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 Post subject: indecision
PostPosted: December 12, 2015, 10:46 pm 
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Joined: November 13, 2015, 1:26 am
Posts: 77
Location: Central Kentucky (Winchester)
Okay, Here is the problem, I want desperately to build a locost 7 or something similar but I really like the idea of making a mid engine.
I started a build log (Kentucky locost duratec build) in the traditional build log section because I kept getting off topic in my other posts and I still am not sure of what I want to build.
I already have a donor car ( 05 focus, 2.0 duratec five speed ) and I also have new front spindles and the 4 x 108 rotors will be here Monday.
I kind of like the midlana but I suck at joining pipe and I don't want something that resembles a street legal dune buggy.
I was leaning toward the locost because of the square tube.
It seems to me to build a locost mid engine you would have to stretch the frame and move the seats forward some?
I am six'1" and not skinny so I need some wiggle room.
I know this is all babbling but I was hoping someone on here might have some ideas?
Sorry to bore you with my rambling.
The car will probably never see a track but will have to be street legal.
All ideas and comments are welcome.
Thanks dave


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 Post subject: Re: indecision
PostPosted: December 12, 2015, 11:22 pm 
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Joined: March 30, 2011, 7:18 am
Posts: 1056
Location: central Arkansas
Look at LateralScience's build thread:

viewtopic.php?f=36&t=16699

He's basically using a Book chassis, modified to take a Honda FWD powertrain in back. When done, the only clue about its mid-engine-ness will be that the rear fenders are slightly behind the back of the cockpit instead of sweeping slightly ahead of it.

Note: given how outrageously clean his work area is, I'm more than half convinced it's all PhotoShop...

LS just whacked the back of the chassis off and built a new structure to hold the relocated driveline. Or you could modify a Midlana or Car9 chassis, or do your own.

You have a complete driveline; all you have to do is lock the rack or replace it with a tie bar and drop it all in place as-is.

By going mid-engine you simplify a lot of things, and you don't have engine heat cooking you, and you have vastly more foot room and a bit more hip room. And no hot exhaust pipe to burn yourself with.


You have to deal with three specific things with a midi:

Radiator: most people put them in front and run water tubes to them, but they work fine in the back, where the low pressure area behind the car helps pull air through them.

Fuel tank: Kurt made a custom tank and put it between the triangular space between the seats and engine. DeTomaso Panteras used a tall tank (sort of like two milk crates one atop the other) mounted alongside the mid engine. I'm putting an off-the-$125 shelf race car tank in front in my build; the weight difference from empty to full is only 60 pounds, and it will be a lot better protected than hanging behind the rear axle of a Locost.

Shifter: The shifter linkage has to be dealt with, but it's pretty straightforward and there are plenty of examples here. For that matter, some front engine cars have to relocate the shifter with linkage.


Last edited by TRX on December 12, 2015, 11:42 pm, edited 1 time in total.

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 Post subject: Re: indecision
PostPosted: December 12, 2015, 11:33 pm 
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Joined: April 23, 2006, 8:26 pm
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Leggman wrote:
... I kind of like the midlana but I suck at joining pipe and I don't want something that resembles a street legal dune buggy...

Ouch, but fair enough. If it's the tubes (pipes are for plumbing) you don't like, leave out the overhead portion of the roll cage, but realize that it significantly reduces its torsional stiffness.

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Kimini book: Designing mid-engine cars using FWD drivetrains, http://www.kimini.com/book_info/


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 Post subject: Re: indecision
PostPosted: December 12, 2015, 11:59 pm 
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Joined: November 13, 2015, 1:26 am
Posts: 77
Location: Central Kentucky (Winchester)
I really didn't mean to offend and I realize that "tubes" are stronger than square tubing, Its just several years ago I built a tube frame dune buggy from scratch and the joints looked like s&%t because I didn't take the time to make it look right. It was totally my fault and I have learned a lot since then so maybe I will try it again.
I kind of like the profusion typhoon and I have a roller for one inch square tubing so I was thinking instead of splicing together the top and bottom rails that run front to back I could just roll them gradually and go more or less along the same lines of the locost.
My donor car is 52 inches inside and I would like to use the same seats so I will probably have to change things up a bit. I realize I can only go so wide with my drive train keeping the body inside the wheels.
I will have the donor car delivered the first part of the week so More measurements can be taken.
Thanks for the comments. Dave


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 Post subject: Re: indecision
PostPosted: December 13, 2015, 12:25 am 
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Joined: March 30, 2011, 7:18 am
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Location: central Arkansas
I guess Major Decision #1 would be "front or mid engine." Major Decision #2 would be "cage, roll bar, or nothing?"

My original intention was "nothing", but my wife insisted on a stout windshield and frame to give some protection against Satan's Own Minions. (Bambi and her posse) The windshield hoop looked out-of-proportion by itself, and I got the idea that some overhead bars might be convenient to grab onto to get in and out; we've both had knee surgery and we expect entry/exit to be an issue. Something had to hold the after end of the grab bars up, so a main roll hoop behind the seats. And might as well run some tubes rearward to triangulate it. And then I wound up with a cage. I still think the cages are fugly, but the "monkey bar" function would be useful, and for that matter, it's a convenient support for a soft bikini top so your brains don't cook on a nice sunny day.

