Sunday, August 15, 2010

Week TechVideo, 2010 #32 - One 8043 MOD

Now that some started to report issues with their 8043 Motorized Excavator sets, namely poor performance on the boom raise, Jaeho Jung (sunsky) did some modifications to his model and produced a nice video playing in a real sand field.

He added some PF parts to the drive train,
  • 2 XL-motors
  • 2 PF Receivers
  • 1 PF Rechargeable Battery (8878)
And removed a lot of gears not needed anymore in the upper structure, while keeping the almost the same shapes.
This way each of the Excavator six functions got his own motor and there no more need to be switching between sets of functions.

While not strictly needed, because there are just two motors on the drive train, Jaeho Jung used two PF Receivers connected in parallel to eliminate blind spots where the receiver won't "see" the remote. This is however not a standard use for the PFS parts and you should be responsible for eventual damages if deciding to give it a try.


Jurgen Krooshoop said...

Nice MOD. But I don't understand why to use XL-motors for driving when lifting the boom is the most underpowered function.

Ulf Andersson said...

Well done indeed, I must say.

I want to share my positive experiences by using
the down gearing shown in this link

No matter which motor you use,
I think that this down gearing is very universal
and can be used in many ways.

sunsky said...

I did not see the Eurobrick forum before I made this mod. And so, I did not know the boom lifting was the most controversial.
Many people in Korea complains about boom lifting, but personally, I was mainly dissatisfied with 8043 set in that

1) assymetry in left/right track driving
2) too complex gear combination

So I did not pay much attention to the boom lifting.

Although I did not like the complex gears, I loved the mechanism that enabled free turning of the upper structure.
So I focused on making it drive without significant blind angle and turn freely at the same time.

If I make further modification on boom lifting, maybe(somehow) I will redesign the right angle connection by THIN bevel gears.
Changing the motor to XL, I am not sure yet. I think the think bevel causes the problem.

I hope some other person will make better MOD :)
And, thank you for praise.

Ulf Andersson said...

@ sunsky
"1) assymetry in left/right
track driving
2) too complex gear combination"

One of the models in the Universal Building Set 8082 from 1993, is a forklift with "track driving" -
even though there are no tracks.
The forklift has wheels, but the steering is achieved by one side standing still and the other one turns - just like a tank or any other "tracked vehicle",
and the driving is four wheel drive
and reminds of 8043 very much from what I can understand from the building instructions made available here at TB.

Ulf Andersson said...

@ sunsky

By the way, it might be worth
looking at the building instructions
of the 8275 Bulldozer (even though it has 2 XL-Motors for the track driving) to compare and make adjustments.

Kind Regards from
fellow builder Ulf
(mostly into Monster Trucks, cars
[Technic - Model Team hybrids] and analogue robots - stair climbers and industrial robotic arms)

TechnicBRICKs said...


guess the XL-motors for driving were used because there was the space to use them, and they make nicer drive performance.
As for the boom lifting, at least it looks reasonable in the video. Maybe also the extra gearing removal had improved a bit with the friction.

sunsky said...

@ Ulf
Thank you for the detailed advices.
I will try if time permits me to (I am somewhat busy these days).

I chose XL motor because
1) XL fitted in the space well
2) overall model was rather heavy
3) XL had lower rpm than M motor and high gear ratio was not needed to obtain smooth(not too fast) motion.

I agree somehow that gear removal improved a bit of power transfer. But the boom motion is not satisfactory yet.

TechnicBRICKs said...


You're welcome! ;)

Robotica said...

HI All,

When I build the model I saw that you have to make sure all turns correctly, during the BI steps!

My model has non of the complains I see, (agreed it uses fresh batteries, and the lifting of the main boom is a little underpowered) but I think all the driving issues has to do with poor building.

regards Martyn

PS I like the solution, since now you can operate all functions at the same time.

TechnicBRICKs said...

For the driving issues I think they are may arise for those who are reporting problems with the boom lifting. In these we must realize the motor which lifts the boom is the same which drives the left track (when seen from the backside).

I had no problems with mine, despite the boom is noticeably underpowered.
However recent and more detailed experiments lead me to the conclusion, that continuous boom operation causes heating on the already struggling motor, which then decreases its performance. it is a vicious cycle...

sunsky said...

