TOPIC:

Hey everyone. New to the hobby and hoping you guys can help me diagnose an issue I’m having with my Frog re-release. 

It doesn’t seem to be accelerating quite right – and that’s if it even gets going at all. When it’s in grass, it sometimes can’t get moving, like it would take more power than the car has available. On concrete, it usually gets going eventually but it just doesn’t have that same pep in its step.

I’ve read about gear box issues and I figured that was the problem, but I took it apart and nothing seems to be amiss. The teeth on all the gears look fine. The pinion was properly adjusted. The sides of the gear box do not look warped. Granted, I don’t know exactly what I’m looking for so maybe I’m missing something.

When I hold the car in the air and gun it, the wheels seem to be spinning as fast as usual. Would this suggest it could be something with the drive shaft or the rear arms?

Again, very new to this so I’m assuming I’m missing something obvious. Thanks in advance for any help.
 

The gearbox sides don't have to be visibly warped to be a problem, the issue is that the diff wants to expand under power making, and the gearbox sides not being stiff enough to resist - a more powerful motor or more use exacerbates the problem.

The problem you're having, has it always been like that or is it a new issue?

What gearing option did you use when you built it, and what motor are you using?

Does the motor spin up but the car fails to move, like a slipping clutch?

What battery are you using, and how are you charging it?

 

Thanks so much for the quick reply.

It’s a new thing. It started when we were running it in probably thicker grass than we should have. 

It’s the “standard” gear, the 50T. The motor is a Mabuchi RS-540SH.

The motor is definitely spinning but the wheels are struggling to turn. No clicking sounds or anything.

The batteries are NiMH 4200 mAh. The brand is Zeee. The batteries seem to be working fine with our other buggy. 
 

Motor pinion grubscrew tight? Both rear wheel nuts on tight & the pins in the back of the hubs still present?

Another idea, are the rims enough tightento avoid tires sleeping around rims? I had a similar issue as you when I ran my rere brat ( same chassis). And I  saw that the 540 wasn't very good for it and I replaced it by a sport tuned. 

Jonny R.: Yes, everything is tight and, yes, those little pins are still in there, as well.

Stingray: I think it's OK? The tires seem to be tight around the rims. 

Try another motor. Same a rs 540 classic. Mine was new but didn't work well. 

If tires happen to be unglued, it will be like having a slipper clutch when driving in tall grass.
As tires ages they might be hard and slips more on the wheels than it did when tires was fresh.
Solution is to glue the tires.

You guys are good.

I took a closer look at the tires and one of them had, indeed, come unglued. That was the issue. It works great now.

Thanks so much everyone.

Thanx for the feedback!