Fellow beginners, take note. Pinion Change Reality.

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Dulb_D

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Location
Twin Cities, MN
Arrma RC's
  1. Senton 6s
Picked up a 15t pinion for my, now monsterized, Senton 3S. Watched as many videos as I could find that were relevant enough and thought this would be a breeze. As a newbie myself, not a pro, here are the issues I ran into that maybe aren't discussed enough on these YouTube How-To videos:

1.) The 2019 Senton 3S motor mount assembly is reportedly easy to remove, if your experience is like mine you are going to need to pry it out with a flat-tip screwdriver and worry about breaking it as well as sacrifice some knuckle skin. It is dovetailed to the chassis and I suppose if it's perfectly clean it may slide out easy but if you used it once expect it to put up a fight.

2.) Once you get that out, before you remove a single screw or bolt make sure you have an appropriately sized allen driver, do not use the short allen keys they include in the kit, you will strip screws - especially the pinion grub screw. Also before you turn the screws with any force make sure the tip fits snuggly into the screw head. Not all 2mm allen drivers are made to the same level of tolerance and if you're driver wiggles even just a tiny bit, you may strip the screw. These things are locked in there and going to take a little force to loosen which brings me to my biggest issue and gripe...

3.) Arrma seems to have used red threadlock on many of these motor mount screws, even ones that screw into plastic... Red=you don't intend to remove, Blue=you may want to be able to remove some day. I don't think there is any need to use red loctite on these cars at all even though I've seen some recommending that - I don't think that's wise at all, and not sure what Arrma was thinking if they in fact are using it in these "hobby grade" vehicles that are supposed to be repaired, not outright replaced. The screws seam to be overly tight or locked. I know you can use heat to loosed the threadlock but you shouldn't have to.

I eventually got my pinion in and put the motor mount assembly back together and am waiting for the blue loctite to set up before trying out the new pinion.
 
Good info sir.
I use a small lighter size butane torch I bought at a local hardware store. It has a small pinpoint flame tip you can direct the tip of the flame to those pucker factor screws you don't want to strip out. Just a second or two of heat seems to aid on breaking the stubborn seal alot easier.
 
Picked up a 15t pinion for my, now monsterized, Senton 3S. Watched as many videos as I could find that were relevant enough and thought this would be a breeze. As a newbie myself, not a pro, here are the issues I ran into that maybe aren't discussed enough on these YouTube How-To videos:

1.) The 2019 Senton 3S motor mount assembly is reportedly easy to remove, if your experience is like mine you are going to need to pry it out with a flat-tip screwdriver and worry about breaking it as well as sacrifice some knuckle skin. It is dovetailed to the chassis and I suppose if it's perfectly clean it may slide out easy but if you used it once expect it to put up a fight.

2.) Once you get that out, before you remove a single screw or bolt make sure you have an appropriately sized allen driver, do not use the short allen keys they include in the kit, you will strip screws - especially the pinion grub screw. Also before you turn the screws with any force make sure the tip fits snuggly into the screw head. Not all 2mm allen drivers are made to the same level of tolerance and if you're driver wiggles even just a tiny bit, you may strip the screw. These things are locked in there and going to take a little force to loosen which brings me to my biggest issue and gripe...

3.) Arrma seems to have used red threadlock on many of these motor mount screws, even ones that screw into plastic... Red=you don't intend to remove, Blue=you may want to be able to remove some day. I don't think there is any need to use red loctite on these cars at all even though I've seen some recommending that - I don't think that's wise at all, and not sure what Arrma was thinking if they in fact are using it in these "hobby grade" vehicles that are supposed to be repaired, not outright replaced. The screws seam to be overly tight or locked. I know you can use heat to loosed the threadlock but you shouldn't have to.

I eventually got my pinion in and put the motor mount assembly back together and am waiting for the blue loctite to set up before trying out the new pinion.
Yeah I'll agree with you. That's why I bought hobby grade tools to get those stubborn loctite hex screws out . They really are a BEAR to take out the first time. As far as the taking out the assembly, yeah I had to pry it out with my small screw driver. Try taking out the outcast 6s center hex screws. Now those are a SUPER BEAR!
 
What tires did you put on the Senton? We have crashed our and slid it upside down on apshalt enough times that I've though about buying a second body, and maybe some tires as well, just because bigger tires would look cooler.
 
What tires did you put on the Senton? We have crashed our and slid it upside down on apshalt enough times that I've though about buying a second body, and maybe some tires as well, just because bigger tires would look cooler.
I am basically doing what Rich Duperbash and others have done to theirs - Granite tires and (eventually) Typhon 6S shocks. I think Rich was still running the 20t pinion though. You gotta raise the body mounts up and trim the body (use a curved manicure scissor if you don't have lexan scissors) or buy a special body but to me it's worth it especially since I run mostly in grass the additional ground clearance helps.
 
The alternative is the motor coming loose and destroying a pinion and/or the spur gear ? Or the pinion coming loose and ending your run. I can just hear the uproar now!

