[WIP] Greyhound - 4WD RC Buggy with BuWizz 2 - Redesigned wheel hubs

[Leonardo da Bricki]

@nerdsforprez I need to do that! I've broken a bunch of U-joints in crawlers. What elastics did you use?

[JonathanM]

That is a handy tip! A cheap and simple way to protect the weakness of the U-joints - thanks for sharing!

[sirslayer]

@nerdsforprez that's is a very good idea.. I have a few small rubber o-rings and they fit tightly around connector.  I would recommend over rubber bands. The higher rpm could throw your axles off from unbalance if you didn't wrap the rubber bands correctly . You can even use the rubber bands around the front bumper to protect from damage. I was thinking to use a can of spray on rubber but that might ruin the bricks. Rubber bands seems to be a better alternative.   

[Didumos69]

Thanks @nerdsforprez! I will certainly be using that. Will probably be using silicon bands to keep it pure LEGO (besides the BuWizzes of course).

EDIT: I ordered 5 CLAAS tires, which were not that expensive btw. Less than 4 euros.a piece.

Edited February 11, 2018 by Didumos69

[imurvai]

I also have cracked U-joints and I reinforced them using a simple thread:
 

[nerdsforprez]

17 hours ago, Leonardo da Bricki said:

@nerdsforprez I need to do that! I've broken a bunch of U-joints in crawlers. What elastics did you use?

I used the elastics from 8269 from years ago.  They actually held up really well despite their age.

https://www.bricklink.com/catalogItemInv.asp?S=8269-1

 

15 hours ago, JonathanM said:

That is a handy tip! A cheap and simple way to protect the weakness of the U-joints - thanks for sharing!

It worked for me!

14 hours ago, sirslayer said:

@nerdsforprez that's is a very good idea.. I have a few small rubber o-rings and they fit tightly around connector.  I would recommend over rubber bands. The higher rpm could throw your axles off from unbalance if you didn't wrap the rubber bands correctly . You can even use the rubber bands around the front bumper to protect from damage. I was thinking to use a can of spray on rubber but that might ruin the bricks. Rubber bands seems to be a better alternative.   

In this build the motors used were XL motors.  @ <300 RPMs, trust me, nothing is going to get thrown off the axles.  Especially when the weight of the elastic is negligible.  Perhaps if I were running the axles at tens of thousands of RPMs you might have a point, but Lego at that speed poises a completely new problem 

4 hours ago, Didumos69 said:

Thanks @nerdsforprez! I will certainly be using that. Will probably be using silicon bands to keep it pure LEGO (besides the BuWizzes of course).

EDIT: I ordered 5 CLAAS tires, which were not that expensive btw. Less than 4 euros.a piece.

I think a used various because I didn't have enough for the front and rear.  In the rear I used those from the set I posted above, but for the front I think I used one official Lego white band while, after running out, used a clear silicone (non-Lego) dental band. 

1 hour ago, imurvai said:

I also have cracked U-joints and I reinforced them using a simple thread:
 

I am surprised this worked.   Again, the advantage I would think that bands would have over string would be demonstrated in the youtube video I posted.  But hey, if this worked, then awesome!

 

[sirslayer]

I found a sharable youtube video and this is so cool!!  

 

Edited February 12, 2018 by sirslayer
grammar

[Didumos69]

7 hours ago, sirslayer said:

I found a sharable youtube video and this is so cool!! 

I don't think this is cool at all. And I would appreciate if we could stay on topic.

[Didumos69]

I installed the CLAAS tires and softened the rear suspension a little. I love these tires! Only downside: While riding circles in ludicrous mode one of the front wheel tires ran off its rim!. In the video below it rides in normal mode (not ludicrous and not fast), because I can't drive and film simultaneously.

 

[DugaldIC]

This thing is epic with the claas tires. Looks awesome and the performance is great. Looking forward to the body! 

[Leonardo da Bricki]

Yes! That is looking awesome! Thanks for using my idea. By the way, you might want to harden the suspension a bit, as you still need to add the body, however light it may be.

