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Superba

Flummoxed

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Hi all, this is an unusual one. My brother has given me his Bigwig to try to fix. It has a similar engine and speed controller to my boomerang but is much slower. It was quick but recently regardless of the motor it is slow. The only thing I can se that’s odd is the front gearbox. What I noticed is that when I turned one wheel the other wheel did not turn the opposite direction. When opening it up the only thing I can see is that the two bevel gears are not meshing with the three dif gears as well as they should. However there is no wear, the gearbox is clean and I don’t seem to be missing anything that might cause this. To all intents and purposes it is in good order. Anyone else ever had this problem? I am stuck on what to do

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Have you rebuilt the gearboxes by following the manual?

Can you inc pictures here?

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I will double check tonight as I have missed bits out in the past. But I did a double check last night and all seemed present and correct. I will try to get some pics tonight

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even if the bevel gears in the diff were totally locked up, it wouldn't cause any drivetrain loss when driving straight because those gears only rotate when one wheel is spinning faster than the other. Try removing the propshaft and turning the front prop joint by hand. If it spins easily then the front diff isn't the cause of the sluggishness in a straight line. If it is hard to turn then at least you know the problem is something in the front gearbox.

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When I turn one the other doesn’t move or moves slightly. But I can easily stop it with no problems. If I turn both at the same time in the same direction it’s easy on all my other cars there is a force you need to overcome. (The engine) I will take a further look tonight and see what I can find

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I often get the motor spacers wrong, which will put a strain on the motor.  I think it comes with a 15t pinion?  If so, you'd need two spacers on each side of the bolt.  If this isn't done right, regardless of diffs, it won't go fast. 

But it is really baffling with that diff.   

I wonder if a bearing is gummed up with something?  Usually though, bearings just get some dirt and would have grainy feel to it. That won't do what you describe. It would have to be fouled up with really heavy grease or something.  

QIi7TK1.jpg

 

 

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I will check the spacers. It has to be something silly that my brother and me have missed. The gearbox is clean as you like. 

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A dodgy bearing could be the cause, at least it was on my sons HB 413. One wheel would barely move and turns out the bearings in one hub were shot. I replaced the bearings in all hubs.

Then the car was never as fast as it should be, and didn't sound great. Replaced all bearings rather than just the wheel hubs and it became a rocketship - had to turn the EPA from 60% to 40% for our backyard, thats how much the dodgy bearings in the 3 diff outdrives were costing.

Another thing I had on my boomerang was the screw holding the steering knuckle on had backed out a bit and was stopping the wheel turn, it could be as simple as that.

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20 hours ago, Jonathon Gillham said:

thats how much the dodgy bearings in the 3 diff outdrives were costing.

Thank you!  That's why I go nuts with bearings!  

 

 

  • Haha 1

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2 hours ago, Juggular said:

Thank you!  That's why I go nuts with bearings!  

 

 

Is that really why? Or is it satisfying lining up all the bearings for a Konghead in order or spinnyness?

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Lol... Come on, you know I was just trying to cover up the perverse pleasure I get from the extra-smooth spinnynes (with "efficiency").  If you must know... I also line things up in order of unspinnyness. (It is satisfying to drop them one by one off a ruler into a bin, like how pirates would make bushings walk the plank. I don't know why pirates would execute bushings, though.  Also, I am not to be held responsible if some 3rd grader thinks "unspinnyness" is a real word...)  

I digress in multiple directions... 

but at least nylon bushings don't seize up (even though they are absolutely positively horrendous and must be replaced at the earliest possible opportunity with utmost enthusiasm--enthusiasm is very important, I think).  Bearings potentially seizing is a necessary risk in our hobby, I'm afraid.  At least, it happens rarely, and rubber-sealed bearings are cheap.  

DORfJjB.jpg

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