@ Robotica
It is a good point that
"you have to make sure all turns correctly, during the BI steps! "
I have similar habbit that I check the mechanisms move smooth during building.
But, we cannot expect everybody to be cautious or sensitive to the Technic parts and mechanisms. Especially for kids.

I am glad that you liked my mod. :)

TechnicBRICKs said...

Mine was also carefully assembled.

But day after day, of intensive tests and use, it is getting worse.
I'm starting to think it depends a lot on how long you play with it, until the motors die.
I started with about 14sec to lift the boom completely and now it hardly goes below 30sec...

Connected to a train speed regulator.

sqiddster said...

I believe the purpose of using the extra recievers was to add power to the motors and not just to decrease blind spots. I saw this demonstrated in a video, but i can't remember where, so, sorry.

TechnicBRICKs said...


probably you have seen it in another recent YT video from sunsky.
But in this specific case, you don't need extra power for the two XL motors, as one receiver is perfectly capable to handle the required current if the motors won't stall (unlikely).
Current limit of the IR Receiver is 800mA.

Anonymous said...

I also made some modifications for this set.

I diden't want to use the Rechargeable Battery because not everyone can effort one.
Because the motors are placed directly on the 8z gear, there is less speed reduction. But the motors have no problems with that the extra speed is more fun to play.

For the upperstructure, I also placed all four motors directly to their functions, and removed of parts like gears and driving rings ( I think I removed 80 parts )
I believe raising the boom works now better because there are a lot of gears and a driving ring removed.

Unknown said...

I am Tomac on the Eurobricks thread and my 8043 is definitely getting worse as time goes on. I am using another set of fresh batteries (Energizer Alkalines, 3rd set now) and the motors perform very very badly.

I have contacted Lego as in all honesty I just want a full refund now. I tried out my 8275 Bulldozer last night and it plays so much better in every way. Nothing is struggling to run, its super smooth to play with, and the batteries in that are 1 year old!! Its brilliant!

8043 is a poor model overall because of all the problems with it. I definitely did not make a fault during the build process, and considering how many other people are having problems, I would say its a design fault with the model.

Jurgen Krooshoop said...

I did some more modifications to my 8043 and made complete instructions for it. Instructions can be found at

It now includes:
* Full independent simultanious controll of all the functions
* Joystick-controller that works just like a real excavator. Based on a desigh by Jason Railton
* 8878 Rechargeable battery
* XL-motor for lifting boom
* PF-lights
* Improved bucket looks and operation
* Improved Dipper range
* All the gear-reduction moved to the undercarriage
* Cabin roof

sqiddster said...

Thanks, I didn't realise.

Ulf Andersson said...

Off Topic:

@ Conchas

May I be so bold to suggest
a "search field" on this blog?
It would make it much easier to find
older posts by typing a key word.

This blog is one of the greatest blogs ever and it´s enourmous.

Kind Regards from Ulf

TechnicBRICKs said...

@Ulf Andersson

But it has!
Don't you see a Blogger search text box above the TBs logo?

Ulf Andersson said...

@ Conchas

Sorry, I thought that it only was
to search for other blogs.

I think I saw the video for the
M1 A2 Abrams Tank here at TBs
and I forgot when the post was published.
The suspension is as simple as it is brilliant.
However, I found the video on YT
and used FlashGot to get it on my harddrive -
for closer studies.

I´ve never been much into tracked vehicles before,
but I always
wanted to build a version of Bigfoot Fasttrax

Of course, Bigfoot´s worst competetor, Bearfoot
also made a trax -
but with almost no
suspension at all.
He seemed to land harder than
Bigfoot at their races.

Would it be possible to ask
for your e-mail address
to present my Technic MOC´s
to you when I have something
worth showing and sharing
with the world?

My e-mail address is:

Thanks for your time and effort.

Kind Regards from Ulf

Unknown said...

Conchas, want to put this info on the main site home page?

I have lots of information about the 8043, direct from Lego UK:

I got a call from a very kind and friendly lady at Lego UK today, and this is what I was told.

