430 Bobileff Motorcar Co. restorations today

Today, there are 4 Miura’s in the sheet metal department in various states of chassis rust repair and chassis strengthening and panel gaps. The typical sheet metal used on Miura chassis is about 0.028”, and we exclusively use 0.042” steel on the chassis, which makes a huge difference in the stiffness of the chassis, when completed. Then, additional stiffeners are added inside the chassis members, where they are hidden. That yields even more strength. In the mechanical shop, there are two more Miura’s being assembled for final completion. That’s not to mention all the 350 and 400GT’s ( along with all the “red” cars, also) here.


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Well, after restoring and rust repairing well over 150 Miura chassis over the years, I have learned many things. It is true that 1.0 MM thickness steel was used on the later chassis. But, that 1 MM steel was not used uniformly on the chassis. Only in certain areas, in limited quantities. I use 0.042" steel every where, and that is the primary difference in strength. The other area of achieved strength, is that all my chassis work is continuous welded, as opposed to the Factory's original " stitch weld", which is a small welded area, followed by a non welded area, then a small welded area again, so on and so forth.
Gary Bobileff

 

Thinner areas may be created by sheet metal corrosion, but the original manufacturing process only upgraded areas that were very prone to cracking. It would seem highly unlikely that the original chassis ever had a stress analysis done. Because if it had, many areas of the chassis would not be built the way they were. That said, as time marched on, repetitive cracked chassis areas would appear, and those were the areas of updates, and thicker material used. This construction technique is very common, highly stressed areas get thicker steel, smaller stressed areas still have the thinner steel . The end result is that even SV's have chassis problems and cracks, so all Miura's need to have their chassis reinforced, early , middle and late series. And with the cars flexing for over 50 years when driven, that in it self yields to a weaker chassis, and cracked welds and stress cracks, even if there is no corrosion . Just try taking a un- reinforced chassis on a Miura, and placing a floor jack on any underside corner of the car, and after jacking up, see how the panel fit and door opening and closing functions alter. Lots of flex in it's stock configuration. That doesn't happen after a chassis reinforcement.

 

Here is an example of a late Miura S that is currently going through the restoration of the process here at Bobileff Motorcar Company.
As you can see after the chassis has gone through media blasting, the chassis has multiple cracks that were covered by paint, this is very typical. Note how crude the welds are.
So with the thicker sheet metal in the later car, you can see that there are few benefits.
This is why media blasting is very important to reveal these flaws, most of the time these flaws are covered by paint – very typical.


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The welding seen here, being extremely crude, is a typical representative of welding done on P400's, S and SV models. This is not the least bit unusual. Notice that in many of the cracked areas, they form right next to a weld, meaning that the temperature ( penetration and duration) of the weld was not correct when the chassis were initially made.
Gary Bobileff

 

Here are welding examples done on one of the first ten cars built. Absurd welding, could this have been done at a high school auto shop class?


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Here is an example of another shop’s frame restoration notice all the Bondo chipping off the lower frame section, this chassis is a Miura SV.


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The lower rear chassis was cut out and replaced, as once the Bondo was removed, it was really " beat up" and couldn't stay that way. Pic's on the way.
Gary Bobileff

 

As requested, these photos are of a Miura P400. Chassis reconstruction at Bobileff motorcar company.


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Notice in this picture, the steel file straight edge, and notice how buckled the upper chassis is from stress and torque. Obviously, this should not be bent and was corrected.
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