[TC25] Mini Extreme Cruiser

[lmdesigner42]

For this contest, I decided to shrink one of my favourite technic sets, 8081 Extreme Cruiser. Using 43 mm balloon tires, with a similar profile to the originals, the scale is about 60%. I plan to replicate all of the features from the original, including the suspension and the fake V4, which will be a first for me at this scale. The overall goal is to imitate the colour choices and “cuteness” of the original, using some of the new small panels.

So far, the rear axle is done, and I have designed a steered and independently suspended 7-stud wide front axle. The next step is figuring out how to add springs…

  

[2GodBDGlory]

Wow, that's an impressively compact front axle! I think I built a similar one once, but two studs wider, so the suspension arms meshed at their end holes. I like it!

[TechnicMOCer]

Looks very cool so far, love that front axle. It's already not another extreme cruiser since I decided to risigne from that and make 3x smaller 8110 Unimog U400.

[lmdesigner42]

Yes, I saw your new topic. I’ll try to come up with a better name. The front axle is nice and small, but it was really hard to get the steering links to fit, had to use a bar with towball.

I made some more progress, with a start on the chassis and some of the key bodywork elements. I narrowed the axles by 1 stud by removing the half bushes to bring it closer to the right scale. As a side benefit, the rear half-shafts are now secured with a half bush.

 

I also made a mini V4, using crankshaft parts for yellow pistons. The next challenge is fitting all the various functions together with strong enough connections.

[Thirdwigg]

As I said to @TechnicMOCer when they started the mini 8081, I love this set, so I hope this project goes well for you too. I like what I see here so far, and I hope you are able to tie it all together.

The body shell looks good, though it's hard to see how the proportions fit with all the separate pictures. But I trust that the scale will work.

I hope the engine works too. It's a good little design, but I hope it's not too tall for the hood at this scale. Will it be mounted behind the front suspension, or on top of it?

[lmdesigner42]

Thanks for the kind words, @Thirdwigg. I hope it turns out too. The fake engine is going to go behind the front axle, I'm actually going to integrate it so that the light gray L-beams in the first picture become the front engine block support. I am concerned about the size of the engine too. The steering shaft, crankshaft, and pistons stack to a height of ~5.5 studs, and the hood is 6 studs tall in scale, so it will be tight.

[lmdesigner42]

I’ve assembled more of the chassis/body, and have run into a small problem, the hood panels are interfering with the engine block and as a result the hood is too high. Hopefully this is visible in the below picture (the perspective isn't very good). There isn’t an easy solution, since both the V4 and 3x7 hood panels are important for the functions and aesthetics of 8081. There is only 1 stud for structural support between the engine and the front suspension at the moment, but I am thinking that if I thin that support to 0.5 studs, and stretch the wheelbase 0.5 studs (which is actually exactly to scale) I can move the engine forward 1 stud and it will no longer interfere with the hood. Any other suggestions are welcome.

 

Another challenge was crossing over the steering and drive shafts in the center of the chassis. Eventually I came up with a small linkage to route the steering around the driveshaft. There is only 3 studs of width available in the center of the chassis, since 2 studs are needed on either side for the seats.

[SaperPL]

23 minutes ago, lmdesigner42 said:

Another challenge was crossing over the steering and drive shafts in the center of the chassis. Eventually I came up with a small linkage to route the steering around the driveshaft. There is only 3 studs of width available in the center of the chassis, since 2 studs are needed on either side for the seats.

Did you try just putting the 16tooth clutch/gearbox gear in front of the universal joint and going around the engine drive shaft this way? This would need either engine to go forward 1 stud or universal joint to go back 1 stud, but that's something that I'd try to make. Alternately you could do the similar thing with gears above and below but connected through chain so the universal joint can stay where it is.

What I don't like about lever approach here is that it will require that place and eventually it'll affect your potential to decorate interior of the cabin. Symmetric setup with gears usually makes more sense.

[lmdesigner42]

On 7/24/2023 at 5:47 PM, SaperPL said:

Did you try just putting the 16tooth clutch/gearbox gear in front of the universal joint and going around the engine drive shaft this way? This would need either engine to go forward 1 stud or universal joint to go back 1 stud, but that's something that I'd try to make. Alternately you could do the similar thing with gears above and below but connected through chain so the universal joint can stay where it is.

