Big Rock Arrma 3s - differential and slipper clutch problems

[Zisko]

I've run out of about 30-40 batteries on my Big Rock and have the first major damage. The ring gear and bevel gear on the rear differential are completely worn out, the ring gear has massive tooth loss around the entire circumference. plastic shavings everywhere. I mostly drive on loose ground, I hadn't touched the setting of the slipper clutch, I tried it afterwards, it was 1.5 turns, as intended by the factory.

1st question: How can it be that after 30 rides the crown wheel is gone - I deliberately avoid wheelies and try to accelerate with a sense of proportion to avoid things like that.

I have now replaced the entire differential and found that the shim under one differential bearing was not installed on the ring gear side as shown in the exploded view, but on the opposite side. When reassembling, however, I had to reinstall the shim on the wrong side, otherwise the gearbox was very stiff and jerky. With the shim on the wrong side, it runs easily and without play.

2. Question: Can anyone confirm that the shim goes on the wrong side.

Going on with the slipper clutch: In the photo below you can see the output of the clutch to the front axle on the left, the output to the rear axle on the right - the one to the rear axle is also on the way to saying goodbye. I also swapped it. After only 2 batteries and a slipping clutch on 2 turns, you can see signs of wear again.

3. Question: Does anyone know the topic? What can you do about it? Now I've played with the slipper clutch. If I pushed the car forward with the hex key inserted (I think the method is well known), the wheels lock up at about 3 turns!!, not at 1.5 or less.

4. Question: What are the settings of your slipping clutches. Does the factory setting tend to be too hard or does my slipper have too much grip?

Looking forward to your suggestions

 

[Michael24]

Your diff gears are plastic and at the rpm's they turn is crazy high, heat, stress, abrupt jarring F/R with throttle is a lot of stress. 30-40 battery pack ain't bad mine didn't last that long! For shimming diff's placing the shim on the gear side tightens the mesh, placing shim on other side loosens mesh yours must have been tight at the factory and they shimmed accordingly. For the clutch i use the rolling method with good results have never bother to count turns. The rear portion of your slipper unit is either just worn or your harder on the throttle than indicated, possibly from landing jump's while on the throttle I've gone through several in the last year. Your slipper might be too tight. Hope that helps.

 

[419RC]

I do the rolling method...then back it off ~1 full turn. I found that with the rolling method until the wheels locked, i was stripping rear diff input gears and cracking slipper hubs, the part you have shown. No issues as of yet. I've never been a fan of wheelies in my 10th scale 3s cars with their transmission setup.

Edit: When youre referring to turns, i think most people talk about turns backing it of from full lock. On my traxxas slash, its set up to go full snug, and then back off however many turns too. From tight, going loose, is the only only "consistent" point of reference.

 

[Zisko]

30-40 battery pack ain't bad mine didn't last that long!

Puh, I bought that thing, as everybody tells you, the arrma 3s are almost undestroyable. 30-40 is too less

The rear portion of your slipper unit is either just worn or your harder on the throttle than indicated, possibly from landing jump's while on the throttle I've gone through several in the last year

I really try to avoid landing while on the throttle. but it's The same, as above: I thought they would last longer. I loosened my slipper at the last repairs - hopefully that helps

 

[Moirae]

Metal gears and yoke such a good upgrade to never worry about it again.

 

[SrC]

I've run out of about 30-40 batteries on my Big Rock and have the first major damage. The ring gear and bevel gear on the rear differential are completely worn out, the ring gear has massive tooth loss around the entire circumference. plastic shavings everywhere. I mostly drive on loose ground, I hadn't touched the setting of the slipper clutch, I tried it afterwards, it was 1.5 turns, as intended by the factory.

1st question: How can it be that after 30 rides the crown wheel is gone - I deliberately avoid wheelies and try to accelerate with a sense of proportion to avoid things like that.

I have now replaced the entire differential and found that the shim under one differential bearing was not installed on the ring gear side as shown in the exploded view, but on the opposite side. When reassembling, however, I had to reinstall the shim on the wrong side, otherwise the gearbox was very stiff and jerky. With the shim on the wrong side, it runs easily and without play.

2. Question: Can anyone confirm that the shim goes on the wrong side.

Going on with the slipper clutch: In the photo below you can see the output of the clutch to the front axle on the left, the output to the rear axle on the right - the one to the rear axle is also on the way to saying goodbye. I also swapped it. After only 2 batteries and a slipping clutch on 2 turns, you can see signs of wear again.

