Gruber
HobbyMasters
M.L. Toys
KidsWheels
Gruber
HobbyMasters
M.L. Toys
KidsWheels
HobbyMasters M.L. Toys
Gruber
KidsWheels
Need new motors? Grind a gearbox? Adding teeth to a pinion?
User avatar
By mrg81
#146980
Hello everyone. My kid's dune racer was always extremely noisy. I always thought that it is due to plastic tires so I was trying to fix that with rubber tires but that didn't help a lot.
So anyway I decided to look closer and I found that the gearboxes are extremely loose and they just keep banging plastic walls and that's what is making most noise.
I've recored two videos to show you what I mean. Should it be like this?? Am I missing any screws here? It seems like gearbox just slides in in to the plastic space and that's it.
I am planning to stuff in lots of rubber to make it tight as possible, unless you guys have a better idea.
thanks for any input
videos:

User avatar
By M.L.Toys
#146982
No, that's done by design. It kinda sorta in a weak way softens the blow of the initial start and acts as a shock control. It's kinda first grade engineering by Mattel but without the movement you will almost definitely see more gear failures.
User avatar
By mrg81
#146993
oh, I was afraid of this. But Thank you
So I will at least add some cushioning Between engine and plastic wall because it hits it all the time even after initial start. This little thing sounds like grass mower with a diesel engine .. and it makes my neighbors not happy ;)
User avatar
By Hammer-fm
#146997
I've used a few layers of thin (0.125") neoprene sheet as a cushion with some success. You definitely want something soft but resilient. In the end that will be better for stress relief than the stock setup was, and quieter...
User avatar
By mrg81
#147048
thanks!
I did something like this (attaching photo) . Seems like it is doing a good job. It is definitely better and gearboxes still have room to move. But moves are now more smooth and it doesn't hit walls so hard.

IMG_6241.jpg


I also added some soft materials here and there where plastic parts work together (for example under the hood) and it made a big difference too.

Now I just need to do somethings with these wheels. Dune racer's wheels have this pattern with big gaps, so plastic edges hit ground pretty hard making noise.
I was wondering if there is a way to get a different set of wheels from a different car but with much smoother pattern. Would any other be compatible? I did put rubber tires on front wheels but I am afraid of doing that with rear wheels for obvious reason.
User avatar
By Hammer-fm
#147060
The "motor mount" looks good!

As for the tires: I've been trying to find something that would still allow drifting, but have a bit more traction than the stock tires and much better wear. The stock tires wear down much too quickly if you are running on pavement and doing any amount of drifting with higher-than-stock speed.

I haven't done a full long-term test, but I've run some time on a new setup on our F150 that attempts to get the right amount of traction and longer wear. I used 1/4" HPDE sheet and cut -- in this case -- to half the circumference of the wheel. I bent it around a 12" diameter form that I had lying around and warmed it up with a heat gun, let it cool, then attached it to the wheel (using countersunk screws).

I then attached a road-bike tire such that the center of the road-bike tire was ~1/4" taller than the HDPE strip. This ensures the bicycle tire is making contact (and thus contributing to the friction of the tire:ground interface), but it's deformable enough that it doesn't exert a lot of force, and thus has a fairly small amount of overall grip. You can modify the amount of grip by stuffing foam or some other deformable material inside the bike tire, or by flattening the bike tire less when you screw it in.

My first attempt had too much grip (foam-stuffed). I removed it and now it's about right for what I want. It does run a lot quieter now than it did.

We'll see how long the HDPE strip lasts (this is only 3/4" wide). These are scraps I had around from another project, and I will be replacing them with wider pieces and also add a 45d chamfer on them so they will slide over small road imperfections when drifting sideways.

One caveat: it's still possible to have moments of "full grip" if you're running on uneven surface and it ends up riding completely on the tire (eg over concrete gutters). Road-bike tires have enough compliance that this may be ok -- I ran the F150 for a few months with a high-torque motor setup and no plastic strip -- or in other words, full road-bike tire contact.

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