I bought my copy of this year's flagship Technic set, 8043 Powered Excavator from Toys-R-Us on the first day it was listed, with expedited shipping. It was completely worth it

Not being satisfied with just following the instructions, I devised some relatively simple mods before I even started building. I will be outlining the design changes in this thread, along with a tutorial or two.

My mods include:

Modified gearbox - no longer has to change between moving and arm functions

Additional motors and receiver - 2 M motors added to the boom, all 6 functions have their own motor

Strengthened the stick - no longer relies on a single 15L liftarm

Replaced PF battery box with 9.6V RC battery pack - MUCH more power than PF box with alkalines and is rechargeable

The first mod I will outline is the adapter for the RC battery pack.

First, a warning for the faint of heart: this mod involves the modification of a Lego element However, unlike the flamethrower, this mod does NOT involve the melting of Lego, unless you're really bad with a soldering iron

You can also use crimp-on butt connectors if you don't have any soldering supplies or knowledge at all and don't mind a kludgy looking finished product.

Also, you follow this advice at your own risk. I have done this mod and can vouch for the fact that it works, but if you do it wrong you may risk letting the magic smoke out of PF components (they do have overcurrent protection and I think they have some protection from being connected to power backwards, but I make no guarantees). It also involves soldering, but is very simple. If you know which end of the soldering iron to grab, you should be able to handle this mod.

That being said, on to the fun part.

For this mod you will need the following components:

Power Functions extension wire currently US$2.99 at shop.lego.com

Single-pole single-throw (SPST) power switch - any type will do (toggle, pushbutton, rocker) but I prefer a simple slider switch. I got 2 small slider switches for about $3.00. Strictly speaking the switch is optional, but if you don't have one you will have to turn the model off by unplugging the battery. A PF toggle switch won't work because it only switches the control signals and passes the 9V power straight through regardless of switch position.

RC battery pack power lead - this is a simple 2-pin nylon plug that is pretty much standard. I got mine at Radio Shack as part of an RC battery repair kit for about $4.00. It came with male and female plugs, you will only need the male side as the battery lead has a female plug.

9.6V RC battery pack - these can come in different power ratings, but the technology is pretty mature so they're all pretty similar. All the ones I've seen look like 8 AA cells soldered together and wrapped in shrink-wrap. I got a 1600mAh NiMH pack with charger for $20.00, which is about what a good set of rechargeable AAs and charger would cost.

Heat-shrink tubing - useful for insulating soldered wire connections. Makes a much neater finished product than vinyl electrician's tape.

Tools you will need:

Wire cutters or other cutting tool

Wire strippers

Soldering iron

Heat gun - for heatshrink tubing. A lighter can be used VERY CAREFULLY, or the soldering iron by holding the heat-shrink tubing very close to the iron element without touching it.

To start with, take the Lego Power Functions extension wire and cut the cable in half

You can use either end of the cable for the adapter, both ends are wired identically.

Now separate the cable down the middle so you have 2 sets of 2 wires. Separate each pair and strip the insulation back on each individual wire. It should look something like the following:

Take the right-hand pair of wires and twist them together. These are the 9V wire and the C2 wire. Slip a piece of heat-shrink tubing over the wires and solder them to one of the switch terminals. Connect the red positive (+) wire from the battery connector to the other switch terminal, covering with heat-shrink.

Take the left-hand pair of wires and twist them together. These are the 0V and C1 wires. Slip a piece of heat-shrink over them and solder them to the black negative (-) wire from the battery connector.

The finished assembly should be wired like so:

Shrink up the heat-shrink tubing, making sure it covers all exposed conductors.

To test, connect the battery to the adapter, connect the PF connector to a motor and turn on the switch. If the motor spins, power is flowing. If not, check your wiring. Next connect a motor to an IR receiver and connect the receiver to the battery adapter. If the green light on the receiver comes on, the wiring is correct. Test the motor functionality with a remote control. If the green light on the receiver does not come on, TURN OFF THE POWER IMMEDIATELY and check your wiring.

Once you've got it working you'll have a powerful, rechargeable power solution for your Power Functions model. You can also use the leftover half of the PF extension cable to make a second adapter.

Stay tuned for more mods!

Edited July 30, 201014 yr by Buffalo

this looks cool keen to see some pics

I had bought all the stuff to do this for a rechargeable 9 volt lipoly battery for mods to my 8258.

why not just buy some high quality cells to put in your PF battery-box instead of all this work?

why not just buy some high quality cells to put in your PF battery-box instead of all this work?

To save some space ?

why not just buy some high quality cells to put in your PF battery-box instead of all this work?

