DeTomaso Mailing List: May 2001, Message #88

Mike,
	I feel that the body brace kit will not prevent the body from flexing,
it may limit the movement but some flex will remain.
	The cause of the cracking is the lead used as a filler. Lead lacks the
necessary tensile strength and over time it work hardens and starts to
crack. It also looses its adhesion to the steel and this too aggravates
cracking. I've seen chunks of lead that you could pop off with a small
screw driver.
	The remedy is to grind ALL the lead from the body when preparing for
paint and use a good high quality body filler. The two part epoxies and
liquid metals I read that some people are using are not suitable. They
lack the ability to flex and will crack over time. Only a top quality
filler should be used because it is formulated to flex, expand and
contract and adhere to the steel.
	In the area of the dog leg at the upper quarter, some have claimed
success by welding in reinforcing but in order to do this it must be
remembered the lead was removed. Lead was used as a filler at the
factory and I have seen it applied to at least a 3/8" thickness around
the deck opening to aid in aligning the deck and I have also seen it
about 1/16" thick to fill a depression a non flexing panel. Both areas
were cracked. Lead was intended to be used as a surfacer after the body
metal is brought to a final contour. The factory used it as a cure all
to remedy ill fitting panels with not much concern to applied thickness.
Over the years it has failed. Modern cars use a synthetic filler at the
seam line between the roof and quarter with no evidence of cracking and
there is body flex in this area.
	Lead was replaced by resins as a body filler in the early 60s with a
great degree of success. The early fillers had their problems but they
were soon corrected. If the directions are followed with minimum
thickness build, today's body fillers are hard to beat.
	With over 30 years working with both metal and fiberglass bodies, this
is my assessment of the problem and I don't think bracing is the answer
without also addressing the lead.
	Fred T.
Mike Dailey wrote:
> 
> There has been some discussion on the list server about flexing of the
> Pantera body and the impact of chassis braces.  I saw one car at Vegas that
> had the back and front chassis support but also had developed cracks in the
> paint in the back hatch opening.  His new paint was fine until he ran one
> time on the track.   He was running a very hot engine and fat tires on 17"
> wheels.  I know that Pantera Performance in CO adds an Y shaped piece of
> metal in this area to carry the load.  I saw quite a few really pristine
> cars this year with paint cracks around the back hatch and front window
> pillars.  Last year I didn't notice any cars with paint cracks and I was
> beginning to think that only East Coast cars cracked.  I was also talking
> with a yellow Pantera owner that had his Pantera completely restored only to
> have the lower front pillar developed a nasty crack.   Paint jobs are
> expensive so there must be some way to keep the cracks under control.
> 
> I've noticed areas on the back fenders on my car vibrating just from the
> movement and sound of the engine at idle.   If the sound of the engine
> rattles my garage windows imagine what the sound waves do to the body of the
> car.  Put your hand on the back fender in front of the wheels when the
> engine is running, you'll be amazed.
> 
> Some thoughts for discussion:
> 
> 1. What experience do the list server members have with body cracking?
> 2. What works best?   Apparently the back body brace is not the complete
> answer.
> 3. What about the complete back, lower and front brace kit?
> 4. Do roll bars help?
> 5. Are certain cars more prone to cracking?  I've seen some original
> un-restored cars with no cracks.  How can this be?
> 6. If you weld the crack on the window pillar what keeps it from cracking
> next to the weld?
> 7. If you were starting completely from scratch what would you do to stop
> cracking?
> 
> Mike
> 
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