BBX BB01 acceleration help

[thecremeegg]

So I've spent the weekend building up a BBX BB01, but I've done a quick test run before finishing and when I floor the accelerator the car barely moves. If I gently bring the acceleration in, it gets going as per normal and builds up speed.
It's like the gears are slipping but 've taken the transmission completely apart and triple checked it, all seems fine.
I have put a brushless motor in, would a slipper clutch help this or not? Used the same motor (Hobbywings 13.5T) in my TT02 and flooring it works fine?

Thanks

 

[tntpoof]

did you check gear mesh ? censored 13.5? with supporting esc. battery fully charged
solder job good?

 

[thecremeegg]

Gear mesh looks fine to me, and it's a sensored 13.5t with matching ESC. Like I said it worked perfectly in my TT02 but that has a different style of gearing. Battery isn't fully charged but it's a Lipo so that shouldn't really matter or does it?

 

[tntpoof]

the state of charge matters. so whats the different style of gering?

 

[RustyUs]

Are you sure you have the ball diff tight enough, and all pins sitting snuggly in appropriate recessed areas throughout the entire driveline?

 

[thecremeegg]

the state of charge matters. so whats the different style of gering?

The TT02 just has a pinion to spur gear with a simple diff, this one has a ball diff etc

Are you sure you have the ball diff tight enough, and all pins sitting snuggly in appropriate recessed areas throughout the entire driveline?

I've done the ball diff as tightly as I can before it becomes gritty/not smooth to turn. I've never built one before tbh so I'm not sure how tight it really needs to go?
All pins are sat correctly as well.

 

[Lumikko]

So I've spent the weekend building up a BBX BB01, but I've done a quick test run before finishing and when I floor the accelerator the car barely moves. If I gently bring the acceleration in, it gets going as per normal and builds up speed.
It's like the gears are slipping but 've taken the transmission completely apart and triple checked it, all seems fine.

Car barely moves; is the motor spinning but the wheels don’t turn, or is the motor not spinning up?

If the motor—esc combo is tried and true up to the pinion shaft, the first question is whether the lack of acceleration is due to something slipping or binding.

 

[thecremeegg]

The motor spins up fine, but as soon as I put it on the grass for example it just doesn't really go anywhere, like something is slipping like you say.
How tight should the diff be tightened?

 

[RustyUs]

Tighten just like the manual says. It should be very hard to turn the diff gear with your fingers while keeping both diff joints/outdrives immobilized.

You will know if the ball diff is loose. A harsh sound will be heard when yanking on the throttle. If you don't hear much of anything alarming when trying to get the buggy to accelerate, your diff should be fine.

 

[Lumikko]

The motor spins up fine, but as soon as I put it on the grass for example it just doesn't really go anywhere, like something is slipping like you say.
How tight should the diff be tightened?

If you already tightened it to the point of not quite binding, it’s probably tight enough. The picture in the above post shows a good method of checking.

Other usual points of slipping are between the wheels and tires if you didn’t glue them, and the motor shaft could spin inside the pinion.

If you can’t find where the drivetrain slips and it isn’t binding either, then the problem should be upstream from the motor: have you inadvertently programmed the esc to limit the amps to a ridiculously low level or something like that?

Also, use a fully charged battery for testing.

 

[nino]

The difference between the motor not spooling up under load at all and something slipping on the way to the wheels should be obviously audible. Anyway, put the thing on the bench, hold the wheels and see where the motion stops on the motor -> wheels path. Spur cover off. Pinion moving? Spur moving? Now take a second to consider ball diffs and how they're just as stupid as their name. Lock the diff if you have to, just for a test. Don't wreck anything or take off any of your digits in the process. Unless you want to, I'm not here to judge.

Hope that helps.