chassis stiffness

[352Ford2]

Any one using this kit, or something like it?

http://www.mustangsplus.com/Merchan...04202&Category_Code=chassis_strengthening_kit

I am building up a heathy street/strip 65 fastback, I was just planning on subframe conectors and a 4 or 6 pt cage for chassis work. My thinking was if I have through the floor subframes and a cage this is just added weight. Love to hear feed back on this sort of thing.

 

[70vert]

well, you are tying the subframes into the unibody structure, and your cage already by sending them through the floor. What this would do is to make that floor and rocker panel connection and torque box area much stiffer.

I feel like boxing in subframes to reinforced rockers would be a smarter use of metal. This kit does give you a rocker reinforcement panel making it stronger like, say, a convertible rocker. If you could just use that rocker reinforcement and use sheet metal or jacking rails to "box in" your newly reinforced rockers and your subframes, that'd be the ticket I think.

 

[352Ford2]

cool thanks

any other opinians?

 

[SuperSnake428]

wow....

So for a little story... I bought a 67 fastback in December. I didn't realize it at the time of purchase, but my car had a very similar chassis stiffener installed.

I removed them to install a new floor pan (the PO had cut the tunnel out of the old one). www.zero-soft.com/gallery to see pictures.

This stuff was HORRIBLE to remove. It looked horrible installed and was a real pain to cut out. Not to mention, it was HEAVY. I installed a new floorpan and put on the TCP subframe brace. The car is MUCH more rigid now and doesn't look horrible.

So, my 0.02... Save someone the trouble of removing this later and put on the TCP subframe connectors now...

Just looking at that kit makes me shudder and wince.

Drew

 

[fasttback]

352Ford2,

I just want to jump off subject for a question: I you running a factory Ford 352 or 302 stroked 3.4" and bored 0.060 over? Or your username is something from the past?

 

[352Ford2]

the more I think about it I really want to tie the subframe conectors into something other than the front and rear frame, floorboard, and the cage. I just have this picture in my head of a really stiff cage and frame, but all the unibody sheet metal aroud it floppy. But I really don't want to add extra un-needed weight.

what are all the hardcore drag and road race guys doing?

I have a 352 FE in my truck and I have been using this user name for prob 6 years. but as far as projects go I have 65 FB, 67 cougar, 88 lx 5.0, 94 cobra, 75 F-250, 72 Harley Davidson FXE

 

[Sicarius428]

I think you would be best off with an 8 point cage and subframe connectors. It will create a better "box" for rigidity. Think of a piece of cardboard... with the floorboard kit you are basically adding another layer of cardboard on top of it. Yes it will definately be a help but now compare it to a cardboard box.
Kevin

 

[352Ford2]

I am already putting in a cage and through the floor subframes, so I just wanted to see if their was a need to add anything else

 

[70vert]

I say, tie it to the unibody structure, SOMEHOW.

to answer your Q, 352Ford2, the drag guys are pretty much all doing through-the-floor subframe connectors. I wouldn't do it myself because I don't want an ugly lump in my rear seat floor, but I got much the same effect by using my convertible subfloor as my through-the-floor bit. Result? Very little loss in ground clearance (already lost some through the convertible subfloor, so no more harm done there) and subframes that are integral to the unibody structure now. Can't hurt, right?

http://web.mac.com/jbauder/iWeb/6970clutchpedals/tinmansubframes.html

result for me: LOTS more chassis stiffness, and when you jack up one corner, the same side's other wheel comes up. Also, if I hit a speed bump at an angle, the car rocks back and forth like a seesaw. Pretty stiff for a convertible.

My decision was pretty easy, having a convertible - I just used the convertible subfloor, but yours is harder - do you really want to hack up the main floor? But I do think there is a huge advantage to making the roll cage/subframe connectors/whatever "endoskeleton" you are giving the car integral to the unibody if it is not too much work.

Torque boxes are just sheet metal boxes, after all, but they more or less work - a sheet metal box or sheet metal between two i-beams, for example, would be pretty stiff.

