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PostPosted: Sat Sep 17, 2016 6:20 am 
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Hello guys,
I am starting to build a locost powered by a BBC 468. I had this engine in my Lamborghini diablo kit car earlier on but now am deciding to put it in a tiny car such as the locost. I reinforced the chassis with a bunch of triangulation and have finally achieved 7300 lbs * ft/deg. I am building this in my apartment since school is in the way and when i take the next term off i should be able to weld this entire chassis up and get it powder coated and reassembled. Pretty much at this stage the car will be in its rough assembly stage. Here are a few pics of the build progress and some final pictures of the design.

My next step is to continue to build the chassis in small steps as well as plan out my suspension. I am using mustang II drop spindles and have all of the dimensions plugged into vsusp. I have another topic started with the hints for the suspension design. however any input would be awesome to get from you guys.


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PostPosted: Sat Sep 17, 2016 6:24 am 
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not sure why the pics posted in reverse order but here is another picture of the final design and the link for my suspension design. i am more than happy to share the cad drawings for the chassis with all of the cut lists and FEA tests.

I will be using the wilwood Mustang II drop spindles and I have deigned them in cad and imputed the correct dimensions into vsusp. here is the link with the suspension design.

http://tinyurl.com/zxhmpeb

In the front i am planning on running 275/40/17 with a 0.24 inch offset rim with a 1.5 inch wheel spacer and in the back i will be running 315/35/17 with a 1.1 inch offset on the rim and will have a 1 inch wheel spacer.

Could some of you guys run through my measurements and recommend any changes? Also i almost forgot to mention, that the frame in the rear is 46 inches wide, this is why i was thinking of adding in the wheel spacers.

I will be using a wilwood brake kit 140-12275-D for the front which will offset the hub by +.55. I have not incorporated that into the program yet so a bit of help regarding that too would be nice.


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PostPosted: Sat Sep 17, 2016 8:39 am 
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Shevalev - the pictures always post in reverse order - that's what the board software does. So post the one you want to be last first, next to last next, ......, and the one you want to be first, last. Photos add to the top of the list as you post them.

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PostPosted: Sat Sep 17, 2016 9:43 am 
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Hi Alex, welcome aboard.
You have a mighty fine start to the frame there.
Let me be the first to say that's a great looking shop also and the view from it sure beats the hell out of the view from my shop.

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PostPosted: Sat Sep 17, 2016 11:40 am 
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Yes, very nice shop. But how do you get the chassis out and off the 58th floor? Must have one large hallway and a very large elevator.
Where in the world are you located?
Cheers,
Roy

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PostPosted: Sat Sep 17, 2016 1:23 pm 
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So...
1. Are you building it in your living room? Welding, grinding, cutting?!
2. How do you get it outside?
3. How complete will it be before construction continues elsewhere?

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PostPosted: Sat Sep 17, 2016 1:49 pm 
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Hi Alex,
you win the most impressive workshop award. :cheers:
Looks like you are looking down on to Canada Place, and I see the Vancouver Sun building. Nice spot. I'd have a hard time keeping all the grinding and welding sparks off those beautiful furniture. As to getting it out of your building, it has been done before. There is a Sonex builder who built it in his apartment. Last I remember, he flew successfully.


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PostPosted: Sat Sep 17, 2016 2:50 pm 
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Hi guys,
I am located in the Fairmont building in Vancouver. The loading elevator is 119 inches tall by 48 inches wide and 102 inches deep. The chassis will be in 2 parts: one is the front chassis up until the rear bulkhead, and the rest is the everything from the rear bulkhead back. The front chassis is 110 inches by 46 by 22 inches so the fit should just be perfect. I will assemble the car completely with the engine and transmission and brakes and everything like that so i have all of the tabs and mounting points figured out and then i will disassemble it and get it fully welded. All of the welding should be done in February or around there as well as the powder coating. Now for the welding and cutting and grinding i am doing all of that on the balcony. I do have to say that the floor here is perfectly level and it makes it an awesome tool for me to check the welding distortion. The first time i tig welded this chassis i was very upset with the result. I ended up switching to stick welding and that worked out much better. My welder is a thermal arc 95s so i have both of those welding options easily accessible. Here is a picture of the two chassis one that was tig welded and the other that was stick welded. The tig one is on top. The use of SolidWorks has been really helpful since i can use diagonals to check how straight my measurements are. I think I have went a bit overboard but the chassis is accurate to 1/100th of an inch. I got a 8 foot machinists rule with r16 grading and that has been the best investment so far.


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PostPosted: Sun Sep 18, 2016 6:53 am 
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We are Slotus!
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Hi Shev!
You must be nuts for trying to build a chassis in your apartment. So, that means you'll fit right in with the rest of us! Welcome aboard!

That's a mighty nice shop ya got there... I'd guess you don't have any goats or donkeys or beagles that wander by while you're working, do you? Other than that, looks like a nice place. :mrgreen:

Big Block Chevy, huh? Hope you got lotsa $$$ in your "New Tire Fund". :mrgreen:

Keep us posted!
:cheers:
JDK

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PostPosted: Sun Sep 18, 2016 12:15 pm 
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I think some welding practice would be a good idea. Your putting in a lot of effort on this and you deserve to be happy with the result. I know the practice is frustrating compared to just getting to the real work.

