42124 Off-road Buggy MODS & FIXES

[Sariel]

Wake up Samurai, we have a buggy to fix ;) In all seriousness, I think 42124 is a great modding material and my first step was trying to boost the performance while staying within the confines of the Control+ system. A detailed explanation and demonstration is in the video below, and the short story is:

- with vanilla 42124 and regular 1.5V batteries I'm getting between 4 and 5 km/h
- by adding a second drive C+ L motor and gearing the two motors up 1:1.6 (theoretically that's 25% more torque and 66% more speed) and still using the same batteries I got between 5 and 6 km/h
- switching from regular 1.5V batteries to 1.2V rechargeable Eneloop batteries produces speed of slightly above 6 km/h

I'm not happy with these results, it seems like the last iteration has a lot of power but it's actually only slightly faster. My conclusion is that the power supply is the limitation here, and to see a significant increase in speed we'll have to double it or replace it with something else, or go full PF on the 42124.

 

[amorti]

Is that dial definitely reading power? I'dhave thought it was reading % of max speed, since that's the feedback the hall effect sensor in the motor can provide.

If I'm right, the motors are running just under 100% of their available speed, which I'd say means you've got the gear ratio bang on.

Actually, the fact you got it to 100% with the wheels lifted up tells me it can't be power, it must be speed. An unloaded motor wouldn't use more than a few percent of its power just to spin the tyres.

Edited December 16, 2020 by amorti

[1gor]

I suppose that you do not have long enough room or hall to test it inside, since asphalt is rough and causes more friction than parquet for example...

[Sariel]

Getting the GPS signal in a room or hall has proven somewhat tricky so far ;)

Edited December 16, 2020 by Sariel

[Bartybum]

Regarding mods, I’d be interested to see how it performs with soft shocks at the front and longer travel at the back

[2GodBDGlory]

If the main problem is that the battery can't provide enough power to the drive motors, perhaps the road to performance is to use 2 Xl motors instead of 2L motors, because I seem to recall reading that they have lower power consumption. Of course, this would only solve (or just alleviate) an electrical problem, while creating the mechanical problem of fitting and attaching the larger motors.

[amorti]

I don't think there is any problem. I think this has already hit the top of what Lego C+ in this configuration can do. I believe the motors are running at 90%+ of available speed, not of potential power, considering the motors only have a sensor for speed not torque. Otherwise how does the display show 100% with the wheels up? That doesn't use 100% of power when unloaded.

Keep in mind it takes a lot more power to get to 7kmh from 4kmh as you've achieved. If you want more speed, it's time for that 150€ Buwizz 3.

Or there's a China kit with a 20kmh top speed for half the price of the Lego kit. Just sayin'

[1gor]

23 hours ago, Sariel said:

Getting the GPS signal in a room or hall has proven somewhat tricky so far ;)

Hm...a bit different situation, but same type of problem I have discovered today; because of obligatory online lessons that I give I have found out that one ISP that also gives service of Internet TV is disturbing GPS and my mobile operators flat internet ... Perhaps you have similar issue, but good to know that I'm not seeing things 

[sonpham510]

axle 3 in gear 36 slips out after a while.  Is there any way to fix it.  thank you

[msk6003]

I made alternative model of this set.

Original set is focused for offroad so I think onroad alternative model will good.

Can use same app for driving but I use brickcontroller 2 in video for better control.

And not tested yet but 41897 tire can fit for If don't want drifting.

[Mechbuilds]

That's not really drifting.. It's just going forwards and doing a 180.. "half donut".. Drifting is long curves.. Could be also user fault because he didn't counter steer in turns. But can't be 100% sure if it actually drifts.

[Jurss]

23 hours ago, sonpham510 said:

axle 3 in gear 36 slips out after a while

Haven't driven so long

Only option coming to my mind is to use this

That pin already has smaller friction (as I have notoced), and with Your driving it will soon become frictionless anyway.

[sonpham510]

What do you think if using axle 2 ?

On 2/16/2021 at 9:12 PM, Jurss said:

Haven't driven so long

Only option coming to my mind is to use this

That pin already has smaller friction (as I have notoced), and with Your driving it will soon become frictionless anyway.

What do you think if using axle 2 ?

[Jurss]

It will then also slip out. But most critical could be, that other end of axle wont be "fixed", that large gear can lean on some side or something.

[Zerobricks]

Regarding axle slippage.

A somple 1x3 tile held by 2 half pins covering the axle should do the job.

[sonpham510]

18 hours ago, Zerobricks said:

Regarding axle slippage.

A somple 1x3 tile held by 2 half pins covering the axle should do the job.

Is this part

[Jurss]

16 minutes ago, sonpham510 said:

Is this part

?!

[sonpham510]

You mean there must be a lego code 32184

[Zerobricks]

2 hours ago, sonpham510 said:

Is this part

 

No, 1x3 tile:

https://www.bricklink.com/v2/catalog/catalogitem.page?P=63864#T=C

Held by 2 half-pins:

https://www.bricklink.com/v2/catalog/catalogitem.page?P=4274&name=Technic, Pin 1/2&category=[Technic, Pin]#T=C

[apachaihapachai]

Made a PF version of the set with BuWizz and Buggy Motor.

Edited June 26, 2021 by apachaihapachai

[Igor1]

@apachaihapachai Where can you buy these tires?

[1gor]

4 minutes ago, Igor1 said:

@apachaihapachai Where can you buy these tires?

This are Fisher Technic tires... I bought it here (part number FT106766 )

[Igor1]

@I_Igor Thank you! For some reason there is not enough information here. No width or inner diameter. How do I understand the outer diameter is 80mm?

[1gor]

59 minutes ago, Igor1 said:

@I_Igor Thank you! For some reason there is not enough information here. No width or inner diameter. How do I understand the outer diameter is 80mm?

Tractor tire D80 means 80mm diameter 

[sonpham510]

On 2/19/2021 at 3:15 PM, Jurss said:

?!

 

On 6/27/2021 at 2:35 AM, apachaihapachai said:

Made a PF version of the set with BuWizz and Buggy Motor.

Can you share io File. Thank you very much