I agree on the concept, but you only need to basically make a box with two diagonal braces to make it sturdy. As far as bolting this together: I'd say no. It wont accomplish anything because the tolarance in the bolt-hole will make the whole system loose it's rigidity. It needs to be welded together and then welded onto the car in one piece. The only downside to making these and distributing them will be shipping. A 6'x5'x6" box isn't something UPS wants to move!

 

NNNNOOOOOOOOOOO!!!!!

right.

106. 7/GS JOHN WHELAN (0.782) 41.207
107. 20/STX JOHN CASERTA (0.802) 41.244
108. 444/STU JOSH HICKEY (0.818) 41.287
109. 88/AS JIM WEST, PHILA (0.828) 41.299
110. 130/STS2 JASON REYNOLDS (0.803) 41.429
120. 85/STS NORM PETERSON, PHILA (0.799) 42.353

 

I fart in the general direction of indexed time....you know I was running STU with pretty much a STS setup (except for the 8" back wheels that put me in STX).

I got by the index just because I was too lazy to get there in the morning and run STX and honest enough to tell them I had 8" wheels on the back (24-pounders that just slowed me down). Else I couldv'e just run STS and nobody ever would have been the wiser.

 

You started it, you would have been at 40.4 or so, I still don't consider that beating up on me. Now if your sub-50 time that you screwed up would have counted..well that starts to get into the beating up range. However, Mr. Rule follower, you are a proponent of the rules and therefore since you did have 8"tires on and hit the cones, you lost on index. If you didn't hit the cones, you would have won on raw and index.
I like to drive, sooner or later I will start spending money on modding, maybe spring, but I still would rather spend my money on driving than modding. So whatever new house we get in March leaves me with money left over enough to do both, great...otherwise expect to see me out there lifting that inside wheel at speed like a sentra or vw.

 

you know I'm just messing with you, right?....you put up way better times than I would have in my once-stock 5th gen, that's for sure......

Trust me, thankfully the car is almost how I want it....that, and I'm also buying a new house this summer (hopefully) so I won't have much "mod money" either until winter (when I work at the ski shop for my "play money").....

 

Yes, but I find it hard to adequately tone sarcasm in email. (referring to my last response)

Thanks, that's actually a compliment if you aren't still messing with me.

How bad are taxes and houses down there? You can get away with a decent townhouse for ~130-190k w/garage and around 2500ft of land. To get into a real house you're looking at ~200-250k, yearly taxes in each case vary from 2300-3300. EXCEPT if you live in the confines of philly, where they hit you with a residency tax and work tax which adds up to like 5%-7%, which is RETARDED for living in philly.

 

it's not the taxes that kill here, it's property value and home prices.

ex:
I paid 200K for my townhouse (built in 70s, no garage but decent size) about 5 years ago.

I expect to sell it for around $375K this summer if current prices hold true.

The next house we buy will be the "long-term" house...so it will be single-family, decent sized yard, and 2-car garage (or space to build one).....for that, I expect that we will have to pay $550K-600K....Fairfax County IIRC has the highest per-capita housing costs in the nation, or close to it.

not looking forward to being broke again!

 

I messed some of that info I posted up previously. The taxes around where I live are wacky, philly is RETARDED, but if you live in my town with a 200k house it's probably around ~$3500/year, and if you go north it's the same. But the town south of me, Wallingford, has no town to it and no way to generate revenue so your taxes could be like $8-12k. NJ is worse, you can pay $5k/year for a $100k house.
Don't misunderstand me though, you can easily pay 5-6-700k for a nice house in my present town, but this town is nice with nice schools etc..etc.
My hometown of Hingham, MA is the most ridiculous home prices I've ever seen. Near the library there used to be an area called millioinaire's row of large houses, now the houses on my old street that people payed 50-60k for in the late 70's are all over a million. No one I know that still lives there, could afford to move there now, and at those prices there's no kids either. When I was young there were 20 families with 2 kids or more on my street, now there is none, and my elementary, junior high school are both closed.
Just thank god you don't live in Cali, those prices are the most ridiculous of them all.

