Hi All.
I'm thinking ahead here...quite away ahead, but I like to be prepared. The back panel of my car has one or two unwanted holes (incorrect positioning of lights!) I think there's a pic on my archive. Rather than make a new panel, I wondered about the best way to fill these as I have now decided to paint it. This would also mean that prior to painting, I could seal the rear wings onto the car using some sort of sealant to stop crap getting between the wings and the aluminium. The down side is that I wouldn't be able to remove just the grp bits for painting, I would have to transport the whole car to a spray shop, or spray it myself (oh dear!) but I like the idea of consolidating the back end!
Anyway, back to the plot. I used to be an aircraft engineer and the way to repair holes in ally was to do an insertion repair, where you make an exact sized insert and rivet it to a back plate, but sod that, it's too much like hard work. Can the holes be fixed using fibreglass mat and P38? If not, why not, and how else? Also, would spraying grp and ally together cause problems when painting i.e would different primers be required?
There I got there in the end!
Cheers
Jon

Why not do an insertion repair but bond it rather than rivet?

Mick

It did cross my mind. What's the best thing to use for bondage (ha ha) but seriously... should I use that PU adhesive that everyone raves about or do you have any other suggestions?
Cheers
Jon

quote:

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Originally posted by Mix
Why not do an insertion repair but bond it rather than rivet?

Mick

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I think PU would be too flexible and the paint may crack quite quickly. The structural adhesives we use are mainly 3Ms epoxy based so for a fairly small repair I would suggest araldite or something similar.

Mick (still an aircraft engineer )

What is the best stuff to use to fill small holes and cracks in aluminium? ( I'm also thinking in terms of imperfections in my insertion repair!)
Cheers
Jon

quote:

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Originally posted by Mix
I think PU would be too flexible and the paint may crack quite quickly. The structural adhesives we use are mainly 3Ms epoxy based so for a fairly small repair I would suggest araldite or something similar.

Mick (still an aircraft engineer )

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Welding?

Double Bond aluminium cream is the best stuff for bonding and filling in the holes, Just bond a bit of ali onto the back of the sheet then fill the reccess in. Normally comes in two 1lt tins, but not sure where you can get the cream from though, if you get really stuck I may be able to nab a small amount from work, dunno if it would be enough though

If you want to go really cheap, hot glue a bit of ice cream lid plastic onto the back of the panel then fill the reccess in with normal body filler. Might work, but for how long it stay's on for is another question.

Cheers
Chris

[Edited on 4/3/05 by flyingkiwi]

quote:

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Originally posted by flyingkiwi
Double Bond aluminium cream is the best stuff for bonding and filling in the holes, Just bond a bit of ali onto the back of the sheet then fill the reccess in. Normally comes in two 1lt tins, but not sure where you can get the cream from though, if you get really stuck I may be able to nab a small amount from work, dunno if it would be enough though

If you want to go really cheap, hot glue a bit of ice cream lid plastic onto the back of the panel then fill the reccess in with normal body filler. Might work, but for how long it stay's on for is another question.

Cheers
Chris

[Edited on 4/3/05 by flyingkiwi]

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There are a few epoxy brands that claim to be as strong as metal and are even silver in colour. However I don't think that strength is the issue here and simply bonding a backing plate behind the holes and filling in the holes with standard filler will probably do the trick IMO. If you are painting over the top it should be pretty easy to cover any small blemishes with filler/primer before applying the top coat.

3M adhesives web site

http://products3.3m.com/catalog/us/en001/manufacturing_industry/engineered_adhesives/node_KTNG5FB982be/root_GST1T4S9TCgv/vroot_WHG0MWH6QPge/gvel_GVTSZ T9BQQgl/theme_us_adhesivetape_3_0/command_AbcPageHandler/output_html

Mick

Simplest way is usually the best, get some JB Weld, stick a bit of ally on the back of the hole and skim with Plastic Padding Elastic filler on the surface. Block this down with 180g abrasive and finish with 360. Use a 2 part etch filler primer to prime the whole rear panel, gently knock this back with 400 dry. The panel will be ready for a wet on wet primer and colour coat. This is what I did with my rear panel, not for holes, but mild distortion on the corners that I had filled. I am pleased with the results
Rescued attachment Rear Panel In Raw.jpg

..and the finished result. I do not recommend you fillet the rear arches to the back panel as you could not remove them later if needed, use tadpole beading as a joint
Rescued attachment Rear Panel In Raw2.jpg

Thanks chaps. I think I'll repair the holes as Mark suggests and then hand it over to a pro for the rest! I'll start saving the shillings then!

Cheers
Jon