Midnight pumpkin clicking noise

[07LowRider]

I recently have reignited my RC hobby that includes an older style Midnight Pumpkin that is about 25 or so years old. I had to reinstall the motor and got it running. Fast as I remember and fully capable of wheelies, but it makes a noise that is similar to that of a fast clicking. Think baseball card in bicycle spokes. Pinion is brand new and the diff seems to be doing what it’s supposed to. Any suggestions as to what it could be and how to fix it?  Also any suggestions where to get replacement parts would be welcome as well. 

[Finnsllc]

clicking means a gear or pinion or spur isnt linked up. Look at where the pinion hits the spur, or the drive sharts meet the gear or wheels. 

[mongoose1983]

I remember that sound on my Pumpkin a couple of decades ago. One of the gears lost one tooth.

[Juggular]

One other possibility is that the pinion's grub screw might not be seated well?  

Motor's axles have a cut facet.  The grub screw should be screwed onto that flat surface.  But sometimes it's off a bit.  Then it could make noises.  

 

You can see how the grub screw (BA6) should line up with the motor axle's flat area. 

(please ignore red and blue lines)  

 

[07LowRider]

Thanks for the tips all. I am going to do this One thing at a time and being as the pinion was just installed, I will check the grub screwn alignment first. 

[07LowRider]

Looks like the main sprocket where the pinion connects is missing a tooth.  Any idea where a spare gear set can still be ordered?

[Mark_C]

Tamiya p/n 5072 is the gear itself - appears to be available on its own: https://www.activepowersports.com/tamiya-counter-gear-5072/

It comes as part of the tool bag p/n 19405329 or 9405329

[Juggular]

Old yellow grease could damage the plastic gear.  I think that's why Tamiya switched from the yellow petroleum based grease to ceramic grease from about 20 years ago.  New gear with new grease should do fine.  

3rd party vendors sell aluminum spur gears. But I would not get it.  It's actually worse.  Nylon or plastic gives a little.  If the gear does not give, it wears out faster.  Aluminum creates abrasive paste and it becomes increasingly worse. 

 

[07LowRider]

Can you recommend a grease if I end up having to replace/rebuild the entire diff?  Thank you all for your input. Funny enough the instruction manual says 1987. Quite possible that’s when this was bought. It was given to me 2nd hand and spent the last 20 years in a damp basement. Still looks good and in great shape otherwise. 

[Juggular]

I use Labelle 106 for most of my RC stuff.

Plastic safe grease with Teflon.  You don't need it as much as other grease.  Think of it as painting it on, instead of greasing. This small tube lasted 3 dozen cars.  Maybe thanks to this, I have not seen the infamous gray aluminum pinion goop.  

https://www.amazon.com/Labelle-plástico-COMPATIBLES-grasa-PTFE/dp/B002MUYOSK/ref=sr_1_1?dchild=1&keywords=labelle+grease&qid=1590531053&sr=8-1

 

[07LowRider]

Just wanted to thank you all for the advice. Replaced the gear with the missing tooth and running smooth again.