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Again another Marui project : Super Wheelie and Big Bear! 10 months 2 weeks ago #75275

After having spend a day fixing my diff design issue (coming from a mistake on the bevel gear on the top of it, I'm now thinking about pulling a Big Bear and a Super Wheelie for next week-end vintage event...

For the Super Wheelie, the bodyshell will be rough, but beside this, I have everything needed... For the Big Bear, I have a lexan bodyshell to paint, and all the parts to be able to make one... Except tires and rims, and there is no way I'm getting 4 molded tires by that time (24 hours cure for each), plus finding a way to glue them, which may need anothe 24 hours to cure... Easy sourcable tires are Lunchbox tires, and I know from a friend that makes the Big Bear working quite well... I have ordered 4 Lunchbox tires for this purpose... Remains to define rims easy and quick to print...

Went for a very simple design this time... And since I don't want to use supports, it is a two part design, using 4 M4x16 screws to do the assembly...



And just to make an idea of how large the Big Bear tires are compared to a Lunchbox one...


I launch the print tonight. I reserve the printer for small ABS or nylon print for adjustments and chassi reinforcement as both chassis I intend to use may require this...
I buy kits to built and ru(i)n them :-)
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Again another Marui project : Super Wheelie and Big Bear! 10 months 2 weeks ago #75280

Among the chassis I have, about 2 on 4 have issues with the body mounts, and one of them is pretty damaged at the front...

For the rear body mounts, I will print some parts. I made one version to reinforce the ones which are still alive, and one to repair the one broken... As matter of fact having a chassis modeled in CAD is making those kind of mods/repair very easy...


Launched some prints to complete 2 of the chassis. I start with the ones in worst state : those two cars I build will be runners...
I buy kits to built and ru(i)n them :-)
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Again another Marui project : Super Wheelie and Big Bear! 10 months 2 weeks ago #75281

About 3 minutes to design the parts... About 50 minutes to get the 6 parts needed for the 2 chassis...

The small repair on a Big Bear chassis front... Easy, fixed with a M4 screw... This will be circled by some springs to maintain a bumper...


On the same chassis, the body mounts are alive. I put a reinforcement, and no rework required...


On the other chassis both body mounts are broken... I put the second version of the body mounts reinforcement which includes the top part, and this is perfect...



And both chassis are now good to go...
I buy kits to built and ru(i)n them :-)
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Again another Marui project : Super Wheelie and Big Bear! 10 months 2 weeks ago #75283

I launched the rims print last night...


Fresh of the printer, mounted the rims with M4 screws and we have rims... The Lunchbox tires are not yet there, but worse case scenario, I can pull the tires of my daughter's lunchbox : they are the only one not glued yet...
I buy kits to built and ru(i)n them :-)
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Again another Marui project : Super Wheelie and Big Bear! 10 months 1 week ago #75284

Rebuild starts...
First a few minutes print to get some shim washers printed in ABS for 1mm to complement the ball bearings which are thinner than the original oiless bearings (that is where I love again my X1C printer)


Then real things can start... With a small issue here : the modern 540SH which I wanted to push here is too large for the motor mount, and additionally it doesn't line up with the holes for the contact at the end... And worse I can not remove it from where it is. Thanks I have a gearbox in addition which will save me for the time being... I rewired the original 480RS crossing my fingers it is in working state...


I put everything in place and got my diff in place (with the new big bevel gear I corrected and printed in Nylon PA12 on the BambuLab X1C)... It works smoothly and pass the 3V test...




Next step is the chassis itself... The instructions indicate a part which you never find with a car you get without the box, so I redesigned one and printed it...


While printing, I prepared the front arms


And then mounted them... The printed part is good an allow to validate the parts around as well...


Then the rigid axle comes in.


I needed a ESC and a servo. The Big Bear wheels are usually heavy, my rims are heavy as the Lunchbox tires are lighter than the original Big Bear tires... This will make up for the motor test, but it needs a bigger servo. I have one oversized in the DT03 I don't use anymore, and it has as well an ESC with no RX... I vampirized it :-) (nb : yes the 20 kg servo is totally overkill for this build :-) )


Remains to do :
- motor connectors
- tires to put in when they arrive
- bodyshell
- front chassis body mount fixing...
I buy kits to built and ru(i)n them :-)
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Again another Marui project : Super Wheelie and Big Bear! 10 months 1 week ago #75285

Well, there is a Lunchbox with unglued tires in my daughter's room, and she is not using it a lot... I'm quite sure she will be unhappy when she will see this, but I had to try (and as soon as new tires arrive, she will have new tires)...


I tried to reuse one of the diff main gears on which I remove some material, but it gave too much lateral play to the main gear when running and it resulted in hitting the 9T of the idle gear badly. I replaced both main diff and idle gears and it is now fine : each time you have an issue with a transmission, it is the weakest point that takes it all first... Now the real question is how long this gears will last, specially on a Big Bear, and I have no clue of this...
I buy kits to built and ru(i)n them :-)

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Again another Marui project : Super Wheelie and Big Bear! 10 months 1 week ago #75286

I hope to be able to paint a lexan bodyshell some evenning this week, but I'm not sure at all it will be possible... In the meantime, I have a hard bodyshell


I raided another car which is missing a RX to build a Super WHeelie chassis...
I buy kits to built and ru(i)n them :-)
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Again another Marui project : Super Wheelie and Big Bear! 10 months 1 week ago #75288

And another print in ABS...


And here is on the car...
I buy kits to built and ru(i)n them :-)
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Again another Marui project : Super Wheelie and Big Bear! 10 months 1 week ago #75291

Nicely done there, Such a good looking body on these :) Looks like you need 1 more tooth on the pinion, The Spur wont last long with such a loose mesh ;) 
If you can't fix it with a hammer, you've got an electrical problem mate :)
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Again another Marui project : Super Wheelie and Big Bear! 10 months 1 week ago #75292

The axis is not maintained at both sides... And I had the same thinking when I did it first time... but one more tooth doesn't fit... And the Big Bear strengthened gear set was done this way...

But I will recheck...

EDIT: I checked, and the calcul are right. The pinion is not so loose on the idle gear... The picture is misleading : to get the diff mounted you need the axle... and I'm still searching a third hand for those pictures (no where to be found obviously) as with the Big Bear axle it is quite hard to take the picture without having the diff gears out....
I buy kits to built and ru(i)n them :-)

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Last edit: by silvertriple.
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