Project: Dodgy Locost (360 LA +442E)

charlesshoults · **Posted:** Sat Sep 24, 2011 12:06 am

This may look a little bizarre. Obviously, it's a composite from droop, ride height and fully compressed. I think I need to increase the angle of the upper bar leaving the back of the camber block another 2-4 degrees in order to get it right. That should give me just a bit more compression than droop.

STARMAN1 · **Posted:** Sat Sep 24, 2011 4:02 am

I think that you need to think about keeping your angle of your member as close to 90 degrees to the line of the shock to minimize the rising and or falling rates of the suspension. That suspension member doesn't have to be straight, mine looks like a bomerang to keep the angleto the shock and the angle to the pushrod at 90 degrees To that thought you can play with the mounting point of the bottom of the shock to place that angle close to 90 degrees. Then, while you are designing, have a look at the camber line through the travel movement. Trying to maintain a similar camber plane from the top, to bottom of suspension travel. By the way, nice solid works. I had to do it with a pencil, dividers, and a calculator. I guess you next step will be to deal with your bump steer and the old Ackerman thing.

AL :chev:

charlesshoults · **Posted:** Sat Sep 24, 2011 5:49 pm

I'm not totally sure what the angle is right now. I'll need to add a drawing layer to see. At full compression, it's a bit more than 90, but at full droop, it's somewhat less. I changed the angle of the upper tube from 16 to 18 degrees and am closer to where I want to be. Droop and rise are nearly equal now. I'm thinking of increasing the upper bar angle to 20 degrees to see if I can reduce droop a bit. That will also produce a bit more rise, which in the end, I can probably limit with a bump stop.

I'm going to add a drawing to place an arc for the upper and lower control arms range of travel, then a line between the pivot points of the ball joints (lower tie rod end eventually to be replaced with a bolt-on ball joint). That should help me identify and adjust camber.

I'm reading "Competition Car Suspension Design, Construction, Tuning" by Allan Staniforth. I can't say that I totally understand Ackerman angle yet, but it's barely been touched upon. I know what bump steer is with a solid front axle on the Jeep, but I'm not sure how it works on an IFS vehicle, or how to account for it.

charlesshoults · **Posted:** Sat Sep 24, 2011 8:39 pm

I'm playing with angles for the lower shock mount. I can pivot the mount about the rail it's attached to, and I can move the rail inboard and outboard as needed. The suspension has the best mechanical advantage when the shock is 90 degrees to the direction of force. If force is applied and the angle moves away from 90 degrees, the force necessary to compress the shock a given amount is reduced because some of the force is translated into angular movement. But, if the resting point is somewhat less than 90 degrees and force application causes the angle to increase to 90, then the suspension feels softer at first and progresses up to the rated weight of the springs.

I can align things so that ride height is 90.19 degrees and at droop and again at compression, the angle is within 11 degrees, but I don't think I really like that. It seems like it would be better to have 90 degrees as close to full compression as possible and be further off at full droop.

Benonymous · **Joined:** Thu Jul 21, 2011 2:25 am **Posts:** 6

Have you considered that your "pushrod" is going to have a very large amount of bending stress on it? From the design, the tube itself is going to act like a spring too. If you're going to cantilever the shocks in this fashion, you'll have to make a triangulated structure to take the load I think. The earlier Staniforth book "Race and Rally Car Source Book" shows some cantilevered designs and they are very stiff in bending as I recall.
Something like this (quick and dirty in SW)

Just my .002c

charlesshoults · **Posted:** Wed Sep 28, 2011 2:47 pm

I started making some changes last night, but nothing nearly as complex as what you show. I've been going off the idea of the Factory Five '33 Hot Rod front control arms. I still have to redo the trailing link. I think the plate for the lower control arm needs some work too.

charlesshoults · **Posted:** Mon Oct 03, 2011 9:40 pm

My frame layout is starting to look a bit better. The front suspension is more or less worked out, although I need to finish the attachment points for the uprights. Steering will be behind and high. I'm reading that ideal placement would put the pivot points for the rack and pinion inline with the frame mounting points for the wishbone. If that's the case, I may need to make a few more adjustments. Radiator will be in front, and there should be plenty of space for the engine. The rear axle is kind of cramped. They can't be seen here, but I moved the attachments for the upper wishbone as far forward as I could to allow space for the coil-overs. The upper shock mount will be under the steel plate the roll bar is attached to and the lower mount will be on the rear edge of the lower wishbone. I tested the fitment of a pair of Ricardo racing seats and they were huge. They took up all available space plus half the transmission tunnel, and were a good ten inches higher than my roll bar. My roll bar is still a little short, about 28". I'm expecting to raise it another 4-6".

