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 Post subject: Re: My messy new shop
PostPosted: Sun May 13, 2012 1:00 pm 
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Marcus, I have often used single shear pivots without issue over the years, usually I simply go up in size and bore a hole through my tube and weld in a thick walled tube for the bolt to run through or lately I have been able to buy these ready tapped thick wall tubes over the counter for cheap, in this case they are 25mm/1" diameter, 16mm/5/8ths thread and 60mm/2.3" long ...

One trick I learnt as a kid from an old timer is when you run a bolt through a tube for single shear applictions is to make sure the bolt is a little undersized so it has room to flex down the shaft rather than just shearing off the end and don't have a sharp inner edge in the tube at the end.


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 Post subject: Re: My messy new shop
PostPosted: Mon May 14, 2012 10:10 am 
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cheapracer wrote:
. . . <snip> . . . lately I have been able to buy these ready tapped thick wall tubes over the counter for cheap, in this case they are 25mm/1" diameter, 16mm/5/8ths thread and 60mm/2.3" long ...


Is your source for the threaded tubes local to you or is there something available online?

Thanks,

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 Post subject: Re: My messy new shop
PostPosted: Mon May 14, 2012 10:34 am 
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Yo Lonnie-
I can"t answer for Cheapracer, but the links below are a couple of sources for swedged tubes in the US, various sizes and lengths are available. There are other sources, most any place that sells to circle-track racers can usually fix you up.

Bet you knew this already... :mrgreen: But just in case, FYI, my .02, etc, etc... :mrgreen:


http://www.speedwaymotors.com/search-swedged-tubes.html

https://lefthanderchassis.com/v2a/viewproduct_group.asp?idgroup=2512077

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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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 Post subject: Re: My messy new shop
PostPosted: Tue May 15, 2012 12:56 am 
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GonzoRacer wrote:
Yo Lonnie-
but the links below are a couple of sources for swedged tubes in the US, various sizes and lengths are available.


Similar concept but not the same.



Lonnie-S wrote:

Is your source for the threaded tubes local to you or is there something available online?

Thanks,


Local, I can buy 10 or a thousand at a time custom made to my spec (within their overall parameters). The stock 60mm long ones have a 30mm deep blind hole but I order them bored/tapped all the way through and they come in a large range of sizes but I generally keep 20mm x 12mm tapped and 25mm x 16mm tapped on my shelf.

Pretty easy to make yourself and I'm saying that from experience as i have made plenty over the years. You don't need any more than a press drill to do them at home.

Marcus, I will have this exact setup finished at the end of the week, stay tuned...


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 Post subject: Re: My messy new shop
PostPosted: Tue May 15, 2012 1:12 am 
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The voice of reason
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Hi Cheapracer, thanks for the comments. Curious about the recommendation for a loose fit though. I suppose too loose would be too much... Perhaps just use a taper reamer to put a couple millimeters of taper at the end of the tube?

I'm guessing you're talking about the trailing arms for the rear suspension? They connect to the back of the dashboard tube, since it's part of the roll cage you can't do the attach directly. I'm being very conservative here so I'm thinking to weld a bracket that stiffens the leg there. The drawing has 4 holes and the prototype might have that many, but I think just a couple of holes might be enough.

I keep meaning to draw a tall front hoop for a more complete cage and then the front hoop might not line up with the dash. Those could be handy then.

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 Post subject: Re: My messy new shop
PostPosted: Tue May 15, 2012 8:45 am 
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Yes, I am refering to the rear trailing link pivots in single shear. I will have mine setup by the end of the week, I'm doing a run through with the first pre-production car right now.

The bolt only has to be a loose fit, no need to go overboard, 1mm or so will be fine. This allows some of the energy to be dissipitated up the shaft rather than simply shearing the end off, mind you this is unlikely as we tend to oversize things on our type of builds anyway.


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 Post subject: Re: My messy new shop
PostPosted: Tue May 15, 2012 1:24 pm 
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Hey Horizon! I like the website you're setting up. Great way to keep all the info organized and easily accessible... Can't wait to start tinkering...


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 Post subject: Re: My messy new shop
PostPosted: Tue May 15, 2012 3:44 pm 
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Hi Krepus, sharp eye! I just barely got started with it. I'm trying to put something together to help folks collaborate on this. Some of the other things I've tried didn't really work. With this folks can get or view documents and files for models etc. easily. For instance you can just view the latest suspension work that SeattleTom has done without downloading files and worrying about what the most up to date material is.

Today I added a chart for wheel offset / backspacing and what the numbers are for Thunderbird, Subaru and Pinto parts.

Krepus, if you would like I can add you to the collaborator list and you can create and edit pages. I don't have something like discussion threads yet. I think this web site can fit a niche between email and the LocostUSA forums though. Any ideas or input let me know.

I think I need to add a page for links to point here for discussion and Jack's site for parts etc.

Thanks for noticing!

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Marcus Barrow - Designer of Car9, an open design community supported sports car for home builders!
SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.


