Dear Eurobricks members!

As few minutes ago I finished my first LEGO Technic RC MOC chassis, I think it's good time to open up my MOC and WIP topic

At this point for my awesome LEGO hobby I have 9395, 8081, 8208, 9392, 8043, 8070 and few hundered spare parts from bricklink

For my first RC model I choose my slightly modified 9395 MOD.

I managed to squeeze in two m-motors and steering with RTC brick, keeping the original dimensions. As the drive engine is on the right side of the car, I used 16t(on motor) + 8t + 16t w.clutch on steering motor axis + 16t gear on main axle combination. (EDIT: this wasn't good idea...)

The problem is, that when I switch from driving forward, to driving backwards a cracking sound comes from the gears. I feel that this might be because due to the space limitations, I used axle pin connector w.o. friction, to add the 8t gear between the two 16t gears. As it isn't on fixed axle, it might move a bit. (EDIT: I fixed it later, but still, the concept was wrong)

I used the same construction w axle/pin connector, to power the winch and lift (though with two db-12t gears powering 24t clutch gear), and without these side effects.

OFC I will try to fix it myself, but in your opinion, is it ok or wrong to use axle/pin connector on gears in drivetrains?

Edited October 2, 201212 yr by Lauris
Update of topic description

okay... a lot of trial and error, and I found a simpler solution to add the motors to the chassis. But there is a lot of wobbling and cracking sound somwhere.

Is this because the 8T gear between 16T gears is moving around too much under stress (switching from driving forward to rear)???

It is now on 3L axis, that is fixed between two angled 3L axle/pin connectors. This is happening even if I try to drive backwards from full stoping e.g. without inertia effect due to the fact, that I used one 16T with clucth on the axis that's connected to the steering engine???

(EDIT: the 8T between 16T gears wasn't good idea as well... it was moving too much, that caused the cracks)

Edited October 2, 201212 yr by Lauris

I don't know what the sound might be, but on my airplane, the cracking sound came from two knob-wheels by the motor. This was because the liftarm frames they were connected to wasn't secured together proberly and so, the 2mm gap that they could move was enough to make a sound and sometimes even stop the XL motor from turning.

This was because the liftarm frames they were connected to wasn't secured together proberly and so, the 2mm gap that they could move was enough to make a sound and sometimes even stop the XL motor from turning.

So I should make the liftarm frames as tight as possible? All the official manuals says, that you should not squeeze the gears too much...

On the other hand, I can visually see, that the small idler 12T-DB gear that is between the driver 12T-DB and follower 24T-W.Cl. gear on the winch and lift mechanism, will wobble a bit, when switching the motor movement direction. It is now on usual 90 dgr axle & pin connector with tan axle pin.

(EDIT: I think, I'll not use any more axle pins in gearboxes - I changed the mechanism puting each gear on proper secured axle (a least 3L) and everything is fine now).

Edited October 2, 201212 yr by Lauris

After about 30 hours of trial and error, I have successfully made my 9395 RC mod chasiss. The design still has to be finished

It has 1-M motor for steering, 1-M motor for lift and winch functions, controled manually via switch and 1-M motor for driving. Ofc, the v6 engine moves with the truck. The steering mechanism has the return to center brick.

I abandoned the concept of having the drive motor side by side with the steering motor. I mounted the functions and steering motor under the truck's cab and squeezed the drive motor side by side to the function changover gears in the right side of the truck -

As I secured all the axles that are involved in any of the motorized functions - nothing cracks or trembles anymore and everything works smoothly. I'll try to post a video once I get my hands on proper camera. Also, I'll try to make photo instructions later.

Edited September 30, 201212 yr by Lauris

Ok, I can report for some sucess in my first more serious MOC (or MOD) now

My 9395 is now RC, and I have managed to keep the original looks for I guess, 90% wich is in my opinion - a great sucess and achievement of the goal I had in my mind when starting this project.

The fake engine in the front is V6 now and the roof is in an angle to make the truck look more "aerodynamical" I guess

It has 4-M motors - two for drive, one for steering and one for functions controlled via switch manually.

At this point, I guess I have to somehow optimize the powertrain in the rear - each motor gives it's power through two 8T, two 16 T and a 20T to in the mid of the car mounted 24T wich is connected to another 20 wich turns the diff. So the gear ratio is 2,5:1 or 3:1 (I am not sure where it should be measuered ).

There are some cracking sounds while switching the driving direction... probably because I didn't use an adder and because the 8T are moving a bit on their axles. I'll report if I am succesful.

More pictures here: http://www.brickshelf.com/cgi-bin/gallery.cgi?f=513278

Ok, there are no more gear cracking in the back and everything works very smooth

Here's picture of the new gear arragement with reinforcements:

nice! any videos of it working soon?