The problem with the PF box is that it holds 6 cells, which is fine if you use alkaline batteries which output 1.5V each, but if you use rechargeable batteries you only get 1.2V per cell. This reduces the voltage of the pack from 9V to 7.2, which makes a big difference in a model like the 8043. The RC battery pack contains 8 cells, which produce 9.6V. This is a huge improvement over even a fresh set of alkalines, since the rechargeable cells' voltage doesn't sag under load like alkalines do.

The other advantage is convenience - the pack can be recharged as a unit, whereas with the PF box you have to take all the cells out, and if you've got one of the 4-cell chargers that seem to be standard nowadays you have to run it twice to charge all 6 cells.

As far as space is concerned, the shape of the RC pack is very different from the shape of the PF battery box, since the cells are arranged in a flat pattern. If they were stacked on top of one another like they are in the PF box it would probably take about the same volume of space.

Fyredog: That looks pretty sweet. Are those cells the same size as a standard 9V?

Yes, exact size as 9 volt.

I used 2 of these in my Red excavator

That's cool. I see they're 170mAh, do they last very long?

I whipped up an LDD mockup of the gearbox in my excavator:

The rest of the 'box is built the same as stock, just without the transverse shaft with the gearshift levers on it. The 1x4 plates on the right support the third PF receiver. They are supported by a 1x2 Technic brick with 2 holes. The third receiver connects to the motors in the boom that drive the stick and the bucket.

For the remote handset I built this.

The bigger battery lasts a long time, the small 9 volt is meant to power 2 micro motors with very little resistance, so I haven't a clue an longevity per charge.

Dude, when do we get some pictures of your Mods? I would normally have modded the 8043, but since I own a red one - no need. I am planning the mods for my 8258.

Soon, I'm at work now and I'll get some pics up when I get home.

Edited July 30, 201014 yr by Buffalo

Just looking and wondering if you could fit 5 m motors there and still have all the gears operational? If you set all motors side by side, that would give you 3 more studs - the width of an m motor.

Just sayin'

I actually did have a plan for that at one point, and it probably would work, but it involves a bunch of 8t gears since some of the motor outputs would have to be offset by one stud. When I started building it I had doubts that I could get it to work smoothly.

Edit:

I got some pictures!

In this one you can see the battery pack and the power switch. The battery connector plugs are tucked underneath the battery pack itself. This battery is lime green and has LIGHTNING on it, so it must be really fast.

The modified boom arm. The motor to the left is attached directly to the frames at the center of the arm and has 2 U-joints to transmit power to the linear actuator that moves the stick. The motor on the right transmits power through 3 U-joints to move the bucket.

One of the motors and its driveshaft.

The second motor and its driveshaft.

The modified stick. It's increased from one beam wide to three, which significantly strengthens it.

Imposing, no? You can see the mounts for the bucket motor and the PF lights mounted to the boom shrouds.

Edited July 30, 201014 yr by Buffalo

The problem with the PF box is that it holds 6 cells, which is fine if you use alkaline batteries which output 1.5V each, but if you use rechargeable batteries you only get 1.2V per cell. This reduces the voltage of the pack from 9V to 7.2, which makes a big difference in a model like the 8043. The RC battery pack contains 8 cells, which produce 9.6V. This is a huge improvement over even a fresh set of alkalines, since the rechargeable cells' voltage doesn't sag under load like alkalines do.

The other advantage is convenience - the pack can be recharged as a unit, whereas with the PF box you have to take all the cells out, and if you've got one of the 4-cell chargers that seem to be standard nowadays you have to run it twice to charge all 6 cells.

As far as space is concerned, the shape of the RC pack is very different from the shape of the PF battery box, since the cells are arranged in a flat pattern. If they were stacked on top of one another like they are in the PF box it would probably take about the same volume of space.

Fyredog: That looks pretty sweet. Are those cells the same size as a standard 9V?

oh yeah, i forgot that they are only 1,2V...

oh yeah, i forgot that they are only 1,2V...

Just a note for Fyredog;

If I remember correctly from my school days the 9V battery has a very low internal resistance therefore dishing more current than 6 x 1.5volts AA. I don't know what is the ratings of the M or XL motors or if it could damage it...

But for sure the 9V is not meant for "current draining" motors.

Speaking of which, I have an old 9.6V deWalt battery at almost 1.2Ah ... there might be some testing ahead...

-Nick

Edited July 31, 201014 yr by Countdown

Just a note for Fyredog;

If I remember correctly from my school days the 9V battery has a very low internal resistance therefore dishing more current than 6 x 1.5volts AA. I don't know what is the ratings of the M or XL motors or if it could damage it...

But for sure the 9V is not meant for "current draining" motors.

Speaking of which, I have an old 9.6V deWalt battery at almost 1.2Ah ... there might be some testing ahead...