My design is not quite a standard Seven. It's going to be a wide body, and not as low as some I've seen, and have a fair bit in common with the Jaguar C,D,E-Type cars. The center section of the body will hopefully be the easiest to do. Made from aluminum, it will have a vertical flange that attaches it to the chassis, then horizontal out for the bottom of the car, then with a radius then more or less flat to at least the height of the middle of the door. My design will not be literal Jaguar anything. I'm working on some ideas of my own. The exhaust will come out of the engine bay behind the front tires and into the void created by the aluminum wrap, down the side and exit in front of the rear wheels. The C-Type had the exhaust running down the passenger side, while the drivers side had the battery, spare spark plugs and a compartment that could be used for a variety of things. The aluminum pods add a good bit of shoulder room to the outside as well.

The horizontal bar behind the seats is measured as 20" on center from the floor tubes. The space between has been opened up to allow pass through access to the trunk if needed. The differential is less than an inch below where the aluminum plating will be. The tail will be a good bit longer than a Locost, to allow for a fuel tank to sit as low as possible. The center of the tubes gives the frame a 46" width, with a true frame width of 47.25". Given the width of the wheels and the aluminum body taking up the space to just past the wheels, I'm looking at an overall width of about 65". Wheelbase is 96", and I'm hoping that overall length is no more than 150". The first Dodge Viper had a 96" wheelbase and an overall length of 175", but it had a big rear end. Corvette and even the 2011 Mustang are even bigger.

horizenjob · **Posted:** Tue Oct 04, 2011 12:27 am

Remember you need strong brackets for the front upper wishbone, because the inboard spring doubles the load.

Your rear suspension loads go into the frame behind your shoulders, but that is connect tot he rest of the car with those low side tubes that are curved. The engine bar looks a little weak near at the top rail, but I don't know how big that tube is. This is a big engine so it's probably hard to do bracing.

charlesshoults · **Posted:** Tue Oct 04, 2011 11:11 am

Double load for the front wishbones, I was not aware, but that does make sense. I'm thinking that wherever possible, my suspension mounting tabs will be sort of a twisted H shape so that they have tabs that are welded to the tubes on three sides instead of being welded just on one. I've been planning for them all to be 0.12" thick.

For the rounded tubes at the rear, I had clipped the corner of the cab and put in the rounded tubes to try to have a little better clearance for the tires, but that didn't work, so I may go back to a square corner.

The engine bay definitely needs more than what's there, but until I can get to Grand Junction to pick up the block and work on building the engine, it's hard to say what the bracing will look like.

I may find myself needing custom length axle shafts to get tires to clear the cockpit sides.

charlesshoults · **Posted:** Thu Oct 13, 2011 10:28 am

Quote:

This thread is really two threads, Charle's frame design and the brazing / welding stuff. If Charles doesn't mind I think we should split it at some point?

I'll make a couple of more comments about Charle's frame project. First, I am not sure that a Maserati birdcage is a reasonable project for an average home builder. It doesn't strike me as an entry level project to design yourself, or to do all the work to carry it off. I'm glad your starting to get serious about the FEA, because that's what you need to do to give yourself the education to do this. I hope that your software package will be able to carry this off, because I think you can see that enering the table of numbers to describe every joint in 3 dimensions is a lot of work. The more tubes the more work :shock:

So one thing is that space frames and ladder frames are different. That means that the black tubes would be the heavy ones in a ladder frame, but not a space frame. The big loads are in the top of the frame. Everything is hanging off those tubes and they are in compression. When you choose size for tubes in compression, you need to consider how slender they are. A tube in tension can be any length and be the same strength. A tube in compression gets weaker according to it's length in a very complex way, because buckling is a complicated thing. This has been discussed at length here in a thread by aero_bro. If the tube is more then about 30-40 times it's width long, you need different math to calculate it's strength. You need to know what the compression load is on every tube in the car. At least to some degree. This is actually why it looks like a birdcage!

