Kamil

Front windscreen area of the 6x6 Bug is redesigned, an openable windscreen is added: All the best

Thank you, White may be? I am looking forward to see how it goes with XL motors. All the best

Inspired by your work, I had a chance to re-work on this vehicle at the weekend. As I have limited choice on colors, I asked a Ferrari designer to create a road version of the bug This vehicle has nearly same dimensions as Lego 8448 Super Street Sensation:

First issue: All differentials in opposite directions? When looking from the bottom side (front is up), front axle first differential main gear is at the left side. Mid axle differential is at the right side. Rear axle diff. main gear is at the left side again. Second issue: It is the mentioned issue before. Check bottom beams between the two L motors and the front axle. Squeeze them if you find them separated apart. This gear can only be used when the surface is flat, and vehicle is at complete stop. Start giving low throttle while on start. Happy you have applied (or trying to aply) new gear ratio. All the best

Really cool, I like it. A spaceship on the road. Good job

High gear is working good in 4x4, but not effective in 6x6 due to high friction. I tried high gear, vehicle cracked and stopped. I thought I have broken red differential case part. However it was the beams (near the front axle) separated sideways under high load. I have re-squeezed the beams into place, and high gear worked again. But this issue is easily repeated. I would prefer to take out the servo motor and connect low gear directly. So, 42099 hub could be used. Otherwise reinforcement may be necessary to hold the beams in place.

Hi @vliet Have you tried to select 42099 x-treme off-roader from your phone app? Or, if you have the 42099 set, than maybe you can use its hub and motors. I would also be grateful to hear more solutions, if any.

All pics in order:

ævliet No problem, my busy days, maybe tomorrow I can upload all in their original resolutions :)

I have limited time at the moment, so I will try to post others later: Hope it helps for now, All the best

@vliet Hi Sander, power is coming from the two L motors from the Lego Zetros set. I think it would be better if you could insert XL's. But the original Ultra 4 Buggy is compact, and may need major changes on the initial design (not tried that). All the best

Thank you, @gyenesvi's original 4x4 model plus some 6x6 modifications.

Hi @vliet, thanks ! Exacly what @gyenesvi has said. I tried this rework of his Ultra 4 Buggy 4x4 without using any extra digital material. I may post all the unclear details about these modifications here. The details of the bogie, and the tail are easy. - You will need Lego 42129 MB Zetros parts mostly. - First build Ultra 4 Buggy (from the link provided by @gyenesvi) - Replicate the rear axle of Ultra 4 Buggy as it is in the instructions (build a copy of the original rear axle). - Connect two rear axles by using the four control arms. - Add tail with rear flexible suspension (actually it is lengthening of the original tail). - Add six tractor tires. - Add exhaust, and some touches if you like. Ready !

Hi, A few changes have been made to the rear bogie of the 6x6 Bug. The lower control arms are lowered two studs below. The upper 16 stud links are doubled on each side. This gives less flexibility of the bogie but better sand performance. Negatives: - Less flexibility so watching the bogie on action may be less entertaining than the old one. - Suspension travel of the mid axle is limited more, so it can not come down as much. - 39 degrees ramp climbing has not worked with this redesign (not included in the video below). - The bending issue discussed above still happens (not included in the video below). Positives: - Better sand climbing performance. - Better overcoming of solid obstacles. - Less mid axle stalls. - Better progress on rough terrain. Well, as this vehicle is powered by two Lego L motors, it may be a little unfair to add new weight to this bug by adding a more complex drivetrain. I think it gives optimal performance here: All the best

@bartybum Hi, thanks ! If I get it right, you are asking this issue below (Pls note, my file size quota for this topic is limited): Yes, that is also a part of the mentioned plays in the bogie. This happens when the vehicle is forced to extremes. Power comes, and the rear axle tends to rotate backwards. The black beam inside the red circle is the only resistance to this rotation. While the axle is rotating, the black beam hits the 16 stud grey link. If the force is high enough, then black beam bends the grey link upwards. This action is limiting the axle from fully rotating. Another reason for bending is; the upper grey links and the lower control arms are too close to each other. I thought to mount the lower control arms into a lower position under the bogie. But, there stands the cv axle, and I had to mount it on a very low position. Then I would lose a lot of ground clearance. Negatives: The rear axle loses some parallelism with the ground when the vehicle is forced to extremes. The CV joint connected to the rear axle comes near to its working limits. Positives: Very flexible bogie. High sideways tilting. The 16 stud grey links act as torsion bars for sideways tiltings of each axle. The 16 stud grey links and the below control arms allow seesaw movement of the bogie. The rear axle trying to rotate backwards means, the axle is doing its job, and playing its role for moving the vehicle on a steep ramp. High ground clearence Lightweight equipment All the best

