So I'm 16 and I bought a running, no rust, great body 1978 280z about a month ago. The worst part of this car was how bad the dash was cracked. I've stripped the whole interior and have the dash completely off also the dash components. On to the point, I've read other forums about beveling out cracks and putting great stuff foaming sealant. I've done all that, but I ran into a problem. After I sprayed foam into the cracks, the foam didn't seal the whole crack or didn't stick at all. Is there a way to make sure that the foam fills the cracks complete, so when I sand it down, the open cracks won't expose??

Edited June 19, 20168 yr by yoshman00

Even if you get the foam to stick the crack will probably reopen, becuase the stuff it's sticking too s degraded.  I haven't done one but if I did I'd fill, shape, and fill with foam again until I had a decent base to lay some thin glass mat or vinyl over.  Just use the old crusty foam as a support for a better skin.

The foam will fall apart for the same reason it cracked in the first place.  It's a tough job.

Congrats on the new project.

27 minutes ago, Zed Head said:

Even if you get the foam to stick the crack will probably reopen, becuase the stuff it's sticking too s degraded.  I haven't done one but if I did I'd fill, shape, and fill with foam again until I had a decent base to lay some thin glass mat or vinyl over.  Just use the old crusty foam as a support for a better skin.

The foam will fall apart for the same reason it cracked in the first place.  It's a tough job.

Congrats on the new project.

So what's your opinion on what I should do to make sure it doesn't crack? Because my last option is send it in for $900 if I can't do it myself

I think that you'll need a skin on the surface that's either flexible so that it can move with the cracking underneath, or a skin that has high tensile strength so that it can resist the cracking.  The substrate, the old foam, is just weak.  You can attach strong stuff to it. but it will fail again. 

Don't hurry, I'm sure that others will have suggestions.  Might take a few days to get the views.

One option might be to feather in a dash cap.  The dash caps are made to glue on top of the cracked dash and tend to look like that.  A glued on cap, with edges showing.  Not terrible, but can be seen as caps..  But, since you have yours out, maybe you could do some cutting and molding to make it look like one piece.  The caps have some other problems also, like making the gauges hard to replace but you might be able to solve that problem while it's out too.

http://www.thezstore.com/page/TZS/CTGY/classic08d04

5 minutes ago, Zed Head said:

I think that you'll need a skin on the surface that's either flexible so that it can move with the cracking underneath, or a skin that has high tensile strength so that it can resist the cracking.  The substrate, the old foam, is just weak.  You can attach strong stuff to it. but it will fail again. 

Don't hurry, I'm sure that others will have suggestions.  Might take a few days to get the views.

One option might be to feather in a dash cap.  The dash caps are made to glue on top of the cracked dash and tend to look like that.  A glued on cap, with edges showing.  Not terrible, but can be seen as caps..  But, since you have yours out, maybe you could do some cutting and molding to make it look like one piece.  The caps have some other problems also, like making the gauges hard to replace but you might be able to solve that problem while it's out too.

http://www.thezstore.com/page/TZS/CTGY/classic08d04

Oh yeah for sure! The foam I put in is just the base, I'm putting on a flexible plastic bumper repair on top of it. I just didn't know if putting something like that will prevent the dash from cracking again.

I suspect the success or failure of the standard foam and epoxy approach is highly dependent on the state of the dash itself. There's some people out there that have reported great results for several years, but I put new cracks in the plastic on my dashboard just giving it a thorough cleaning.  There's no way my dash would hold up, and I won't even try: I'm going to put down a couple layers of fiberglass instead and work from that.  I'm basically echoing Zed here, but if you're concerned about the dash re-cracking, you probably want to go with something more structurally sound than expanding foam insulation.

Read this thread. The original poster "Bruce" did the job in 2006 an another member has the car now. The repairs are holding up well when I ask 2 years back. Although the car is now looked after really well and protectd rrom the elements.

Patience and dedication to quality are the keys to success.