 

"Sturdy" is a relative term. Why have "sturdy" when you can have "sturdier"?

Welding everything together is not an option, even notwithstanding the shipping issue. The SFCs will have to be as tight to the underside as possible so that they don't kill ground clearance, and if it's all welded then it won't be removable in the event that any work needs to be done in the undercarriage (e.g. on the exhaust).

Besides, bolting stages 2 and 3 to stage 1 wouldn't necessarily be as bad as you think. If you orient the bolt holes horizontally, as I suggested, and make the mating surfaces flat and as big as possible, it'll be fine. You could also have holes that run across the mating surfaces and use more bolts with wide washers to prevent sliding movement.

Heck, doing it that way would even permit the use of shims to accommodate for a chassis that's slightly tweaked in some way.

 

Didn't notice that. You're right, horizontal would be the way to go. I'll have to think about how to design it from there (I already have ideas running wild in my head....). I think I can design it so that is is actually removable, shippable and sturdy. I still think there'll have to be some welding (gotta weld tabs to the car to give mounting points for the bolts), but I think we can keep this to four tabs. Thanks for the idea!



BTW: I know I'm in sales as an occupation, but I went to school for Mechanical Engineering. Just to clarify if I do design this thing with Redlinemax. (Corey: if you're reading this: I'll charge you the materials for the prototype to do this. This is fun stuff for me!)

 

wait a sec, you mean none of you guys is a professional in this field?? Isn't it easier for find a professional rollcage shop that will design the SFC "professionally?"

BTW: What's wrong with Pipers, did they refuse to do that or something?

 

Oh absolutely. I was assuming a design with the longitudinal members welded to the frame rails and the x-bracing bolted to that.

Why keep it to four tabs? If you had more (assuming all were on the longitudinal members), you could line up the additional ones with the mounting points for the horizontal members.

How about this (black bits are welding tabs, red marks are bolt points):



If the mating surfaces are big enough, this should be pretty solid.

 

Grab yourself two stir sticks and position them parallel to each other.

Think of all the different ways in which they could possibly bend and move when stress is applied only at the ends of the stir sticks.

Now, think of how to prevent that movement and bending by attaching the fewest possible number of additional stir sticks to the first two.

Presto. There's your basic design. The rest comes down to:

1. Materials -- which will be easy because of cost constraints (has to be widely available and easy to work with)
2. The details of fabricating the mounting points, which is also pretty simple stuff.

We may not be pros, but this isn't really all that complicated. As long as we're not mouth-breathing idiots, we should be fine.

 

True, I have no doubt that we will come up with something that will work. The question is, will it work as good as a professionally designed SFC... People have been designing car chassis for over 100 years. Every year they come up with something better than before. Professionals know everything that people tried during this time and will not make mistakes that previous generations made.

Also, how do you know what kind of materials will work best?

Another argument (not considered important by some people) - how will the car with SFC behave in the event on a high speed side impact. Will it bend around the tree in a safe way?
Will it direct most of the impact forces away from the occupants?
Will the chassis rip apart due to something not getting sufficient reinforcement?
And probably many more similar questions.

If it's ganna be mass produced I think it'll be much better if pros were the ones to design it.

 

1. How "professional" do you want the design to be? We're not designing a chassis from the ground up, or even trying to modify the stock chassis. We're coming up with ways to stick big metal bits onto it to help keep it from flexing. Companies who do that for a living still come up with extremely basic stuff.

2. Such people will see the design before it's produced anyway, so we'll have their opinion.

3. I think you overestimate professionals in general. Theoretically they have the expertise and the resources, but that doesn't mean they're smart, capable, or motivated enough to use them. It also doesn't mean they'll consider it worth their time and money to do so when they can just sell a simple product for similar profit. Look at Warpspeed, who produced a design that so many of the "amateurs" in this thread are already seeing as crap and trying to improve upon.

