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MG Midget and Sprite Technical - Panel beating advice needed

In renovating the Frogeye I have the original front end and rear shroud (deck part). I've filled (and continue to fill) various dints and keep finding more but there are some upward pointing bumps and creases I need to remove. I'm no panel beater but have read a lot about using shrinking hammers and dollies (I have neither). So, what is the best technique for an amateur? I realise that simply hitting a bump directly will further stretch the metal so I don't want to make matters worse. Is it best left to a pro? Trouble is they're hard to find - one I knew of has long since retired and is uncontactable. Any advice is most welcome.
Bill Bretherton

I tried the heat and shrink with a wet towel method on the lower front wing behind the wheel arch on mine. It worked to some extent, but had a tendancy to move the blimp along the panel causing more distortion. The more attempts I made, the worse it got. In the end I had to slit the panel and reweld and then use filler to get it right. Not a method I would repeat.

Small localised high spots do knock down pretty well with a hammer. The froggy metal is thick enough to accept the hammer blow and not then bounce back, as a modern car bodywork would. Once the high spot is slightly depressed (maybe just a trifle sad) it will then skim over very easily.

I found it easier getting shapes right if I knocked raised areas back without using a dolly behind. Then once they were low either to just fill, or to push them back out again by beating on the back whilst this time using a panel dolly on the front.

I know you are not asking about filling and painting yet, but I spent much longer on mine with panel beating and filling than in retrospect was necessary. General shape is important and those who are properly proficient in panel work will delight in showing how well it can be done! See some of the U-Tube stuff which is amazing! In practice one doesn't need to be anything like as meticulous as later stages with filler, still thinly but properly applied, work wonders!

Having spent a lot of time with thin skims of filler on mine I have since learnt better practice from the professional who is advising and showing me how its done. He said my filling was good, and then showed me how to get it 10 X better! My method had been too cautious, dealing with irregularities too piecemeal, using the wrong filler and the wrong abrasives at each stage.

First tip was not to use the "easy sand" U-pol type of filler as sold by Halfords. It is too gritty and drags when you spread and shape it. Get a fine grade filler. Spread directly onto steel that has been cleaned wih 120 grit or coarser to key the metal, or any earlier filler. Spread it over an area about 3 times the size of the area that needs filling and then with a single movement strike off the surplus with a long straight edge like a 12" steel rule. If its a convex surface hold the rule at an angle and curve it with your fingers to the right shape. When hardened use a long bed sander with 40 - 80 grit to cut off the surplus back to the shape. Drag the sander across sideways, not back and forth, whilst pressing firmly and using just a few strokes. Keep changing the angle. When the shape is feeling right put a first coat of high build primer and guide coat and then block sand with 180 grit. 2nd primer, guide coat and the sand with 400 grit, either on a hand block or DA.

No doubt others with lots of experience will have other wise variations on technique but the results are looking good on mine so far.


Ideally when trying to shrink metal with a hammer you use a soft faced hammer not steel.
David Billington

Whatever you do dont hit it in the middle of the bump. Start right on the extremity of it and work in circles to the middle. If it's small use a small ball pain polished hammer as a dolly.

T Mason

Guy, thanks that's really useful. I've read about using a steel rule so will try that. What make of filler should I get then? (Currently P38 as you might have guessed). I find compound curves difficult and apply maybe 4 or 5 coats until the curves feel right. I know the purists will argue that the metal should be beaten to shape but there's no way I can do that.

Davd, yes I've read of using a soft hammer but the Frogeye metal does seem quite tough to work.

Trev, I've read that too but there's a lot of technique involved I think. You can tap gently and nothing seems to happen! I can only admire expert panel beaters - they're magicians.
Bill Bretherton


There is another article about panel beating dents in the latest Practical Classics, not read it as yet.
richard b

Thanks Richard, I don't often buy it but will have a look in this case.
Bill Bretherton

My "advisor" keeps saying how nice it is to work with proper ms steel panels that respond nicely to the hammers. He spends all day doing work on moderns with their very thin panels made of specialised steeel alloys that he says are very difficult to work with compared to the Frog.

I have had success by heating with an ordinary blowlamp. I can get the dent to a dull red, at which point it has expanded and become deeper. It helps to knock it out from the other side so it's a bump not a dent, and then while keeping it hot flatten it with the hammer and dolly, starting round the edge and working inwards. When it cools it shrinks and tightens. A previous owner of my Frogeye inexpertly gas welded the sills on and buckled the footwell side panels. One side I managed to flatten with this method (the other I had to replace). Years ago I even managed to flatten a huge dent in the roof of the family Escort, caused by a roofing tile from next door. It wasn't perfect but the car was an insurance write-off anyway so it got a new lease of life.

L B Rose

A leather sandbag is a handy thing to have as well as a dolly.
John Payne

Les, I tried heat on a door which has bowed a bit (from welding) but with limited success. Perseverance I guess.

John, I don't have proper dollies, just use another hammer, maybe lump hammer. Decent panel beating tools seem expensive. I presume the cheap ebay kits are rubbish. There is also a "slapper" - I love the terminology!
Bill Bretherton


Slappers are good for moving metal around, but you need a shrinking hammer and dolly to take out surface area. As has been suggested you need to work from the outside in, and have minimal contact with the metal, unless you anneal things on the way.
Donít skimp on bodywork tools, you can always sell them when youíre done.
All that said, it is an art, and it takes time. Best of luck!!
Kurt Barker

Ah yes Bill, I also bowed my door skins when learning to MIG weld! I did get them flat again with heat and hammering - well flat enough for the filler.

L B Rose

Kurt, I've thought of getting a shrinking hammer but I've seen it suggested it's better to use a wooden hammer to shrink i.e. soft as David suggests above. There does seem to be conflicting information on the internet!
Bill Bretherton

My Frog took a great hop forwards yesterday !


very nice Guy
William Revit

Just showing off Willie, although with the amount of panel beating those rear wings and rear deck have recieved it does qualify for this thread!

Must feel good Guy! I'm gradually getting rid of the dents and bumps in mine. The P38 has nearly run out so I'll get something smoother next.

Bill Bretherton

This thread was discussed between 16/06/2019 and 21/06/2019

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