{Chrysler 300} Hood Springs CDE

Hi,

Maybe more than you want to know about springs, but background matters.

As most of you know, we made a run of heavier wire hood springs trying to solve the CDE falling hood issues ; while not bemoaning it, it turned into a tough effort, more than expected, as it turns out the mopar spring design was right on the edge due to the space they allowed for it, trading the small folded length vs the max extension they had designed in. It should have been an inch longer folded and a wider space for it. . The spring engineer we retained for this commented on that, ---What it means : when fully extended the spring wire (stock spring ) is just gettin toward or into the yield point of the steel. Depending on steel materials and other variations if pulled beyond yield it will "take a set", and the initial pull goes down. Variations in all this (and hood weight) are why some stock are ok and some not. The first time it was pulled down may yield an inferior spring in seconds ,---- it is then , by degrees, toast.

Same effect with overextending getting it in, but that turns out to be not the issue.

On our cars , we now think the spring was designed for a 57 new yorker hood-- and ours is sufficiently heavier plus years of bondo , paint etc that it is often quite marginal, especially if a weaker or yielded spring from day one is involved . And a yielded (overstretched) spring won't hold it up .

So we tried to get more spring in the same space with this engineer, but the only way to do that is thicker wire and / or a wider / or longer spring coil . Wider is limited by hitting, relaxed length is fixed, leaving only the thicker wire. However thicker wire also means fewer turns end to end when folded, so the difference between folded and extended is even more limited, you hit yield again, possibly even sooner . We were told better material fixed that ,(?) but several times we saw some issues are still there. So the spring was reduced one turn, fixed most of this but the yield monster shows up again.

We were just not satisfied with all this, nothing is ever as easy as it first looks, and revisited it. Thanks to Tony Bevacqua !!

We still have the heavier spring, often much better than a "dead" stock one, but we also took a new engineering approach which is an inner spring that fits inside our larger one . This inner spring adds quite a bit ---but being made of smaller wire it has many more turns when relaxed and should not yield --ever . Initial Tests look good.

For those who bought a heavier spring , we are shortly mailing a kit of the inside springs at no charge, and will be changing the on line listing (Forward Look Parts ) to offer the heavier spring and the lighter adder spring, one or both . We plan to look at whether the new inner spring can also be added to the stock spring; the first try it was very difficult to get in.

Just an update, more help on the way.

All our best,

John G