Gaz 66 trial truck with RC system and 1,9" tyres

[Tamas Juhasz]

Hello!

After a while, I'll post mocs again, and for starting, I choosed one of my latest creations, a Gaz 66 trial truck. This is my third Gaz66 Lego trial truck, now with 108 mm RC4WD custom tyres, as many technic vehicle has. Equipped with two RC buggy motors for propulsion and one PF M motor for steerig, built in the front axle.

The two RC motors are linked together with a central axle, however, they are located separately near to the front and rear axle. With this technique, they can help each other to move this truck over obstacles.

I tried to get close to original Gaz66 with the body, but angles and others, like ground clearance were also important. It can be precisely driven, thanks to the RC throttle with 3 levels and linked pendular suspension. This was made first of all for a Lego truck trial competition, organized by HUNLTC in Hungary:

Gaz66-024

Gaz66-023

Gaz66-022

Gaz66-021

Gaz66-020

Gaz66-019

Gaz66-018

The RC unit is also part of the frame:

Gaz66-016

Gaz66-015

Details:

Gaz66-013

Gaz66-012

Gaz66-010

The power transmitter axle between the two motors:

Gaz66-011

Gaz66-009

Gaz66-008

Gaz66-007

Gaz66-006

Yes, some scratches appeared after a long run on rocks and others, but I don't care, it's an outdoor built moc.

These angles can be done by suspension:

Gaz66-005

... and steering:

Gaz66-004

Gaz66-003

Top view:

Gaz66-002

Nowadays I have a new semi-pro camera, so from now, you can watch 1080p good quality videos, in my new creations. (but for old mocs, which are waiting for publicizing, I still only have the 480p videos). The slow motion parts were filmed with 1080p60fps and 320x240 at 240fps.

Video:

Edited August 14, 2016 by Mbmc

[miguev]

Impressive. Never seen 2 buggy motors do so well in a trial truck, and it seems a whole lot more stable in action than at first sight.

[MaxSupercars]

Hmm interesting MOC but was is not possible to place long liftarm under the front axle higher? The sense of using portal hubs for higher clearance is then missing...

Max...

Edited July 2, 2015 by MaxSupercars

[Tamas Juhasz]

If you build a trial truck, you will see, there is many (more) important things beside 1 stud more ground clearance under axles. Rigidness of the axle, keeping wheels strongly in position, prevent wheels to slide off from axle, etc. The portal hub of the 8110 and 9398 makes these also possible, but they are used first of all to decrease the stress, the load of the universal joints in front axle. Every other thing is far secondary. In case of these large wheels, without portal reduction the load would be way higher in U-joints, than they can handle.

In solid axles, even with portal hubs the ground clearance is maximum as high, as the center of the wheel (except special constructions):

https://www.flickr.c...tream/lightbox/

http://www.brickshel...y.cgi?i=5018201

http://www.brickshel...y.cgi?i=4974606

Anyway, good observation, I'll think about it, but because of the 24 and 36t gears, I see little chance to move higher the connector beam.

Edited July 2, 2015 by Mbmc

[pierremacchangstein]

Nice! I really have to get a couple of those motors one day...tires too.

Best part about your trial truck? Annoys cats.

[MajklSpajkl]

Very good performance, besides the good setup and weight distribution, these custom tires make miracles. I'm afraid that with LEGO tires it wouldn't be so good. How much does it weigh?

[Tamas Juhasz]

Thanks guys.

I'm afraid that with LEGO tires it wouldn't be so good. How much does it weigh?

As I wrote in the video, 1934 g. Of course it wouldn't be this good with Lego tyres, it's a fact for every Lego trial truck, that's why many of us use customs. But with PP wheel, I think it could do nearly the same. Weight would be increased, but there is some reserve in the motors, AND I can decrease it's weight with the ballast: side tanks and a Lego ship weight in the rear axle are built in specially for ballast.

But why would I use PP wheel, when it's made for custom wheels? Many technic mocs have nowadays custom tyres. And yes, as you wrote, weight distribution helps a lot, it has about 57 - 43 % (front - rear).

Edited July 2, 2015 by Mbmc

[MaxSupercars]

@Mbmc:

All the points you mentioned about trial truck priority are clear. It was only question from me... Maybe you could save 1 stud... I don't know what combinations you have tried... No problem... :)

Max...

[AndyCW]

Looks and performs great. I think that there is a great deal of margin left in those motors. It appears that it is geared 27:1. I think that you could easily go down to 9:1 and gain drive train efficiency by eliminating one of the 3:1 exchanges. You might even be able to run off of the fast output. Wheel speed matters.