You need a load path from the front coilover to the rear coilover. The cockpit is a difficult area for this, especially with regards to making it stiff to twisting. Perhaps you can post a picture of a birdcage frame for us to refer to. Most space frames make obvious efforts in this area.

It will be difficult to put a real ( that is spec. ) roll bar into this type of frame because what do you connect it to? A bunch of 1/2" tubes? There can be real devils in this area - the original probably didn't have much.

I've become a firm believer in building a spec ( SCCA or NASA ) roll cage and then connecting the rest of the car and frame to that. It's not a Birdcage Maserati, but it's safer, doable and you can drive it on a track. There's a whole world of bodywork you could put on that.

I agree. The design and construction of a birdcage has little to do with the differences between welding and brazing, other than the fact that the birdcage was. Sort of. I don't have a new picture of my project, or the potential frame I'll be building but it's sitting at home right now rendering one.

charlesshoults · **Posted:** Thu Oct 13, 2011 12:39 pm

I don't really know what my problem is. I got the Lotus Seven chassis to a point where I considered it more or less complete, where I could have started building it. I started working on suspension parts and had to change the chassis a bit. I found that with some minor differences, the chassis used for the Jaguar C-D-E are pretty close to the Lotus Seven. Wanting to build a car primarily to be used on the street, I started working toward a wider chassis. Most cars look like they have a face, Jaguar sometimes more so than others. The C-Type seems to have a permanent sense of surprise or disgust. http://battletechlive.files.wordpress.c ... c02593.jpg The D-Type, while it has a nice overall shape, looks like it's in a state of shock, as if you just ran over it's best friend. http://battletechlive.files.wordpress.c ... pbc_01.jpg The E-Type, and the Eagle e-type Speedster has a better look. It looks more like it's yelling than screaming. http://battletechlive.files.wordpress.c ... ster-1.jpg But I'm not sure if I'm all that pleased with the styling of the Jaguar. That's when I started looking at the Maserati birdcage. The exterior styling of the car looks mean and pleasant at the same time, but we've seen that the chassis overall is kind of a mess.

I started to make tubes for the birdcage heavier in an attempt to increase the durability of the chassis for road use, but quickly doubled the weight. After stretching and widening the chassis for a V8 and Thunderbird running gear, adding a transmission tunnel and trimming all of the tubes, I'm up to 170 pounds, which might be a bit much. A few days ago, I stumbled across a build log of a couple guys building a Maserati 450S replica. The 450 went a very different direction from the birdcage, as shown in the first picture below. Far fewer tubes, and the tubes are heavier. It's more of a ladder frame with lightweight tubes welded to it. I have a large number of pictures below, in no particular order, but a chassis like they've produced here does look a lot more manageable than a birdcage chassis, and the aluminum body they produced is gorgeous.

cheapracer · **Joined:** Wed Nov 12, 2008 6:29 am **Posts:** 2592

charlesshoults wrote:

I don't really know what my problem is. I got the Lotus Seven chassis to a point where I considered it more or less complete, where I could have started building it.

Lots of creative minds share the same problem, choice is fun.

However, a Locost is well proven from design to resale value, for the first time worth sticking to it and do something else on your second attemp if you get there.

charlesshoults · **Posted:** Tue Oct 18, 2011 12:43 pm

I'm looking at engine choices and found one thing kind of odd. I realize that cost is a function of demand, but still.