[sirslayer]

I just got myself Lego Tire 68.7x34 and those Claas tires are they bigger then 68.7  I should of gotten a set Claas!!  Your set looks better with the Claas tires and can't wait for your next video!  

 

Edited February 15, 2018 by sirslayer
grammar

[Didumos69]

10 hours ago, DugaldIC said:

This thing is epic with the claas tires. Looks awesome and the performance is great. Looking forward to the body! 

Thanks @DugaldIC! And thanks for pushing me in the RC direction. It's really fun and building something that doesn't fall apart during a rough is an even bigger challenge than with a manual model.

9 hours ago, Leonardo da Bricki said:

Yes! That is looking awesome! Thanks for using my idea. By the way, you might want to harden the suspension a bit, as you still need to add the body, however light it may be.

They do not really look like dirt grabber tires, which is why I didn't consider using them before, but eventually I have to conclude they do add to performance and overall look. As for hardening the suspension, I tuned the suspension to an extra weight of 500gr. With the extra weight, it sits approximately one stud deeper in its suspension which makes the wheels really glue to the ground on uneven surface.

7 hours ago, sirslayer said:

I just got myself Lego Tire 68.7x34 and those Claas tires are they bigger then 68.7  I should of gotten a set Claas!!  Your set looks better with the Claas tires and can't wait for your next video! 

Thanks! The CLAAS tire size is 107x44. They are the biggest LEGO tires that exist.

Edited February 15, 2018 by Didumos69

[kbalage]

19 minutes ago, Didumos69 said:

The CLAAS tire size is 107x44. They are the biggest LEGO tires that exist.

Buggy looks great with the new tires! Would be cool to see a video with high/ludicrous mode activated  Do you have a tripod to film? 

(Btw Power puller tires are very similar in diameter/width but much-much heavier)

[Didumos69]

49 minutes ago, kbalage said:

Buggy looks great with the new tires! Would be cool to see a video with high/ludicrous mode activated  Do you have a tripod to film?

Thanks! Yes, I have a tripod, but I'm waiting for good weather, because riding with ludicrous mode in our living room does not seem like a good idea .

[kbalage]

Just now, Didumos69 said:

Thanks! Yes, I have a tripod, but I'm waiting for good weather, because riding with ludicrous mode in our living room does not seem like a good idea .

Haha, I know the feeling  Sitting in the room while it's raining outside and can't really test the 4WD 42077 with ludicrous mode either 

[proran]

I can watch that video with you compressing the suspension forever. It "feels" so soft and responsive. And the outdoor performance is incredible! That thing is one of a few examples where the current Lego motors provide a real playable off-road experience, not just crawling. Fantastic job.

[Didumos69]

2 hours ago, proran said:

I can watch that video with you compressing the suspension forever. It "feels" so soft and responsive. And the outdoor performance is incredible! That thing is one of a few examples where the current Lego motors provide a real playable off-road experience, not just crawling. Fantastic job.

Thanks! I made sure it can be build without any illegal steps or constructions, so eventually I will be sharing photo instructions.

@kbalage, I took the tripod and filmed some indoor driving excercises . This kind of treatment does not cause any displacement of parts. Only a serious frontal crash causes displacements.

Edited February 15, 2018 by Didumos69

[kbalage]

Amazing, thanks for the video! Can't wait to see it running outside 

[agrof]

Hi @agrof, I remember you are using this 2L bar with tow ball in the steering setup of this model. 

Can you - or whoever knows the answers - tell me how tight the bar end sits 1) in an axle hole?, 2) in the small hole of a 2L pin with friction ridges while that pin is connecting two pin holes?, 3) in the pin side of a half pin which is inserted in a pin hole? and 4) in the knob side of a half pin which is inserted in a pin hole? Would one of these options sit more tight then a pin with tow ball in a pin hole? I'm looking for a way to improve my steering rods in my 4WD buggy. The pin with tow ball I'm using disconnects when the front wheels generate too much traction.

