Best ways to brace a roof

[Buck 5,000+ posts]

You turn your nose up at the amount of work it would take to fiberglass the roof, but then agree to this idea of making individualized roof braces out of wood that will need to be adhered to the roof anyway? Seems like coating an old tee-shirt in resin, and then rollering it to your roof, would be a much simpler project than making all those custom braces. But to each their own.
But if you must use the wooden brace method, plywood is much stronger than mdf laterally, and will do the job much better.

Fiberglass scares me, but wood cutting doesn't.

if ya dont wanna cut up a ton of wood... put about 3 pieces going across and fill in the void with spray foam... works like a charm

I'm going to fill extra gaps with spray foam.

 

[bassicwilson]

I need to brace my roof. Deadning just isn't going to cut it......

Have you tried sound deadener? I was surprised how much difference it made on my old set up.

 

[VWBobby 10+ year member]

I agree, deadening makes a huge difference. Not only does your ride not sound like a woodpecker attacking a garbage can, the cabin can gain a db or 2 and road noise goes down. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

Please don't kill more cars with spray foam. I absolutely hate seeing that posted on this forum time and time again.

Spray foam, carpet, open cell foam, etc all trap condensation (moisture) against the metal panel. After a few years (months?), surface rust and finally cancer can form under the panels.

Here is what a VW Beetle looks like in the C-pillars, which are spray foamed from the factory:

I charge a pretty penny to fix that cancer. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif Imagine if you had holes like that in your roof.

http://www.tcpglobal.com/3m/3m600-9.aspx

http://www.tcpglobal.com/autobodydepot/evercoat-maxim-adhesives-sealants-foams.aspx

http://www.tcpglobal.com/autobodydepot/semadhesive.aspx

I highly recommend you buy this stuff locally so your jobber (paint store) can set you up with the gun needed also.

You could also use a product like Liquid Nails, but a 2-part epoxy or urethane is light years ahead than any 1-part product.

 

[keep_hope_alive Premium Member]

I don't like expanding foam either. But I see why it's used in SPl builds, those vehicles are destroyed usually anyway.

I agree a 2-part epoxy would be a good idea. The roof will be heavy, some side pillar supports will help.

 

[basscort2009 5,000+ posts]

1. take 1/4" mdf cut a little bigger than allowed roof area

2. bow it so it forms to your roof and fits where the headliner would on the sides front and back.

3. use self tapping screws to screw to the roof ribs or supports

4. drill about 4 holes and spray foam all in there real good like

5. duct tape the holes until dried and expanded.

6. resing the mdf, then pait to whatever color you want for a nice shiny interior matching finish

 

[basscort2009 5,000+ posts]

1. take 1/4" mdf cut a little bigger than allowed roof area

2. bow it so it forms to your roof and fits where the headliner would on the sides front and back.

3. use self tapping screws to screw to the roof ribs or supports

4. drill about 4 holes and spray foam all in there real good like

5. duct tape the holes until dried and expanded.

6. resin the mdf, then paint to whatever color you want for a nice shiny interior matching finish

 

[FtheNutHuggers]

buck, silicon works. i've done MANY vehicles using silicon and a plied wood of some sort. when you connect two layers of material (in this case wood with metal) with a layer of silicon, you make a very thick composite panel. thick composite panels do not like to flex. also, find an old truck hood or car hood somewhere, clean a section about 8" x 8" and cut a piece of plywood 7" x 7". silicon the plywood down, about 1/8" thick silicon at the outer edges, so if the hood is rounded like most hoods, it is even thinner in the middle. let that cure. now grab that square wood piece at opposite corners (representing equal tensile force) and PULL until you create 5 hemorrhoids or your entire lower intestine pops out of your @ss, cause that silicon is not going to let go. "bass" is not going to whip out a knife or sharp object, start at one corner of your wooden structural enhancement and slice the silicon in half or peel it from the steel. the only thing you have to do when using silicon to adhere the wood to your roof is tape or temporarily hold the wood in place while the silicon cures.

 

[keep_hope_alive Premium Member]

take note that if you used 1/4" MDF without reinforcing with spray foam and resin, you'll lose SPL in that panel flex. the goal with this is to completely eliminate flexing. spray foam isn't an elegant solution, but it is an effective one.

for that matter - your door speakers are going to flex under pressure and waste SPL. they are a weak link as well. if i were competing in SPL, and i had to have speakers for music, i would have panels that could cover them up so that pressure wouldn't be lost there.

i agree silicone is a good adhesive - it's also always flexible and isn't as rigid. the plywood in the previous example will have some movement to it.

 

[Buck 5,000+ posts]

This isn't for SPL, just daily driving.

 

[keep_hope_alive Premium Member]

You may not be competing, but this thread has turned into a general discussion on roof bracing to reduce roof flex and increase SPL. Good info here for anyone interested.

If you reduce flex, you will increase SPL in the cabin... All else equal.

 

[Buck 5,000+ posts]

Flex is pretty much lost sound. I do know that much, lol, been around long enough.

I have so much work to do //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif