Frame Modification Before Powder Coating

[mjazzka]

Before I send my frame off to get sandblasted and powder coated, I am going to try to do two frame mods. My primary concern is structural rigidity being compromised as a result of these. I emailed Factory Five about it, and they understandably told me they couldn't endorse any change to the frame. I figured I would ask though

The first is an undercar exhaust that Mark Dougherty did in Virginia. This can be seen HERE. The primary concern is cutting the hole in the horizontal 4" tubing and welding a perpendicular 4" tub to it. I will do some SolidWorks modeling this week when I have some time to see if I can do my own analysis, but Mark thinks it will work just fine.


The second is moving the cockpit top side bars to the middle of the car, as shown in the crude picture below. I may have borrowed the picture from SeattleDad (thanks!). Since I already took my body off, hopefully I can get a measurement from someone on what the clearance is from the top of both the roll bar and windshield bar to their roof.

Coupestuff239_zps4286b423.jpg

Do ya'll think these are reasonable, or should I modify my plan? Thanks

[CHOTIS BILL]

I believe that moving the cockpit top side bars to the middle of the car will weaken the structure quite a bit and wouldn’t do it if any track time is contemplated. I never had the chance to use FEA on any of the frames I designed but did make 1/5th scale models out of welding rod and from that experience I think you would lose a lot of strength.

Of course I may be wrong and would love to see the SolidWorks results.

Bill Lomenick

[skullandbones]

I remember reading an extensive technical discussion about the 4 inch tube mod (not sure if it was that one). They came to the conclusion that it was sound with the proper materials and good welding technique. On the second mod concerning the cage: that would be a big no. In my opinion, it would not pass inspection as it would create an unsafe crumple zone. That's why the motor cycle industry is trying to develop "air bags" for helmet and neck areas for motor cyclists (no halo). Disclaimer: not an engineer. But seriously, while building roll cages, we always included the halo and as many articulating/intersecting bars as possible within the project constraints like the FFR version. Will you be publishing the SW results? That would be interesting. Good luck.

WEK.

[John Dol]

Michael,

Are you trying to make T-tops?

John

[mjazzka]

I believe that moving the cockpit top side bars to the middle of the car will weaken the structure quite a bit and wouldn’t do it if any track time is contemplated. I never had the chance to use FEA on any of the frames I designed but did make 1/5th scale models out of welding rod and from that experience I think you would lose a lot of strength.

Of course I may be wrong and would love to see the SolidWorks results.

Bill Lomenick

I'm not planning on doing any track time in this car, so I won't have to worry about that specifically. However, if I were to get in a wreck somewhere and the corners of the windshield and roll bars caved in on me, I probably wouldn't be too happy. MY gut feeling is that what you're saying is right on this mod, but I'll look into it some more.

I may or may not do the analysis on the halo area, it is a bit more involved in the parts and analysis than the 4" tubing will be.

[mjazzka]

I remember reading an extensive technical discussion about the 4 inch tube mod (not sure if it was that one). They came to the conclusion that it was sound with the proper materials and good welding technique. On the second mod concerning the cage: that would be a big no. In my opinion, it would not pass inspection as it would create an unsafe crumple zone. That's why the motor cycle industry is trying to develop "air bags" for helmet and neck areas for motor cyclists (no halo). Disclaimer: not an engineer. But seriously, while building roll cages, we always included the halo and as many articulating/intersecting bars as possible within the project constraints like the FFR version. Will you be publishing the SW results? That would be interesting. Good luck.

WEK.

I think you are probably right about the halo area, but I'll look into what some T-Top cars have done and maybe something will come up. I don't plan on tracking the car. Finding another way to distribute some support to the roll bar and windshield may be an option, I've seen that in a few cars.I probably won't do the analysis on the halo bars due to complexity, but we'll see. I'll definitely share the 4" tubing and whatever else I do, though. Thanks!

[mjazzka]

Michael,

Are you trying to make T-tops?

John

John

Actually this is more for headroom, although I haven't ruled out a roof modification yet. After sitting in my Coupe my head is an inch or two from the bar, and I get bad juju just sitting there. In other words, it's in my "bubble". I figured moving it to the center might be a good way to keep some support while giving me more headroom.