ZBLJ's Panther ran 9:1 5292 motors with V1 rx. You have roughly 3+ times more torque delivery capability with the RC unit.

I ran 9:1 gearing on 5292 motors with v2 rx and PP tires and had no problems spinning them.

I wouldn't be surprised if you could go all the way to 5:1 gearing with the power delivery capabilities of the RC unit.

Let her rip, tater chip.

v/r

Andy

[MajklSpajkl]

As I wrote in the video, 1934 g.

Ups, sorry, I missed that...

So your rules for TT races allow custom parts? Our LUG sticks to all LEGO and only PF system, no RC...

[Tamas Juhasz]

@MaxSupercars:

Ok. No problem too : )

It appears that it is geared 27:1. I think that you could easily go down to 9:1 and gain drive train efficiency by eliminating one of the 3:1 exchanges. You might even be able to run off of the fast output. Wheel speed matters. ZBLJ's Panther ran 9:1 5292 motors with V1 rx. You have roughly 3+ times more torque delivery capability with the RC unit.

I ran 9:1 gearing on 5292 motors with v2 rx and PP tires and had no problems spinning them.

I wouldn't be surprised if you could go all the way to 5:1 gearing with the power delivery capabilities of the RC unit.

There is 18:1 gearing. The 24:12 gearing before U-joints doubles the 9:1. One unwritten rule is the following: if the whicle has some weight (so not a crawler), the minimum reduction with 108 mm wheel and RC motors powered from RC unit is 15:1. In general, It SEEMS to be, it has enough power with less than 15:1 gearing, but once if you try to climb hill backwards, and there is some grass, RC motors became stucked. I have real RC technic, and believe me, Lego RC motors are very very weak. They just seems to be strong, because PF motors are even weaker.

But back to the theme: This truck has 1,1 km/h speed, which I think is enough. I thought about 15:1 reduction, but as I wrote, in same cases wouldn't enough. Imagine: there is more than 1 kg on the front. It's a lot in terrain, but it has climbing advantage, and it's a truck, needs a "heavy" body in the front. The crawlers you mentioned, like Panther are in other category. They are way more lighter, and have 50-50 % weight distribution. The relationship between power and weight is not linear in this scale (Panther has 400 g axle load --> in a truck with 1,2 kg axle load and 3 times more power than Panther wouldn't be 9:1 gearing enough). That's why you can't compare. I built this truck with 15:1 gearing and PP wheel, and it was the motor's limit:

--> it was 4 kg, 4 RC motors, 2 RC Units.

5:1 gearing in this Gaz truck would make absolutely no sense. Would be very, very weak. Even with 9:1 gearing. With 15:1, or with the fastest output would be good, but not better. (I use fresh, new, quality batteries, only 3 gearing to be effective, connected motors, so the performance depends on RC system).

Ups, sorry, I missed that...

So your rules for TT races allow custom parts? Our LUG sticks to all LEGO and only PF system, no RC...

No problem. Yes, we allow custom tyres, and other small usual custom things (rope, covering material in the back, O-rings, rubber bands). I think, SBrick is at least as custom, as custom tyres, maybe you should legalize them in races (we allowed SBrick too, however, I never would use it). PF system really sucks in outdoor conditions, as you know. Why do you only use PF? Sun could make the control really annoying. Old Lego RC system is better in this case, but has it's disadvantages, too, but for me, for this truck is perfect, makes the frame more rigid, and increases the control range.

After a bit of thinking, I realized, this truck will be good for any types of TT races:

1. failure point matters: good because it's climbing, stability, precise control options

2. time matters: pretty fast, way faster than 5:1 geared XL driven vehicles. If there is a weight/motor ratio, can be easily done, since it's nearly two kg heavy, won't be too light. I can even decrease the weight with the mentioned ballast, if rules allows.

I'm sure, it will be a participant in future Hungarian TT competitions.

Edited July 2, 2015 by Mbmc

[MajklSpajkl]

Why do you only use PF?

Yes, everything you said about PF system in the outdoor is sadly very true. We decided to go only with PF system, because RC system and buggy motors are quite rare and PF system is widey available. So to keep it in the same range for everybody we decided for PF and to be honest a PF TT stands no chance against proper RC TT. Another problem is, that we are quite a small bunch of TT drivers, so asside PF system, original LEGO parts and 30 studs wide gates, everything else is loose in order to get as many people as possible to join the race.

