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Here’s the build thread for one of my current projects, a 1/24 scale RV Conversion based on a Peterbilt 379. 

Imagine taking a retired truck and building your dream RV from it?

This build will be mostly custom work, just like the real thing. These rigs don’t roll out of the ‘ol Winnebago factory…and you find models like this in a kit, either. 
IMG_8996.jpeg.5e88eec8a4efa6c5f4a4118b674d3ea6.jpegInspiration for this project came from rigs like this, (though the one above is a 389) where a used or factory-fresh commercial class 8 chassis is stretched and a coach body is added, creating the ultimate RV.

The ultimate RV starts with the ultimate engine. Some may argue differently, but I think Cat’s 3406e from the late 1990’s is the finest example of diesel power, especially when it’s been decked out in aftermarket chrome and ceramic performance parts.

I started with a resin Cat 3406E from Jamie at Moluminum. I detailed it using Ken Smith’s Car Modeller article on Fotki. I used 3d printed elbows from modelbuildermatt on Shapeways and metal fittings from Detail Master.IMG_5667.thumb.jpeg.dea640c97ef849258c8a3fb277a4d534.jpegIMG_5668.thumb.jpeg.ce3553bd6fdd95f3b3f4f89808bee1f4.jpegIMG_5669.thumb.jpeg.4f8482f7d4c16052ecc6e3f1e38ae755.jpegIMG_5671.thumb.jpeg.b91a6d89aaf3826ac25e26bc334403f9.jpeg

Several engine components were scratch-built. The 18 speed Eaton Auto-shift transmission came from Moebius, with a lot of detail parts added using reference photos. IMG_5717.jpeg.1ffdfe19c4927a04b28b7aac873dacc2.jpegIMG_5781.thumb.jpeg.0bc7f0f4508b47343d4338527cf5f6cb.jpeg

Jamie’s casting didn’t include the 3 dimensional “CAT” logo on the chrome timing cover, but I added one using a casting of a Cat lapel pin I found on EBay that was the perfect size. I’m not a pro resin caster by any means, but I’ve found casting small, very simple parts, to be useful in this project.IMG_8997.thumb.jpeg.dcfebfa522df5efcc2254a9d124c7ace.jpeg

IMG_8999.thumb.png.d6e2c60d794157cc80ee1635dd1dc136.pngIt took me several attempts to get the valve covers looking good. I finally found putting Molotow down first, then adding the black in the recessed areas via a Molotow black pen was best. Careful painting of the red stripe and a triangle-cut of a yellow decal finished the iconic look of the Caterpillar 3406e’s valve covers.IMG_8998.thumb.jpeg.48097951a0cee3f3ff7aa2b136fb5f9f.jpeg I also put together a simple engine stand using square styrene tube. I still use it for other engines that are waiting to be installed in the next chassis.

That’s the basic engine so far, more about the other engine components when we get to the chassis installation. Ask questions, I’m sure there’s explanations I missed.

Next, let’s get the frame rails laid down…

Edited by vincen47
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Next up is the chassis. I wanted a strong frame, as this is a big model. I scratcbuilt the frame rails with styrene strip/sheet and added brass angle to the inside. IMG_6779.jpeg.b93092e0028d12d77e50bbd514bdc175.jpegThe frame rails are thicker than the Italeri ones, so I had to modify the ends of the Italeri 378 crossmembers to fit. I then began work on the front axle and suspension. I wanted to model an air ride front axle with a 16k capacity. IMG_6839.thumb.png.607c284cd83dd874f22831d106747958.pngAgain, this model represents a retired Pete 379 that’s been retrofitted with a heavier axle and aftermarket suspension during the conversion to an RV.IMG_6911.thumb.jpeg.ad281b1f8bd6057a3fc5cac1bdb04637.jpeg

I used brass for the single leaf spring, auslowe air bags and components from the parts box, along with parts from a glue bomb Italeri 378 - Used parts getting a new lease on life, just like the real thing.IMG_6910.thumb.jpeg.ca64cbc990fad7cec6623016f38a4ab1.jpegIMG_6912.thumb.jpeg.86493fd5746e34d0925d25c0b9474c15.jpegIMG_6921.thumb.jpeg.e88b80a17322d94bdebad5e06f735216.jpegIMG_6922.jpeg.822c80736102ce0f00fab78d7c6b54e7.jpeg

Here you see the shocks in a slightly different position. I changed the angle later on. Spring hangers are from the Italeri kit. On the theme of a sturdy frame, I added a metal front axle from Auslowe.

For the rear axles, I cut off the ends and I carved out the inside a little to be able to insert metal tubing to make them stronger.IMG_6864.thumb.jpeg.152ab369f90417d9794e1721d794b0c7.jpegIMG_6865.thumb.jpeg.21644792368cdfad76560d7d588b97a3.jpeg

I cut the tubing to match the width of the original kit parts.


Edited by vincen47
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Now onto the rear axles, suspension, hubs and brakes. The main chassis color is Tamiya Semi Gloss Black.


The rear axles needed a sleeve of wider tubing to fit the wheel hubs. The beautiful real aluminum hubs are from M&R Wheels. Highly recommended. I got them to go with the Keystone Aluminum Peterbilt Alcoa wheels, which are fantastic, but didn’t come with hubs with a socket for the axle stubs. More about the wheels later. IMG_7026.thumb.jpeg.b6c954a35cea93bdfc4e7cb8430e5186.jpeg

I added resin Bendix Air Disc Brake assemblies from Moluminum. Drilled them out to fit over the hub axle mounts.IMG_7027.thumb.jpeg.87ddba0789bea57d7ab66e0c4a106edf.jpeg

I included air lines to the brake chambers, and ran the lines up to the frame rails. I didn’t bother running lines further than that, because, well, none of this will be seen on the completed model. The frame rails are devoid of bolt detail for the same reason.