-Nick

That 9.6V battery is probably very similar to the RC battery pack inside. It should work, assuming the cells are still good.

Even if a 9V has low internal resistance, the motors should only draw as much current as they need to operate. In any case an XL motor would drag the 9v battery's voltage down so much I don't think you'd have much to worry about.

i have a li-po pack 11,1v 2200 mah on my 8043

much more power and much faster!!

i wil make some pictures later

greetz

here some watch stuff

i also closed it up a bit to make it look nicer

the inside desing from jurgen krooshoop

electric tips to weld the stuf togetter thanx to Buffalo also on this forum

it plays verry well now! incredibel stong now thnx to this forum it is a sucses!

Rien, that looks great. I'm glad I could be of help

I've made use of some of Jurgen's ideas in my 8043 as well. I've removed the gearbox section, and getting rid of a bunch of the gearing has made a big difference in how well things work. My R/C battery is now mounted in the bottom of the rear section where the motors used to be. I've also replaced the 16t clutch gear/driving ring assembly through the turntable with a differential. Now there is very little slack in the track drives. I'll try to get some pics after work.

Edited December 16, 201014 yr by Buffalo

I bought the 8043 for Christmas.

Got the new fixed version so no problem there.

I didn't like to have to switch mode to be able to turn around so I decided it was time for a mod.

First idea. Use a Micro-motor to drive the switching and use the fourth motor to do the turning.

It works but it's to slow.

Second idea, do it right :)

In other words do a full six motor mod. I like the original battery box so that should remain.

So where should I put the two extra motors?

I didn't want to put them in the arm since lifting is underpowered already. I wanted to improve the lifting if possible while still using a medium motor. After trying some not so good solutions, I came up with an idea.

Directly behind the pivotpoint for the arm there is a grey 13 beam. Behind that there is a black 15 beam. I removed that black beam and the geartrain for the lifting function. The 10 axle was replaced by an 8. By lowering the black 15 beam that's just ahead of the battery box 2 holes I got a hole long enough for a medium engine!. And since it now drives the lifting without a lot of gears it got a little better.

That was one motor. One left to place and as stated earlier in this thread there are space for five medium motors in the rear so lets place it there.

The leftmost motor (looking from behind) drives the right track.

The next motor drives the dipper-cylinder. To make the drive train for this as easy as possible I used a 3 axle out of the motor to a 4 long U-joint and a 4 axle followed by another 4 u-joint and a 3 axle and that reaches the 16 gear in the pivot.

The middle motor drives the left track strait through the old gearbox.

The next drives the bucket. It has the same transmission as the dipper

The last motor controls the turning.

The extra reciver was placed on the right side of the lifting engine.

I'll try and fix a picture later on (no battery in the camera)

I bought the 8043 for Christmas.

Got the new fixed version so no problem there.

I didn't like to have to switch mode to be able to turn around so I decided it was time for a mod.

First idea. Use a Micro-motor to drive the switching and use the fourth motor to do the turning.

It works but it's to slow.

Second idea, do it right :)

In other words do a full six motor mod. I like the original battery box so that should remain.

So where should I put the two extra motors?

I didn't want to put them in the arm since lifting is underpowered already. I wanted to improve the lifting if possible while still using a medium motor. After trying some not so good solutions, I came up with an idea.

Directly behind the pivotpoint for the arm there is a grey 13 beam. Behind that there is a black 15 beam. I removed that black beam and the geartrain for the lifting function. The 10 axle was replaced by an 8. By lowering the black 15 beam that's just ahead of the battery box 2 holes I got a hole long enough for a medium engine!. And since it now drives the lifting without a lot of gears it got a little better.

That was one motor. One left to place and as stated earlier in this thread there are space for five medium motors in the rear so lets place it there.

The leftmost motor (looking from behind) drives the right track.

The next motor drives the dipper-cylinder. To make the drive train for this as easy as possible I used a 3 axle out of the motor to a 4 long U-joint and a 4 axle followed by another 4 u-joint and a 3 axle and that reaches the 16 gear in the pivot.

The middle motor drives the left track strait through the old gearbox.

The next drives the bucket. It has the same transmission as the dipper

The last motor controls the turning.

The extra reciver was placed on the right side of the lifting engine.

I'll try and fix a picture later on (no battery in the camera)

U say the arm is slow to lift,i taught the new la,s were faster and smoother no?

U say the arm is slow to lift,i taught the new la,s were faster and smoother no?

They are better than the old ones, but that is still a lot of weight for an M motor to lift. My excavator has 2 M motors mounted in the boom, and the original motor was able to lift it, but I had to gear it down so it ended up being too slow. I'm now using an XL motor to lift the boom, which has no problems at all. The motor doesn't even really slow down when the LAs hit the end of their travel and the clutches kick in.