3. Question: Does anyone know the topic? What can you do about it? Now I've played with the slipper clutch. If I pushed the car forward with the hex key inserted (I think the method is well known), the wheels lock up at about 3 turns!!, not at 1.5 or less.

4. Question: What are the settings of your slipping clutches. Does the factory setting tend to be too hard or does my slipper have too much grip?

Looking forward to your suggestions

View attachment 223770

30-40 packs in, and you are wondering why these parts failed???
You got your moneys worth. Will do no better. Is what it is. Just normal wear and tear. RC parts don't last as long as Real cars do.
Just replace them with stockers, and consider yourself good if you get another 40 packs on them.
40 packs in, I would overhaul the whole rig, including opening the motor for servicing if you haven't already. Checking the BB's all across the rig etc.

 

[Crunchy Gears]

SRC is right, unless you're putting in a more powerful set up, the plastic diffs are fine especially when a complete stock replacement can be had for peanuts on jennys compared to the metal upgrade.

30 packs is average life from what I've seen for arrmas plastic diffs. Drive train items are wear and tear items that need maintenance and repair no matter what rc you have. So nothing crazy going on here it's just time to give your ride some tlc.

If your hubs are getting worn like above said, your slipper probably just a little tight. I've never damaged mine beyond use yet. I have stripped the adjustment screw once before tho overtightened it though. These days I never fully tighten, I just roll the wheels and then back it off, drive it around some and tighten by half or quarter turns until I like it.

 

[Hector_Fisher]

I've run out of about 30-40 batteries on my Big Rock and have the first major damage. The ring gear and bevel gear on the rear differential are completely worn out, the ring gear has massive tooth loss around the entire circumference. plastic shavings everywhere. I mostly drive on loose ground, I hadn't touched the setting of the slipper clutch, I tried it afterwards, it was 1.5 turns, as intended by the factory.

1st question: How can it be that after 30 rides the crown wheel is gone - I deliberately avoid wheelies and try to accelerate with a sense of proportion to avoid things like that.

I have now replaced the entire differential and found that the shim under one differential bearing was not installed on the ring gear side as shown in the exploded view, but on the opposite side. When reassembling, however, I had to reinstall the shim on the wrong side, otherwise the gearbox was very stiff and jerky. With the shim on the wrong side, it runs easily and without play.

2. Question: Can anyone confirm that the shim goes on the wrong side.

Going on with the slipper clutch: In the photo below you can see the output of the clutch to the front axle on the left, the output to the rear axle on the right - the one to the rear axle is also on the way to saying goodbye. I also swapped it. After only 2 batteries and a slipping clutch on 2 turns, you can see signs of wear again.

3. Question: Does anyone know the topic? What can you do about it? Now I've played with the slipper clutch. If I pushed the car forward with the hex key inserted (I think the method is well known), the wheels lock up at about 3 turns!!, not at 1.5 or less.

4. Question: What are the settings of your slipping clutches. Does the factory setting tend to be too hard or does my slipper have too much grip?

Looking forward to your suggestions

View attachment 223770

The shim should go on the "proper" side. There is no standard side here. Someone could say "put it on the gear side", but that might create an overly tight mesh for your particular situation. And the opposite may be true for shimming the non-gear side. You need to add shims to whichever side is needed so that the gears are as close as possible without binding. If they're binding, it's too close. Too far shimmed the other direction and you'll only have a portion of the gears teeth engaging and you'll over-stress the teeth. It's an iterative process where you'll be dialing in the gear mesh for every gear, down to the specific truck you own, down to the specific diff. In other words, every diff is different, and every truck is different. you'll get the most life from gears in general if you spend extra time to get good gear mesh.

SRC is right, unless you're putting in a more powerful set up, the plastic diffs are fine especially when a complete stock replacement can be had for peanuts on jennys compared to the metal upgrade.

30 packs is average life from what I've seen for arrmas plastic diffs. Drive train items are wear and tear items that need maintenance and repair no matter what rc you have. So nothing crazy going on here it's just time to give your ride some tlc.

If your hubs are getting worn like above said, your slipper probably just a little tight. I've never damaged mine beyond use yet. I have stripped the adjustment screw once before tho overtightened it though. These days I never fully tighten, I just roll the wheels and then back it off, drive it around some and tighten by half or quarter turns until I like it.

