I'm starting this thread, because of my current discovery on how Toyota handles the "mid-chassis" stiffening issue. Toyota recently introduced and fitted ALL of their Prius models with a NEW "improved" chassis stiffenting brace. I studied the design and its implications extensively and applied my years of experience with "metal fatigue" to my study. It's possible that those Prius owners, who have adopted some aftermarket stiffening plates could eventually damage the mounting rails in the exhaust system tunnel. I've uploaded a photo of Toyota's NEW design brace. It is very rigid, when "bending" forces are applied to the ends, but NOT as resistant to "twist" applied to the ends. The car's rails and the bolted on brace or stiffening plate form an "H" shaped assembly with very long "vertical" elements. Bending the short connector line of the "H" applies very little force of the "joint," even if the connector is made much stiffer. Swinging the free ends of the "H" applies a lot of force to the two connections of the lines of the "H." If the cross connector is very resistant to the "torque, torsion or twisting motion," much or nearly all of the stress imparted by the long lever arms of the free ends of the "H" assembly will be applied to the connection at the crossbar. Instead of the "chassis brace" absorbing and attenuating the shock of the torque, the sheet metal of the connecting bolts at at rails will creat a "stress riser" or "pinch point" that will eventually crack or fail as a consequence of metal fatigue. It's like taking a paper clip and bending it "again and again". The "crystals" or bonds of the atoms and molecules of the steel metal alloy will weaken and separate and "crack" or break. This is called "metal fatigue." So, it might not happen for years in the future or maybe not at all. But, I have considered Toyota's designe and incorporated it in all of my designs. For those, who have not understood my findings, I hope this explains it better. Mike500
Thanks for the enlightenment Irv. I know I am enjoying my front brace a lot. It sure cleaned up the sloppiness/mushiness around corners. Thanks!
Yeah, Peter, Since a lot of these "aftermarket" suppliers guarantee their products for only one year from the date of purchase, they really don't need to consider the long term ramifications of their design. Some like Cusco and these current ones on eBay; 2005 2006 2007 2008 TOYOTA PRIUS DOOR UNDER FLOOR SUPPORT BAR JDM JAPAN | eBay 2012 2013 TOYOTA PRIUS ZVW30 ZVW35 DOOR UNDER FLOOR SUPPORT BAR JDM VIP JAPAN | eBay ,whether if by design or shere luck, Got it right! If the cross brace is too rigid to "twist," stress is concetrated in the mounting bolts and the area in the sheet metal of the car body, where the brace is mounted.
118,000 miles and 7 years of pushing the curves as hard as I can get away with on my gen 2 with a stiffening plate and TRD sway bar with zero ill effects.
Metal fatigue can take years to show up. My 77 Chevrolet's frame craced after 10 years and 275,000 miles. Then, again, the Douglas DC-3 was so well designed in the 1930's are still flying, today. Some are WWII surplus C47's. That's amazing for aluminum alloys, since steel generally last longer under repeated stresses. I'd doubt if Toyota would have made such a complicated composite piece steel brace with 7 welds, if it was as easy as using a thicker flat plate.
How about this one? Rakuten: Beatrush floor performance plate Toyota Prius [ZVW30], prius α [ZVW40,ZVW41]] fs2gm LAILE curtain rod *- Shopping Japanese products from Japan
Interesting find. Still. it is a complicated design with multiple bending and torsional flex modes due to the "decorative" lightening cuts that are there to impress the buyer and the user. My designs, due to their simplicity. have smooth load vs. strain curves due to their design. Like a archer's bow tensioned with a drawstring, it does not have multiple stress nodes. It means that my designs bend smoothly and rebounds smoothly. It might sound complicated, but it means that there is no uneven "jerkiness" in the flexing and un-flexing of the brace member. This is the simplest and most efficient design. For Sale - "Bulletproof" Gen III or Prius"v" mid-chassis under brace $65-77 delivered (US) | PriusChat This design achieves extra bending stiffness with less torsional or twisting stress on the chassis rail mounting points. For Sale - Latest version of Lightweight Gen III or "v" box beam chassis under brace | PriusChat The additional of a "front" under chassis bar, like Spiderman noted, achieves additional control. For Sale - Prius GenIII or"v" bulletproof front under chassis and lightweight box beam mid chassis sets | PriusChat Mike500