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 Post subject: Re: My messy new shop
PostPosted: Sat May 19, 2012 5:55 am 
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I'm watching extremely closely... Not stalker close, but almost...! lol! I really love the way the design is evolving. What would it take to leave a little more room in the rear behind the axles for trunk/touring sized fuel cell? 10-12 gallons?


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 Post subject: Re: My messy new shop
PostPosted: Sat May 19, 2012 5:50 pm 
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krepus wrote:
... What would it take to leave a little more room in the rear behind the axles for trunk/touring sized fuel cell? 10-12 gallons?

Good catch!

Fuel consumption & fuel cell size will be an important issue in a track car. I know my Evo gets terrible mileage in time attack tune - roughly 3 mpg on a track that's 85% WOT. That is running E85, which helps with costs, but it means the stock fuel tank is sometimes only good for about 15-20 minutes of track time before it starts to slosh & starve out in hard corners. That was alright for time attack where the first three laps are the ones that count, but in a 40 minute sprint race, I would have been sunk.

Conversely, when we were running normally aspirated 2nd gen MR2s around the track, we usually saw about 11-12 mpg. One of those could easily have run a full 40 minute race on a much smaller fuel cell.

A reasonable comparative vehicle might be a FFR Cobra spec race car. I would be willing to take a guess that the engine being used is a mildly modified Ford pushrod V8. I'm sure the fuel cell would be sized to cover typical sprint race lengths. For those building with this design and using smaller engines, a smaller fuel cell could obviously be fitted.

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 Post subject: Re: My messy new shop
PostPosted: Sat May 19, 2012 11:11 pm 
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The reason the seat belt brace is above the rear hoop tube is to allow the fitting of dual 50 gallon fuel drums, and still provide for driver safety in situations requiring -- wait are we talking pre or post apocalypse?

I wasn't supposed to tall about that...

I originally was fitting an 8 gallon wedge shaped tank behind the driver and passenger. Since then I've been tilting the roll bar a bit and I'm not sure it seems that easy to make with the differential and all. So I'm thinking a fuel cell in the passenger area for serious track use and a more conventional location otherwise. I think 10 gallons is doable. I'll try to draw something up. If it's in reach of a broken half shaft, I'd like an extra layer of sheet metal in between.

Krepus do you have any tanks in mind or should I just draw one up? Summit has a 16 gallon fuel cell that is 25"x17"x9" and a 10 gallon one that's 16"x16"x9". They seem doable, let me check the drawings...

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SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.


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 Post subject: Re: My messy new shop
PostPosted: Sat May 19, 2012 11:41 pm 
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There is a pretty big variety of tanks available. We may have to extend the rear hoop backwards just a little bit. The bracing can basically stay where it is. I'd like some space between the rear of the car and the tank.

The tubing behind the driver is not as big a contributor to car stiffness as I had hoped. So it exists for occupant protection and roll hoop bracing and those needs are meet pretty easily.

We can make more room it just depends a bit on what you would like the car to look like. I'd like to see a boat tail like earlier roadsters, but that doesn't work with the required roll bar bracing. Well, maybe it does, I don't know yet.


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Car9Gstab29tankA.jpg
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SketchUp collection for LocostUSA: "Dream it, Build it, Drive it!"
Car9 Roadster information - models, drawings, resources etc.
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 Post subject: Re: My messy new shop
PostPosted: Sun May 20, 2012 12:02 am 
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lol, yeah, those might get the Evo around Road America a couple times...

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 Post subject: Re: My messy new shop
PostPosted: Sun May 20, 2012 5:45 am 
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I honestly hadn't looked in a while... I was thinking a 12 gallon or so tank from Summit

Ok, so there doesn't appear to be a 12 gallon option... but I found this!

http://www.summitracing.com/parts/SUM-293220-S/

I know it's a 20 gallon, but if there's room for that, everything else should fit just fine... only 10" deep...

Just had another thought... A fuel tanks mounting position can't be rotated because of internal baffling... scratch the 20(24x20x10)... The 15 gallon road raceable tank is 18x20x10, the 10 gallon road race tank is 16.5x16.5x9...

Found the 16 gallon tank you mentioned: http://www.summitracing.com/parts/SUM-290108/

Is the plastic approved for racing? road and autox...?


Last edited by krepus on Sun May 20, 2012 5:59 am, edited 1 time in total.

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 Post subject: Re: My messy new shop
PostPosted: Sun May 20, 2012 5:55 am 
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horizenjob wrote:
There is a pretty big variety of tanks available. We may have to extend the rear hoop backwards just a little bit. The bracing can basically stay where it is. I'd like some space between the rear of the car and the tank.

The tubing behind the driver is not as big a contributor to car stiffness as I had hoped. So it exists for occupant protection and roll hoop bracing and those needs are meet pretty easily. Cool, so it's relatively safe to modify if necessary

We can make more room it just depends a bit on what you would like the car to look like. I'd like to see a boat tail like earlier roadsters, but that doesn't work with the required roll bar bracing. Well, maybe it does, I don't know yet.At first, I thought you'd mounted jet engines on the back... lol


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