But if by "professionally designed" you mean "designed and tested by high-level chassis engineers", then such a product very well might be better than what we can come up with ourselves. It will also be one HELL of a lot more expensive.

Besides, keep in mind that this project, like all others of its kind, is by, for, and about people who are totally willing to take their cars' behaviors into their own hands. The manufacturer does not and will not support this modification, and if it is found to cause a problem in a collision then we won't be able to count on the government or legal system for sympathy either (except in an extreme case).

Of all the most widely available types of steel, we need the most rigid one that is easy to work with, rust-resistant, and compatible with the kind of welding we would need to do to attach it to the frame considering what kind of metal the frame rails are made of. These criteria are very simple to work with for any competent metalworker with the most basic resources.

Better than stock. Don't know if you noticed, but while manufacturers use crumpe zones in the front and rear, side impact protection (at least as far as the frame is concerned) consists of reinforcement by rigid beams. You always want the front and rear to absorb the impact, which you can do because they extend beyond the cabin. You always want the cabin area itself to be as rigid and strong as possible because there's no further room to absorb -- all you can do is deflect.

How is there a safe way to bend a car around a tree?....

Possibly (depending on the nature of the crash), but you can't count on it. Only a rollcage can reliably do that.

What are you asking for, anyway... chassis reinforcement or extra crash safety? If it's crash safety, you're definitely driving the wrong car, and no practical amount of metalwork will change that...

Not a chance.

In a relatively high side impact that does not involve the lower frame, there would be little to no difference. In a low side impact that does involve the frame, crash performance would be significantly better.

Okay. If you want to pay for high-level chassis engineers to design, build, and crash-test this thing -- and yes, what you're asking for would definitely involve crash testing -- then you have my admiration and respect.

Unfortunately, though, I for one am still on a budget...

 

Do you think every roll cage shop has a PE on staff or something? What do you consider proffessional? You realize that the guy that started the fire proof suits (brain farting his name, he now owns "impact" which also makes suits) was NOT a proffesional if I'm reading your idea of a pro correctly.

Umm...you're fooling yourself on this one, proffesionals know the probabilities of certain things happening and cutting corners to cut costs. Remember the fiasco with the GM pickups with side saddle gas tanks?
OR much more recently, how about Dale Jr.'s crash in that corvette that erupted into flames.
The boys that started the HANS device in the beginning wouldn't meet your criteria for pros either (they did have a engineer on staff though)
Dale Sr. would have been better off if he went with a non-pro idea and product.

what's the difference? Steel, aluminum (well...aluminum is a headache to weld, you need a pro welder to weld aluminum), carbon fiber are all possibilities. If it makes you feel better I'll call up some ME PE's I know and ask, but I know their answer will be the same as mine.

I think you're fooling yourself if you think pro shops crash test their rigs to compare things.
AND there is no way you WANT a car bending around a tree, you want it to retain it's shape and spin off the tree. Side impacts are the most dangerous impacts at most speeds because the protection is very little. Front and rear impacts are far more easily survivable (obviously except for head on). Why do you think all this side impact air bag thing has taken off as of late?
And despite being pros, the co-driver of a Citrogen FIA rally car THIS PAST YEAR died after they went off and had a side impact into a tree.
Why, even up to this year, do cars still perform badly in crash tests?
The mistakes of pro-shops are written in blood, just like the mistakes of car engineers, plane engineers and a number of other engineers.

If that's your opinion that's fine, but I seriously doubt a "pro" shop can do better than the talent you have here. Why, primarily because a "pro" shop will spend as little time as possible to produce an "adequate" or "acceptable" product for the price. This auto-x merry band of idiots will spend an untold amount of time...for free..to make sure that this thing is as good as it can be.
AND there is engineers in the ranks anyways

 

I KNEW there were some things I hadn't thought of. Well put.

Haha, maybe we should have co-written our monster replies as one post...