As far as the chassis stiffening kit, do your own experiment with plywood and 2x4s. make a square of plywood - how stiff is it in twisting? Now nail 2x4s around the perimeter and make another square of plywood and nail that in on the other side. (or glue, as is more appropriate to what a weld would be like) You have a pretty damn stiff box. That is what the TCP kit tries to do, or at least what sheet metal would do when welded to the rockers on one side and a subframe on the other. Remember to put a metal member at the front and back of the "box" too.

 

[DukeGnarley]

70vert,

Are those SFCs fabricated from scratch, or are they meant for a coupe?

 

[70vert]

Duke,

they're from tinmanfabrications.com. Meant for a coupe, "modifications to the floorpan to fit a convertible" - the original floorpan is untouched, but the convertible floorpan reinforcement is what I went through.

 

[Jester67]

As far as sub-frames go, there is only one manufacturer IMHO http://www.maierracing.com/

 

[352Ford2]

thanks guys

 

[70vert]

I second what Jester67 is saying - if I didn't have a convertible, I'd buy Maier. (they don't make one for convertibles) They use 3 attachment points, IIRC - one front, two rear, IIRC, thus avoiding the subframe being just a "pivot point" for the flex in the frame. At least on the rear if nothing else.

 

[truck90278]

We used the mustang plus, put them on and then took them off and trashed them. Went to Maier racing and got theirs - a little more expensive, but uses a "truss" method - Welds in at four points instead of just 2 - works great!

 

[66Runt]

There is a great thread on this subject at corner-carvers

Which is where I think 70Vert is getting his information. One of the engineers on that site mocked up a model to see what would really work to prevent unibody twist.
A very good read. Before you spend a dime, I'd suggest reading through that thread, and a few more on the same subject.
If you are building alot of power into your car you need more than just strength in beam. you need torsional stiffness as well.

Good luck,

 

[Jester67]

Which is where I think 70Vert is getting his information. One of the engineers on that site mocked up a model to see what would really work to prevent unibody twist.
A very good read. Before you spend a dime, I'd suggest reading through that thread, and a few more on the same subject.
If you are building alot of power into your car you need more than just strength in beam. you need torsional stiffness as well.

Good luck,

I agree that is a very good article it is what inspired me to add a passenger side front torque ,box 67’s only have a driver’s side one, and to add the Maier racing sub-frames. I already had the heavy export brace and straight Monte Carlo bar.

 

[68converted]

I went around and around with this issue and what 70vert did is what I have finally decided to do. I will use the Tin Man Fab. units and hope to figure a way to tie in the rocker rails in a more "solid" manner than original, maybe adding some sort of jacking rails?

 

[70vert]

cool. My body guy who welded them in is obsessed with rust and didn't weld them to the extra convertible floor pan at all points where it bisected them, just spot welded them to allow a place for water to escape between the two. Might be your style, might not.

I'd be curious to find out the effect if you do the jacking rails or something else connecting the two. When you're done, we could maybe both jack up our cars the same amount at the same jacking point and then measure the amount of lift we get at the other jacking point on the same side. Sound scientific enough? I am sure there are other factors involved, but 68 and 70 have more or less the same chassis - same width, same floor pan, at least. The suspension would skew the results unless we had the same spring rate and same anti-sway bars. Oh well, could be interesting anyway.

Yeah, 66runt is right, corner-carvers is exactly the kool-aid I've been drinking. One thing to consider is those guys are almost exclusively race-only, they don't care very much about comfort for the street.

 

[68converted]

I have a ways to go with the EFI swap, I had to take time away from the project after my dad died. Too emotional everytime I even thought about it. I spent the entire day cleaning off the dust, and finishing the surgery to repair the previous owners stupidity with wiring/hacking in under the dash. I counted it all up and I have 14 wire connections to finish, Fuel pump install w/ lines, various plumbing connections, and I can start the darn thing up.

As soon as I have it running I will do the connectors. Winter is coming quickly. I just want to drive it for a few days before it gets cold and snowy. I would be glad to do the comparison with you. It would be a cool test of various stiffness add on's. Not too scientific but who cares.