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PostPosted: September 1, 2019, 3:21 pm 
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Joined: August 26, 2019, 2:22 am
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As the title suggests, Im looking to build my first locost. I want to use the Ford Duratec Inline 4 Engine, an NC Miata Six Speed, and a solid rear axle, likely from a ford.

My only issue is that Im about 5 foot 10, a size 12 wide shoe, and Im a bit bigger. I fit in my NA Miata, but I had to remove my door handles to be comfortable.


Whats the smallest frame I can go with a locost?


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PostPosted: September 2, 2019, 10:22 am 
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Joined: October 24, 2008, 2:13 pm
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Location: Carlsbad, California, USA
There's the "people" answer to that question as in, "How wide does it need to be to have a comfortable cockpit for my body?" And then there's the technical answer to it, which is, "How wide/narrow does the chassis have to be to use my particular live axle?"

If you know what axle you are using for sure, then it's a matter of picking the widest chassis design that will work with that axle. Of course, you may still need to sign up for Weight Watchers to fit inside [LOL].

You probably know there are a series of McSorely designs that vary the width and height of the basic Champion ("Book"). There are other variations based on the Haynes Roadster too. I would have made mine a little taller, mostly to enclose the taller engine better. But, these things vary. It helps to have your mechanicals selected before deciding on a chassis.

Cheers,

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886


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PostPosted: September 2, 2019, 11:41 am 
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Joined: July 17, 2008, 9:11 am
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Location: West Chicago,IL
I think the size 12 Wide shoe is the biggest factor. 6'0 and 240 ish fit well in my book(42"wide frame) Seat design and steering wheel layout is critical. I had kept the donor's tilt function (albeit I removed some of it's weight and size) as well as included a removable steering wheel. Seats took every bit of available space. No Kirky or bomber style seats here. Minimize the tunnel to as small as possible. Then it comes down to the size and construction of the pedal area. Cross-Fit shoes will not work IMO. Look for as narrow a shoe design as possible even if it means driving shoes. Then it becomes a matter of how little room can you deal with and still feel confident.

It does not necessarily come down to frame size. It is how we choose to design around the space available. One 42 inch book frame in not the same as another.

As far as axle width is concerned, IRS can eliminate that constraint. You can make it any width you want.

You don't mention your location. Locoster's are a good bunch. There might be someone near you that you might talk into a trial fit. Again, it is not necessarily frame size. It is how we choose to design around the space available. One 42 inch book frame in not the same as another.

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“Any suspension will work if you don’t let it.” - Colin Chapman

Visit my ongoing MGB Rustoration log: over HERE

Or my Wankel powered Locost log : over HERE


Last edited by rx7locost on September 2, 2019, 1:58 pm, edited 1 time in total.

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PostPosted: September 2, 2019, 12:48 pm 
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Joined: December 17, 2010, 1:24 pm
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Location: Gainesville, Mo.
I was just looking at your Facebook post, and you mentioned a 17" wide seat. Looking at my 2-2-1 drawings, you should have 1/2" to spare. A 2-2-1 is 42" BETWEEN the frame rails across the cockpit. Subtract 7" (this can vary from car to car) for your driveshaft tunnel. This would leave 17.5 on each side, but (there's always a "but") in many cars the tunnel is offset to one side or the other due to the driveshaft mating up with an offset pinion shaft. On the plus side of this "but", many times the tunnel dimensions CAN be fudged a bit to give more room.

Chuck has a lot of good ideas. He built a very nice car! I'll second his suggestion of giving your location.

Hope this helps! :-D

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PostPosted: September 2, 2019, 1:09 pm 
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Joined: December 17, 2010, 1:24 pm
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Location: Gainesville, Mo.
Question! Since you're basically going with a Miata drivetrain, why not use the Miata rear suspension, too?

