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tamiya hornet geatbox issue?

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Hello. I have rebuild my tamiya hornet and i have ran it two times so far. I have a hobbywing 1060 esc and its ball raced and has a black sports tuned motor. The issue is that it seems there is a power loss and a weird noise, like a zzzzzzzz :D on the air it sounds okay and it spins great. On the road, i punch forward and seems the noise is faster than the move, like its slipping. I thought it was the rear wheel adaptors but those were okay. I also took apart the gearbox and all gears, diff and all pins and stuff were okay and present. Now cause i bought it second hand and it was my first time building it, i didnt have the tamiya grease, so i used the Hudy graphite grease. I didnt follow the manual, but instead i put a generous amount of the grease in all gears etc, until they all became black :P Would this be the issue? and if yes, can i clean and reuse the parts? gears, counter gear, diff etc? can i wash them with water and let them dry? how do i clean them? and should i use again that graphite grease or should i get a tamiya grease? if i cant find one, what other grease can i use?

thank you all 

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I also greased up the axles. I read somewhere that if we use ball bearings dont grease up the axles. Anyhow thats all Thanks :)

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Check to make sure the pinion grub screw is tight on the motor shaft and is on the flat part of the shaft, spinning up fine with no load but the zzzzzzzzzzzz noise could be a loose pinion grub screw gouging a groove round the motor shaft where it's loose when a load is applied to the transmission. When I need to clean gears I use turpentine substitute (White spirit). Water and soap is pretty useless against most greases.

PS, It's still a good idea to put a small smear of grease on the axles where the bearings touch. If you run the car in the wet and moisture leaches between the shaft and the roller bearing, the one won't rust solid against the other.

Can't advise on the graphite grease as I've never used it, but Tamiya cera grease is very good for plastic gears in small quantities. If it's very sticky viscous grease, it would probably be a good idea to wash it off and use something else, but sticky grease would not cause a noise, it would just cause extra drag and cause the motor to get hot. Sounds more like a badly meshed or loose pinion to me. Have you counted the teeth on the pinion to check the correct one is fitted, given that it's a second hand car.

 

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Might be a loose pinion (grub screw) or the small joint pin that goes between the axle gears missing.

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Hello again, and thank you for your responses. I have taken out the pinion gear and i have reinstalled it making sure that the screw sits on the flat surface. I have also glued the rear wheels. I will again try to run it tomorrow and see the results. I am sure the small join pin and the differential shaft and all small stuff are there. About the pinion, if i counted correctly i think is 19t instead of 18t which comes with the hornet? ill see in the morning if i counted correctly cause i was watching juventus at the same time and i think i may have counted wrong :P if its not 18t ill get the robinson that suits the sports tuned motor. emm and probably i will again reopen the gearbox tomorrow and confirm that everything was installed correctly, for the 5th time :P

Thanks guys for your help. ill let you know how it goes

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The Hornet Gearbox is not the smoothest around and is pretty loud normally.  I'd check that Pinion again as I don't believe you can fit a 19 tooth pinion. It's physically larger and would be forced against the Counter Gear causing extremely tight gear mesh. 

If you did replace the pinion are you sure it is the correct pitch?  If you do in fact have a 19 tooth pinion in there I would go back to the factory 18 tooth and look very closely at the counter gear for wear. 

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Hello and thanks for the response racer1 ;) i have disassembled the gearbox again as i couldnt sleep thinking about it hehe. The pinion gear is 18t. I counted it again. It is the original that came with the hornet. Btw the hornet was bought second hand, but from my friend who build it from new in his childhood. So everything was stock and nothing was ever replaced. Before selling it to me, it was running much quieter etc. I dont know if its the ball bearings, the sports tuned and all these kind of stuff, or the hudy graphite grease which i read that it has particles in it, and probably not good for plastic gears. Anyhow, i opened the gearbox again, and i confirm that everything looks okay. Here is also a picture i took just now.

