Tamiya BBX Problem

[BlueMallard]

Hello All,

I’ve just finished my BBX and tested it, but it really doesn’t sound right, quite rattle and not smooth at all. Admittedly my 22t pinion doesn’t fit amazingly with the Sport Tuned Motor, but I can’t help thinking it’s something more. Just wondering if anyone else has had this problem and or any ideas on how to fix it.

 

Thank you! 

[Otis311]

The drive line of the BBX should sound very smooth. Can you better describe the noise and whether its frequency is related to motor rpm or wheel rpm? First thing to check would be pinion gear mesh. There will always be some inconsistency in the sound as spur gears typically wobble and pinion gears are never perfectly concentric to the motor shaft. 

[BlueMallard]

Thanks for the reply, the sound is a rattling wine that gets worse with speed and particularly when it’s driving under its own weight. The pinion is meshing well apart from the fact that the sport tuned motor shaft is to short and the pinion can’t mesh totally.

[Honza]

Is it a 48p pinion? Most other Tamiyas use m0.6 pinions, they look quite similar, but don't mesh well.

[Otis311]

Short motor shafts are definitely a problem in the BBX, among other cars as well. If your gear mesh is all good though I would maybe check that the motor sounds ok when removed. Also, when the motor is removed do the wheels spin freely.

[El Gecko]

Maybe also check the driveshafts and make sure they're not binding at various points in the suspension stroke.

[BlueMallard]

Yes, it’s a 48p pinion and the wheels spin freely without the motor apart from a slight rattling, and yes the motor is fine on its own.

[BlueMallard]

Actually the sound is a bit more of a whirling, as tho it’s rubbing on something.

[Juggular]

When there is a noise like that, I'd say 95% of the times, it's the grub screw on the pinion. 

It's got to be nicely seated to the cut facet of the motor shaft.  But when it's not, the shaft turns, but the pinion doesn't want to. 

It just slips when there is a load.  If you check, the motor shaft might have a ring around it from the slipping grub screw. 

 

[BlueMallard]

Yes, thank you for that, I’ve moved and it definitely sounds better! I think the best thing for me to do it to by a pinion that fits better.

[GTodd]

19 hours ago, BlueMallard said:

Yes, thank you for that, I’ve moved and it definitely sounds better! I think the best thing for me to do it to by a pinion that fits better.

Tamiya made  48P pinions for the DB01/TRF5XX cars that were longer. Check to see if you can find any of those.