There have been a few creditable reports of this S4 problem (S4 = Second Stage Sun Seizing).
Here is another one:
I don’t yet know how much of a problem this is going to be but this is what I recommend to teams:
Take apart your Banebot 56mm gearbox and inspect it.
- I would look for contaminated grease (shavings, brass powder, whatever). If you find contaminated grease, I would clean out the entire
gearbox and carefully re-grease everything with an automotive or lithium grease from your local hardware store (you don’t really need any super duper grease for this application). Make SURE you lube the output shaft/second stage sun surface. 1. I would make sure that the output shaft/second stage sun interface has been greased well – check both the sun’s internal surface and the shaft’s external surface. - While I am looking for grease, I would make sure that both surfaces are smooth. Look for pitting, gouging and/or scoring. If I found any thing that bothered me at all, I would used some fine emery cloth to clean the two surfaces up and then I would clean out the entire transmission and re-grease it.
- If this S4 failure happened after I knew that the interface was smooth and well greased, I would consider cutting off the output shaft so that the second stage sun just floated in the gearbox. There are many proven transmissions that work this way. I would use it as a last resort, but it is an option to consider.
If any more teams see this S4 failure, please post a note in this thread.
More to come. Stay tuned.
Joe J.