material that can be cut to match the same pattern? 

BTW, some of the brown in the photos is not rust, but residue from where a PO glued down carpet to every surface in the car. 

[Mark Maras]

 I have stripped all the tar from a 240Z. I was surprised to find more rust in places that seemed impossible. Like in the center of a tar mat, that was sealed all the way around. If you don't remove it, you'll always wonder what is lurking under the tar.

[Warty]

Kind of coming around to it. I found this great thread here, with templates to create your own new tar mats, and link to place to buy similar-to-Z mats. Lots of paint involved, and probably overall a solid extra 7 days of labor, but... Probably the right thing to do. 
 

 

 

[Richie G]

I just stripped all the tar from my deck in a 71 and lo and behold lots of surface rust where there was zero indication.  It's worth chipping up if you want to do it right.  One tip, use the dry ice method rather than hammer chissel or whatever brute force you go with.  It comes up incredibly easily with zero mess as the ice passes straight to gas.  I did my whole trunk in maybe an hr or less with very large pieces just popping off after they froze. Just wear protective gloves and a mask or keep the doors open so you don't get so much C02.  There's plenty of you tube videos on dry ice tar mat / sound deadener removal.

[Warty]

Thanks for the suggestion on the dry ice. I didn't see that until I had chipped up under both seats, but it saved a lot of time on the front pans. I didn't get it quite right when I started, but eventually figured out that I needed to crush it smaller, and use more alcohol. 

I used WD-40 to clean up the tar that was left after chipping. You can see where the rust was pretty clearly now. Passenger side worse, but a little rust on the driver side, too. 

This is my plan, please shout out if you think I should do something differently. 

1. treat rust and bare metal with RustBullet Metal Blast rust remover. Probably do some sanding/scrubbing of rust as well, depending on how magical Metal Blast ends up being.
2. Apply POR-15 Patch (POR-15 epoxy in a paste form) to the 2 through holes, plus to the holes left by carpet screws. 
3. Sand away the remaining glue from the seat risers and other painted spaces that will be visible when carpet is peeled back.
4. Apply Rustoleum primer (metal, light rust) (brush)
5. lay down tar (do you glue tar in? or does it stick based on being heated with the heat gun?)
6. apply primer to tar (brush)
7. apply base coat 903 blue (sprayer)
8. apply clear coat (sprayer)

 

[Richie G]

Wow that wd40 did a great job.  I'm going to follow your method when I do mine in a few weeks.  From my initial inspection it looks like I have the same areas of rust as you and probably half the people on here lol.  Heating the tar mat going down all depends on what product you buy I guess.  I used kilmat 100 ml which was a great price to performance ratio for me.  The only down side is it's not really paintable because of the foil backing.  It's super easy to go down though, can be cut with metal shears like butter and has a peel and stick application approach.  You'll use a little muscle rolling it all down properly but I was real happy how the trunk area came out.  i used that por patch and was super impressed how hard it set up.  One lesson i learned is be sparing if you intend to sand and paint over it as it's a bit tough to totally smooth down if you aren't careful.  When I removed the glue from the trunk area the goo b gone worked well wnough i didn't really have to sand much if at all.  Good luck show us the results.