IMG_0524.jpg

 

Anyhow, i checked also the small screw on the pinion gear and screwed again on the motors flat surface as per the responses i got, and i also glued the rear tires as they felt like sleeping when i was holding the plastic rim. I will run ti probably tomorrow and see how it goes. Comparing that mechanically i changed the msc and silver can  and plastic bearings, to hobbywing 1060 esc, black tamiya sports tuned and ball bearings, the only other change inside the gearbox was the hudy graphite grease. I believe at the end, this could be the issue, if the above dont solve it. 

Also, i forgot to mention, that, when i was hitting brakes, the hornet didnt stop instantly, instead it was like slightly reducing speed until stopping, just like an old beetle car that doesnt grab brakes instantly. Probably it was the unglued tires?

Thank you all for your patience and your kind help :)

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problem with the photobucket pic, so here is the gearbox opened. Doesnt it look okay? ;)

IMG_0524.jpg.2cd6b1bb5171aff06929b669a22010bc.jpg

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from vague memory...

Some diff gears (the big one holding 3 bevels) had a different offset/"dish" and only went in correctly in 1 way; other way it jammed against gearbox side... but if you were really hamfisted you could still force the screws together 

Output half axles... some have a pipe spacer between gearbox side and the side bevel. Sometimes this gets lost in the degrading then omitted on rebuild, if you're not the fella who originally built it.

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@WillyChang Thanks for your response buddy. About the spacer, do you mean the BD3? everything in the manual was included when i disassembled the gearbox, nothing seemed to have a problem or missing, even this spacer.  about the diff gear which holds the 3 bevels, i didnt pay attention to it, i mean i just hypothesized, that in any way it goes in, should be okay. So i dont know if this is the issue. Eitherway, when i installed it i check it while turning the one axle, before attaching the whole gearbox assembly, and even when i assembled it it looked okay and everything was spinning okay. If i hold the rc car on the air, it spins okay and sounds okay. But when its on the road it seems like slipping. I glued the rear wheels and i will check again today and let you know if these were the issues. Thanks for your kind response :)

 

gearb.jpg

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A few things to look at here .

On the video it sounds like the thickness of the 'sticky' grease on the gears making the 'zzzz ' , it is kind of like a glue that sticks and unsticks with each tooth rotation . If you rotate half the gear box by hand you will hear / feel the 'stickiness' of the grease , which is in turn being amplified when it is all shut in together and run at speed . Once you have cleaned all of the grease off , put it back together with minimum specified grease , give it a light run and see if it is quieter . It is unusual for the tyres to spin as these 3 piece wheels bolt up tight onto the tyres .

Check the gears are installed as per manual , the right way round as said before .

Also check that the MG2 gears are not rounded off or cracked where they fit onto the hex on the axle shafts.

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@KEV THE REV hello buddy and thanks for the response. I checked every gear etc and everything was alright. I also used a new gearbox assembly. About the graphite grease, i contacted a friend of mine who has an rc shop and confirmed that it is okay to use it in the tamiya plastic gears. About the rear wheels , 1st) i though about the plastic adapters which bolt onto the axle pin, and as i read somewhere about the power loss when the adaptor is spinning inside the wheel. I did noticed that they are a bit tricky to lock into the wheel. 2nd) i thought about the tires, cause it didnt have maintenance after 30 or so years from my friend, so after checking them i saw the would spin. So i glued them on.  Also by the fellow members that also kindly responded to my issue, i took off the grub screw from the pinion and placed it again securely on the flat surface.

Now the good news :))) MISSION ACCOMPLISHED. There is some zzz but i noticed that was from the savox servo i have in it and its metal gears. BUT, i took it for a spin now, and guys, all i can say that the power is doubled from the run i had two nights ago with the issue, and is now running smoothly without any issues. Now the only problem is i cant control it hehe and it drifts :P i use a 2s lipo with the sports tuned and the hobbywing 1060 esc. 

This is from minutes ago ;)

So basically, the issue is fixed. Now what fixed it i suppose could be the unglued tires or the pinion gear, as these were the only changes i made, plus i carefully locked the rear adaptors inside the wheels, as are a bit tricky to lock.

So, i would like to thank you personally to each one of you, who took the time to read my post, and had the patience to reply :) Thanks again guys.

 

IMG_0529.jpg

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