@bartybum @zerobricks Update: This 6X6 vehicle behaves different on sand and solid surfaces. Video below shows the effect of replacing red springs of the mid-axle with the grey springs, overcoming solid obstacles, overcoming obstacles on sand (comparison), climbing a 39 degrees ramp, and the two speed of the vehicle on solid surface. All the best

@gyenesvi Thanks :) I initially used two black 1x9 links (32293) instead of the inner dark grey beams between two axles in my first prototype. Those were looking far better, but I think there would be too much stress on these parts. Yes, the last version is built as simple as possible, to the minimum requirements for maintaining integrity during trials. It was also tried to be consistent with the overall structure of the original model you have created (less weight addition, don't make it look like it was added later etc.). I also thought about making the rear axle with independent suspension, but since the upper body, to which the suspension would be attached, was very thin, it would need to be reinforced. Plus the angle of the bottom control arms would be too steep etc. My conclusion: To be honest, this vehicle delivered more than I expected. I am also planning to tune the mid-axle suspensions to softer grade for giving better bouncing height to the stalled wheels. Of course this is not initially my MOC, it is grown from an existing platform. If I were to build a 6x6 from the beginning, I would follow more a bug's leg principles (like your front suspension design in Ultra 4 Buggy). All the best

Okay, @zerobricks , @Bartybum thanks both. I havent given the suspension details, and it is hard to see from previous video. Actually, the bogie is constructed by using double control arms on each side (the two light grey 16L technic links are visible from outside, the other two are hidden inside). These provide parallel movement of the two axles. If not, the CV axles come loose. However there is also some play here as I wanted flexibility. I have used most loose parts in building. When the rear axle is forced to the extremes, then another movement starts to happen. I have seen many videos about 6x6's, and there the mid axle loses contact with the ground while the vehicle is going through a flat surface to a steep incline transition. In this vehicle this was prevented to some degree. How? Well it comes from the mid-axle tilting from the original design. Hard to tell, so maybe an update video is better:

@Bartybum Thank you ! While building the rear bogie, I tried to maximize articulation at the rear axle. So I preserved the two red springs of the mid-axle (coming from the original design), then I added two softer and longer springs to the rear axle. This is good for articulation, brings visual as you mentioned, but I think these softer rear springs are also the main reason for some of the mid-axle stalls, as the rear axle can not put the necessary pressure on the terrain. I could use four red springs, or I could use four softer suspensions at the bogie. The first choice would limit articulation and not sure what would happen if I use four soft springs.

All the best

This model is a clear summary of your previous opinions about 42129's playability. Impressive job, thanks for sharing !

I had another goal in mind when I did the above, I have slightly modified the Ultra 4 Buggy (designed by Victor Gyenes) into the Ultra 6 Buggy - The rear axle of the Ultra 4 Buggy is replicated and modified - A tandem style super flexible rear bogie is built - Red touches are added - Openable rear covers are added - Designed for low gear ratio of the Ultra 4 Buggy. High gear is usable but not recommended (may break parts if used without caution) - Oiling may be necessary for better performance

Thanks a lot ! It is well built, and I like its minimalist style. I think absence of a differential lock here did not seem to matter with this vehicle. Even if one wheel spins, the other three wheels provide traction. It is more energetic, more active, and far more easier to drive than official Zetros truck. Yes, this vehicle stalls with these 107x tires at the start of a hill at high gear in my video. Your observation is most likely correct. Although my batteries are 6 x 1.5V Duracell pack, they were also used in my last MB Zetros beast mode trials video before. So, these batteries may already have lost some of their power. It might be better to replace batteries, and take it to a faster riding outdoors terrain like you did before. All the best