Amp Rack: Liquid Nails or Gorilla Glue?

Hey guys,

Looking for the expertise of Wakeworld once again.

I am building a semi-freestanding amp rack inside my observer compartment and need to anchor it at a couple points to keep it from moving (see pictures). I plan to glue (2) 2” x 2” pieces of 3/4" MDF to the port side wall and then screw into that (it's not shown in the pictures below, but I added a little "L" piece off the rack on the inner verticals).

I bought (2) types of Liquid Nails – the general adhesive and woodwork-specific. I figured that the woodwork-specific stuff would be the “right” choice as it recommends usage with MDF. I did a test piece underneath my dash before I committed to the real thing. After about an hour, I could feel the piece rotate a bit when I tested it to see how well it bonded. I just left it and will check tomorrow.

I thought this stuff bonded after like 30 minutes? I’m wondering if there is a better choice for adhesive. Should I use the Liquid Nails general stuff? What about Gorilla Glue? What exactly are you guys using for amp racks, etc?

Thanks for the help! Can’t wait to get this damn stereo done! Way too much to do and not enough time. It’s killing me Larry!!!!!!!!! (obscure Sit 'N' Sleep reference...don't know if anyone will know what I'm talking about)

Danny

I would use the general liquid nails personaly. Becarful with gorilla glue as it expands more than you think.

I would use the 3M 4200 marine adhesive or if you know you will never remove it, the 5200. This is GREAT stuff for boats.

PL400 would probably be better than the liquid nails. It is an exterior rated glue (the PL200 is not).

Also, why MDF?? The 3M stuff or the PL400 will hold treated plywood. I would use treated 3/4 plywood or a treated 1 x 4 ripped down.

Another vote for 3M 4200.... or just straight up epoxy resin.

MDF seems an odd choice - how are you going to seal it? The lamination on it now is not going to last very long.

I don't think you should anchor it with glue, it could break loose when you hit a double up, that's a large structure and a lot of weight with amps on it and several coats of epoxy. Here's a trick. You can make a little raised boss to put a screw into by taking two 1"x 4" strips of fiberglass cloth and making a little cross. Then, take an ice cube and "tape" it to the hull with the cross of mat and some resin. When the ice cube melts, you have a raised fiberglass boss that you can drill a hole into. The mat makes sure it really holds a screw, and you don't have to cut away much carpet, if any. Mount four of those to the hull wall and mount the rack to them.

Psyclone - Ths sounds a really obscure thing to do.... Why not just use a little block of wood instead of the ice cube? or a block of plastic foam??

Have you ever actually done this? Surely it'd get really messy and the ice cube wouldn't be square....

Thanks for the input, guys. Lots of different thoughts here.

I checked my test piece this morning and it was solid, so I went ahead used the Liquid Nails woodwork stuff. I didn't want to use the 3M stuff because it sounds like that is super permanent and that could be trouble if I want to remove in the future.

Brit and FJK: No particular reason on the MDF other than it's what I already had. This boat has been in the rain and that wall has never gotten wet at all even though the rest of the boat was completely soaked (floor, etc.) I know it's possible, but I'm willing to take the risk I guess. I haven't had a problem with similar installs in the past.

Psyclone: The structure touches the floor firmly all the way around, so the rack itself is supporting all the weight of the amps. The anchor points are only there to hold the rack from "hinging" inward, and even that force is pretty negligible. With all the amps loaded up like in the above picture, the rack wants to lay inward automatically, so I really don't think the anchor points need to be super engineered. I'll find out soon enough though!

Thanks again.

Danny

Brit,
Yes I've done it, it makes a little dimpled out fiberglass bubble that you put a screw through. I don't like using wood for mounting because it can become damp and separate, even when epoxied. I peel back the carpet and make an attachment point that I can mount stuff to without cutting things up too much. The method I suggest can be a pain if you are not careful with resin, but I try to take my time with that. I guess you could just as easily put a square of plastic or foam under the strips. I have not had to get fancy to match the hull curvature, but you could do that with foam. One nice thing about this method is that you can cut them off easily with a cutoff wheel with no evidence.

I have mounted amps both ways, when glueing a piece of MDF to the hull sometimes that glue doesn't set up really well and it is hard to go back to stock once you've cut up large sections of carpet. Once liquid nails has cured, it can be very difficult to remove the old mount if necessary.

Anyway, good luck Danny, looks good so far!

Figured I'd post the final product. Not quite done with the rest of the stereo yet, but I was able to power everything up with the Music switch, so I was PUMPED yesterday. The turn-on relay worked correctly and everything came on first try. Got some music to come through the cabin speakers. Just have to put the sub box in, button some things up, and tune her in. We should be rocking soon!! Unfortunately, I will be out of town starting today so I can't finish it and enjoy a nice hot weekend with it!

Oh, yeah...major props to installers that do this, do it well, and do it quickly. This was a giant pain in the a$$. Working with 1/0 power cable, 3 amps, and all that wiring in a tiny space is not easy. I've spent probably 12 hours inside of that damn observer compartment. It is not a place for a 6 foot, 190lb person. I am going to have nightmares. I am glad to be DONE in there!!

Danny








Power and ground pass-through:



Power and ground behind rack:





Upper mounts:


Lower mount:








We've got lights!!!!

Definetely different but looks like it works nicely.

Very, very nice work.

Nice work man..

Thanks for the compliments, guys. Yeah I didn't want to do the standard "big board on a wall" trick. This let me arrange the amps in an aestetically-pleasing, unique way and still fit in the vertical direction. I also figured that the air flow will be better having more of the amp surfaces exposed. If heat becomes a problem (which I doubt because I have no desire to blast my stereo at full volume for any length of time like some people do!), it would probably be easy to put a fan behind the rack to draw air through the port at the bottom, over all the amp surfaces, and out the top.

It worked out perfectly because all the amps are the same chassis size, have signal input on the left side, and have the power-in/speaker-out on the right side. So the wiring was able to be done pretty clean (well, as clean as I could get with all the 1/0 power and ground cable!)

Now I just have to put her through the ol' double up test. I think the design is sound, and my feeling is that it's going to be rock solid.

Danny

Looks good. Great design. As you mentioned plenty airflow, and looks rock solid.