Cage Painting?

[BLKMGK]

I got my car back from the chassis shop - woo hoo! All fixed, have rear vision, and the bar is right where I wanted it They even patched a hole that was found in the floor covered in fiberglass (grr).

 

Now then - bar is bare metal and has some surface rust - already hosed one pair of pants getting into it! I've now primed it with Veriprime etching primer and expect to paint it with something tomorrow. If the body shop suply were open I'd try for a small amount of auto paint but I really don't want to mess with that. Oh yeah - I primered with a foam brush - done right it self levels and looks GREAT.

 

Ideas on paint? I'm thinking about some of this "epoxy" spray paint I see around. Over the Veriprime it ought to hold well, yes? Most of the cage will be covered with foam anyway but some will obviously be exposed and I'd like it to look good. Epoxy stuff okay? Or is there something else the body supply place might have that would work better - that could be brushed perhaps? Just want a hard finish in black is all without a ton of overspray around. I've masked but I know how overspray can be...

 

P.S. Brushing sounds cheesy I know but I learned with the primer that if you're careful and have no runs it will work out fine. The Veriprime stuff was cake to apply and I did the entire front of my parts car with it after sandblasting and it looks sprayed (shrug). Use a foam brush though - bristle brushes would probably look terrible!

[BLKMGK]

Went for the Epoxy stuff. It's used on appliances and it ought to dry super hard. Man, trying to get all th eangles and to get the side that shows through the quarter windows is a bitch! Pulled the masking so I could see through the window - missed a ton. Now I'm going to be scraping the paint off the windows... Haivng the primer made it easier to see at least. If you do this pull your seat belts all the way out so any paint gets on an area that's normally rolled up Yeah, still have use of my stock belts!

 

Almost done - next coat in a few then I'm through. Hope it wears well, this was a PITA! Sound deadener, insulation and then the rest of my interior is yet to come.

[pparaska]

I'm going to foam brush POR-15 on mine.

POR-15 levels out very well.

It sounds like spraying it was no fun!

[BLKMGK]

Heh, didn't even think of that! But doesn't POR NOT like UV? Now that it's pretty well done it looks good but geez what a pain. Be sure to pull as much stuff out as you can or mask EVERYTHING - that mist goes everywhere!

 

Tonight I began installing the rest of the DynaMat sound deadener. There are several panels in the Z that ring like bells. Pull your interior and tap a few of them - you'll be surprised, sounds like hitting a 50gallon oil drum!

 

I had bought the DynaMat trunk kit - smart move! Used the heat resistant stuff on the tunnel, a bunch on the tin panel covering the fuel cell (much quieter!), a pile in the doors, and now I'll be covering much of th efloor with it. Even a few squares on the cargo panels to quiet them down

 

I'll try to take pics of it before laying carpet. There's a spot just behind the seats that angles upwards from the floor mounts - it really rings. Did the rear wheel wells, rear quarters (foam DynaMat spray too - not worth it), and will now do the floor proper. Heat gun is a must and I suggest a wood roller too. Heat it till it's really soft and roll the goo so it sticks good. Bought some foil covered insulation from the Home Depot to cover the floors and under the seats after the sound deadener - it'll quiet things too. I figure that this puppy might get warm once I run duals under it.

 

Have yet to put foam on the cage but I will "soon". That's the easy part. Big thick racing rated stuff too - not the crap they use on A/C lines!

 

P.S. Make sure you get under the bars. This is a place you don't usually see and have to stand on your head to view. Sure as heck - it'll be unpainted if you're not careful, trust me

[pparaska]

Yeah, I think the POR-15 is not UV resistant. The stuff that Hirsch Automotive has is also the same kind of paint (they call it Miracle Paint), that is a moisture cured urethane. All but the clear that they have is not rated for UV. The black is ok. with UV (they say) and the Silver very good.

[clint78z]

My new big fat idea on rustproofing is the new roll on bedliner . It's fairly easy to apply, it's ureathane and very durable, a water tight seal . It will also prvide sound dampening . It plan to use this instaed of undercoating when I get new floorboards .

[BLKMGK]

A silver bar would be sweet

 

As for the bedliner... I actually checked out some of the spray on stuff that I saw advertised. Honestly I think that migh tbe a good idea if you could keep it under control and not have it go everywhere. It ought to damp sound well too! I worry that it might trap water under it though so be careful - you don't want your hardwork undone in a few years. Find out what heat will do to it too!

 

I got a bit more DynaMat done tonight - I only spent an hour on it. Would you believe that I may have some left over from just the trunk kit?! Mind you I'm not going nuts trying to cover every square inch of metal - you don't need to - but geez, I've got a decent chunk left! I may do most of the tunnel with it even though I suspect it doesn't resonate very much. Much of the floorboard is covered, chunks on both rear strut towers, rear quarters, tunnel by your feet, bunches in the doors, etc. etc. I can already tell a difference when I tap on various panels that used to ring!

[pparaska]

BLKMGK, the tap test is cute, and effective . All of these liners and sprays add some weight if applied liberally, and may trap water, as you pointed out. Not all the surfaces in the car are going to vibrate. But finding the vibration anti-nodes (that parts tha really move around and make noise) is tough, as your tap test may miss a resonance with teh exhaust - but it's a tried and true method of vibration damping /noise control. Where is that accelerometer instrumented hammer anyway .

 

The point is if you just treat the areas that really vibrate, it's alot less coverage than doing the entire car. Dynamat ain't cheap!

[clint78z]

I also used a jute foam like in carpet uderlay under the carpet of spare tire well, this helped a fair bit . Alot of noise came from whete antenna is mounted the exhaust loves to resonate this panel, a chunk pink poofy fiberglass insulation fixed that

 

This cut my noise in half, the boxes behind the seats are also a big problem .

 

2 ways of sound dampening, weight the panel down and lower resonant frequency or you can absorb it with a foam . My Z wasn't exactly quiet like a new car after this, but cut the noise in half . Stick on Lynel floor can be used as a cheap Dynamat !!

[pparaska]

Clint78z wrote:

quote

2 ways of sound dampening, weight the panel down and lower resonant frequency or you can absorb it with a foam.

 

Actually, cutting noise has two approaches, absorbing the sound once it's in the air (the foam, or other acoustic absorbing materials or techniques - including active anti-noise) and controling the "source" (the sheet metal in this case). Mass loading (weighting the panel to lower the resonant frequency) or damping (not wetting ) the the vibration of the panel through energy absorption.

 

There are two ways to do the vibration damping, passive (coatings) and active (drive the panel with an actuator to cancel the vibration).

 

Tar, bedliner, non-foil covered Dynamat, etc. are passive coatings that have some energy absorption (as well as mass loading) due to the hysteretic properties of the material - called viscoelasticity. These are called free layer damping materials, since they have no "constraining layer" on the top of them. They absorb the vibration energy as well as mass load the panel to lower it's resonance frequency. So if you still hit the resonance frequency with the noise, the vibration is still cut down by the damping properties. Mass loading alone (inefficent damping material like tar) doesn't have that benefit.

 

The foil covered Dynamat is called a constrained layer damping material. It does a better job of damping (higher damping coefficient) for the same thickness of viscoelatic material. The foil cover acts to amplify the strain in the viscoelastic material (the gooey stuff) and get more damping out of it.

 

Both the free layer (e.g., bedliner) and constrained layer (foiled Dynamat) have frequency dependent damping properties - they act in a range of frequencies dependent on the viscoelastic properties of the gooey stuff, the thickness of the goo, and the thickness and material type of the "foil".

 

More than you wanted to know, but the upshot is mass loading works, but if you use a lighter foiled dynamat, it can be more effective and lighter. Also, adding it to just where the panels vibrate is weight efficient as well.

 

(I used to work in the field of submarine quieting Believe me they want those things quiet!)

[BLKMGK]

Thank you Pete!

 

Actually that was very informative and now that you've explained th efoil covered stuff I better understand how it works and why DynaMat had intended that for the trunk lid

 

I didn't weigh my box of DynaMat but I'd be shocked if it weighed more than 10lbs or so. I can handle the added weight for a nice quite sound! In the end the trunk kit allowed me to cover a great deal of the floorpan, lots of pieces in the doors, rear quarters, and basicly everywhere there was a free span of metal. If it could be tapped and just thunked or felt solid I didn't worry as much but the tin covering my fuel cell was covered on both sides! That puppy rattled like mad before I did this - now not a peep.

 

I still have a can of foam left to use and now that it's been brought up pink attic insulation in the rear quarters might not be a bad idea. Bed liner and vinyl flooring also sound like good ideas - too late for me

 

I'm now to the point where I've just finished with the foil covered buble wrap stuff. I've got two cans of undercoating to use in some areas underneath and carpet to put back in. I covered the tunnel, floors, and the side of the cargo bay facing the drivers area with the foil stuff. I took pics while I was at it and if this makes a big difference I'll try to write it up along with the SubtleZ hood.

 

fun fun!