[AndyCW]

Interesting. I thought the middle gear exchange was 24:8. You make a good point about weight and how required gear ratio and weight do not necessarily scale in a linear fashion with one another. Moving to an S-Brick could be advantageous. The sequence of trophy trucks that were on here a couple of weeks ago make that plainly clear.

I currently run 2X 5292 motors through 5:1 gearing with the 107mm tires and it is capable. It pulls a wheelly when sudden direction changes are initiated and spins the tires on tile floors. It also has enough torque to crawl through most anything. Admittedly my truck only weighs 1.4 kg, is relatively balanced fore and aft, uses a 3S Lipo, and a non-lego motor driver/rx.

Despite my questions, I love the truck and would love to have the same kind of competitive community on this side of the 'pond'. I envy you.

v/r

Andy

[Paul B Technic]

The level of detail in this is amazing, well done and thanks for sharing :)

[Tamas Juhasz]

We decided to go only with PF system, because RC system and buggy motors are quite rare and PF system is widey available... Another problem is, that we are quite a small bunch of TT drivers, so asside PF system, original LEGO parts and 30 studs wide gates, everything else is loose in order to get as many people as possible to join the race.

We have a usual team with about 6 constantly partcipating member. Four of them have RC system, and if necessary, we can loan motors and RC units to each other, who have more. That's why we could make a TT race only with RC, but it never happened, as you wrote, people want to use the PF, and in some design, only PF system is allowable. I totally understand you with the small bunch of TT drivers. In Hungary, mostly I'm the organizer and the most participated in TT races, and nowadays we are happy, if we have 6 competitor each race. Every of us got job, finished university, got much less time to build and particpate in TT competitions. But we have at least one bigger TT race each year, soon I'll create a topic for hungarian TT events.

Moving to an S-Brick could be advantageous. The sequence of trophy trucks that were on here a couple of weeks ago make that plainly clear.

I currently run 2X 5292 motors through 5:1 gearing with the 107mm tires and it is capable. It pulls a wheelly when sudden direction changes are initiated and spins the tires on tile floors. It also has enough torque to crawl through most anything. Admittedly my truck only weighs 1.4 kg, is relatively balanced fore and aft, uses a 3S Lipo, and a non-lego motor driver/rx.

Despite my questions, I love the truck and would love to have the same kind of competitive community on this side of the 'pond'. I envy you.

Thanks. Yes, SBrick uses better also the original Lipo battery, and some builders use custom LiPos (and imho it makes a moc an RC/Lego hybrid creation). Can you send me here or in pm, which truck is in the quoted part? I haven't found. One more thing: Trophy truck have good climbing ability with help of their speed, that matters a lot. Trial trucks have nearly no speed compared to them. And.. custom LiPos: they provide much more power than PF LiPo, and some of them even more, than Lego RC unit. So with them, with non-Lego rx, it's easy to reach that power/weight ratio. Soon we need two separate categories for mocs: mocs with only original Lego parts, and mocs with significant custom modifications. With Lego, you can't compete with them. People are wonder about their performance, and the title says, it's Lego, but the most important part isn't Lego. So there is no wonder in performance of these mocs (I accept custom tyres, that's all). IMHO.

Back to the theme, I just want to say, you can't compare a moc with custom battery and RX, with a moc which has original Lego RC system.

The level of detail in this is amazing, well done and thanks for sharing :)

Thanks, I tried to improve the cabin and side parts a bit.

[__________________________]

This looks great! Does it have a gearbox?

[Tamas Juhasz]

@TheLegoExpert: no gearbox built in, doesn't need it. RC system provide the speed and torque too.

@Mbmc: All the points you mentioned about trial truck priority are clear. It was only question from me... Maybe you could save 1 stud... I don't know what combinations you have tried... No problem... :) Max...

Ok.. so I thought about the modification, and I could make an improved version, in which the long cross beam disappeared, and the whole width of the axle got 1 stud higher ground clearance:

One strong 3x3 dkBLgray plate holds the thin liftarms together (these connections are stronger than pin connections):

And the whole bottom:

Thanks for the idea, I wouldn't improve it by myself. It's as strong, as the old version. Interesting that I never used any of those 5x3 thin liftarms, this is the first time I use them, after 10 years of making mocs.

Edited July 3, 2015 by Mbmc

[AndyCW]

That change to the front axle is ingenious.

Could you turn the rear motor 180 degrees, move the RC unit aft and eliminate the need for the ballast brick?