- The Lego designers in Denmark are aware of the problems with the Excavator
- They have pulled 50 (fifty) models from storage and built them. ALL 50 had problems
- At first the models work OK, then the performance drops over time (as with mine and others)
- They think it might be transmission related but are not 100% sure
- Problems were not noticed during design phase
- Not a high population of users have complained about problems (I guess that doesn't mean they don't have issues, just not reported them)
- They think it could be a bad batch of models

- They hope to have full results in 7 days
- There will be a redesigned model with fixes, hopefully within a few months (3~ months)

I have been given a full refund on mine now which is great news. I am taking mine apart tonight and sending it off. I have to say Lego have been very good about this situation and they are working very hard to trying to solve the problems. For now though, I'd rather have the money back until it is fixed.

Hope this helps.

TechnicBRICKs said...


I've seen your post at EB just before, and since I was planning to answer in another thread I will answer to this now.

I've been doing also many test now.
However I don't plan an announcement here right now, until I get some feedback.
Honestly I don't find it much useful at this point. However I do not regret that you published the information that you received. Just think that some of the conclusions are not right.

Dominic said...

Slightly off-topic, this set is currently listed as "not available in this country" for the US.

According to a LEGO S@H supervisor, the US-allocated stock for this set has been sold out and there are no plans to sell additional stock within the US.

This is by far the shortest run that I have ever seen for a Technic set (less than 13 days!)

TechnicBRICKs said...

It looks it has been removed from S@H listings in every country.

Guess this set is returning to the benchtop for a major redesign, if not dropped at all..

It may take us sometime to know what will happen with it.

TechnicBRICKs said...


guess you have not played enough with it.
Too much LEGO to play with. ;)

Initially I didn't play with mine so much, either.
Only the later tests have taken it behind the limits...

Ulf Andersson said...

@ Conchas
"It looks it has been removed from S@H listings in every country."

I can confirmed that 8043
has been removed from S@H
with Swedish prices.

Kind Regards from Ulf

Unknown said...

Yep, like I said in my post, Lego UK told me today that 50 sets were testing frmo stock and built, and every single model had problems.

It is now having a redesign which will take around 3 months.

Ulf Andersson said...

Maybe it would be a good idea
if they(Lego) copied the boom
lifting features from
8258 Crane Truck?

And I´m amazed to hear about the failures
of the boom raising -
considering the powerful
Electric Power Functions
Linear Actuators (x1918cx1)

Not having bought 8043
and therefore lacking
experiences from building
the model, I´m listening
with interest to this

It´s also very important
in what way one is expecting
the Motorized Excavator to
we must not forget that the
excavator have motorized
functions which have limited
performaces to let´s say a
metallic mechanical excavator
for kids, which is operated


Anonymous said...

I believe problem is that under the manufactureing that use a small and light dipper. and than at last miniute, idiot on LEGO imagine that it shall look better with a biger and heavier dipper to the exavator.. and not "test it after the exchange" and naw we have problem whit exavator. the only solution to the problem is for LEGO to change the dipper to a smaller. because when you take of dipper of arm the problem is not left. to exchange out many part or re build should cost for much for LEGO.

TechnicBRICKs said...


I think you meant the shovel.
But now you really dive into speculation about what happened...

What I think is that the test phase was not really conducted as it should be in the development process.
However we don't know exactly how the TLG process is, and there are several possible causes for it to happen as it did.

Related Posts Plugin for WordPress, Blogger...

© 2007-2014 TechnicBRICKs
TechnicBRICKs contents may be sporadically updated, if the authors finds further relevant info about a certain post, or content/spell mistakes. Hence please don't be surprised if you find few changes at later visits, relative to a previous read.

TechnicBRICKs often shows other peoples' creations and/or images. We always try to credit the author(s) and link to their main publishing website, and if possible with their name in real life.
Since this is not always possible, we request that if you find something here that is yours or from someone you know, you leave a comment on the respective post and claim the authorship.

TechnicBRICKs is optimized for Firefox 16.0 and 1600x1200 resolution displays or wider.

LEGO® is a trademark of The LEGO Group of companies which does not sponsor, authorize or endorse this blog.
LEGO, the LEGO logo, the Brick and Knob configurations, the Minifigure and MINDSTORMS, are registered trademarks of The LEGO Group.
Original LEGO images are copyrighted by The LEGO Group and are used here in accordance with their fair play policy.
You can visit the official LEGO® website at