Help me diagnose what my problem is

[Bainesy30]

Ok so I own a 5th scale petrol rc buggy and suddenly started playing up. I thought it was the air filter at first cos it didnt sound right but the air filter is fine. The problem is when I throttle it. The engine revs but the wheels do not spin unless its revving high or the car is above ground. And even then it's going slow. After a bit of testing, I noticed when I use the throttle and the car revs theres a bad metal sound so before anything else gets damaged can anyone tell me what they thinks wrong. And als how I would fix it. Can only find youtube vid for nitro cars.

 

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[KORB]

42 minutes ago, Bainesy30 said:

 

Ok so I own a 5th scale petrol rc buggy and suddenly started playing up. I thought it was the air filter at first cos it didnt sound right but the air filter is fine. The problem is when I throttle it. The engine revs but the wheels do not spin unless its revving high or the car is above ground. And even then it's going slow. After a bit of testing, I noticed when I use the throttle and the car revs theres a bad metal sound so before anything else gets damaged can anyone tell me what they thinks wrong. And als how I would fix it. Can only find youtube vid for nitro cars.

 

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Sounds like the drive square (s) that are grub screwed to the drive shafts could be lose , that will cause the the shafts to turn but not the wheels when on the ground. Take the wheels off and check the metal squares , they'll be a flat spot on the shaft that the grub screw fastens down on, if it is that then you should buy new grub screws and a bottle of thread lock to keep them in place. 

 

Let. Me know if that is or isn't the problem?

Edited May 31, 2020 by KORB
Typos

[Bainesy30]

Thanks going to check tomorrow. I've got some medium strength thread lock. This forum is actually so helpful. Will let you know.

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[spents]

you say buggy mate, what sort is it? hpi baja ?

if its a an hpi baja then start at the clutch bell, from what you say with the bad metal on metal sound, the original baja clutch bells had the bearing post welded to the bell and that was a weak point, the welds would sometimes break and the bell spun freely without turning the actual pinion,

again it could be the pinion isnt seated correctly on the bell shaft as well, sometimes they will back off the bolt and the pinion moves outwards a tad so it wont spin under load,

also baja bells have a habit of snapping off the pinion retaining bolt which also leads to the pinion coming loose,

next check the dogbones to see if its snapped a pin off one,

also check spur and pinion to make sure neither is stripped,

then if it aint any of those then start digging deeper into the gearbox and check for stripped/ broken gears and or broken drive pins,

if it aint any of those then strip the diff itself and check for stripped gears or broken drive pin inside the diff,

could also be the clutch perch thats spinning freely on the crankshaft as well,either loose retaining bolt or just been spinning so long its finally given up the ghost,

 

[Bainesy30]

Ok so its 26cc petrol yama buggy. And its is not the grub screws I have check them and they're are fine. Any suggestions? The problem is that when I rev the wheels dont spin immediately and when they do it makes a bad sound.

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[spents]

43 minutes ago, Bainesy30 said:

Ok so its 26cc petrol yama buggy. And its is not the grub screws I have check them and they're are fine. Any suggestions? The problem is that when I rev the wheels dont spin immediately and when they do it makes a bad sound.

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not sure how the yama buggy is set up mate, but i'd asume its either similar to hpi baja, or a combination of hpi/fg etc,

work through the list i posted above and see what ya can find,

start with the easier accessable bits then work towards to more complicated that need more dismantling,

so, start with the clutch bell/pinion/spur and dogbones then work deeper if you dont find any issues,

 

[Jd101]

Probably the diffs or diff. This is my rear diff. The truck wouldn't move under load but was fine when not underload 

Edited June 1, 2020 by Jd101