I agree that custom batteries can make a huge difference. The point in my comparison is that my setup allows me to 'use 5292 motors to their full potential' and the RC unit 'should' do the same. The key difference seems to be weight. If I were to run on a 2S Lipo then the comparison would be even better. You are absolutely right that once you cross over into the dark side of including non-lego components, it becomes hard to determine where to stop.

Here is a link to the last iteration of my truck.

http://www.eurobrick...opic=102138&hl=

My newest version has the capabilities listed previously.

My builds tend to be neither trophy truck nor trial truck, but closer to King of the Hammers and Rock Bouncers.

v/r

Andy

Edited July 3, 2015 by AndyCW

[MaxSupercars]

@Mbmc:

That looks better! :)

Max...

[nerdsforprez]

Thanks guys.

As I wrote in the video, 1934 g. Of course it wouldn't be this good with Lego tyres, it's a fact for every Lego trial truck, that's why many of us use customs. But with PP wheel, I think it could do nearly the same. Weight would be increased, but there is some reserve in the motors, AND I can decrease it's weight with the ballast: side tanks and a Lego ship weight in the rear axle are built in specially for ballast.

But why would I use PP wheel, when it's made for custom wheels? Many technic mocs have nowadays custom tyres. And yes, as you wrote, weight distribution helps a lot, it has about 57 - 43 % (front - rear).

I have written on this and other forums the lack of utility of the PP tires. They are even mor expensive than RC tires, do not perform as well, and can even be dwarfed by the right tires. Below is a pic of tires I used on my unimog compared to the 8110 tires. Clear difference. I (as you can see in the pics below and on my MOCpages) am a big fan of rC tires. The only reason I can see for the PP tires is if one is a LEGO purist....which I am not

[Tamas Juhasz]

I have written on this and other forums the lack of utility of the PP tires. They are even mor expensive than RC tires, do not perform as well, and can even be dwarfed by the right tires. Below is a pic of tires I used on my unimog compared to the 8110 tires. Clear difference. I am a big fan of rC tires. The only reason I can see for the PP tires is if one is a LEGO purist....which I am not

PP tire is very good at it's own. They are heavy, move down the centre of gravity, looks good for monster trucks and for any big and wide wheeled vehicle. Using larger than 108 mm tires (PP is also 108), leads often to the damage of drive train, extreme loads and stress can appear. Of course, not in mud, slippy, or flat terrain, rather in heavy conditions, like rock crawling or in truck trial stages. So both the Lego wheels and RC wheels have advantages. Imho the RC tyres we use are for replacing the 94,3 and 94,8 mm Lego tyres, not the PP.

But back to the topic, please don't make off like these.

Yesterday I finished the LDD file. Does someone needs an instruction? I have a new, quick method for making quality stop-motion instructions in LDD. I can adjust logically the building steps, which is really missing from the LDD automatic instruction generator.

Edited July 4, 2015 by Mbmc

[Tamas Juhasz]

Could you turn the rear motor 180 degrees, move the RC unit aft and eliminate the need for the ballast brick?

Andy

I forgot to answer. So the situation is the following: when we have Truck Trial races in hungary, sometimes time matters, the faster wins. To compensate the motor's power compared to each other, whe have motor/weight ratios for every drive motor. XL usually has 750 g, which means, if you use two XLs, your truck needs to be minimum 1500 g. RC buggy motors usually have 900-1000 gramms. So this truck, if I want to be legal in competition, has to be minimum 1800 g, maximum 2000. If the lower limit will be in the rules, I take off weight, if the upper, I add a little more (now it's 1940 g). So it's good for any ratio and any kind of rules. We sometimes regulate the width, usually between 25-30 studs. It's 28 studs wide. I designed it specially to be acceptable for nearly all kind of TT competition rules (only the "one-motored" and "only-PF" rules can make it illegal).

Edited July 6, 2015 by Mbmc

[GI_Jack]

That is a very cool model, really like it.

I also wanted to build that interesting piece of Soviet / Russian engineering. You have done it very well.

[Block_Smarts Lego Technic]

Like the use of rc motors, high rpm means lots of potential torque! I should try that!!

[Tamas Juhasz]

Thanks guys.

@Block_Smarts Lego Technic: yes, RC motors have more power ( torque [Nm] * angular velocity [rad/s] ) than PF motors. Basically, with no gearing the stronger output has about 12 Ncm max (stalled) torque. If you try, you should use the RC unit, PF LiPo and AAA BB can't deliver the needed current for maximum power.

Edited July 10, 2015 by Mbmc