Mach1 Driver

Ronald Reagan is on a rotisserie constantly flipping over in his grave, seeing what his state has become. Many believe the Dems have been taken of by politicians that are literally insane. Maybe all that sunshine cooks their brains? I still call it home, but I'm very glad I left.

I like your little fixture on the band saw

Yeah, I know- lots of people do, but its not my opinion, its the result of the test ¯\_(ツ)_/¯

My fastback is all stock, a southern California car with 77k on the odometer and no rust. I tried picking it up from the drivers front torque box. The front passenger tire stayed on the ground but the suspension unwound, same with the rear drivers tire. So three down one up. Just out of curiosity I'll have to see what goes on with the coupes construction (behind the rear seat?) that stiffens it up. I wonder if I could get three in the air if I put in an export brace and a solid plate behind the rear seat. From the torsion test the export brace gives a 25% improvement, and a rear seat divider is 11%. A Monte Carlo bar does 0%- it just keeps the towers separated. Welded-in SFCs without cross bracing give 0%.

Here is a picture of Total Control Products SFCs that fvike mentions above. They are obviously a whole lot less work than inner rockers. If I may intercede here for a moment, what aslanefe is trying to verify is what happens if the cross bracing is removed. What we were shown by the torsion test is that with only the rails installed and no cross bracing, three wheels should stay on the ground and only one wheel will lift (the chassis will twist). That would confirm aslanefe's contention that it is the cross bracing connecting the two sides that will best prevent torquing (twisting) of the chassis. If I've misspoken here please correct me. This would be a very important test, and a big PITA for fvike, but a teaching moment for all of us.

since the 69s come with torque boxes all around, I assume this is for those years that don't have torque boxes?

reminds me of the cross bracing in the bow of an icebreaker ;)

thank you so much, and it explains so much

I was thinking today that I should ask here for help in a "design of experiment" to test the difference made by adding various structural components as I restore my car. OK engineers here is your chance for input. The first step is to review the only other chassis twisting test: https://www.stangnet.com/mustang-forums/threads/torsional-rigidity-test-67-coupe.723029/. This is a long thread running over 5 years with a summary in post #79. Maybe someone can come up with a "sag" test too.

Whose SFCs do you like?

Wow, inner rockers, SFCs, seat pan, and a roll bar!! That's about as good as it gets Bob. My brother-in-law had a 64 T-bird that got a flat. He jacked up one rear corner with a bumper jack and both sides came off the ground. Then it would teeter on the jack and fall over off the jack. He had a heck of a time changing the tire. I hope yours isn't that rigid ;)

Yeah you're right about the one piece seat riser, but the dang things screw-up the shift console. I have a very good sheet metal shop that would do the inner rockers parts so I just have to drill for plug welds and then weld them in place (along with everything else). Every 2-3 years we go down to Florida with our Vette club and may pass by, if so I will PM you as well.

Yes I'm an electrical engineer and get the difference. I don't have any particular complaints about the chassis as my car is in good shape- at least for a 50 year old sheet metal box. It lived with me for 46 years in southern California where it seldom rains and it only has 77k on the odometer, so its well preserved. As you say, inner rockers give the most bang for the buck. BTW, Bob (RPM) has a fastback, inner rockers and a roll cage so he has the best possible combination. I would just like to stiffen mine up a bit as I intend to almost double the hp (that's pretty easy on a 351w 2v). I'm like Bob and would rather work on the the car than drive it- although driving it is fun. I have only seen one test done on a classic Mustang and it was for "twist" on a car with SFCs. As you indicated it did absolutely nothing (zero) for twist. We have an occasional poster here whose car is a self proclaimed rust bucket with 500 hp. He said SFCs turned it from a wet noodle into something more manageable, and said it was the best modification he ever did. Even if SFCs haven't been tested there are lots of people who claim that their car "feels" stiffer and better. I'm guessing that not all of this is placebo. I may do both, although I am also thinking about cutouts with side exits and SFCs would get in the way. We'll see. Hey I see you're in middle GA, and I'm north of Atlanta- we should get together some time.

My Dad worked in maintenance for Chrysler for 42 years at the LA assembly plant. When my twin brother and I graduated from High school, Dad got him a job at the plant. He would drive the cars from the end of the assembly line to the parking lot. One day he was in a 440 with a 6 pack driving along the outside road of the lot beside a chain link fence. He jumped on it and the car torqued over so much he side swiped the fence. His supervisor grinned and said "they've got a lot of torque don't they?". He knew Dad and wrote it up as a stuck throttle. I think he experienced a little of that twist you mentioned.

I was talking about the part you marked as "inner". Perhaps its inaccurate to say its not structural, but I elected to say that instead of explaining why I didn't attach the bottom of the inner rocker to that surface: that surface is not rigid enough to prevent flexing and therefore movement of the bottom of the inner rocker. Instead I elected to add a 14ga bracket at the bottom that ties directly to the pinch weld. I didn't feel the need to explain all of that on the drawing. Does that adequately explain my reasoning? The "outer" is pretty resistant to flexing and twisting, that's why I wanted to grab that bottom flange.

Well... the floor isn't 14ga and it doesn't attach to either pinch weld so I didn't want that to be the bottom attachment point. Do you think its more work? I don't have to cut the floor loose and remove the flange. I would drill the same number of holes- in fact since latoracing mentioned the lower cover plug welds are a weak spot, I like the idea of a continuous fillet across the bottom, which requires 1/3 less holes. Running a bead across there would take less time than drilling a row of holes. You can't beat the Dynacorn rockers for one piece convenience. I just think that cutting the floor and removing the flange is an unnecessary step that weakens the floor structurally. With the Dynacorn parts the floor is attached with only plug welds and no return flange to give it extra strength. Just my opinion, but I always come down on the side of too much instead of not enough.

Good point, I could wrap the cover on the inside of the bottom piece, then run a continuous fillet. I intended to use 14ga steel which is .0747, and yes it will be formed on a power brake. There is nothing wrong with my existing rockers, I just wanted to firm the old girl up a bit ;)

Is this on your website under technical info, or someplace else? BTW, its pretty difficult to figure out what they are about from the truncated title without opening all 26 and actually viewing them- not very user friendly.

There is the outside rocker, and then the thin vertical cover on the outside of that. This thin cover doesn't do anything to hang the rocker on the car- it just covers it while the rocker and pinch welds do all the work. Are we talking about the same part?

ever seen one of those NERVOUS signs that seem to move as you're looking at them? ;)

In step 5 you would weld the small bottom flange to the bottom pinch weld only. In step 6 you would weld the bottom of the inner rocker "from the top" to the bottom flange through the holes drilled in the floor in step 3. You can't see this too well on your little phone can ya? You need a 'puter with a big monitor.

Yes, these are like picture C in my first post. The flange at the bottom is what necessitates cutting the floor with this construction on a fastback. Of course they were made for a convertible which has a narrower floor. Ridge- what if any problems do you see with picture 7?

Because they have added vert inner rockers, I would particularly like Ridge Route, latoracing and RPM to comment on the following proposal, and of course anyone else. I can see a couple of problems but won't mention them until later. Hopefully I can get all six pictures in this post- I think there is an upper limit on attachments but don't remember what it is.

Yes I agree