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PostPosted: September 2, 2019, 1:32 pm 
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Joined: April 22, 2010, 4:43 pm
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Location: Livermore, Calif.
You've got some very good comments above. I found the McSorley 442e chassis the most accommodating. It will take the Miata IRS and the tall Miata plus a tall Honda S2000 engine nicely. It also can accommodate a 17" seat, leaving room for a nice center tunnel. On my second Locost I added some additional room for the old feet (no matter what size shoe). See my build log for details. I also made the gas pedal and brake plus clutch pedals somewhat adjustable. So there's plenty of "foot" room.

You might also want to list you first name so we don't have to call you "trizvi".

Cheers,
Roy

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Build log http://www.locostusa.com/forums/viewtopic.php?t=16510


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PostPosted: September 2, 2019, 2:16 pm 
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Joined: July 4, 2006, 5:40 pm
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Location: Novato, CA
I'm a big fan of the book frame. IMO it's almost too large. Plenty of length for a six-footer as noted, about 17-1/2" between the frame and the trans tunnel, and if you go with the traditional bench seat, you get to use all of that 17-1/2". I was in doubt about this early on, so I built a mock-up frame out of wood to try it out before I started.

As mentioned, a size 12 shoe won't work in a book frame. I'm a 10-1/2 and with the wrong shoes my toe scrapes the top tube under the scuttle. You could possibly lop off a section of that tube, it would still be strong enough with the scuttle installed, but a 1" taller frame would probably be a better solution.

I'm also a big fan of solid rear axles. Much easier to build and stronger, IMO, because the mounts tie into the main frame structure and not the rear overhang. You can figure the approximate frame width by taking the rear wheel track of the donor axle and subtracting the width of a tire. The frame has to be at least an inch narrower than that to accommodate the trailing links, and you probably don't want it more than 3-4" narrower. If the track is 56", for example, and you have 9" wide tires, frame width should be between 42" and 46".


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PostPosted: September 2, 2019, 2:25 pm 
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Joined: August 26, 2019, 2:22 am
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Wooof

Response.

Yeah so, I wear Onitsuka Tigers as my driving shoes. Thats what I wear in my Miata, my Subaru, etc. I want to keep the solid axle just for authenticity and feeling in addition to not needing to re engineer the rear end.

Beyond that, yeah, I did want to utilize a 17 inch kirkey style seat.

Im actually also located in the bay area, I know a couple of people exist around here, but thats about the lot of it


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PostPosted: September 2, 2019, 3:07 pm 
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Location: Gainesville, Mo.
RoyzMG wrote:
You might also want to list you first name so we don't have to call you "trizvi".

Cheers,
Roy


I've seen his first name. Kind of a mouth-full. :wink:

You got a nick-name you go by? Or maybe your initials?

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PostPosted: September 2, 2019, 4:02 pm 
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Joined: August 26, 2019, 2:22 am
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ngpmike wrote:
RoyzMG wrote:
You might also want to list you first name so we don't have to call you "trizvi".

Cheers,
Roy


I've seen his first name. Kind of a mouth-full. :wink:

You got a nick-name you go by? Or maybe your initials?



I just go by TJ


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PostPosted: September 2, 2019, 10:06 pm 
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Joined: December 17, 2010, 1:24 pm
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Location: Gainesville, Mo.
Alright, TJ it is then! Glad to might you, TJ!!! In case you haven't already figured it out, I'm Michael Severson from the Facebook group. Just plain "Mike" will do just fine, here or anywhere else. You'll find a great bunch of guys here, and you'll enjoy getting to know them!

:cheers:

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PostPosted: December 7, 2019, 8:08 pm 
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Joined: May 25, 2006, 9:39 pm
Posts: 344
I gotta say I'm a big fan of live rear axle and book sized frame as well. I did widen mine by an inch but didn't need to. I also raised my frame an inch to accommodate my toyota motor. Because an offset nose on my toyota rear axle my drive shaft was shifted an inch to the right. Footwell is tight but enough. I guess the reason I like the smaller stuff is that I'm not a big fan of big motors in this particular car. Any how look at my build and enjoy. David's Homage to Skinny G and Collin Chapman


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