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MG MGA - Intro & rust

Hi all,
I've just purchased a 59 1500 Coupe restoration project. I've not had much chance to really look closely at the chassis but from first inspection it looks reasonably sound but with surface, the body panels also have plenty of what looks to be surface rust on them. There are a couple of holes in the boot and the rear valence needs replacing with fresh metal. It looks like the most of the paint was removed. Possibly, a restoration was started but didn't complete!?

The car has been standing for some time and there is a lot of dust and other bits of debris in it so a good clean out is necessary.

Does anyone have any advice regarding stabilising the surface rust? I'm on a tight budget so will probably go down the sanding route.
Regards
Kevin
Kevin Sheahan

Phosphoric acid is very useful to keep handy for removing rust and it is a constituent of many of the commercial rust removing treatments. However, they tend to be expensive if you've a lot of rust to remove so I would suggest you buy a litre of 80% acid and dilute it four or five times with water. It is available on Ebay as 'pH Down phosphoric acid'(see for example item 2803 4417 1281) and about £7 a litre which will make up a gallon of treatment. Make sure there's no grease on the surface and brush it on, leave for 10-20 minutes and wipe off with a wet cloth. It's safe to use and I don't wear gloves. Don't rinse the acid off completely otherwise the surface starts to rust again immediately. The surface dries white which is a phosphate layer giving some protection against further oxidation. I use this stuff a lot but if you have a thick rust layer it will take several applications and you may have to give a helping hand with wire wool.
Another very cheap rust removing solution for small items,nuts & bolts,etc. and if you have plenty of time is a solution of molasses (black treacle) about 10 or 20 to one. You can get this from a pet food store - used for horses/sheep/ etc. - and around £5 a gallon. If you make up a bucket of this and as you remove nuts and bolts drop them in the bucket and leave for several months (yes it is slow but it is a benign solution and does not attack the parent metal) and you will be pleasantly surprised.
Quicker is the electrolytic method where all you will need is a battery charger, container and some sodium carbonate or hydroxide. There's plenty of information on the net about this.
If you are after speed then you can also use sand blasting but to do it yourself you have to buy a very expensive large compressor. Sand blasting equipment for hire is not easy to find in the UK. If you get a firm to do it for you make sure you research them very, very carefully, including references because they can ruin body panels in no time if they are heavy handed with air pressure,grit size,etc. Mike
m.j. moore

Phosphoric acid works great! I cut it 4 to 1 with water and apply it with a spray bottle. (it is the only thing keeping my "A"s body rust free now that it is completely striped of paint. In the states I have found it in Home Depot made by Klean Strip called Prep & Etch . It also "etches" the metal and creates a better surface to except primer.
I have never heard of electrolytic method where all you will need is a battery charger, container and some sodium carbonate or hydroxide. But I will look it up now .
Chris Velardi

Many thanks for the info on Phosphoric acid.

I assume the best way then is to give the panels a sanding with my angle grinder to get off any loose rust with a fine grit then apply the phosphoric acid?

Kevin
Kevin Sheahan

Yes the more you can remove mechanically the easier the job the acid has. Suck it and see as they say! Mike
m.j. moore

Be careful with the angle grinder on body panels, they can be aggressive even with fine grit paper. I wouldn't use it at all on the aluminum boot, bonnet, and door skins.

George
G Goeppner

Hi Kevin,

I have been using Poly Abrasive discs, on my angle grinder, recently and find then excellent for removing paint and surface rust without being too aggressive (unlike flap discs). They do not clog so are a very quick way of cleaning body panels. The only down side is that they don't last very long (dont press too hard!).
Chris.
Chris Bond

Kevin,
If you're looking for something to clean off surface rust and paint check these out (see image). They work amazingly well and last quite a long time. They don't load-up either. I think they are made by other suppliers than 3M, but I like theirs best. Safe to use on aluminum as well, but be bit careful. You can use the flat side or the edge. You need to mount on an arbor and put it in a drill motor or similar. I prefer my pneumatic die grinder. Turns at a fairly high speed and cuts/cleans quickly. There are versions that have the arbor built in.
I love these things!

Gerry


G T Foster

Further to Gerry's comment, above, I can confirm that 'scotchbright' discs are wonderful - the motorcycle fraternity all seem to use them; the one in my garage is in regular use and they last a long time. We've just used to to clean and polish con-rods (you can get other discs that can be loaded with polish etc). I can post supplier details if of interest
Best of luck with it
Andy
A S Duff

I'd like to give scotchbrite discs a go, Andy if you have details of a supplier that would be great. Although I assume Halfords/B&Q would have them.

I've got some Jenolite which contains phosphoric acid, anyone had any experience with Jenolite?
Kevin
Kevin Sheahan

You can pick up Scotch-Brite wheels on an arbor at Wal-Mart, or in bulk at any paint supply store. Great for stripping paint without damaging metal, and for stripping carbon out of an engine without damaging aluminum pistons. If you use the flat side it is very mild abrasive, more like polishing, but will take off a lots of paint or carbon in a hurry without loading up. Using the edge is much more aggressive for ripping off paint and carbon or even light rust down to bare metal. Do not use the edge of the wheel on sheet metal parts. See here: http://mgaguru.com/mgtech/tools/ts111.htm

When I stripped my whole outer car body last year I used a few flap wheels in the angle grinder for the steel panels, really fast like 30-45 minutes per panel, no problem. For the aluminum panels I used a variable speed sander running medium speed with finer grit sanding discs and light pressure, more like 45 minutes per panel for the four pieces but no warpage. See here: http://mgaguru.com/mgtech/restore/rt627.htm

When you get to bare metal, get the primer on it ASAP, then don't let the primered parts set in humid environment for too long.
Barney Gaylord

Hi Kevin - I got my disks from www.perfectpolishingkits.co.uk. Warning - do not do what I did and buy everything on the site! - most of it will languish in your garage. Do buy plenty of the abrasive disks - I promise you'll be using them all the time. I bought an arbor to convert a £10 bench grinder - brilliant for giving something like a bolt threads a quick clean before crawling back under the car - so nice when the threads run smoothly (well, that and copperslip!)
Best of luck with it
Cheers
Andy
A S Duff

Thanks for the link Andy,

Managed to get the driver's side front and rear wings off today. Turned out to be a bigger job than just removing seized bolts.

The front wing was bolted along the top but was welded along the bottom edge, similarly the rear wing was welded very neatly down a portion of the B post and along the bottom edge.

Anyway, after a bit of careful use of the angle grinder I managed to get both the wings off. What's underneath isn't too bad, there's been some previous repair work on the footwell side wall and thankfully the sills seem very sound.

Lots of surface rust though which I've used a flap wheel on to good effect, I'd like to paint this area and was thinking of using Hammerite direct to rust since it's hidden, anyone used this?
Kevin
Kevin Sheahan

Kevin,

Have you had a really good look at the sills (or are you referring to the sill cover panel?) I would consider it more than a little unusual if someone has made a good job of the sills and then welded the wings in place!

Check Barneys site:
http://www.mgaguru.com/mgtech/restore/restore1.htm

I personally do not rate Hammerite at all. POR 15 seems to be the stuff to use, but you really need to shotblast first for best results.

It is well worth making sure the structure of the sills is right or you may have door shut (and open!) problems in future. Also any flexing here on the coupe can cause cracks in the paint (at best) along the join between roof and rear panel and at the bottom of the windscreen pillars.

Neil
Neil McGurk

This thread was discussed between 22/08/2009 and 31/08/2009

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