"Nothing" saves a great deal of aggravation, expense, weight, and looks better. And eleventy-zillion Lotuses, MGs, Triumphs, Miatas, and Cadillac convertibles got along just fine without roll bars.

Now, if you decide to do HPDEs or track days, you need to see what their rules say. Some places won't let you run a topless car without a roll bar. When a friend was doing track days with his Corvette, they told him he couldn't run with the top down, but they'd let him on track with the top up. Like the top was going to provide some kind of protection... he went to buy a roll bar, but another group he drove with had a rule that no bar was fine, but if it had a bar, it had to meet all sorts of specifications, including being several inches too high to get the top up over it... it got pretty silly for a while there.


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 Post subject: Re: indecision
PostPosted: December 13, 2015, 12:30 am 
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Joined: December 17, 2010, 1:24 pm
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Location: Gainesville, Mo.
Quote:
My donor car is 52 inches inside and I would like to use the same seats so I will probably have to change things up a bit. I realize I can only go so wide with my drive train keeping the body inside the wheels.


Here is another point in favor of a 'middy'! With the extra length between the seats and the rear axle, you'll have room to taper the chassis from a wide cockpit down to where it fits between the wheels again without the taper looking too abrupt! also with the 'middy', you won't have to put a driveline tunnel between the seats, thus giving you MORE room. Just something else to think about.

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 Post subject: Re: indecision
PostPosted: December 13, 2015, 12:51 am 
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Location: central Arkansas
Leggman wrote:
My donor car is 52 inches inside


The body of the Focus goes past the outside of the tires. You lose some due to door thickness, and get 52 inches. But the "body" of a Sevenesque is the frame, which has to fit *between* the tires, with room for any forward links and tire movement. In practice, you're looking at 40 to 46 inches, outside-to-outside of the chassis. Minus the thickness of the side tubes and the center spine, which doesn't necessarily have to be on center. With a mid engined car you can narrow the spine to just wide enough to run the shift linkage through and get more hip room, not to mention the foot room from not having to accomodate a transmission and bellhousing.

Quote:
I will have the donor car delivered the first part of the week so More measurements can be taken.


I worked back-to-front. I didn't want to have custom axles made, so the inside-to-inside width between the tires, minus linkage, side rails, etc. set my chassis width. It all worked out fine for me, but I was prepared to pull the axles out a bit in the tripod joints to get another inch or two, and maybe use wheel spacers if I had to.

Since I was using aftermarket wheels, I backfigured from those, not the stock wheels.

The distance from the center of the tire to the front of the exhaust manifold (or intake, if you have one of those bassackwards engines) determines where the firewall goes. You can angle the axles forward a bit if you want; not all cars have the axles going straight out.

With the firewall, you then figure the angle of the back of the cockpit, which would ordinarily be close to the seat back angle. That gives you a triangular space across the middle of the car. KB58 welded up a custom fuel tank and put it there. I'm using it for storage.

With the back of the cockpit set, you can find out how long the cockpit needs to be. Sit on the floor with your back against the wall and measure to the soles of your shoes. Then add room for pedal travel; four to six inches, perhaps. That establishes the front of the cockpit.

While you're against the wall, put your hands out at a comfortable "holding the steering wheel" position and measure that. Note that you'll be leaned back a bit in the car. Add four to eight inches and that's the distance to the dashboard.

The base of the windshield can be anywhere from the back edge of the dash, forward.

The front wheel centerline can be anywhere ahead of the front bulkhead. If you use the Focus rack and pinion you can ignore the "front steer" vs. "rear steer" question and just go with what you have. Unless the Focus rack is pathologically wide or narrow you can lay out the front suspension geometry to accomodate it.

Doing the front end geometry isn't as intimidating as it looks. You'll also probably wind up designing your own independent rear end; I don't know if the Focus uses McPherson struts, but if it doesn't, they're usually too tall to use without sticking out the top or making a really high rear deck. If they're not you'd have a big win as far as saving time and effort, though.
(note: there are now short struts and strut inserts to accomodate the "slammed" custom car market)

You'll have to do the front (and probably rear) suspension no matter which end the engine is in...


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 Post subject: Re: indecision
PostPosted: December 13, 2015, 1:18 am 
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Joined: November 13, 2015, 1:26 am
Posts: 77
Location: Central Kentucky (Winchester)
TRX You are so right about your build strategy. I would like to use the donor car seats because 1. They are in really good shape and comfortable and 2. I am a serious tightwad. I will have to measure the seats when I get the car home to see if they are going to work. I am sure with the narrower tunnel I can fudge some inches here and there.
Yesterday I removed a manual rack from a 2nd gen rx7 I had in my yard and I might just use it. although the focus rack might be better?
Seeing how winter will be here in a couple of days I will have time to maybe even make a wooden mockup of the frame on my build table to check everything out first. Then just make the metal bits to match the wood. What could possibly go wrong :roll:
I will print out your build strategy and hang it in my shop to remind me.
I have one other little project to do (splicing a frame section on the back half of a ford ranger) then I will be building my table and get started with the fun stuff.
I am of course anxious to get this started but living in Kentucky the weather is crazy, Its 70 here this weekend and it will be 25 here next weekend. It will be bitterly cold out in my shop and I usually don't get much done out there in the winter. I guess I could put a heat source in there and never come in the house. Hmmmmm
Thanks again for all ideas.


