New Redcat Gen 7 Owner - Differential Issues

[TheLimey]

Hi folks,

Newbie here. First, fantastic forum. It's really helped me as I start out with Crawling - what a great way to get back into RC many years since I last did as a teenager. Man, the technology has changed!

I purchased a Redcat Gen 7 Pro for me and my 7 year old to drive around trails here in Los Angeles (so far we've mostly had hikers, dog walkers, and mountain bikers telling us we shouldn't be using it... but we're respectful and always stop when people go by, and I can't find anything in local municipal codes other than about RC flying machines... but that's another thread for another time).

We've only been out with it a handful of times. Trails are very dry and dusty. We've been going from full forward speed to full reverse instantly for dramatic skids and turns (is this bad for it?)

When cleaning it yesterday I noticed that the rear axle gearbox sounds like there's something rattling around in there. (After I filmed the video below I removed the wheels to remove their bearings from the equation and isolate it more).

I've posted a video so you can hear it.

https://youtu.be/S6F50QqlQWY

I'm not super mechanically inclined and don't want to needlessly strip down the gearbox. I'm assuming we've broken it somehow, but am trying to ascertain if it's user error (dust, incorrect throttle use) or if I should be asking Redcat to warranty a new diff gearbox as it's only a week old.

Thanks all.

ps. Mods - if this is in wrong place, sorry! Please move as needed.

 

[lonleycreeper]

Going from full forward to full reverse is definitely very hard on things. If you did this in a full scale car things go terribly wrong, very fast.

As far as people on the trail, I usually try to avoid highly populated trails, but inevitably run into a few out there. Like you, I tend to pull over, completely off trail, and greet people with a smile. Granted I am in a state that seems to be a bit more polite than L.A. (I was born and raised there) I have never had a problem with people telling me I shouldn't be out there. I have been mocked a few times but turn it into a joke by commenting on the classic adage of men and boys, and the cost of their toys. I usually have one of my dogs with me when I am out, and she follows the truck, stopping when it stops and moving when the truck does, lol. I have had a few people comment on how the truck might be destroying the trail, but I preach tread lightly and usually pick up trash, leaving it in the back of the truck, showing off the evidence. (Most of my rigs have open beds) I also show that my trucks have less impact on the terrain than a hiker. If there is a soft spot the truck will usually float over the surface that someone previously stepped in. Horses always get the right of way and I stop and pick up my truck before they get too close and wait for them to pass.

Hikers are generally more concerned with conservation, in my experience. Dog walkers are concerned about their dogs.(will they get hurt or hurt something\someone) Mountain bikers are concerned with their trails being more crowded. (Anybody not Biking is in the way) Horseback riders are similar to the dog owners, with an added issue being, horses spook at unknown, and the rider can be thrown or otherwise have a ride they do not desire.

Obviously not everyone in these hobbies feel strongly, but I have noticed these trends when on the trail with my toy trucks. I find being pleasant, polite and happy disarms people and dismantles their complaints.

When I get a moment, I will watch the vid, but sounds like a damaged ring/pinion gear inside the axle.

 

[TheLimey]

When I get a moment, I will watch the vid, but sounds like a damaged ring/pinion gear inside the axle.

Thanks for your detailed response lonleycreeper. Should I keep driving it on the broken part? Is the worse case I fully break a part I'm replacing anyway (ie. nothing to lose) or could the ripple effect mess up other parts of the drivetrain?

 

[lonleycreeper]

I got a chance to watch it this afternoon, and it sounds like a broken tooth...

I would in your shoes, disconnect the driveshaft, and confirm this by spinning the axle by hand feeling for the notchiness. I am not familiar with the gen7, but a broken tooth can wreck the rest of the teeth in there, and replacement parts should be inexpensive. The dificulty of removing the gears is not very hard at all.

https://www.hobbytown.com/redcat-everest-gen7-differential-cup-ring-gear-set-38t-rer18009/p711764

 

[Timmahh]

Something is amiss I have a Gen 8 Axe so very similar, but beefier in the needed spots over the 7. Obviously this is not an issue I have had yet.
Could be a broken tooth. Whatever it is, seems to be 'trapped' in one slot, as it seems to only make any noise once a revolution, like its trapped in a Slot that allows whatever it is to slide from one end to the other end of the slot as it turns.

Trying to think of what that could be in a Gen 7 diff is escaping me. so ya, a broken tooth that is still sliding in its own path is the only option I can derive.

Vid would be good. Its not hard. These taxles are pretty simple. A pinion gear driving the Ring gear. Pinion is driven by the axle, and the pinion drives the ring gear, which in turn drives the axle shafts to the wheels So there are only a few options, and with both wheels turning the eliminates an axle shaft, leaving pretty much a ring gear tooth as Lonely mentioned.

A few bolts and the pumpkin side is off. remove the screws holding on the diff cover and you'll be able to see the ring gear/diff cup. That will allow you to check all the teeth on the ring gear, suspecting you'll find one partially or fully broke.

The fact it turns and doesn't seem to miss a tooth says it may not be TOO terrible a break if it is indeed a ring gear tooth. You may be able to get the broken part out, add a little grease while your in there, and put the cover back on and drive.

No it shouldn't break that soon. If you do have a bad bearing, or broken ring or even a pinion gear, take a pic of the issue. Call Red Cat and get their CS/Warrenty people on the line. I have not had an issue to call them to date, but I have read/heard they are great to deal with. The pic and Vid you have will help show the issue. They will likely get th new parts off in the mail soon after from what I have been reading about those that have had to call.

Let us know what you find. Sharing any pics like the vid can help.