Thanks!

Hi Didumos!

To keep the relevant informations in one place, I answer here. I just checked for You:

1) Like a flick missile, not very tight, not very loose.

2) Same - that's why I also have blocking structure below.

3) Super loose.

4) Quite good, You can pull the half pin out without any separation wilingness of the towball.

5) No.  (I tried old Binocle ones - don't know if these have been changed during the years.)

"The pin with tow ball I'm using disconnects when the front wheels generate too much traction." - Can You explain this in details to understand the phenomenon?

[Leonardo da Bricki]

Wow... Great speed, was it sliding?! With Claas tires?! Awesome... Cannot wait to see the body for this.

[Zerobricks]

Great idea using L motors directly coupled to the wheels!

I had same idea a week ago, but I used L motors coupled with power puller wheels and tyres uisng CV joints and hubs and made a VERY capable monster truck chassis.

I suggest you try use the CV joints and hubs inetad of U joints. Sure the CV joints WILL suffer and get slightly flat, but they seem to hold on better than U joints and because hubs do all the weight carrying, there is less friction in the axles.

Edited February 16, 2018 by Zerobricks

[Didumos69]

10 hours ago, agrof said:

I just checked for You

Thanks! This is very helpful. It means I also need some kind of blocking structure.

10 hours ago, agrof said:

Can You explain this in details to understand the phenomenon?

The steering rods shown below - with Ackermann geometry - are placed at the back side of the front axles and are connected to the gearrack with pins with tow balls pointing backwards. When the model takes a climb, the traction of the front wheels pulls the steering rods outward, causing the pins with tow balls to disconnect. I can't make renders right now. I'll post some renders tomorrow to explain better.

8 hours ago, Leonardo da Bricki said:

Wow... Great speed, was it sliding?! With Claas tires?! Awesome... Cannot wait to see the body for this.

Yes, it slides with Claas tires. Even on the carpet . The sharp steering angle is paying off.

8 hours ago, Zerobricks said:

I suggest you try use the CV joints and hubs inetad of U joints. Sure the CV joints WILL suffer and get slightly flat, but they seem to hold on better than U joints and because hubs do all the weight carrying, there is less friction in the axles.

Thanks @Zerobricks! I agree using hubs to carry the weight is better, but I think you missed the fact that I'm using turntable based wheel hubs (see video in OP, I now use 4l axles with end-stop instead of pins to connect the wheel to the hub). I don't like the slack in the standard wheel hubs and I wanted a decent steering angle. With the U-joints I have a 30 degree steering angle and with the turntables I have less slack. Currently I have wrapped white silicon bands around the axle holes of the U-joints (4 times), as was suggested by @nerdsforprez, and I haven't had any problems since.

Edited February 17, 2018 by Didumos69

[Didumos69]

14 hours ago, agrof said:

Can You explain this in details to understand the phenomenon?

Here is a render showing the area where the steering rods connect to the gearrack and a render of the complete gearrack assembly. The problem is that the steering rods pull the pins with tow ball out of the gearrack assembly.

There is some space in front of the gearrack assembly and the steering rods, but practically only half a stud, because of the knobs of the blue half pins holding the motor assembly. So I'm looking for a way to block the suspension arms, which takes only half a stud of space. Preferably, the blocking structure should be connected to the gearrack assembly, so it moves along with the gearrack and steering rods.

Edited February 17, 2018 by Didumos69

[Lipko]

Could you block the steering rods with the chassis instead? I know it would cause sum rubbing but maybe it would be acceptable. You could then replace the blue half-pins with a pin with pinhole and place a 180° axle connector between them with the center hole pointing upwards. I guess the movement of the rack is +- 1 stud, so the tiny edges wouldn't mean a problem. Or something like that... Or maybe the pin with a pinhole parts' pinholes should point upwards? You have some place in the chassis to fix their orientation.

Edited February 17, 2018 by Lipko