Where are you getting the stock diffs for peanuts??? I'd like to know! $31 for the two input gears and a full diff (plus whatever shipping costs) is still nothing to sneeze at! And let's not even talk about the costs of the slipper assembly....

 

[Velodromed]

The shim should go on the "proper" side. There is no standard side here. Someone could say "put it on the gear side", but that might create an overly tight mesh for your particular situation. And the opposite may be true for shimming the non-gear side. You need to add shims to whichever side is needed so that the gears are as close as possible without binding. If they're binding, it's too close. Too far shimmed the other direction and you'll only have a portion of the gears teeth engaging and you'll over-stress the teeth. It's an iterative process where you'll be dialing in the gear mesh for every gear, down to the specific truck you own, down to the specific diff. In other words, every diff is different, and every truck is different. you'll get the most life from gears in general if you spend extra time to get good gear mesh.

Where are you getting the stock diffs for peanuts??? I'd like to know! $31 for the two input gears and a full diff (plus whatever shipping costs) is still nothing to sneeze at! And let's not even talk about the costs of the slipper assembly....

Really? Compared to retail, yeah. Peanuts.

 

[Crunchy Gears]

The shim should go on the "proper" side. There is no standard side here. Someone could say "put it on the gear side", but that might create an overly tight mesh for your particular situation. And the opposite may be true for shimming the non-gear side. You need to add shims to whichever side is needed so that the gears are as close as possible without binding. If they're binding, it's too close. Too far shimmed the other direction and you'll only have a portion of the gears teeth engaging and you'll over-stress the teeth. It's an iterative process where you'll be dialing in the gear mesh for every gear, down to the specific truck you own, down to the specific diff. In other words, every diff is different, and every truck is different. you'll get the most life from gears in general if you spend extra time to get good gear mesh.

Where are you getting the stock diffs for peanuts??? I'd like to know! $31 for the two input gears and a full diff (plus whatever shipping costs) is still nothing to sneeze at! And let's not even talk about the costs of the slipper assembly....

If you read the whole post, you'd know the answer to your question.

You can buy 2 completely assembled diffs and replacement input gears off Jenny's for less than the cost of just one assembled metal diff, and as Velo said compared to retail price it's peanuts.

Regardless $30 IS nothing in this hobby. For better or worse this hobby is expensive compared to some and even if you do everything right, some things need to be replaced regularly or eventually fail. Am I being trolled?

 

[Moirae]

I think it's really just buy cheap and replace when worn or spend a bit more up front and never worry about it again. I can totally see the argument for staying with stock if you've kept the stock electronics. Personally I upgraded my typhon 3s into a monster with tp 4040 and a move to 4s. I felt like I HAD to go metal gears as the power increase was just wrecking the plastic ones. I think the metal gears are totally worth it if you add any more power.

The cost it adds definitely sucks though and its just another reason why I won't ever tell someone to get a 3s rig over a 6s rig. Literally better off running the 6s rig on 3s or 4s.

 

[Velodromed]

If you read the whole post, you'd know the answer to your question.

You can buy 2 completely assembled diffs and replacement input gears off Jenny's for less than the cost of just one assembled metal diff, and as Velo said compared to retail price it's peanuts.

Regardless $30 IS nothing in this hobby. For better or worse this hobby is expensive compared to some and even if you do everything right, some things need to be replaced regularly or eventually fail. Am I being trolled?

ugh (couldn’t resist)

 

[Hector_Fisher]

If you read the whole post, you'd know the answer to your question.

You can buy 2 completely assembled diffs and replacement input gears off Jenny's for less than the cost of just one assembled metal diff, and as Velo said compared to retail price it's peanuts.

Regardless $30 IS nothing in this hobby. For better or worse this hobby is expensive compared to some and even if you do everything right, some things need to be replaced regularly or eventually fail. Am I being trolled?

We both must be missing each others sarcasm here then. And my budget must be significantly lower than yours!

I think i was trying to get at that $31 for two input gears and an assembled diff from jennys is more to some and less to others.

 

[Crunchy Gears]

We both must be missing each others sarcasm here then. And my budget must be significantly lower than yours!

I think i was trying to get at that $31 for two input gears and an assembled diff from jennys is more to some and less to others.

