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'wittle 'wesistor (Mini Jeep)

6924 Views 152 Replies 6 Participants Last post by  remy_martian
For my next creation, I've been thinking about building a go kart sized jeep (mini-Jeep)
...but first, here is some Jeep info.

"The Jeep marque has been headquartered in Toledo, Ohio, ever since Willys–Overland launched production of the first CJ or Civilian Jeep branded models there in 1945. Its replacement, the conceptually consistent Jeep Wrangler series, remains in production since 1986. With its solid axles and open top, the Wrangler is the Jeep model that is central to the brand's identity.

At least two Jeep models (the CJ-5 and the SJ Wagoneer) enjoyed extraordinary three-decade production runs of a single body generation.

In lowercase, the term "jeep" continues to be used as a generic term for vehicles inspired by the Jeep that are suitable for use on rough terrain. In Iceland, the word Jeppi (derived from Jeep) has been used since WWII and is still used for any type of SUV.

Prior to 1940 the term "jeep" had been used as U.S. Army slang for new recruits or vehicles, but the World War II "jeep" that went into production in 1941 specifically tied the name to this light military 4x4, arguably making them the oldest four-wheel drive mass-production vehicles now known as SUVs. The Jeep became the primary light 4-wheel-drive vehicle of the United States Armed Forces and the Allies during World War II, as well as the postwar period. The term became common worldwide in the wake of the war. Doug Stewart noted: "The spartan, cramped, and unstintingly functional jeep became the ubiquitous World War II four-wheeled personification of Yankee ingenuity and cocky, can-do determination." It is the precursor of subsequent generations of military light utility vehicles such as the Humvee, and inspired the creation of civilian analogs such as the original Series I Land Rover. Many Jeep variants serving similar military and civilian roles have since been designed in other nations.

Development – 1. Bantam Reconnaissance Car
When it became clear that the United States would be involved in the European theater of World War II, the Army contacted 135 companies to create working prototypes of a four-wheel drive reconnaissance car. Only two companies responded: American Bantam Car Company and Willys-Overland. The Army set a seemingly impossible deadline of 49 days to supply a working prototype. Willys asked for more time, but was refused. American Bantam had only a small staff with nobody to draft the vehicle plans, so chief engineer Harold Crist hired Karl Probst, a talented freelance designer from Detroit. After turning down Bantam's initial request, Probst responded to an Army request and began work on July 17, 1940, initially without salary.

Probst drafted the full plans in just two days for the Bantam prototype known as the BRC or Bantam Reconnaissance Car, working up a cost estimate the next day. Bantam's bid was submitted on July 22, complete with blueprints. Much of the vehicle could be assembled from off-the-shelf automotive parts, and custom four-wheel drivetrain components were to be supplied by Spicer. The hand-built prototype was completed in Butler, Pennsylvania and driven to Camp Holabird, Maryland on September 23 for Army testing. The vehicle met all the Army's criteria except engine torque.

Development – 2. Willys and Ford
The Army thought that the Bantam company lacked the production capacity to manufacture and deliver the required number of vehicles, so it supplied the Bantam design to Willys and Ford, and encouraged them to enhance the design. The resulting Ford "Pygmy" and Willys "Quad" prototypes looked very similar to the Bantam BRC prototype, and Spicer supplied very similar four-wheel drivetrain components to all three manufacturers.

1,500 of each model (Bantam BRC-40, Ford GP, and Willys MA) were built and extensively field-tested. After the weight specification was revised, Willys-Overland's chief engineer Delmar "Barney" Roos modified the design in order to use Willys's heavy but powerful "Go Devil" engine, and won the initial production contract. The Willys version became the standard jeep design, designated the model MB, and was built at their plant in Toledo, Ohio. The familiar pressed-metal Jeep grille was a Ford design feature and incorporated in the final design by the Army.

Because the US War Department required a large number of vehicles in a short time, Willys-Overland granted the US Government a non-exclusive license to allow another company to manufacture vehicles using Willys' specifications. The Army chose Ford as a second supplier, building Jeeps to the Willys' design. Willys supplied Ford with a complete set of plans and specifications. American Bantam, the creators of the first Jeep, built approximately 2,700 of them to the BRC-40 design, but spent the rest of the war building heavy-duty trailers for the Army.

Final production version jeeps built by Willys-Overland were the Model MB, while those built by Ford were the Model GPW (G = government vehicle, P = 80" wheelbase, W = Willys engine design). There were subtle differences between the two. The versions produced by Ford had every component (including bolt heads) marked with an "F", and early on Ford also stamped their name in large letters in their trademark script, embossed in the rear panel of their jeeps. Willys followed the Ford pattern by stamping 'Willys' into several body parts, but the U.S. government objected to this practice, and both parties stopped this in 1942.