 

wtf is going on here? This is a simple thing, ladies......we're not building a full roll cage or anything, just a couple of longitudinal bars with (perhaps) some cross bracing.....don't get your panties in a twist. I have talked to Piper and they didn't give me any "new" ideas vs. the warpspeed that will keep me SCCA legal (my main concern).....we will see what happens....I just want them by the start of the season, so if Redline can do it by then, I'll good to go. If not, I'll have to go to Piper I'll still work with Corey though, even if I have Piper build them....I'm sure Piper wouldn't mind a custom design they make for ME being used as basis of a product for RedlineMax.

 

Will those of us not worried about SCCA rules get our X-bracing?

 

twist twist

 

Your post wasn't up when I started authoring my war and peace diatribe. I could have just written an adendum if I saw it.

 

Not a professional? Hello? I'm a mechanical engineer. If you'd like me to supply you all the data on the stresses each component can take and each joint would feel if said stress was applied, I can do that.

 

If you're referring to my statements I meant PE

 

If you're not joking around about being a ME, then I have some questions to ask you, since I'm trying to become one myself.....

 

alright... it seems like it's not as bad as I thought...

 

You got through all that blitzkrieg information?

 

Being a PE really only means you passed a test. Granted, a really, really, really freakin' difficult test, but...

I'm not saying I know as much as a PE, but I ain't no dummy either!

I went to Rose Hulman Inst. of Technology for a year and a half (freakin' tough a$$ school!). Finished up at Purdue with a 3.8. Whatcha talkin' 'bout willis?

 

Great ideas going on here. Thanks for taking the inititive, Irish.

You got dat right! The more SCCA classes these are illegal for, the better IMO.



And now, I have two points I will make:

1. I think the main tubing that goes along the length of the frame rails should be STEEL—nothing else is practical—and it should be a proper grade of steel. Probably carbon steel or some ultra-high strength steel is out of the question due to cost, but people designing this should evaluate the different types of steel tubing available to find a cost-strength tradeoff. Weight is not an issue, I think most steel weighs about the same. It makes no difference to me whether this weighs 30 lbs or 75 lbs; if it is stiffer I'd take the 75 lbs of weight at the bottom of my chassis, hands down. I don't think drilling holes in the tubing in an attempt to save a couple of pounds is worth even considering.

2. The main tubing should be ROUND, absolutely not rectangular (much weaker), and it should be pretty thick and beefy. It's really not going to affect ground clearance at all.

Is there a reason you guys haven't closed the box in your proposed designs? IOW, made transverse connecting beams at the front and back of the two "Stage 1" tubes? Do you know that it would it not add much strength, or is it an oversight?

Thanks to DrKlop to directing me to this thread from that other thread. I never read this forum so I wouldn't have discovered it.

Also, I will be driving out east between March 11 and 20...and I might be willing to spend a couple of days at Redline's shop to be the test-fit car, or if someone else already has, just for installation....

 

Ya, I definitely appreciate the time you guys spent writing those!

 

I was referring to stillen's fstb...which easily does it's job very well...it is made of T6 6061 aluminum a very light and strong variant of aluminum...don't know who strong or expensive other types of aluminum are...

I know WSP says their stage 1 & 2 totals to 35lbs...and they are working to make them a tad lighter...I certainly don't think making bracing that is 75lbs would substantially increase the rigidity over what you can do with materials that total to 30lbs...if they end up being even 50lbs, I would think that either the material being used is to heavy or to much bracing is there that is unnecessary...

good luck with this whole project, I can't wait to have an alternative out there to the WSP ones...I will definitely be in line waiting eagerly!

 

aluminum is out of the question. It simply does not have the torsional stiffness necessary for good stiffening in this particular case....unless you were to use a SOLID high-strength aluminum tube...which would be pricey. That, and you would need a specialized aluminum welder to both make it and install it (if it was shipped to you).

 

The shop I am bringin my car to, to get the SFCs fabricated looked at the Warpspeed design and said the tubing looked plenty thick and that anything else would be overkill and just add weight.

If you wanted the SFCs stiffer you could fill them with foam and get them as stiff as you could possibly ever want. Than weld them to the frame rails and foam the frame rails and you'de have all the stiffness you'de ever want. The bottom of your car would be more stiff than some cars with roll cages most likely.