I gotcha. Yeah $31 is expensive. It's an oil change and up till recently it was a full tank of gas. I totally get that

Anytime Ive talked about something rc related being cheap or expensive it's within the scope of the hobby. My budget isn't anything special. I piece my rc's together alot of the time just for the lower upfront cost, even if it is technically more money spent total it's easier on the finances to burn 20-50 bucks at a clip instead of half a grand especially if you don't wanna wait and like building. I recently hodgepodged a 2WD Senton together for my boy out of spare parts I can't use anymore, a couple things like wheels and body shell off Jenny's and the motor out of the Granite since it's busted right now. He has a Voltage but I can't figure out what's wrong with it and I'm not dumping anymore money into it until I do. I just took it completely apart to put a new idler gear set in and replaced the spur and it's still acting like everything is stripped so not sure if I somehow put it back together wrong or what and don't wanna completely tear it apart again to find out

When I got back into this hobby I wanted an Outcast 4s. I saw em when they first released and I didn't have the finances for it, and by the time I did it had been discontinued. So I bought a Granite instead last year and eventually over time I built my own Outcast 4s out of it . And now I got a Noto as well. And unless some amazing deal appears that'll probably be it for awhile just because of how crazy everything is. We'll see

 

[Hector_Fisher]

I gotcha. Yeah $31 is expensive. It's an oil change and up till recently it was a full tank of gas. I totally get that

Anytime Ive talked about something rc related being cheap or expensive it's within the scope of the hobby. My budget isn't anything special. I piece my rc's together alot of the time just for the lower upfront cost, even if it is technically more money spent total it's easier on the finances to burn 20-50 bucks at a clip instead of half a grand especially if you don't wanna wait and like building. I recently hodgepodged a 2WD Senton together for my boy out of spare parts I can't use anymore, a couple things like wheels and body shell off Jenny's and the motor out of the Granite since it's busted right now. He has a Voltage but I can't figure out what's wrong with it and I'm not dumping anymore money into it until I do. I just took it completely apart to put a new idler gear set in and replaced the spur and it's still acting like everything is stripped so not sure if I somehow put it back together wrong or what and don't wanna completely tear it apart again to find out

When I got back into this hobby I wanted an Outcast 4s. I saw em when they first released and I didn't have the finances for it, and by the time I did it had been discontinued. So I bought a Granite instead last year and eventually over time I built my own Outcast 4s out of it . And now I got a Noto as well. And unless some amazing deal appears that'll probably be it for awhile just because of how crazy everything is. We'll see

I think you make a valid point. For how many standard diffs someone might go through, it might makes sense to spend the change and upgrade to the steel diffs. Unfortunately, just this last weekend we broke my sons granite (motor plate, spur, and diffs have seized up) and my big rock (esc and rx fried themselves) all in one sitting. This week was a good example of how things often go from "what upgrade should I get" to "what's the bare minimum I need to get my trucks running".

FWIW, my son also had the voltage. I hated working on it. Thought it was a pretty good deal until it broke and I had to actually work on it...

I respect the upgrades that people do, especially taking a brand new truck and dropping several hundred dollars of goodies into it. Those trucks are awesome to see! Some people though have to make do with patches like this just to get running:
https://www.arrmaforum.com/threads/when-its-a-beautiful-day-but-all-of-your-rcs-are-broken.51310/

 

[Crunchy Gears]

Nice! Sick emergency repair.

I think with the plastic diffs it depends on how much you run. 30 times before changing them on average might be a whole season for some, and might be couple weeks for others.

I still stand by unless you're putting a more powerful system in, the plastic diffs are the best bang for your buck.

 

[Velodromed]

He has a Voltage but I can't figure out what's wrong with it and I'm not dumping anymore money into it until I do. I just took it completely apart to put a new idler gear set in and replaced the spur and it's still acting like everything is stripped so not sure if I somehow put it back together wrong or what and don't wanna completely tear it apart again to find out

Hey man, can you post a quick video of your boys voltage so I can hear what you mean?
You replaced both the differential and idler gear, yes?

First though check both rear wheel hex. I just had the same situation occur with my voltage and the right wheel hex was stripped out. I’ve now had three of those stock wheels strip out over the last couple years...not made from the best plastic.

Horizon even warrantied a full set back when I first got into the hobby. I’d only asked for 2 tires, so perhaps it’s a common problem. I think it starts when the wheel nut loosens a little bit, the soft plastic begins to go and finally strips.

I figure you’ve already checked all the drive cups? When one of those strips out the same thing happens.