In fact, on the rear axles, all you’ll see is the outside wheels and tires. But, I guess I know the brakes and lines are there and that’s what matters.IMG_7030.thumb.jpeg.2ae36283f3be83fae3921021a5eef808.jpeg Much of this project has been striking a balance between the sane and crazy, right? 


The front axle has disc brakes, too. I painted and decaled the shocks to represent Bilstein commercial truck/coach shocks.IMG_7031.thumb.jpeg.3fb415c6ec525f8c4fb3340c8f423ede.jpegIMG_7032.thumb.jpeg.8b4c17745f8afbdfef892ef739d5debf.jpeg

The front brake assemblies were also run with lines, along with the air bags. Air Bag Levelers were added using bits from the parts box. These details make more sense because they will be seen when you tilt the hood.

The air lines to the bags are braided line from Detail master with their fittings connecting to the mounts and to the frame rails. The resin air bags are painted in Tamiya rubber black. I opted to go with solid bags rather than rubber ones because of the potential amount of weight they’ll need to support. Also, the hubs are fixed in place, not enabling the model to roll, though the front axle steering is functional.IMG_7095.thumb.jpeg.417850b4eafa9c99a8b3334ad4a02ce7.jpeg

Edited by vincen47
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Wheels and Tires…

Most 1:1 RVs of this size are running 315 (or larger) tires, especially in the steer position. The hobby market, in my opinion, is lacking in accurate big rig tire offerings - don’t get me started on the generic junk that comes in kits that really look like 1:1 all-position retreads more than anything else…

So, I searched for a while looking for detailed, modern tires that would be accurate for the build. A&N Resin came to the rescue when they introduced the perfect tires - Michelin X-Line Energy Z Coach 315/80r22.5 Steers and X-Works 315/80r22.5 Drive tires. Incredibly detailed.


At first, I was disappointed they were hard resin, but that turned out to be a blessing as they’d support the weight. I now prefer hard resin tires. Painted with Tamiya Rubber Black, they look the part. 

The wheels are real aluminum Peterbilt Oval Alcoas from Keystone Aluminum Model Miniatures. Unfortunately, he’s no longer around, but M&R offers great ones, too.


The rims fit the M&R hubs perfectly. However, the A&N tires had to be sanded out larger to accommodate the one-piece wheels. Not a fun thing to do. I used sand paper wrapped around a broom handle, gradually adding layers of paper. 10 tires took a while, as you can imagine.


I detailed them by adding Acorn nuts from Keystone, Alcoa decals from Model Truckin’ and scratch-made valve stems from Detail Master #1 line and fittings. Tedious, but worth it.


I don’t think I took any photos of the rims before I mounted the tires. Wish I had.


The outside wheels have inside-facing  valve stems, just like they should, but pardon that dust on the rims in the close up.


The tread and sidewall detail is fantastic on these tires. They are geared towards the Euro truck market where it’s more common to run 315s in line haul service, but it’s great having the option here in the U.S. for a unique build like this one.

A&N also offers heavier tread pattern 315s, along with 385s for highway tread steer, heavy tread steer, and drive treads, for your North American fire, construction, and logging equipment needs. They also have resin wheels designed to easily fit their tires.

Edited by vincen47
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Posted (edited)

Now that we have a rolling (non-rolling) chassis, time to install the engine and add the radiator and charge air cooler. 

IMG_7105.thumb.jpeg.f0e909b6142e0e624cbfd433553b56de.jpegIMG_7108.thumb.jpeg.3090b593c73fad056cef106e061aea86.jpegIMG_7111.thumb.jpeg.fb4b7098f6d1030fde3bd0dd974447c2.jpegIt’s a squeeze, but she fits. There’s a lot of extra parts adding to the overall engine width, like the serpentine bracket, so I made sure to measure and test fit beforehand.

IMG_9063.thumb.jpeg.f7e6e75f3781e121e66d456731d4d129.jpegTo connect the driveline, I made three driveshaft carrier bearings from styrene to keep each driveshaft section a realistic scale length. 

Onto the CAC:

IMG_7122.thumb.jpeg.fee470ee9165c1784d47dd39139d5fb6.jpegThere’s certainly a void in the aftermarket for a proper charge air cooler/air to air aftercooler. Italeri tried, somewhat, to have one on the Series 60 in the 378 kit, but it leaves a lot to be desired. I used the Italeri kit parts as a basis for creating an aftermarket CAC in the style of a Duralite unit.

IMG_7146.thumb.jpeg.2b7c3a34e6a45723b830a9d4c0bf34d9.jpegI added photo etched radiator mesh and modified the side of the kit radiator, carving out some plastic and folding in the outside edges. Then, I added styrene sheet, aluminum tube, and putty to create the overall shape needed. The 378 kit’s radiator coolant reservoir was added to the top at this point, but I will replace it later with a better version. 

IMG_7156.thumb.jpeg.a564ec8e961dbd0869714649c12fb86c.jpegIMG_7157.thumb.jpeg.b256c3a98110bdd552fc253530228a41.jpegIMG_7163.thumb.jpeg.7d8a1dc736a8ac8b9b1367a263a8e175.jpegIMG_7175.thumb.jpeg.e86074f8ddb5c0c5db1e98bc5c86a52b.jpegOn the front side, I added a parallel flow AC condenser unit, made with photo etched mesh. I’ll add the lines to and from it later, as well as the air intake connectors and pipes to the turbo and engine block.


Edited by vincen47
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