Recommended Posts

I decided to start a new supercar project and after lots of thinkign decided to make an ute just because nobody else made one yet AFAIK.

For those who don't know what an ute is, it's when a pickup and a normal or sports car really like each other and end up having a child like this:

Holden-ute-cover-MAIN.jpg&f=1&nofb=1

For this project I set myself the following goals:

  1. Unibody construction - The model will have no chassis per-se, the body will be load carrying, something @nicjasno is really good at.
  2. Convertible - If you have a sports pickup, why not make it a convertible? This will also force me to make the unibody extremely solid, since there wont be any roof support.
  3. Motorized with gearbox - I am using a new high efficiency gearbox idea. Power will be delivered by 4 PF trains motors
  4. Realistic suspension - High-gearing solid axle in the back and McPherson suspnsnion in the front

Here's the current progress:

The gearbox has a total of 4 gears. Wave pieces are used to switch between them.

800x423.jpg

Here's a more detailed view of the setup. As you can see, I used a tilted axle for the overdrive gear:

800x423.jpg

Since the wave selector pieces can't cope with high torque, the gearbox is designed to work with high speed and low torque. That is why it will be powered by the fastest currently available motors - 4 PF train motors spinning at over 2000 RPM generating around 10Ncm of torque.

The rear axle is an inverted portal design. It' made to be low as possible so that the bed can be placed nice and low.

800x423.jpg

The axle has a total of 1:12 gear ratio in order to get useful torque from the fast spinning gearbox. Double 24 tooth gears are used in final drive because I expect the car to be quite heavy.

800x423.jpg

 

So that's the basic idea for now. I will update the topic as I build.

Edited by Zerobricks

Share this post


Link to post
Share on other sites

Looks very interesting! But that tilted axle in gearbox... will it be reliable enough? I understand the torque is low, but... I hate u-joints :) Without reinforcing they break very often. Btw, currently I'm in building process of 1:8-1:9 scale car with 8 xl-motors coupled all together... And I can't decide - to use a gearbox or not to use at all. Cars with gearboxes look more complex, but... Is the usage of a gearbox always efficient? Tests will show.

Share this post


Link to post
Share on other sites

Some more progress.

The rear axle was redesigned, so that the drive axle is placed higher, so that there is minimum angle difference from the gearbox:

800x423.jpg

800x423.jpg

800x423.jpg

The bed is slowly taking shape, and there is enough space in the back for a spare wheel:

800x423.jpg

Share this post


Link to post
Share on other sites

I'm currently driving a 2017 Redline four door sedan in Light My Fire paint just as your inspiration photo. Your progress looks great. 

Share this post


Link to post
Share on other sites

@Zerobricks I've done a mod of your transmission and I don't own any of the Rotary catches, but I was just curious if the element rotary catches would slide the non friction red color 8 tooth gear on the output axle to engage and disengage to the 24 tooth gear?? ?? here is an example i've built but just a wip!!

 

 

 

 

Technic Changeover Rotary Catch
Item No: 35188
dot.gif Orange
 
35188.t1.png
35188.png
12848.t1.png
Color Images
Large Images
 
Lego Technic Changeover Rotary Catch

Share this post


Link to post
Share on other sites

A few things:

If you are doing a gear reduction in the diff, use the new planetary hubs. The rear axle is way too big and heavy.

When doing a live axle like that, i'd consider using a torque tube.

When making a unibody, have the drivetrain (gearbox+engine) removable and not part of the structure of the car, like in TLG models.

You want to save weight werever possible.

Edited by nicjasno

Share this post


Link to post
Share on other sites
3 hours ago, sirslayer said:

@Zerobricks I've done a mod of your transmission and I don't own any of the Rotary catches, but I was just curious if the element rotary catches would slide the non friction red color 8 tooth gear on the output axle to engage and disengage to the 24 tooth gear?? ?? here is an example i've built but just a wip!!

 
 
   

It should work, but you need a spring to put the gear back when not used.

53 minutes ago, nicjasno said:

A few things:

If you are doing a gear reduction in the diff, use the new planetary hubs. The rear axle is way too big and heavy.

When doing a live axle like that, i'd consider using a torque tube.

When making a unibody, have the drivetrain (gearbox+engine) removable and not part of the structure of the car, like in TLG models.

You want to save weight werever possible.

1. I'm intentionally not using the planetary hubs, because they are inefficient and don't have the high enough gear ratio for what I need.

2. I could use a torque tube, but I'm trying to avoid use of rare elements like this.

3. Since the car will not have the roof, the gear tunnel will have to support a lot of weight. The gearbox can still be made removeable as long as the tunnel is part of the unibody.

Edited by Zerobricks

Share this post


Link to post
Share on other sites

That's a nice idea, but a torque tube means the axle would swing and that would mess up my double shock absorber setup.