[skullandbones]

Michael,

What about the "butt" mod where the seat is lowered by cutting and welding a concave shape into the cockpit floor to make room for a racing seat. I think it gives you about 2 extra inches. That would probably cover your head clearance issues. you must be a big dude. I don't have a coupe but I love them so I follow the threads a lot. I'm sure someone can remember where that is. Of course, you probably know about the Gurney bubble. If you did that you would even be adding an authentic feature that is pretty unique.

Note: EBarnes did the Salvaggio mod on his coupe on the driver's side so you should PM him for info. He said it lowered his Kirkey seat 2 inches. Of course, Karen S on this forum should know of the mod first hand. Either way you should get some good info.

WEK.

[mjazzka]

I'm 6'3", so I'm at the upper end of what I hear fits in these cars. Of course if you talk to Mark Dougherty who says he fits just fine at 6'5", he'll tell you Hakeem Olajuwon would fit in these things I think he gets some kind of cut from FFR for every kit he convinces people to buy (kidding!).

I think I might've read about the seat lowering mod a while back, that could definitely help me out. I'll see if I can drum some stuff up on that. I'm not too worried about contact with the bar really, it's more of thing where the bar is so close it bothers my sense of space inside the car. The bubble I just don't like the look of, but to each their own. The seat lowering might be the answer to my problem though, so thank you!

[Hankl]

Here you go.

http://thefactoryfiveforum.com/entry...lding-a-Legend

Hankl

[RonSchofield]

My cockpit top side bars where down quite far and I was able to hit my head on them sitting in the car and I and 5'10". I removed the 1.5" pipes and are replacing them with two 1" bars higher up and then welding the two pipes together. I am doing this soon so I will post some photos.

As for changes to the frame. I don't know where to start with what I have changed. LOL

First thing I changed was the seat belt mounting tabs. The inboard ones are unsafe.

Here are the new inboard mounts for the seat belts.

[RonSchofield]

Here is what I did to change the seat mounting. I actually have tracks on them.

[mjazzka]

Thanks Hankl and Ron, I'll refer to both of those!

[CraigS]

Realizing we all have opinions and this is just mine, I will state it anyway. There is no way I would ever do that mod done to Karen's car. Way too much metal cut out of the main structure for me. I would be looking at a thinner seat instead.

[RonSchofield]

Craig,

Which mod? I haven't done the computer analysis, but i suspect that my mod actually adds strength to the frame. Here is an earlier photograph which shows the additional brace.



Ron

As for Hanks mods, the removal of the center tubes is mitigated by the outside cages.

[Mark Dougherty]

Sorry guys
I do not get any kickbacks from FFR. Great idea though. It is just fun to share my like of such a great product.

I do fit in the coupes when using a kirkey 16" seat ( after being modified by a large bonk )
The seat must be on the floor no carpet underneath either.

When I have a helmet on it it hits the roof and the roll bar, so I have to slouch down a little.

The original coupes and early ffr coupes used a .095 wall tubing for the main rails
Now FFR uses .120 wall tubing same as the roadsters. I drill through the 4" round tube and add the exhaust tubes. I use a 4 1/2" long .250 wall piece of 3.5 dia. Dom tubing.
If you do the Rick Anderson / Karen Salvagio dropped seat mod. Then you will not be able to add Undercar exhaust.
I understand the want to remove the halo bar around your head, but removing it renders the safety aspect of the cage useless.

[Jacob McCrea]

Here are my thoughts, for what they are worth:

(1) I would not touch the halo bars for the reasons many have noted above. I would instead lower the floor of the car as laid out in the link Hank posted.

(2) If you lower the seat, look into also lowering the bearing that locates the steering shaft (on the 2x2 tube right in front of the steering wheel). At my height (5' 10.5") I think it is too high and I have not lowered the floor.

(3) While you have the welder out, I would weld in some tabs to mount a dead pedal, and maybe cap off some of the open holes in the various tubes to prevent water infiltration and rust.

(4) Go over the entire frame and grind down areas where the weld bead will prevent the aluminum sheet metal from laying flat.

(5) Check the entire frame for areas where, for example, the welder at FFR went almost all the way around the tube, but missed a little bit. I still need to weld one area that I only noticed after powder coating.

Good luck, it sounds like you have a great project ahead of you.