 

I was just speaking hypothetically; I wasn't saying I wanted it to weigh 75 lbs, just that weight is not the primary concern for me.

 

Good timing... I was just going to post a revelation I had.

Technically all you need are two bars along the frame rails and two more diagonal bars connecting opposite corners. Everything else is icing on the cake. It's simple geometry: ANY movement resulting from force applied at the corners would require at least one of those bars to stretch, compress, or bend, which means that that design would resist all those forces.

That said, horizontal members could be good if they serve to distribute the forces so that they're not all borne by the weld points at the four corners. That's why I insist that there should be horizontal members that bolt to the frame rail bars at points that are aligned with additional weld points. More weld points means the frame rail bars work better anyway.

I also insist strongly that any cross-bracing members be solid all the way across (from one frame rail bar to the other). They could be indented where they meet so that they fit together, and could bolt together at that point.

 

Right on. If we want to maximize rigidity, we need to minimize the bolted connections. WSP's design with the center hub thing is stupid. No wonder people don't notice much difference between their Stage 1 and Stage 1 + 2.

 

Well when I get it done I am not gonna do a center hub, all the crossmember peices are going to intersect at one point in the middle and they will be welded together so they are one solid peice. I think what needs more engineering than anything else is how to absolutly eliminate movement in the parts that are bolted on. How to make it so that the bolts dont move in their holes and the holes dont get bigger over time because of stress put on them.

 

It needs to made out of steel because 1)it's next to impossible to weld alum. to steel and get it to hold up and 2) alum., as Irish said, can't take the stresses steel can. No need to "close the box" only because the cross bracing creates the triangle shape you're looking for. The strongest two dimensional geometric shape is a triangle. No need to add more weight than you need to. Also, I agree with more than four mounting points now that I had some time to think it through a little. You actually need three on each side to keep the car's frame rails from buckling away from the SFC during cornering. I will also look for a way to attach the center of the X to the car once I get either mine or Irish's in the air. That would completly eliminate the chances of the chassis buckling in the horizontal. the only way to stiffen it more, as was mentioned above, is a roll cage.

BTW: I think I can make this thing so it can be bolted and unbolted, but still retain the rigidity of a welded system and allow for easier shipping. There will still need to be tabs welded on the car unless I can find good, solid mounting holes in the frame rails. Also, I think that the side rails would help with launching in drag racing as well. I was talking with JP about his launches and have been thinking about how to put the kind of power he's got to the ground. I think he's getting some chassis flex (I can feel it in mine when I really get on it on sticky pavement). Some of the hop might be attributed to the chassis loading up and unloading. Adding the side rails should stop the car from loading up. just a thought.

 

I think I know how to improve Warpspeed’s center hub design without any welding:


(the red things are the bolts)
Those triangles will make it almost as solid as a welded hub. What do you guys think?

Edit: The center bar would have to be welded like this:

 

I was going to have the SFCs welded to the frame rails in 6 spots anyway as I thought thats how they did the Warpspeed kit.

This is what I was gonna get done.



Possibly with the addition of 2 lateral bars at either end in addition to the one going across the middle. Where all the cross supports come together will be a welded plate like the similar to the tabs. It wont be a center hub with bolts in it like the warpspeed unit though. So if you wanted to unbolt stge 2 all the cross supports would come off together as one unit. I think any setup more complicated than this is just kinda silly. The only way you could make this significantly stronger would be to make it 3 dimensional because although this setup is stiff left to right and forward to back its not stiff up and down.

 

Very cool idea... It looks like if there was stress pushing the cross bracing together it would be very effective at evenly distributing stresses but my question would be how much stress would there be on the bolts if the cross bracing was being pulled away from each other. Why not just weld it all together.. shipping will be higher but not by a whole ton. You already have to ship steel tubes that are several feet long. If you had a long wide thin box it wouldent be that much money. Shipping cost is more determined by weight of the package.