I wanted to use the 16 tooth clutch gear as you suggested at first, since that was what the original 8081 had, but there wasn't enough space lengthwise to move the u-joint (+ cv joint) back. Since I'm going to try and move the engine forwards anyway, the clutch gear is definitely something to revisit.

I liked the lever because it was simple, compact, and the steering shaft barely rotates anyway, but it does rub the driveshaft a little and takes away space for mounting the seats, as you mentioned. Now that I think of it, the u-joint could be replaced with 8 tooth gears which would make space for the clutch gear. Thanks for the suggestion!

[lmdesigner42]

Another progress update. I extended the wheelbase by 1 stud, 0.5 was not enough, and a gear train now routes the steering axle around the driveshaft.

Most of the bodywork is done, except for the fenders and headlights. The hood now fits around the engine, but is 1 stud too tall since clearance is needed for the pistons (last pic). This rather hurts the looks of the front, so I am going to try and replace the camshaft with a smaller one in order to drop the engine and hood 1 stud.

     

[lmdesigner42]

All finished!

I successfully shrunk the camshaft to 2 studs and lowered the V4 to make the hood at the proper height. This resulted in a few other internal changes such as 8:16:8 gearing for the steering and a 2L section of ribbed hose in the drive shaft to accommodate the 0.5 stud offset.

Some comparison pictures are included below with my TC22 entry and the 8081 Extreme Cruiser. My 8081 is rather heavily modified inside, but the exterior is unchanged. I am happy to have captured important visual details such as the distinctive headlights and taillights, the license plates, red stripes, and blue/grey seats, but some smaller things like the stickered red stripes on the roof are missing. The steering is also routed to the HOG with two yellow knob gears like in the original. I feel like the miniature version rides about 0.5 studs too low, due to a combination of play in the suspension and the slightly too thick fenders, but it’s not worth it to me to figure out a way to redesign the chassis to eliminate that.

All the pictures are on Bricksafe.

Next up is the entry post.

Edited August 20, 2023 by lmdesigner42

[SaperPL]

Looks really good, but there are two details that caught my eye - the windshield's lower edge arc is sticking out over the hood and while I know it was kind of like that in the original model, it feels weird. The second thing is that the doors are not sitting flush with the rear wheel arches.

I would recommend either trying to re-take the photos or tweak brightness/contrast on the photos because with a lot of black, it's hard to look at the details in dark areas.

Also if you want to put comparison shots like in the last group of photos, I'd rather be looking at a single scene where I can see the details, or maybe put one above the other if they are horizontally wide, rather than just "a proof" that there is a side-by-side comparison, beacue this wide strip with 6 photos i hard to see actual details and compare things. Shots from upper left and bottom right look okay, just make them fit both in one rectangle for 1024x1024 requirement, if you are planning to put them in the entry.

[lmdesigner42]

Yeah, the windshield is a little awkward, and the smaller scale emphasizes that. The doors can sit flush if they are pushed in all way and pop past another piece, I didn't notice that when I took the pictures. You've got a really good eye for detail!

Photographing black is always difficult, and it doesn't help that my main light source is a window on the side. I'll try to lighten the pictures a bit though.

Thanks for the photo advice. I combined the two comparison images you mentioned for the entry post. I know it's hard to see details in smaller images, but I felt like a combination strip showing the overall similarity was less overwhelming than 6 full-size images comparing the same two models from different angles.

[SaperPL]

7 hours ago, lmdesigner42 said:

Photographing black is always difficult, and it doesn't help that my main light source is a window on the side.

Try to use morning light, open up windows/doors to let as much light in, and if your phone camera app isn't letting you tweak the exposition/white balance, you can try openCamera app. I guess next time when you'll be making some photos/video.

Anyway, do you have an ldd/studio model for this? I'd be nice to leave those things that you've figured out here with the front axle with suspension and engine behind for future reference for others :)

[lmdesigner42]

I don't use studio much, but I made a quick model of the front suspension and added it to the Bricksafe folder. Here's a direct link. Maybe other software are better, but in my limited experience it is hard to properly connect parts and assemblies in studio at the unusual angles that are often used in MOCs.

[Thirdwigg]

Thanks for completing this. I love 8081, and your were faithful in your redesign. I didn't think the wheel/tire choice was going to work, but it turned out well.