rwallace612

Lunchbox slow as molasses on grass

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Hi Everyone, I am kind of at my wits end with my Lunchbox... It's annoying the heck out of me..

I bought it last year and assembled it. with the stock silver can motor its OK speed-wise on pavement. Utterly useless on grass. So I tried using a 2100kv and 5700kv brushless motor in it. Both times I experienced issues with with mesh , and I finally got it resolved on the 5700kv motor. But on the 5700kv motor, 5minutes after running it, the transmission seized up.. I took it all apart, and it all looks perfect. So I re-assmebled it, and the transmission is fine..

 

I don't get it.. Anyone ever run into similar issues? Maybe I need  to shim it, or put more or less, or better grease in it? I basically just want it to be fairly fast on road, and not useless on grass.

 

Thanks!

 

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The transmission actually seized up, preventing the motor from turning, after running on grass? If so, that's a major problem that altering grease is not going to fix. That particular gearbox design is generally exceptionally strong if everything is correct. Are your wheels spinning in the tires when traversing grass? It wouldn't show up as readily on pavement. I had a Lunch Box that refused to wheelie on grass (normally, a high grip terrain) and it was because the wheels were slipping inside the tires.  

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I am not an authority on this but experienced exactly the same problem & it was, as Saito2 said, the wheels spinning inside the tyres. I am referring to a cw01 unimog which rubber bands around the wheels only partially solved the problem, silicone or glueing is my next move.

 

Anyone make Lunchbox sized beadlocks?!

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Had the same spinning  problem on a Wild WIlly 2 when I put a brushless in it. Thought he pinion was slipping or had chewed up a  gear. Bit of superglue later and off it went. The transmission seizing up sounds weird. If it had seized I would expect it to still be seized.

Are you running the stock white bushings or have you got bearing in the transmission?

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I've built a few Lunch Boxes over time and had one gearbox get gritty and seize.  Taking apart the gearbox didn't reveal anything obvious, and it would work fine for a short time then act weird and seize again later.  Turns out I had forgotten to install BC6, the differential pin that fits between the two axles and positions the big differential spur gear.  The whole diff spur gear was being positioned by the inner spider gears making contact with the axles.  So, under harder loads the diff gear might skip and cause one of the spider gears to jump by one tooth, which then made the diff action gritty and semi-bound up.  If it jumped again then it was game over.  Once I realized the mistake and installed the differential pin, all the problems went away.

Make sure your BC6 is installed, and it wouldn't hurt to try adding some thin shims or washers between BC7 spacer and MG1 axle gear to take up some of the play in the diff without making it gritty.

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8 hours ago, LeftyAl said:

Had the same spinning  problem on a Wild WIlly 2 when I put a brushless in it. Thought he pinion was slipping or had chewed up a  gear. Bit of superglue later and off it went. The transmission seizing up sounds weird. If it had seized I would expect it to still be seized.

Are you running the stock white bushings or have you got bearing in the transmission?

I put ball bearings wherever I can :) .. I hate bushings

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8 hours ago, speedy_w_beans said:

I've built a few Lunch Boxes over time and had one gearbox get gritty and seize.  Taking apart the gearbox didn't reveal anything obvious, and it would work fine for a short time then act weird and seize again later.  Turns out I had forgotten to install BC6, the differential pin that fits between the two axles and positions the big differential spur gear.  The whole diff spur gear was being positioned by the inner spider gears making contact with the axles.  So, under harder loads the diff gear might skip and cause one of the spider gears to jump by one tooth, which then made the diff action gritty and semi-bound up.  If it jumped again then it was game over.  Once I realized the mistake and installed the differential pin, all the problems went away.

Make sure your BC6 is installed, and it wouldn't hurt to try adding some thin shims or washers between BC7 spacer and MG1 axle gear to take up some of the play in the diff without making it gritty.

Thanks for the tip ! I am going to re-check the instructions for the transmission install and compare it to what I've done.

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Tyres would be my guess if you haven't glued them. Damp grass in particular will provoke it because moisture can get between the tyre and rim.

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Besides what has been said so far, the Lunch box tyres are simply not very sticky tyres.

If you do a lot of grass running, consider switching to the Monster Beetle wheels and tyres. They grip better and they give you better ground clearance on grass, with less resistance.

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so I finally had a chance to glue the tires today and try it out. it's like night and day!! Even with the slower 45t crawler motor I threw in it, it hauls on grass now!! Thanks for the advice everyone 

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