LocostUSA.com

I'm wondering what size square tubing brunton chassis are running. The book is 1". But they don't plan on a "heavy" and torquey SC v6 in there.

I was thinking of building the "super stalker" the SC 3800. I have thought of bringing up the tubing to 1-1/4. Would this make sence?

I have drawn a 7+442 with the 1-1/4" tubing in Pro-Engineer and i have 90% of it in there and it weighs ~98lbs. Does this sound right?

Thanks
Ken

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Ken

You are right in the ball park relative to Wt. Increasing the tube size is the easiest route to increase the stiffness of the design. You could add more triangulation in each bay while using the smaller tubing, look at some of the Ozzie builds, but the actual saving ln Wt Vs design and build time may not be worth your effort. If you plan to on racing, then the wt saving is going to be a higher priority Vs construction.
Good luck on the build, Dave W

Thanks Dave,

Yes i plan on more triangulation on the engine bay and welding in steel panels. I will race the car, primilarly Auto-x and some track time.

I just don't want to make a car and then read that i should have used someother type of steel that would have made it stronger and lighter.

I'm currently reading about the frame. That someone has written about and it is very interesting, like what tubes to remove an such.


I will gusset and triagulate as much as possible

Thanks
Ken

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R-Someone told us here that on the Stalker the upper rail is upgraded to 1.25". The best way is to e-mail Dennis Brunton. He seems to be quite open (answered my e-mail once).

I myself build a heavy V6 locost. All my lower rails are 1.25" gauge 16.

Philippe.

I remember reading somewhere that you gain more strength from increasing tubing size than you do tubing thickness. I would think that as long as you stayed with 16 ga. or thereabouts your chassis would be quite stiff without being too much heavier.

Thats cool that dennis is open about his product! I was thinking of buying some Stalker parts from him, like his wiring harness and computer. Yes it is expencive at $1500 but sure would make it alot more reliable, as wiring scares me...

As it sits now i'm using all 1-1/4 tubing @ 16 guage.
This is what it looks like

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Ken,
As a footnote to my reply I should add that IMHO more cross bracing (triangulation) is more important than the size of the tubes you are using. I recommend to you in the Clubman builders resource sites to look up australian chassis mods.

Philippe.

Thanks Philippe.

I have a few images of the Aussie mods, and a write up about the chassis.

I will keep looking for more information.

Thanks

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Ken

If you do plan on racing then visit the Caterham web site, and look at the "R" serie frame. They have excellent triangulated design. You'll notice that several of the tubes are actually smaller in diameter and also lighter gauge on the 250 HP model.
The reason you go to larger tube size, Vs triangulated is that it is easier and quicker to build. If you are going into production then that would be the way to go, and still have sufficient torsional stiffness.
If you are racing, do not weld in steel as shear planes. The wt will go up big time. Stick with Aluminum and use higher strength rivets and bonding.
I would also recommend that you not remove tubes, As Philippe has suggested, you are going to have a much stiffer frame with added triangutation.
Dave W
i

Dave do you have a link? I looked both the USA and the England site and did not see any pics of there frames

Yea i drew the peice of sheet steel that goes under the seats @ 16 guage (heaver than i would need) and that came in at ~25lbs and aluminum at 8.6lbs.... If i go with 20 guage (.035 swg) that brings me down to 14.5 lbs. What weight will rivits add? Well i guess "none" seeing how you have to drill to install them.... (or not enough to worry about)


Thanks guys!

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ken


Try searching for www.mycatherham.com Dave W

Found it.


Thanks for your help

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Kenlude -
There are a few threads which discuss the Stalker on this forum. Without taking the time to search for myself, I think that the upper and lower rails have been increased to 1.25", the other tubes are still 1" (this is all heresay as I have never seen one in person to measure) Also I think the Stalker is about 2" wider than book, not 4"

I have emailed Brunton a few times and never received a response. I specifically asked how his chassis compares to a "Book" locost. I find his lack of response totally understandable. I'm not so sure I would want someone copying what I was trying to make a living selling. For now I'll have to make my own, but if I can ever afford a Stalker, you can bet your ass I'm getting one.

As pointed out above, aussie mods and increasing the size of the tubing without increasing the gauge is a great way to increase stiffness.

I have commented on a few other threads, but will add here too - I am building an inline 6 BMW based locost. All tubing is +.25" i.e. all book 1" is 1.25" in my build, all .75" becomes 1" etc. Still sticking with 16 ga.

Good luck,

Eric
Locostmonkey

Locostmenkey, The search function is not that great on this forum.... I tried I got like 150 hits.... i will keep reading and see what i come up with. Humm that is interesting that it is not the full +4 wide. That is good i guess that it is not then there should be no problem fitting the L67 in there that i plan... I did not know if it would be a really tight fit or not.

Yea i would not expect him to be completly open with everything about his chassis. It's his livelyhood. I'm not going to buy one i will just build one That sure will be fun to drive!

The picture that i posted is not the completed chassis. I will add the aussie mods and some other that i "dream up"

Thanks
Ken

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It's 1.25" for the main frame rails, that's off my brother's Super-Stalker frame he just recieved. I assume the tubing's the same size for the N/A version.

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