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MG MGB Technical - Resto Question ***2*** Underseal

So far, I have a bare body shell which has been blasted, primed and painted. the underside is currently finished in a 2-pot gloss black on top of 'POR 15' rust proof paint(as all the running gear).

I was not going to apply underseal due to the fact that water can get trapped between it and paint starting the cancer process again.

will this be significantly more noisy?

also, has anyone found a suitable (cheaply available) sound deddener for the floors under the carpet?

thanks for your opinions
innes
Innes Bint

Several people as well as myself have been investigating using the spray on truck bed lining in place of underseal. From what I have found out, it can't be sprayed overhead, so would have to be applied to a bare body which can be rolled or placed on a rotisserie. This stuff is almost impervious to anything and is designed to be applied over paint, so there should not be any voids for moisture unless it comes in from above. I was considering using it both under my car and in the boot area, (MGA so no cockpit floors to worry about). There are roll on or brush on products as well, just don't know about the quality of the finish. Certainly would act as sound deadener as well as offer excellent protection to the body from road debris.
Bill Young

I used Rhino Line in the boot of my 77 MGB. Very tuff seems to give some sound deading, easy to clean and tuff as a Rhino. I love it. If it gets on bolts and other stuff easy to get off with a small blade. Boot cost me about $175.00.
Tommy

I was in the same situation with my freshly cleaned and painted floor (No matt under carpet). I checked around and found that the regular venders did not have a sutable material to go around the floor ribs.

One emailed me back to say that he had the floor sound deadening kit but would not sell them because they were hard and brittle.

I ended up getting two EVA mastic sound and vibrations damping sheets # 9709T39
.o79" thick 32" X 54" from McMaster Carr.
The total cost with shipping was $42.49
This was sugested by others.

This is a flexable rubber mat with a tar based glue on one side. The thickness is less than original but I think it will be ok under the carpet.

I used paper to draw a pattern of the complete floor and layed it on the sheet to cut it in one peace. The original was in 3 peaces with gaps along the edges. I made it flust to the sides. Use a heat gun to warm the floor and activate the adhesive.

I finished it this past weekend, 10 degrees out side - warm in the garage.
DWM

Without underseal, your car will be liable to the gloss black paint chipping and rust starting unless you are prepared to constantly touch up any paint damage.
If you decide not to underseal your car, I would paint at least the wheelarches in stonechip type paint.

MGBs were not factory undersealed and I dont think that there will be a dramatic rise in noise without underseal.
R J Collier

Have thick is the spray on bed liner, and how runny? I All i can do is elevate my B on jack stands. Just the idea of slow drips makes it seenm messy. Is there nothing that could perhaps be brushed on ?
G.L Lodge

G.L. I don't know how thick the spray on material is, I assume you're refering to the consistancy rather than the coating thickness, but I was told by one company that they couldn't spray the material overhead, only on horizontal or vertical surfaces. It does have to be 'thick' enough to stick to the sides of pickup beds. I haven't talked to anyone who has use the diy bed liner products that brush or roll on, so can't comment on their use overhead.
Bill Young

thanks for the opinions... as it happens, my car is on a roller so i can easily access the underside.

i will investigate the truck bed compound bill... thanks for the idea.

the reason i finished the underside in gloss black was that i figuer it would easily wash down.

as far as chips go, the paint is pretty tough... POR 15 rust proofing paint (hammer hard) then a 2 pack primer followed by 2 pack gloss Black.

thanks DWM for the floor mat tip. im still looking for an alternative but will use that as a backup.

innes
Innes Bint

Undercoat, truck bed liner and other materials will not last forever. When they dry and crack, it's a terrible job to remove the stuff.

Even if the paint on the underbody does eventually crack, the POR will most likely last as long as the car. I wouldn't worry about rust.

As for noise, I doubt the undercoat would make a huge difference, assuming you have sound deadening material under the carpets. It may reduce noise or vibration somewhat though.
Steve Simmons

This thread was discussed between 26/02/2007 and 28/02/2007

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