I know it's a pain but it's much easier with a decent set of hex drivers (I never use Allen keys) and experience. I started with nitro and you had to use red loctite on certain things due to engine vibration. So I'm used to it. Also, legit gripe on the motor module. Arrma has a video showing how to remove it and the guy just lifts the tab and pops it out ? Riiiiiiight.
I am basically doing what Rich Duperbash and others have done to theirs - Granite tires and (eventually) Typhon 6S shocks. I think Rich was still running the 20t pinion though. You gotta raise the body mounts up and trim the body (use a curved manicure scissor if you don't have lexan scissors) or buy a special body but to me it's worth it especially since I run mostly in grass the additional ground clearance helps.
If you run the 20t pinion with the Granite tires you will definitely have heat issues. It will also stutter from a start. You might want to think about an adjustable motor mount and going no bigger than maybe 17t. Even 17t will be fast. Like 55 mph fast.
 
The alternative is the motor coming loose and destroying a pinion and/or the spur gear ? Or the pinion coming loose and ending your run. I can just hear the uproar now!

I know it's a pain but it's much easier with a decent set of hex drivers (I never use Allen keys) and experience. I started with nitro and you had to use red loctite on certain things due to engine vibration. So I'm used to it. Also, legit gripe on the motor module. Arrma has a video showing how to remove it and the guy just lifts the tab and pops it out ? Riiiiiiight.

If you run the 20t pinion with the Granite tires you will definitely have heat issues. It will also stutter from a start. You might want to think about an adjustable motor mount and going no bigger than maybe 17t. Even 17t will be fast. Like 55 mph fast.
I would understand if it was just the pinion gear, but even then, red loctite is overkill IMO when you have a motor shaft that has a flat edge for the pinion grub screw to secure against. It was getting hot but not as quickly as I thought and Rich Duperbash was still running his with a 20t so I thought it would be ok and maybe it is if you are running it across smoother surfaces than grass. I'm anxious to see what the 15t will be like. I mean 20t even with SCT tires on it was probably faster than I would ever need it to be. I'd rather have a little more torque and a little less heat. ;)
 
I would understand if it was just the pinion gear, but even then, red loctite is overkill IMO when you have a motor shaft that has a flat edge for the pinion grub screw to secure against. It was getting hot but not as quickly as I thought and Rich Duperbash was still running his with a 20t so I thought it would be ok and maybe it is if you are running it across smoother surfaces than grass. I'm anxious to see what the 15t will be like. I mean 20t even with SCT tires on it was probably faster than I would ever need it to be. I'd rather have a little more torque and a little less heat. ;)
I've had pinions come loose with blue loctite. And it was cured. I'm sure this is just an Arrma CYA situation. Better safe than sorry.

A stock 3s truck running Granite tires and a 20t pinion is capable of speeds in excess of 60 mph. 15t is around 50 mph.
 
I’m starting to come around on the pinion size argument. I used to think faster was always better. But the cogging at low speeds is more detrimental to me than not being able to hit 60mph. I had been using my Typhon as a speed runner and had a 27T pinion in it. It cogged a lot on that pinion, of course. I recently went back to the 18T and found it is much more enjoyable to run. The low end punch is back and makes for much better bashing. Temps are also much lower too.
 
Yeah I'll agree with you. That's why I bought hobby grade tools to get those stubborn loctite hex screws out . They really are a BEAR to take out the first time. As far as the taking out the assembly, yeah I had to pry it out with my small screw driver. Try taking out the outcast 6s center hex screws. Now those are a SUPER BEAR!

Thanks for the heads up! I just picked up a new Outcast 6S so when I go to change out the diff the fluids, be ready for a fight!! ?
 
I’m starting to come around on the pinion size argument. I used to think faster was always better. But the cogging at low speeds is more detrimental to me than not being able to hit 60mph. I had been using my Typhon as a speed runner and had a 27T pinion in it. It cogged a lot on that pinion, of course. I recently went back to the 18T and found it is much more enjoyable to run. The low end punch is back and makes for much better bashing. Temps are also much lower too.
I think everyone who starts out wants to go as fast as possible. In my case it was a converted Granite Mega 4x4. I hit nearly 60 mph, tires all ballooned up and almost no steering control. That's when I realized it was a monster truck and I drove it only on dirt to do jumps. It didn't make sense to have that kind of speed. It bashed just as well with a top speed of 50 and that's what I gear the 3s trucks to, which is basically stock. Obviously none of this applies to street runners and speed rigs.
 
I've had pinions come loose with blue loctite. And it was cured. I'm sure this is just an Arrma CYA situation. Better safe than sorry.

A stock 3s truck running Granite tires and a 20t pinion is capable of speeds in excess of 60 mph. 15t is around 50 mph.
You are probably right about it being a CYA thing. I get that.
 
Get a cheap pencil torch. It will save you a lot of pain and suffering. You can also use a soldering iron for a more control application of heat.

With pinions, I've had very few come loose with blue-gel loctite, as long as I let it cure at least overnight.

Diff screws in alloy cups in the 6S trucks on the other hand needed red as did the input cups on the diff pinions on the 6S trucks. Blue just didn't hold up for me on my outcast.
 
Get a cheap pencil torch. It will save you a lot of pain and suffering. You can also use a soldering iron for a more control application of heat.

With pinions, I've had very few come loose with blue-gel loctite, as long as I let it cure at least overnight.

Diff screws in alloy cups in the 6S trucks on the other hand needed red as did the input cups on the diff pinions on the 6S trucks. Blue just didn't hold up for me on my outcast.
I used blue on my diffs. If it comes apart I'll upgrade the diff bells and run red?
 
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