The cost per vehicle trended upwards as the war continued from the price under the first contract from Willys at US$648.74 (Ford's was $782.59 per unit). Willys-Overland and Ford, under the direction of Charles E. Sorensen (vice-president of Ford during World War II), produced about 640,000 Jeeps.

Jeeps were used by every service of the U.S. military. An average of 145 were supplied to every Army infantry regiment. Jeeps were used for many purposes, including cable laying, Sawmilling, as firefighting pumpers, field ambulances, tractors, and, with suitable wheels, would run on railway tracks."

I came across this drawing
...& it seemed like a pretty good guide

So, I'm thinking maybe ~50% should work for a mini jeep, I'll just have to calculate a ~2:1 reduction ;)

Wheel Tire Wood Font Rectangle
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Discussion Starter · #101 ·
Did anyone notice that the front upper shock mount only has (2) bolt holes?
...& not (4) like the rear
Bicycle tire Bicycle Bicycle frame Wood Vehicle

It's because, the (4) level selectable "lift" concept could not be used (on the angle) in the front (like in the rear) due to the shocks hitting/clashing with the axle tube
...& having the (4) holes horizontally, didn't effect the height very much

A solution (many Jeeps use) would be to make a couple of "modified" lift pieces (upper shock mounts & shackles)
...but, they would probably be height specific (meaning a different set of brackets would be needed, for each height)
Font Parallel Handwriting Rectangle Wood

I'm not "messing" with this, (for now) I just wanted to mention it, before moving on ;)

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Discussion Starter · #102 ·
Design Evolution
In the first designs, that I drew up of this mini-Jeep, it was to simply have dual (1) piece curved Trailing Arms.

The idea was just to give it some suspension, that kinda look like leaf springs.
Aircraft Vehicle Line Parallel Airplane

Then, the front Trailing Arm evolved into individual Trailing Arms (to aid articulation)
...then, (with Brians help) the front individual Trailing Arms evolved into individual Leading Arms

Now, (with the "break" in the middle) we have IMO a custom front suspension that looks like a Jeep
...& may even have a bit of articulation to it, like a Jeep :)
Bicycle handlebar Gas Drinkware Wood Bicycle part

* Trying different options, it's looking like having the steering linkage (tie rod) in front of the axle (with the Spindle Arms "leading") will work out better (for suspension travel clearance & for steering shaft attachment)

** Also, notice I'm using CAD to mock a floorboard ;)

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Discussion Starter · #103 ·
We now have what would be referred to, in the go kart world, as a "roller" (just a frame with wheels), I've been "knee deep" in CAD (Cardboard Aided Design) working on a/the body ;)

Design Options
Flat sides or a couple of transitions

Here is what the floorboard would look like if we went with just "flat" sides
(The side body panels, would pretty much just be flat, all of the way from the front to the back)
Wood Rectangle Flooring Composite material Hardwood

Here is another view (from the front of the vehicle) of the "flat sides" floorboard concept
To elaborate, the floorboard has flat sides
...then, the inner fender curve to meet the body
...& then the sides would just go straight back
Wood Floor Flooring Wood stain Hardwood

Here is a view of the transitions concept
The floorboard has flat sides
...then, the inner fender would curve slightly
...& flattens out, in the cowl area
...then slightly curve again, to meet with the body
...& then, it's pretty much straight back
(kinda like this)
Tire Wheel Automotive tire Tread Wood

Another view (of the 2 options) from the rear (transition on the left & flat sides on the right)
Wood Automotive design Automotive tire Automotive exterior Floor

Side view, of the flat side concept
* Notice how the side would be just totally flat, from the front wheel well to where it curves the rear
Tire Wheel Vehicle Automotive tire Motor vehicle

...& another view
Wheel Tire Automotive tire Vehicle Tread

IMO the flat side concept would be easier to do (accomplish)
...but, I think we're going to try to do a couple of transitions :)

It's kinda starting to look like a Jeep :cool:

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Discussion Starter · #104 ·
Some may ask, "Why ya workin on the body already?
...ya ain't even got the steering assembly done yet."

Well, it's because "the foot bone is connected to the leg bone" if ya know what I mean. ;)
...& we can't advance on the steering until we know where the upper steering will mount
...& we won't know where "that" is, until we establish a/the dash bar
...& we can't establish the dash bar until we know where the cowl will be
...& so, we need to work on the body :)
Wheel Tire Hood Automotive tire Tread

The dash bar is/will be the "main mast" that supports, the upper body
...& also, a place to mount the upper steering bushing
but, & also,
I was thinking, if strategically positioned, inside/under the front edge, of the cowl will provide a good-n-strong place to mount the hood hinges
...& the windshield hinges too:cool:

* Notice the body side transitions? (flat-transition-flat-transition-flat)(y)

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Discussion Starter · #107 ·
The cowl is/will be wider than the frame rails are, the sides of it should extend down to the floorboard
...& then, angle/come inwards, to intersect with the frame rails

