Does anyone have photos of body strengthening techniques used to prevent flex cracking in the common areas? I've read that the seams are re-welded and some vendors actually sell pieces to be welded in. Any pictures? Will
I don't have any photos, but here is some general info on chassis/body reinforcement. Often, the upper and lower rear subframes collapse from age and use at unpredictable angles and amounts, probably partially due to poor quality welding, partially due to corrosion and maybe partly due to owners who drove their Pantera as if it was a real race car. So, if you plan to drive your Pantera in track events or run big sticky street tires, which are typically 3x the size and 4x the adhesion of the original tires that Dallara designed for, you should seam-weld the entire body. There are leaded areas around the windshield posts at the fenders and below the taillights where stress cracks in the paint show up as a result of the work hardened lead filler cracking. There are commercial sheet-metal doublers available to weld-in and stiffen these areas, but any good body shop could whip some out in 10 minutes from scrap. Many believe seam-welding works better than any of the aftermarket stiffening systems, at similar cost. But, because it destroys the paint in numerous places, hardly anyone does it unless the car is already stripped. The removeable crossmember referred to earlier was replaced with a bolt-in version by the factory in 1980.
And finally, get the correct upper camber-bar which goes the bellhousing to prevent subfame collapse. The stock unit is utterly useless, as are most of the pretty aftermarket ones, because they all depend on bolts in big slotted holes thru thin sheet-metal tabs to brace bumps and side-forces of the rear tires during cornering. IMHO, the only bar worth carrying around is the cheap black steel unit first sold by Hall, now by everyone. It has longer ends that jam fully into the welded pockets made for the bar, and transfers loads thru the sides and back of the pockets. The 2 bolts thru the thin tabs simply keep the bar from from popping out due to vibration. If you must use one of the blinged-out aluminum versions, have a good welder add material to each end so it fits as described. It will be heavier than a steel one but will at least properly brace the upper rear subframes.
Anyway, here are some snippets I've collected on this subject from the DT Mail List...
Leading roof pillar to quarter panel You will receive many opinions on this subject and here are mine.
The cracks you have experienced are for the reasons you have stated. They come from the inability of the work hardened lead to flex. There is no need to reinforce the corner sections as many would have you do. The remedy is to completely remove all the lead and use a top quality body filler applied to clean steel roughened with a 60 grit grinding disc for a good tooth for the filler. The long strand filler you mention is a good choice. Apply the filler and shape to a satisfactory contour, prime and paint. You shouldn't have problems with future cracking. Fred T. in respnse to: > My Pantera has the signature crack at the junction of the roof pillar post to quarter panel joint. Only the left side is affected so far. > > I started getting the lead out and don't want to put lead back in. I have leaded before and I don't like it and there must be a modern day solution. > > Can anyone say how they have filled this area and had success without re-cracking. > > Lead has little mechanical strength, virtually no elasticity and is extremely soft. > > Has anyone used long strand glass like the 3M stuff which is stronger and resistant to cracking ? How about metal to metal. I don't think its tensile strength is as strong as long strand.
<< First, I would like to know if someone has photos and/or advice they could send me of where and how the body can be reinforced to prevent cracking. I will be installing a chassis-stiffening kit, but I would still like to have the added assurance of some reinforcement in key places for the day I acquire that dream motor... >>
Guys building a full-bore road racer strip the body, remove the body-lead below the tail-lights & around the windshield posts, and the factory bondo in the fwd edge of the rear clip, and seam-weld every panel and crossmember where it was originally spot-welded. This is all EXCEPT the rear crossmember under the engine which should be made removable, for oil pan removal without pulling the block. Unfortunately, the engine & transaxle must be removed to do this, unless you are patient & don't mind getting incredibly dirty & tired sawing the crossmember out with the oil pan just above it. But if you pull the powertrain, then you can pull the gas tank and attend to any rust damage to the weldments behind it. The e-brake bracket should also be cut free of the subframe and an angle-iron piece added to the stock bracket so that too can be unbolted for oil pan removal. While you're at this, remove the windshield & attend to any rust pits in the lower channel, from water that ran down under the gasket & sat there rusting. The lower edges of the windshield posts often crack from the stresses of big sticky tires and stone-stock engines, so sheet-metal doublers might profitably be added there and wherever panels overlap such as below the tail lights. Good luck- J DeRyke
<< I have to say he grabbed these areas and there was a tremendous amount of flex that extended all the way up the rear quarters! >>
Couldn’t hurt- anything that stiffens up the whole structure does good things for your paint and handling. Just below both tail lights is an area that often cracks paint from flexing. The seam is leaded, but the lead also cracks; many simply continuous-weld the seam rather than rely on the factory spot welds & cosmetic lead. There are other areas of similar concern such as the lower windshield post-to-front-fends: at those points, small hand-sized doublers should be welded in. Good luck- J DeRyke
Chassis Strengthening Subject: [DeTomaso] Primer and Picklex 20 Tue Jan 10 15:18:27 EST 2006
Another thought as long as you are taking it to bare metal. With your strong engine, now would be a good time to do some chassis strengthening. For example you could weld the seams at the 4 corners (they are just spot welded) and add doublers. Same for the area just above the little window next to the black gills (this is where a lot of people find paint cracks.) Add doublers to the tops and bottoms of both A pillars. Weld the seam that's in the engine compartment going up from the front of the inner fenders. On the outside of the body shell, weld the lower seam that runs the length of the car at the bottom of the doors, including the rear fender. (Dennis Q does this just because it make the paint job look better not having the seam cavity to paint.) Also the short seams on the cowl next to the black inlet grills. – Jeff
Chassis Stiffening systems JDeRyke at aol.com Wed Jan 11 02:42:42 EST 2006
John, your question should really go to Bobby or Don Byars re when to install their stiffening kit. And since you're already stripping the car for paint, consider seam-welding the car in the weak areas: The front windsheld posts need a doubler welded on top of the fender & around the posts to reinforce them.
The rear body behind the fuel filler (both sides) has a spot-welded seam-overlap that should be continuous- welded over the spot-welds. Below both tail lights is another overlapped spot-welded seam that should be continuous-welded seam. And all the lower frame cross-members are spot-welded to the longerons. Many spot-welds will likely be popped loose.
All these areas of the body will be covered in body-lead from the factory, or bondo if they've been locally repaired. Reportedly, the continuous welding of the formerly-spot-welded areas alone stiffens up the body/chassis enough so paint cracking is greatly minimized even with big wide tires and "vigorous" driving; with the stiffening kit added on top of this, your Pantera should be set for life! The Byars can also arrange to have your car straightened if you'd like.
Those giant frame-machines are awesome to watch in operation, with two craftsmen- one operating the hydraulics & the other easing the metal with a rosebud torch- while the metal creaks, groans & moves back in place! Done inexpertly, its quite possible to rip a car or big truck completely apart on one of these monsters. Prior to the Pantera, I bought a Porsche 914 that had hit a bridge abutment at 60 mph with the rt front corner (driver heart attack). Unbelievably, 2 hrs of expert pulling restored the chassis to factory specs.
I agree with Garth. Fill that damn spreader bar hole, but easier said than done. I have been looking for months for a show quality spreaderbar like in my Group 4 (in the photo). I hear the guy I got the car from had an aluminum piece built custom for the car. All I need to do is find a hotrodder metal fabricator willing to duplicate one for my GT5S. I am surprised to see those funky small spreaderbars even sell, look nice however.
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