Take some pieces of your chassis material that are at least a foot long and weld a "T". Just do one edge of the square tubing and then put it in a vice and you should easily be able to bend it until it breaks. After it breaks, then you get to weld it on again a half inch away from the last weld. You should not get any breakage in the weld area and you should not get any weld bead that separates from the tube.

Put your tack welds on the corners of the tubes. They make good places to start and end your welds and help prevent cratering at the end of your beads. It also makes the frame pretty strong while you're working on it.

Grinding the welds is just not a good idea, especially for a beginner. It is specifically prohibited by many racing organizations.

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PostPosted: Sun Sep 18, 2016 4:15 pm 
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Yeah, your distortion issues are caused by the gaps that you are trying to close. TIG is sensitive to fitment. If you get a nice tight fitment, it'll flow together like butter and it won't warp hardly at all. Those big gaps mean that there is a lot of molten metal cooling down. Cooling metal contracts, pulling on the two pieces it is joining. This results in residual stress in the frame. It can be fun cutting that apart; things will bang and pop as you start cutting your welds apart and all the stress is relieved. It is very much worth the time to make a tight fit. I always err on the far side of my line, leaving a little too much material after cutting, then I file to fit. Also, if possible, clamp the joint you are welding together. It will help the two pieces flow together nicely as well. If your weld bead is much wider than 2x the thickness of the material you are joining, then your gap is too big. Of course I'm talking about this in the theoretical, perfect world, where every joint is perfect. It's an ideal to strive for; you choose when it is beneficial to stop short.

Maybe I'm showing my prejudice, but TIG should give you better welds on thin material like this than stick will. I think your observation that stick is producing a less warped structure suggests that you are welding too cold. TIG is also cleaner, reducing the risk of damaging your lovely floors with sparks and slag.

EDIT: I re-read this and wanted to add some more up-beat input. I like what you're doing. The design is good, your joints look clean and have a good cut quality. I think you'll have a tiger by the tail when it is done with a 468 in it. I'm too lazy to calculate or look it up, is that a 030 over 454 or is it some combo of stroke and bore on something smaller? What sort of torque do you think you'll be creating your vaporized rubber with?

EDIT 2: It is 060 overbored 454 for anyone wondering, and it looks like they often make in the neighborhood of 600ft.lbs. :shock: I don't know how you will manage all that torque out of a big cube engine. It'll be making a lot of that torque right off idle. What are you thinking your tire and wheel package will be?


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PostPosted: Mon Sep 19, 2016 7:24 am 
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esp42089 wrote:
What are you thinking your tire and wheel package will be?
I don't know about Alex, but I'm thinking that his tire and wheel package will be "COOKED about 30 ft from the start line." :rofl:

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"Gonzo and friends: Last night must have been quite a night. Camelot moments, mechanical marvels, Rustoleum launches, flying squirrels, fru-fru tea cuppers, V8 envy, Ensure catch cans -- and it wasn't even a full moon." -- SeattleTom


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PostPosted: Mon Sep 19, 2016 1:26 pm 
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Quote:
often make in the neighborhood of 600ft.lbs. :shock: I don't know how you will manage all that torque out of a big cube engine. It'll be making a lot of that torque right off idle. What are you thinking your tire and wheel package will be?


Some numbers, the T56 has a 2nd gear ratio of 1.78 and typical rear end ratios might be something like 2.75 - 3.0 ( don't remember off the top of my head ). That would multiply to an advantage of 5.34.

For round numbers if the car has 1000 lbs. on the rear wheels and 24" tires ( he probably has 27" or so, but 24" means the radius is 12" which works nice for foot-lbs. ), so he would have 1000 ft. - lbs. of traction using tires with a coefficient of friction of 1.0. His tires would likely be a bit better, but they are almost certainly designed for a much, much heavier car. A soft compound for a 4000 lb. car is not so soft on an under 2000 lb. car.

So if you had for example 1000 ft. - lbs of traction and then apply that to the engine, it would be reduced by a factor of 5.34 by the gearing and you see the motor will smoke those tires at 187 ft.-lbs..

Outside of reverse, it doesn't really seem like this actually needs a transmission, maybe the gas pedal should just be connected to the idle air control. :(

Motors with top end power and wimpy bottom ends are what make these cars enjoyably drivable.

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PostPosted: Mon Sep 19, 2016 8:10 pm 
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Well, Hoosier makes drag radials up to 17" in width. Get a set of those on there and see how strong that poor little 8.8 is!


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PostPosted: Mon Sep 19, 2016 11:02 pm 
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Quote:
Motors with top end power and wimpy bottom ends are what make these cars enjoyably drivable.

Marcus, we're on the same page. Must be that FF background. I've got maybe 100 ft/lb torque, but a 172hp at 13,000 rpm. I ain't spinning tires, but surely sound like Michael going up the front straight. :rofl:
BTW, having only raced FF and Honda Michelin (a spec series), tire spin = down two places. :shock:

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