[ROVERNET - UK] Alum/bonnet straightening

[Fletcher]

Kathleen,
The damage you describe  should be repairable by someone who knows what 
they are doing, BUT, if they don't KNOW, they will screw it up to the 
point of not being salvageable at all. I have repaired this damage as 
follows, on Rover bonnets and other things with steel ones.
The rule is that damage must be removed in the opposite sequence to how 
it was produced. Whatever caused the nose ding pushed the edge back, 
giving a large bulge in the top, and resulting in the buckle in the 
little ridge on the top panel. Look at the panel from all directions 
with a single light source moved around at a low vision angle to see 
where the distortions are. If any attempt is made to flatten the buckle 
without pulling the edge forward, the entire panel will distort and no 
amount of fiddling will fix it. If a method to apply a constant pull on 
the bonnet edge can be arranged*, you will see the bulge reduce; then, 
it is entirely possible that ONE well applied  hammer blow with a dolly 
underneath will unlock the buckle in the face panel ridge. It will be a 
very gentle blow with the correct shaped hammer. There is almost 
certainly a corresponding buckle in the bonnet side edge at the little 
rubber bumper hole, and a bit of bending in the X support, both of which 
can also be straightened with the forward pull still in effect. The ding 
itself probably affects an area no more than 4" across. Drilling a few 
1/4 holes in the support structure can allow the gentle application of 
small shaped punches to work out the ding. I have been known to make a 
half dozen punches with different end shapes and bends to work out 
similar dings. Again the repair procedes opposite to the damage - 
outside first, then work toward the center. GENTLE is the operative word 
here!
*To pull, you will likely have to make a shaped wood block to fit under 
the bonnet edge, and possibly a matching shaped piece for the outside so 
you can clamp them together. You do not want to put stress-locking dents 
in the inner support structure, as they may lock the damage into 
permanence, even though you can't see them when all is done. The 
C-clamps used here are a good thing to pull on. Then arrange a comealong 
to the garage rafters so you can pull with the bonnet open (and the 
handbrake on with wheels blocked), and pull on the wood - Gently! - 
while the bonnet is free to align itself with the pull.

Some of the best panel men in the world are in SoCal, the following 
links should help to find one:
http://www.metalshapers.org/
http://www.tinmantech.com/html/kent_white.html
http://www.metalmeet.com/

While Paul's comments about shrinking are true, you do not need any 
shrinking now, and will not if someone doesn't attack the thing in the 
wrong way. Minor amounts of shrinking can be done cold in any event, and 
if heating is resorted to, much danger results. It is very easy to melt 
the aluminum into a useless puddle, and even if successful, the metal 
will be mush soft unless it is overshrunk and then cold worked back to a 
reasonable hard condition.  NEVER hammer on hot aluminum - it is "hot 
short" which means it cracks or crumbles if hit hot. No nails, studs, or 
holes, should be used on any panel unless you are looking for a crappy 
bondo finished job, or know how to weld and cold finish the results, in 
which case you would know how to do it without them. If by "shrinking 
hammer" Paul means any of those with teeth, or swirls and cam 
mechanisms, I would say that the only legitimate use of such is to beat 
senseless the guy who sells them - they do evil damage to the metal.
FRM