Dr Jim's 2S Senton Mild Build

drjim

Old And In The Way!
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Arrma RC's
Limitless, Senton
Not getting crazy with it, just want to do some upgrades to enhance the curability and run time.

To begin with, I'm going to try the Granite tires to give me some extra ride height, and I'm changing the motor pinion to the 14t Granite pinion to keep the gearing about the same. An ARRMA aluminum adjustable motor mount is being added so I can set the gear mesh more accurately, along with replacing all the OEM bearings with Avid "Ceramic Revolution" bearings.

I'll also be replacing the servo with a DS3225, and use a Kimbrough servo saver, and swapping out the receiver for a Futaba R304SB.

The ESC and motor will remain "As Shipped" for now, although from the posted experience of others here, I think I'll be doing a "Budget Brushless Conversion" before long!

One of the things I'm learning in doing this is the whole ARRMA product line, and what assemblies are different between families, and what are common.

One of the things that impresses me about these vehicles is the clever, economical design and "modularity" of their product lines. It's very much like the Platform Concept that the big automakers use now, swapping engines and drivelines among various vehicle styles to make the most of the up-front cost of vehicle design.

Since I'm not familiar with the type of differential used in the Senton Mega (same as the Senton 3S; different than the Senton 6S), I ordered a couple of "spares" from a breaker on eBay. I'm really big on having a unit to just take apart and examine, and learn about, and boy, did I learn a lot! After I cleaned out all the grease these had packed in them, and completely scrubbed them, I found several glaring (to me, at least) faults.

I'll get into the "Differential Experiments" I did in the next thread.

Hang on, 'cuz I think this is gonna be a whole lot of fun!
 

drjim

Old And In The Way!
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Location
Fort Collins, CO
Arrma RC's
Limitless, Senton
Yow....Three Months since I updated this? Ahhhhh....life intrudes on our hobbies sometimes.

I cleaned off the Hobby Bench, and started dragging my poor disassembled Senton down to the basement so I could get it back together.

DSC_1809.JPG

I was talking to one of my neighbors the other day, and he mentioned he saw me running it in the street. Turns out he has a car, too, and used to use it to chase the Canada Geese out of our cul-de-sac! Since I have a mount for my GoPro now, I'm going to do a bit of "Bird Hunting" with the Senton once I get it back together.

Tonight's task is to finish up the diffs, grease the ring and pinion with the Mobil 1 in the pic, and then get them back in the chassis.

DSC_1810.JPG

I learned quite a bit about the diffs and the gear mesh by buying a pair from a breaker on eBay, and taking them apart. Getting the internals properly shimmed is fairly easy, but I was going nuts trying to get them to spin smoothly when I put them back together in the plastic "yokes". Putting in just the differential case assembly, and leaving out the pinion gear, the case would spin smoothly. As soon as I put the pinion in and reassembled it, it would bind over part of the rotation.

I made a bunch of measurements and decided the plastic yokes were "off" in dimensions, so I ordered two Hot Racing aluminum yokes. Again, just the case would spin smoothly, but installing the pinion showed it still had some binding over ~30* of the rotation.

Carefully inspecting the all-plastic pinion gear showed that the gear is not molded concentrically to the shaft! OK, I'll order the Heavy Duty input gear with the metal shaft. Should be made better, right?

Surprise!

It's better than the all-plastic input gear, but it's still off enough to feel some binding over part of the rotation. Yes, I experimented with different thickness shims, and even with NO shims in the yokes it binds.

So I set them up "best effort" to get the clearance right, and I'll just live with a bit of binding. The OEM diffs I took out run much smoother, so I'm making a SWAG here that they have to "run in" a bit.

More to come now that I'm working on stuff again....
 

drjim

Old And In The Way!
Premium Member
Build Thread Contributor
Messages
545
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886
Location
Fort Collins, CO
Arrma RC's
Limitless, Senton
Got her all put back together, and went bashing a bit out in front of the house.

DSC_1814.JPG

The new 25Kg servo definitely makes the steering more responsive, and dropping the pinion to 14t from 17t really makes her "Jump Like A Willys In Four-Wheel Drive"!

Why the pinion change? To keep the gearing the same when I swap on the wheels/tires from a Granite, of course!

DSC_1815.JPG

Still haven't tried to fit them up yet, but that'll be Real Soon Now!
 
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