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 Post subject: Re: indecision
PostPosted: December 13, 2015, 10:34 am 
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Location: central Arkansas
I built a cockpit model back in 2000 when I welded up my first build, just to make sure I could get in and out. I'm doing it again this time for the same reason, and to determine whether I need an adjustable driver's seat, pedals, etc. due to the difference in height between me and my wife. A couple of guys here built complete full-scale chassis out of wood to make sure everything would fit properly. None of them has implied their time was wasted.

A wooden mockup also gives you one last chance to step back and say, "Whoa! Do I want to build one of these or just order a Cobra kit?"

--

The weather here in Arkansas is similar, with extra helpings of damp. I use one of the 175,000 BTU kerosene bullet heaters from Tractor Supply; it will bring the temperature in my 20x35 shop from 30F to 70F in half an hour. Practically, a heater half that size would work. I use Diesel fuel in it; it's less than half the price of kerosene in my area. Diesel gives a small puff of smoke when the heater kicks on, but after that it actually has less odor than the kersoene. Most of my friends with kerosene heaters have switched to Diesel now.

My Dad's woodworking shop was twice the size of my shop and "insulated" with a one inch layer of fiberglass batt. He has one of those cast iron wood stoves and it did a good job of keeping the place warm. He fed it with shop scraps and cordwood.

If you have access to a supply of used motor oil I have a design for a DIY waste oil heater I came up with. It's a variant of the old Mother Jones design scaled down to fit a 20-pound propane tank. My prototype burned clean without needing forced air.

Even a *little* insulation makes a big difference. Stapling plastic between open studs is way better than nothing. A roll of R13 riberglass batt is $15 or so, you could get one or two every payday.


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 Post subject: Re: indecision
PostPosted: December 13, 2015, 10:59 am 
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TRX wrote:
I have a design for a DIY waste oil heater I came up with. It's a variant of the old Mother Jones design scaled down to fit a 20-pound propane tank. My prototype burned clean without needing forced air.


TRX, you need to create a new topic on this right now! :P You have a very interested audience awaiting the details on the heater. How much oil does it burn per hour?

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 Post subject: Re: indecision
PostPosted: December 13, 2015, 11:06 am 
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Joined: April 23, 2006, 8:26 pm
Posts: 5586
Location: SoCal
Google "waste oil heater"; there's much information on them that's already out there. It's a controlled oil fire that burns so hot that a properly operating unit emits no smoke or smell.

_________________
Midlana book: Build this mid-engine Locost!, http://www.midlana.com/
Kimini book: Designing mid-engine cars using FWD drivetrains, http://www.kimini.com/book_info/


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 Post subject: Re: indecision
PostPosted: December 13, 2015, 12:39 pm 
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Location: central Arkansas
I'll dig up my notes and pictures and start a thread in a couple of days.

When I built it I had access to all the waste oil I could haul, in 55-gallon drums. Before I installed the heater in the shop my source went away. [sigh]


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 Post subject: Re: indecision
PostPosted: December 13, 2015, 2:05 pm 
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Joined: November 13, 2015, 1:26 am
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Location: Central Kentucky (Winchester)
I reworked my shop last year. Gutted the inside and reframed all the walls using 6 inch insulation. I even reframed the ceiling and insulated that as well. I am sure your waste oil heater would keep me cozy all winter.
Right now I just don't have time for anything. Sales are way up at work and I am working seven days a week. It usually slows down in the spring so thats when I will get busy.
Half of my shop is woodworking so making a wooden mockup of the frame will be fun.
Back to the car, I have thought of making the body wider ahead of the rear wheels by a couple of inches tucking half of the rear tires inside the body but that might make it too long and longer means heavier.


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 Post subject: Re: indecision
PostPosted: December 13, 2015, 3:32 pm 
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Location: Cornholio OR "Where the magic happens"
One thing about converting a forward motor to a mid is the driver location.

To do a mid motor right, the driver should to be moved forward.

This means front steer and some foot room considerations and what ever else that needs to get juggled.

Just adding a mid motor to a front motor frame will make a chassis that is maybe longer than you want.

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 Post subject: Re: indecision
PostPosted: December 13, 2015, 7:05 pm 
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Bent Wrench wrote:
To do a mid motor right, the driver should to be moved forward.
+1 on that, but fortunately, when you move the engine to the back, you no longer have a bell housing between the driver's and passenger's feet, so you can move the occupants forward with minimal chassis mods.

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