[WIP] [Mod] 42109 w/Power Functions

[johnnym]

Hi there

as nobody else yet presented a PF mod of the 42109 car (@ozacek?), I gave it a try yesterday afternoon/evening and did a quick & dirty PF mod.

The result is a replica that's not totally identical in all details but comes very close to the original from the outside with considerable changes on the chassis.

Differences:

* Very obvious, the colors, but that was not important for the intended task. Initially I wanted to build it in red and black, but soon switched to orange and black and later just ignored the colors to save time when searching the needed parts - I have two many models built ATM and hence am low on some essential parts in the initially desired colors. The upcoming digital model(s) will use (a) more pleasing color combination(s).

* The beam connecting both sides of the cockpit was moved 1 stud forward and was constructed differently to hold the PF AA battery box in place

* As I couldn't find a position for the PF Servo motor that is low enough that the hood can be closed as much as in the original 42109, I used a 1 x 9 bent liftarm to fix the hood at an elevated position, imitating the look of a huge hood scoop. This way the hood is kept shut very tightly btw.

* I used curved 11 x 3 panels with 2 pin holes for the side skirts, as I find them visually more pleasing then what was used in the original 42109.

* The chassis is somewhat different: Instead of 11 x 7 frames I used 7 x 5 frames as I don't have 11 x 7 frames yet; 8L axles with stop for each rear wheel - so the axles can't be pulled out, but the wheels can still get loose, though I haven't seen this yet during driving and some other minor differences. The car doesn't use a differential but drives each rear wheel with a single PF L motor.

Power Functions parts used:

* 2 x PF L motor

* 1 x PF Servo motor

* 1 x PF IR V2 receiver - optional (not needed with BuWizz)

* 1 x PF IR remote control - optional (not needed with BuWizz)

* 1 x PF AA battery box - optional (not needed with BuWizz)

[* 1 x PF control switch - actually not really needed, if the drive lines are set up in a way that both PF L motors can run in the same direction  (not needed with BuWizz)]

I.e. the PF equipment that came with the 9398 - not that I have one.

Enough talking/writing, here are three shots, digital model(s) will come later:

Using a BuWizz instead of the PF remote control equipment saves a lot of space and weight and will make this car faster. So far I haven't used it with fresh AA batteries but only with used AA batteries and a BuWizz and even in normal mode the car seems to be quicker, not to speak of fast and ludicrous modes, where the wheels start slipping on carpet and laminate floor when going backwards at full speed in fast mode or both ways at full speed in ludicrous mode.

[sirslayer]

I would like to request a video if possible. It does look like it can haul fast. Even though some parts didn't color match correctly , I do see your vision.  Great job !!  

[johnnym]

18 hours ago, sirslayer said:

I would like to request a video if possible. It does look like it can haul fast. Even though some parts didn't color match correctly , I do see your vision.  Great job !!  

Thank you @sirslayer! I'll try to create a video of it driving but can't promise - weather is very unsettled ATM, maybe next week or so. Inside it feels pretty quick and powerful with a BuWizz - I still have to try with fresh batteries and PF RC equipment, but want to save that for the video shooting.

Just now I came up with a quick mod that allows to use the rear wheel type (49.5 x 20) also on the front axle, which would give a little extra ground clearance there. One just needs to remove the two liftarms 1 x 3 with 2 Axle Holes and Pin / Crank that connect the two side panels on each side partly behind the front fenders to make enough room for the wheel to move when cornering.

[johnnym]

@sirslayer: Ok here's a short unedited video showing it drive with BuWizz 2.0 in ludicrous mode. As it was very sunny, I didn't drive it with PF battery box and IR.

Coloring is now also more solid, with only three panels missing in the desired color:

[sirslayer]

@johnnym Your model in red really looks great , A lot of eye candy for sure..    The performance is good but I think it can be faster...  If you only have a buggy motor..   You can even make tighter turns by changing the front axles steering pivot closer to the tire ..  like this video for an example .. 

 

https://youtu.be/LYBsR5akgHY

 

 

 

Edited January 20, 2020 by sirslayer

[johnnym]

12 hours ago, sirslayer said:

@johnnym Your model in red really looks great , A lot of eye candy for sure..    The performance is good but I think it can be faster...  If you only have a buggy motor..

Thanks, I actually have a few of those since a while - see for example my Turbo Racers vs Police Interceptor series - but here I wanted to show what can be accomplished with PF motors alone.

12 hours ago, sirslayer said:

   You can even make tighter turns by changing the front axles steering pivot closer to the tire ..  like this video for an example .. 

https://youtu.be/LYBsR5akgHY

Do you have a detailing post about that front axle somewhere and would it fit in the available space (see first picture in the first post)?

[sirslayer]

I don't recall who post it was on , But the axle is in the axle thread and I did find a picture of the close up where the steering pivot is inside the rim/tire .. using the same size tires and rim from your model, the pivot actually can be more to the center of the the tire if that little notch was removed!!   i think that notch inside the rim is acting like a pivot limiter???  odd but with the notch inside , the steering pivot is more or less 1/4 to the center of the tire.. center would be ideal!! and it still better then Lego default pivot which is outside the tire ..  

Lego technic steering by victormendoza_jr, on Flickr

 

Edited January 21, 2020 by sirslayer

[sonpham510]

On 1/21/2020 at 12:24 AM, johnnym said:

@sirslayer: Ok here's a short unedited video showing it drive with BuWizz 2.0 in ludicrous mode. As it was very sunny, I didn't drive it with PF battery box and IR.

Coloring is now also more solid, with only three panels missing in the desired color:

The car goes straight for a bit, it swerves to the left or right, it's very difficult to control, is there any way to fix it?