I thought about using this MacPherson front setup, but the shock absorber is too bendy IRL:

800x423.jpg

I would need a firmer design, or switch to a normal double wishbone setup.

Share this post


Link to post
Share on other sites

Use a different shock absorber setup then. Why are you engineering yourself into a corner?

I'd use an elevated double wishbone setup in front.

Edited by nicjasno

Share this post


Link to post
Share on other sites
22 minutes ago, nicjasno said:

Use a different shock absorber setup then. Why are you engineering yourself into a corner?

I'd use an elevated double wishbone setup in front.

I already found a solution by using two soft shock absorbers instead of a single hard one, which doubles my stiffness and helps balance out the force more evenly. Same concept as the double shock abosrbers in the rear, they keep the axle straight and minimize it's bending when accelerating.

Share this post


Link to post
Share on other sites

I'm just gonna follow this thread in awe :wub: Same when you start your next project, Nicjasno. You guys always break new ground :wub:

Share this post


Link to post
Share on other sites

Here's the updated front suspension assembly:

800x423.jpg

As you can see, the whole suspension is at a slight caster angle (5 degrees at the moment). Dual shock absorbers are used to increase stiffness of the arm. The whole upper attachment point can swing in all directions just like a ball joint.

Share this post


Link to post
Share on other sites
33 minutes ago, Nazgarot said:

Very interesting solution. How much weight are you expecting this to handle?

-ED-

 

I expect the model to weigh around 2-2,5 kilograms. Each small soft shock absorber can handle up to 500 grams, so 8 of them should do the job.

Share this post


Link to post
Share on other sites
23 minutes ago, Zerobricks said:

Each small soft shock absorber can handle up to 500 grams, so 8 of them should do the job.

You always have to remember - that shock absorber can handle 500 grams only if the compression force direction perfectly aligns with the central axle of that shock absorber. That's the basic mechanics, I'm sure you know that. Let's just take a look at 42110 suspension. Model isn't very heavy, TLG used 2 hardest shock absorbers for each wheel, but suspension is soft. And that all is because of the use of the class 3 lever-based suspension.

Sorry if I explain basics :) but in case of your suspension struts there are some different calculations.

Edited by romashkaman

Share this post


Link to post
Share on other sites
2 hours ago, romashkaman said:

You always have to remember - that shock absorber can handle 500 grams only if the compression force direction perfectly aligns with the central axle of that shock absorber. That's the basic mechanics, I'm sure you know that. Let's just take a look at 42110 suspension. Model isn't very heavy, TLG used 2 hardest shock absorbers for each wheel, but suspension is soft. And that all is because of the use of the class 3 lever-based suspension.

Sorry if I explain basics :) but in case of your suspension struts there are some different calculations.

Mine will carry the whole weight directly without any levers.

I made the first physical gearbox test model:

1280x960.jpg

It works very smooth. The idea is to have each of the car's modules (gearbox, engine, axles, etc..) built seperately and to have them removeable.

Share this post


Link to post
Share on other sites
3 hours ago, Zerobricks said:

I expect the model to weigh around 2-2,5 kilograms. Each small soft shock absorber can handle up to 500 grams, so 8 of them should do the job.

I would be suprised if you can keep the weight below 2.5 kg. My NSX weighs in at like 2.9 kg, and there are no electronics involved :oh3:

Still, 2 Hard springs per wheel should be able to support 3kg as well. Good thing you are using a solid rear axle, this way the shocks dont have to face the leverage disadvantage which exists in a independent suspension setup.

Share this post


Link to post
Share on other sites
Just now, Gray Gear said:

I would be suprised if you can keep the weight below 2.5 kg. My NSX weighs in at like 2.9 kg, and there are no electronics involved :oh3:

Still, 2 Hard springs per wheel should be able to support 3kg as well. Good thing you are using a solid rear axle, this way the shocks dont have to face the leverage disadvantage which exists in a independent suspension setup.

I plan to optimize the crap out of the unibody, which will be more or less entirely panel and frame based. If weight exceeds what soft shock absorbers can support, I can easily swap them for hard ones. Actually I'm thinking of using hard ones in the back, so I can carry stuff in the bed.

Share this post


Link to post
Share on other sites
56 minutes ago, Zerobricks said:

I plan to optimize the crap out of the unibody, which will be more or less entirely panel and frame based. If weight exceeds what soft shock absorbers can support, I can easily swap them for hard ones. Actually I'm thinking of using hard ones in the back, so I can carry stuff in the bed.

Soft Springs? For real? I dont doubt you are able to create a very light unibody, especially if the car is not modelled after a real car, so you have more freedom in panel placement. But do think hard springs will be nececary.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.