Duratec 2.5L engine from a 2010 Ford Fusion with 14,000 miles - $1625.00
Duratec 3.0L engine from a 2009 Ford Escape with 12,000 miles - $1093.00
Duratec 3.5L engine from a 2007 Lincoln MKZ with 15,000 miles - $450.00

How good is aftermarket support on engines this new? Summitracing has 234 parts available for the Lincoln MKZ but only 13 of those are engine parts and those are limited to oil filters, pulleys and belts. Basically consumables. How does a person rebuild an engine like this? Do you have to get all of your parts from Ford?

charlesshoults · **Posted:** Thu Oct 20, 2011 11:38 pm

Ok, back around to the idea of a relatively straightforward Locost design. Almost. I'll show what I've got so far, and I have some suspension questions. Shown below, I've kept a 96" wheelbase and a 61" track width front and rear, although I have pushed both axles back a bit to give some space between the passenger compartment and the rear wheels. I've also widened and lengthened the engine bay a bit. The foot box is 13" wide at it's narrowest point and I'm hoping that's enough for size 8 shoes. You see a rail that runs along each side. This is at door sill height, 9" above the floor and gives a bit of side protection, as well as a place to rest the arm. The rear end angles up six degrees and the radiator support will angle up five degrees. The 442E had the frame height at the bulkhead at 11". I have raised mine to 15" and have it sloping down toward the nose. Constructed primarily of 1" square tube, there is a bit of 7/8" tubing and some 3/4".

Suspension questions. For the front end, the upper ball joint should be behind the lower ball joint to create caster. While the ratio of upper to lower wishbone length should be about 2/3, they should be positioned in such a way that about 1/3 degree of camber is gained for each inch of suspension travel, if I remember right. Now, are the rules for the rear the same? Should the upper be behind the lower? Same 2/3? Same camber gain? To maintain the 96" wheelbase, my rear wishbones are a bit odd. The lower has the front leg longer than the rear in order to move the ball joint pivot back and my upper's don't have a great deal of space at the moment. The upper ball joint location is almost inline with the rear leg of the upper wishbone. I don't think I like that very much, so I've got some work to do. From inner pivot to outer pivot, the lower wishbones are 18" long and the uppers are 12". I'm also wondering how close to the centerline of the wheel the ball joint pivots should be. The rear wheels of course won't be steering, so there will be an adjustable link forward of the ball joint for setting toe and correcting for misalignment. I've not settled yet on the type of ball joints to use, whether a bolt-on style or the style that fits inside a ring. My Jeep uses the ring style and I need to replace a couple, so I'll do that and see what I think of them, but the bolt-on style might just be easier to work with.

The front end is not designed yet.

charlesshoults · **Posted:** Mon Oct 24, 2011 9:26 pm

This evening, I replaced the radiator in my Jeep to much irritation. I noticed a leak a few weeks ago and have been losing about 1/2 jug of antifreeze each week. The radiator came in today, so I got to work before our expected snow storm tomorrow night. I learned a few things in the replacement. First, the plastic fittings used for 'quick disconnect' points on transmission lines and such, really suck, especially when you don't have the tools for separating those kinds of joints. I collected almost all of the antifreeze in a plastic bucket, separated the transmission line further toward the engine and removed the short section of line with the radiator. I tried pinch and pull, thin screwdrivers in the gap, more pinch and pull and cussed at it a bit. I thought about replacing the section with a piece of 6AN Aeroquip. I found my stainless braided line, but none of my fittings, so I went back to cussing at the line. I hunted around my garage for anything that I could think of to make an improvised tool and found a roll of copper strap. I cut a small piece and bent it into a sleeve that I then shoved into the gap between the brass hard line and the fitting. With a bit of shoving and pulling, I managed to get it to release. Putting the new radiator back in wasn't so bad, except for one or two screws that really didn't want to line up. In the end, it took me just under 3 hours to finish. The lower radiator hose is truly a bugger to reconnect.

I poured as much antifreeze as the radiator would hold directly into the radiator, then put on the cap and filled the overflow bottle. I started the Jeep and let it run until it stopped producing bubbles, but I estimate that the system was still holding about a liter of air. I shut it off and came back inside to scratch my head. 15 minutes later, I went back outside to check on it and maybe try squeezing the upper radiator hose to see if any more bubbles came out and found that the engine had drawn almost all of the coolant from the overflow bottle into the coolant system. I poured the rest of the antifreeze into the overflow tank and added a bit more from a fresh jug and so far it seems okay. I'll watch it for the next several days to make sure I don't have any further leaks.

LocostUSA.com

Project: Dodgy Locost (360 LA +442E)

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