Iv just finished my excavator and I have to say I love it , new la,s seem to work well as it's not that slow,only small thing I notice is when I'm rotating the cab/digger my tracks seem to move very slightly some time too,anyone see this problem,also if I drive in a straight line the cab moves slightly as well,anyone notice this as it's very slight?

Iv just finished my excavator and I have to say I love it , new la,s seem to work well as it's not that slow,only small thing I notice is when I'm rotating the cab/digger my tracks seem to move very slightly some time too,anyone see this problem,also if I drive in a straight line the cab moves slightly as well,anyone notice this as it's very slight?

Just build jurgens model and it is much better also with new la's the remote is verry awsome!

Iv just finished my excavator and I have to say I love it , new la,s seem to work well as it's not that slow,only small thing I notice is when I'm rotating the cab/digger my tracks seem to move very slightly some time too,anyone see this problem,also if I drive in a straight line the cab moves slightly as well,anyone notice this as it's very slight?

The tracks moving when the cab rotates is an unavoidable consequence of having the track power go through the turntable. As the cab rotates, it's turning the axles that drive the tracks. The way to minimize this is to have as much of the gear reduction as possible done after the drive passes through the turntable, which the excavator does reasonably well in stock form. Jurgen's Ultimate 8043 improves on this by moving more of the reduction gears into the base.

The cab rotating while driving the tracks shouldn't happen, as the cab is driven by a worm gear that can't be back-driven by torque from the tracks. This effectively locks the turntable in place when there's no power being applied to the motor that rotates it. Does it rotate continuously, or does it move a bit and then stop? If it only moves a short distance, it's likely due to the slack in the gearing, which isn't really avoidable and is made worse by the worm gear drive.

*EDIT: if the cab moves slightly one way going forward, then moves the other way going backwards, you might try reversing one of the bevel gear sets under the turntable. Test it to see which track changed, then flip the black reversing switch on the remote that drives that track so the controls still work as expected. If both drives going through the turntable are turning the same direction when moving in a straight line, that will try to turn the superstructure. If they are moving in opposite direction the torque should cancel out and it should move less.

The one thing that really bothered me about the stock model is the large amount of slack in one of the track drives resulting from the combination of clutch gear/drive ring extension/drive ring/clutch gear that transmits power through the turntable. I replaced that assembly with a differential, which made a huge improvement but required a bit of modification to the area where the turntable mounts to the superstructure. The gearing is the same because I replaced the 16t drive gear/16t idler with a 24t drive gear and 8t idler to drive the 24t end of the diff, and the 16t end drives the original 16t gear in the track base.

Edited December 30, 201014 yr by Buffalo

The tracks moving when the cab rotates is an unavoidable consequence of having the track power go through the turntable. As the cab rotates, it's turning the axles that drive the tracks. The way to minimize this is to have as much of the gear reduction as possible done after the drive passes through the turntable, which the excavator does reasonably well in stock form. Jurgen's Ultimate 8043 improves on this by moving more of the reduction gears into the base.

The cab rotating while driving the tracks shouldn't happen, as the cab is driven by a worm gear that can't be back-driven by torque from the tracks. This effectively locks the turntable in place when there's no power being applied to the motor that rotates it. Does it rotate continuously, or does it move a bit and then stop? If it only moves a short distance, it's likely due to the slack in the gearing, which isn't really avoidable and is made worse by the worm gear drive.

*EDIT: if the cab moves slightly one way going forward, then moves the other way going backwards, you might try reversing one of the bevel gear sets under the turntable. Test it to see which track changed, then flip the black reversing switch on the remote that drives that track so the controls still work as expected. If both drives going through the turntable are turning the same direction when moving in a straight line, that will try to turn the superstructure. If they are moving in opposite direction the torque should cancel out and it should move less.

The one thing that really bothered me about the stock model is the large amount of slack in one of the track drives resulting from the combination of clutch gear/drive ring extension/drive ring/clutch gear that transmits power through the turntable. I replaced that assembly with a differential, which made a huge improvement but required a bit of modification to the area where the turntable mounts to the superstructure. The gearing is the same because I replaced the 16t drive gear/16t idler with a 24t drive gear and 8t idler to drive the 24t end of the diff, and the 16t end drives the original 16t gear in the track base.

It only moves a small bit while driving maybe 3mm to one side but then stops so it's prob as u said just down to slack in the worm gear,I'm not too worried about it ,I'm very happy with the model ,the centre la is a bit slow out near full extension but that's all,I might oil all the gears now with virgin olive oil,might modify it at some stage but I'm happy at the moment.