TLDR: What is the chemical composition of the dash's soft foam material? foam rubber? poly-ethylene? polystyrene?

Hi all. I am working on a budget recondition of a 1971 MGB GT.

The problem: The vinyl on my dashboard has cracked,broken,and mostly fallen away from the foam, but as far as i can tell it has left the shape of the foam in tact. I am aware that replacement dash pads are available, but i am not willing to spend 300+ on a new one. Given that the foam is in tact and still supple-ish I thought i'd give it a go to recover it on my own.

The plan of action: I'll remove the dash and components and carefully finish removing what remains of the original vinyl. Once it's bare foam, I'll wipe it down using a non solvent cleaner followed by wiping with a damp cloth, let it dry. I have access to a vacuform table, and plan to purchase high quality upholstery vinyl for recovering the dash.

The holes in the plan: 1. I must take care that the foam is not heated to the point of malformation or melting. 2. The solvents int he glue that i use to attach the vinyl must not have a poor chemical reaction with the foam itself.

To plug the holes in the plan: 1.The dashboard will not be placed directly beneath the heating elements of the vacuform table. I can keep it removed from the table until the vinyl is ready, turn off the heat lamps,quickly place the dash on the table and turn on the vacuum. I don't believe the vinyl itself will heat to the point that it could melt the dash foam or mis-shape it. It is possible that once the vinyl has formed to the dash and allowed to cool that the vinyl will hold it's new shape and can be removed from the foam in order to apply the glue, but i'll have to experiment a little before I attempt the dashboard itself, but this would be the ideal situation.
1a. If the vinyl will not hold its newly assigned form, then I will have to apply glue at the same time that I am vacuforming, and allow it to cool and dry with the vac-table left on.

2. The glue. I plan to test various glues on hidden areas of the foam, but i'm betting that either contact cement or spray adhesive for foam will work without a problem.

So the question is: In order to predict which glues might work, and to what temperature the dashboard can safely be heated, I'd like to know what the chemical composition of the dash foam is. Does anyone have this information?

Not to divert you from your plans, but if you feel the foam is in good shape, you may consider a ready made solution, like this. It is also made of leather (supposedly!)
https://www.ebay.co.uk/itm/BLACK-STITCHING-DASH-DASHBOARD-LEATHER-SKIN-COVER-FITS-MG-MGB-STYLE-2/351326883213

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"... the motor car, after woman, is the most fragile and capricious thing on earth." - London Daily Mail 1908

^That's not a bad solution and definitely cheaper than a new dash pad, but this is a budget reconditioning. I've got more time than money and what money I have for the project I'd like to go toward more critical components and higher quality paint at the end. upholstery vinyl and glue should only set me back by about $30 in materials and some cautious work. Can't really beat that with a stick (provided this plan can be implemented).

Hi Simon,

I like your approach, to do it your self.

I have no idea about the composition of the foam, but consider that these dashes have been exposed to sun and can get very hot, greater than 50 deg C, so that is a datum you can use for heating your vinyl.

Herb

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Use spray can foam from the hardware store and shape it once it hardens

Ozieagle, good point about the dash temps over the years. That's a metric I hadn't thought of.

Bleteaches6, do you mean to apply the vinyl once the *glue* hardens? I assume you mean let it dry to the degree that one would normally let a contact adhesive set before attaching the pieces. I am a little concerned that the vinyl itself will become somewhat harder/brittle once cooled after applying heat that approaches the vinyl's melting point (which is what will allow it to stretch so well). I am partly concerned about what effect heat may have on the adhesion properties of whatever glue I use,whether it is the spray type or brush on.

Great project - sorry I don't have the answer on the foam but hope you can post pics of the progress.

Tbird, no worries. I will post photos as soon as I get to that point. Research stage at the moment. The car should be here in about three weeks. I promised not to put it into the garage until the 1980 Roadster hits the streets lest I become distracted. The roadster's going to be a driver but the GT is going to be more involved and thorough recondition. I'll probably do a time lapse of the project as a whole including the various sub-projects involved like the dash.