Dashbar (V1)
This version seemed like at the bottom, where the bars angles inwards, it would intrude into the foot area too much
Brown Handwriting Rectangle Font Wood

Dashbar (V2)
This version wouldn't intrude into the foot area
...but, IDK, I just wasn't "feeling it"
Brown Handwriting Rectangle Font Tints and shades

Dashbar (V3)
This version is nice-n-simple
...& will just need a couple of extensions added, for mounting to the frame rails
Handwriting Rectangle Font Material property Tree

Nerf Bars
Nerf Bars have been added to Jeeps to provide additional side impact protection
...& as "step bar" to help folks get into the vehicle when they have "lifted" bodies/suspensions

They also, provide "slide protection" for if/when "off roading"
...&/if the vehicle slides sideways, down an embankment, the Nerf Bars help protect the body from tree trunks, boulders etc.

So, I'm thinking adding Nerf Bars will enhance the "Jeep look"
...& give me a good-n-secure place to mount the dashbar.

Kinda like this
Ring binder Rectangle Font Triangle Handwriting

So, I incorporated them into the design & added some Nerf Bars
Wood Gas Table Wood stain Automotive exterior

Mock'ed up the Dashbar (nice-n-square)
Wood Tool Gas Automotive exterior Bumper

Wood Table Floor Flooring Gas

...& tac'ed in place
Wood Floor Flooring Hardwood Gas

* I even deviated from the "scale" a little bit (for my buddy Remy) :cool:
...& made the dashbar height, an extra ~2" higher (~17") ;)

** It was supposed to be ~14" at the bottom
...& ~15" on the top (y)

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When you do that, check how compressed the bushings are. With one side full up, your "leaf spring" mounts get a fair bit shorter on the transverse axis...

You'll have a tradeoff there on stability and dynamics during turns, vs articulating without binding, possibly needing an arm from axle center to the frame. I think I mentioned this before.

Looks good though...

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Discussion Starter · #112 ·
When you do that, check how compressed the bushings are. With one side full up, your "leaf spring" mounts get a fair bit shorter on the transverse axis...

You'll have a tradeoff there on stability and dynamics during turns, vs articulating without binding, possibly needing an arm from axle center to the frame. I think I mentioned this before.

Looks good though...
Hey Remy,
Thanks! :)

Yup, we previously discussed the possibility of needing a Panhard Bar
...but, thinking about it, I cannot remember ever seeing one on a Jeep like this before (& I've towed a lot of Jeeps), we'll re-address the issue "if" it becomes an issue (y)

* I'm mainly building a piece of Functional Art to "run" in our yearly local Jeep Fest parade :cool:
...not really for intense off-roading (but, ya should know, I'm going to do some "testing") :p
...& I'm just trying to incorporate as many Jeep-like features as possible
...& also, using my mini-Jeep as a "vehicle" to demonstrate some DIY building techniques for you'all ;)

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5,397 Posts
Glad you're being a sport about "our" inputs and critique 😛

Yes, it should be a fairly easy retrofit if there's no binding right now, and your bushings aren't being severely compressed, during articulation.

Yup, picking up a lot on methods and techniques. Thanks for sharing your bag of tricks here. Even if it inspires one kid to get off a Nintendo and build one, it's a raging success, imo.

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Discussion Starter · #114 ·
Hey Remy,
Your very welcome.
I enjoy sharing ;)

I agree 100% (video games & smart phones SUCK, in that regard) :mad:

Here is what she looks like with the Nerf Bars
...& the body side (with transitions)
...& the cowl (with the dashbar underneath)

* Notice how the Nerf Bar can/will act as a step too (just like on a full size Jeep)
Purple Wood Flooring Hardwood Space

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Hey Remy,
Thanks! :)

Yup, we previously discussed the possibility of needing a Panhard Bar
...but, thinking about it, I cannot remember ever seeing one on a Jeep like this before (& I've towed a lot of Jeeps), we'll re-address the issue "if" it becomes an issue (y)
Jeeps with actual leaf springs do not need track bars and most YJ's that came with them from the factory end up with them in the scrap pile because they inhibit articulation. TJ and newer jeeps with coils do require them to locate the axles laterally. There is nothing else to keep axle centered

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Discussion Starter · #120 ·
This is not a Jeep and the lateral stability of leaf springs is gone in this build. What he's doing may be ok for a low speed toy, so not a problem.

I have yet to see a leaf spring car with a Panhard bar.
Hey Remy,
"This is not a Jeep", it's a mini-Jeep ;)

I remember changing the Panhard bar bushings on the front of some of our (early 2000's) Ford F550 tow trucks & flatbeds (& they had leaf springs) in an effort to eliminate the re-occurring "Death Wobble" (didn't help) :mad:
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