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Message: <blockquote data-quote="SIIaCanuck" data-source="post: 1357479" data-attributes="member: 21003">OK, I'll grantyou that my reply was pretty sharp but it was deserved.Before you read on, remember one simple fact; I didn't force anyone to answer my question!If you read my original post again, you'll see I asked a specific question.  It is blindingly obvious that I was interested in chassis stiffness with the obvious inference that I'm interested in predictable response to suspension tuning.A couple of guys queried my aim of avoiding through-floor connectors, quite legitimately as what I'd proposed is simply another way of doing the same job.  I explained that I didn't want to get that invasive in the floor.  What I didn't mention is that through-floor connectors reduces re-sale value of the car unless you find a buyer specifically looking for a car to prep for competition.  As this will be a daily driver, I wanted to achieve a similar effect without cutting the floor pan.Building anautocross or road course car requires the floor pan to be stiffened to arrest chassis flex to an acceptable level (minimum of 10x the impedance of the stiffest suspension member, with 20x being an aspiration). Full length sub-frame connectors help, through-floor connectors are the next step up and a roll bar/cage, tied in to the floor pan and rear shock mounts, adding to the mix.What I waswondering was whether the effect of the through-floor connectors could be achieved by welding in a sheer web between the normal full length connectors and the floor pan . . . along it's whole length.I asked if anyone had done it and how it worked! If nobody had, then that's fine. As it turns out,I got the answer I was looking for from Jack at Maximum Motorsports. He's a great guy to get advice from and I'm glad to report real engineering at the core of what MM does.  To illustrate what I mean, I'll give you a quote from one of his emails to me:"Two of our major design intents are that any suspension or chassis component needs to be designed for adequate stiffness and fatigue resistance. When this is done, yield or tensile strength is virtually never an issue."Unfortunately,after weeks of reading threads from various forums, it would seem that 90% of comments on chassis mods or suspension  mods come from people who don’t understand what Jack is saying in this sentence (although CC is generally populated by those who would).  I am and engineer and have spent a lot of time on the track on a motorcycle, and in a car before that, so Ia ppreciate a technically correct response from someone who understands the subject.  I don't have a CC account so asked here.A hot rod frameadds neither stiffness nor fatigue resistance in an efficient manner. For it to add stiffness, you would also need to tie it to the floor pan along its entire length. Then you need to address the sub-optimal suspension configuration of your typical hot-rod setup . . . more weight and money.One step forward, two back . . .In the SN95, the floor pan is the problem. It is insufficiently stiff and, as a side effect, suffers localised fatigue cracking where it buckles the most.  It's that problem MM and Griggs tackles and I'd like to avoid the through-floor sub-frame connectors IF I can achieve my goals without them. My car will not be an all-out road race machine, if it was, then I'd call Griggs and start cutting metal.  I’m looking for a balance between street and track. What I’m not building is a Saturday night cruise machine to shine up and park next to a '33 Coupe.  I want to be able to run quick laps on Saturday and then pack away the tyre warmers and track tyres into my wife’s Explorer, re-set the caster/camber to a street setting, ease off on the sway-bar and damper settings, put my kids in the car and drive home.  On Monday morning, I’ll drive it to work.  Somewhere in there is my limit on the street/race compromise and the limit varies from person to person.  I have a wife and kids so I don’t want to drive an American Iron car on the street, whereas 15 years ago, I’d have thrown in the full Griggs treatment, burnt the carpeting, thrown out the stereo and put in ear plugs.The reason for my terse response is simple; a newbie to performance modifications and/or Mustangs will search these forums for guidance on where to start.  If they're fortunate enough to have an engineering and track driving background like me, they'll be able to sift out the wild conjecture and BS from real engineering.  If not and they're lucky, they'll find the CC forum first.  If not, they could end up like thousands of Mustang owners who spend thousands and end up with a complete dog.Like the poor bugger who was advised to fit spherical jointed UCAs and LCAs on the back end of his SN95.  Off he goes to try road racing and finds out that the back end is binding up and is a vicious, evil handling dog that will soon rip out it's own torque boxes.  A few thousand more of his hard earned clams later, he installs a TA and a few years on, by all accounts, setting a serious pace among American Iron drivers.I had a similar experience with an aircraft.  Fortunately, I discovered the problem before I got it flying but it's cost me considerable time, engineering and cash to put right.  In that case it was the company's own marketing department that was talking total BS, but that's another story for a different forum.</blockquote>