SCCA D Mod build questions

[Kent2]

Questions regarding roll bars:

For a less than 1,500 lb car, 1.25x.090 DOM is required.
One continuous loop.

I would like to do two loops, one where the windshield would go and one in the normal spot. Connect them in the center with two straights. How much weight would you figure this would add? What else is needed for track worthy safety?

I will have two seats in the car.

Any other ideas?

[horizenjob]

You can use a site like online metals to find the weight of tube or sheet stock and also things like tolerances for the sizes.

For road racing the SCCA spec for a 1750? lb. car is 1 3/8 x 0.083 DOM tube, just as another data point. The 0.090" isn't a tube size, but that may be a tolerance allowance for 0.095" tubing.

I don't want to be pushy, but I wonder if you missed my post about Car9, it is the last post on the first page of the thread. In that car I combined the roll cage and basic frame. So it's much stronger than a Locost and I think a bit lighter than a Locost with an added roll cage.

[GonzoRacer]

Car9 [snip] In that car I combined the roll cage and basic frame. So it's much stronger than a Locost and I think a bit lighter than a Locost with an added roll cage.

Marcus stole this idea from Team Slotus...

2 15 10 Frame n Cage.jpg

If you lay out/tack the lower frame rails then build the cage upwards from there, you can "omit" the fore and aft and side frame members in the cockpit area. Instead, let the main hoop, front hoop and "door bars" take the place of the frame. It's lighter/simpler than having frame with cage around it. It looks to be stronger than the frame alone. What's not to like???

All IMHO, my .02, Your Mileage Might Vary, Prices Slightly Higher West of the Mississippi, etc...

JDK

[Kent2]

You can use a site like online metals to find the weight of tube or sheet stock and also things like tolerances for the sizes.

For road racing the SCCA spec for a 1750? lb. car is 1 3/8 x 0.083 DOM tube, just as another data point. The 0.090" isn't a tube size, but that may be a tolerance allowance for 0.095" tubing.

I don't want to be pushy, but I wonder if you missed my post about Car9, it is the last post on the first page of the thread. In that car I combined the roll cage and basic frame. So it's much stronger than a Locost and I think a bit lighter than a Locost with an added roll cage.

Thank you

Great info again, just what I needed. I'll be duplicating your design

[Kent2]

Car9 [snip] In that car I combined the roll cage and basic frame. So it's much stronger than a Locost and I think a bit lighter than a Locost with an added roll cage.

Marcus stole this idea from Team Slotus...

2 15 10 Frame n Cage.jpg

If you lay out/tack the lower frame rails then build the cage upwards from there, you can "omit" the fore and aft and side frame members in the cockpit area. Instead, let the main hoop, front hoop and "door bars" take the place of the frame. It's lighter/simpler than having frame with cage around it. It looks to be stronger than the frame alone. What's not to like???

All IMHO, my .02, Your Mileage Might Vary, Prices Slightly Higher West of the Mississippi, etc...

JDK

I'm very thankful for all the info. I have yet to cut any steel, still working on a design and am happy that is all I have to change,

[GonzoRacer]

Marcus stole this idea from Team Slotus...

Wow! I seem to have gotten away with saying that... Marcus must be taking a nap or something.

JDK

[wrightcomputing]

Marcus stole this idea from Team Slotus...

Wow! I seem to have gotten away with saying that... Marcus must be taking a nap or something.

JDK

No I think you are right JD. Marcus definitely stole the idea from you. I think he should be sending you royalties from all the profit he is making. Maybe just renaming the chassis from Car9 to JD9 would be acceptable.
(I'm just joking by the way)

[horizenjob]

Hi Gonzo, thanks for giving me the credit to see the Slotus wisdom. I remember before I started to tag along on the Slotus path I was just like wondering in the woods - just thrashing and hacking and slashing, like a savage really. I had finally got to the point where I had a couple of tree trunks that had forks at both ends. Those where hard to find, no matter how many trees I pulled down they usually only had a fork at one end. I finally managed to get a couple of huge square rocks lashed to the ends of these trunks, but I was having an awful time with the corners on those rocks.

It was a discouraging time in the project. I had been pushing it around the forest for days trying to make the corners on the rocks smaller. I did a lot of this at the meadow by the river because the cute girl in the second floor walkup cave would sometimes throw an apple at me. Clearly it was the corners on the rocks that were going to be the downfall on this project. If I could make the corners smaller, maybe me and the girl could push this next weekend to the place where they light a fire and make giant shadows on the cliff rocks. We could sit in it and watch.

I was mystified by her behavior though. The apples seemed like a simple act of charity, but other times she would come out holding this, that or the other thing in the air and seemed to think I should do something about it. Once she held up something that even looked like me, but much smaller - I was terrified now. But nothing fixed the corners.

I awoke after dark having passed out in the sun in the heat of day. A couple of apples lay about. In the distance I could hear happy music and see lights in the trees. The sound grew louder and i saw they wore wonderful decorations on their heads and carried beautiful green and purple flames on something called "bamboo poles". They were so far ahead of me I decided I must travel with them and learn.

This part of the story would take hours to tell, but it brings us to today where I have my own "bamboo poles" and a tube steel frame much like Gonzo's. I have even talked other people into doing this too. We all have nice frames on tables with legs instead of huge square rocks. The thousand hours of math i did on top of this seems inexplicable. I don't think I'm going to be able to get these table legs to roll any better than the rocks.

Now though I have the distraction of slathering a bunch of pretty purple and green paint on it and will read more of Gonzo's log. I hear a big noise in the distance so this path should lead somewhere

[GonzoRacer]

Oh my Goddd.... Marcus, that was wonderful!
Best laugh I've had since looking at TWWTFM's hair after her nap yesterday!

JDK

[Kent2]

So I went ahead and started. What better way to figure out what I need to do.

[wrightcomputing]

Whoop whoop great job, time to start a build log.

[geek49203]

Well, damn, he's started it!

[GonzoRacer]

Geronimooooo!!!!

[Kent2]

Whoop whoop great job, time to start a build log.

I can do that.

I used some 1/8" for the sides, the rusty stuff I had laying in my shop. I'll be bringing down some roll bars here and wanted a little extra. I'll use it in a few more spots.

[Thinkkker]

Seems like a good spot to post up. Looks like I will be in the fray soon as I picked up a DM Birkin. For aero, I understand the front splitter setup and such, but not sure how to really tie it to the car. It looks like you would need a solid bit to go over the wheels and such.

Can anyone explain this a little more?