Kraton broken diff pins

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Thank you both, I will grab a set!
 
2.25
RCbuzz said:
This link takes me to the 2.3mm is that what you got? They fit? Or go with 2.25mm?
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2.25 its just the link for the item. I tried to link the 2.25 but its goes to 2.3. Yes you want the 2.25mm blanks. I'm not a fan of any thing from aliexpress because one you don't know the quality of the item most of the time. Two shipping will be long no matter the item unless you pay insane prices for 2day or something like that. But when I'm getting stuff in bulk that I know I'm going to use and its ok to order way ahead on its cheap.
 
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RCbuzz said:
It makes me wonder how the Fireteams are holding up with regular diffs. They are crazy heavy.

What failures did you have with your diffs?
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All I know is that with 17 pounds that FT weighs, that the center diff gets Really hot. 150ish F. I even upped it to 800k- 1 Mil cst. Runs hot. I imagine this is why the FT came with a metal RTR upgrade diff cup out the box. I removed my Hand brake. But if you like using it alot, I could see the center diff not lasting long.
 
ross_jsy said:
I was pro BLX diffs being built right, but after 2 failures in one day I am converting mine to EXB as they fail
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Nothing truly against LSD 29mm diffs. But they are a whole new ball of wax. Dialing them in can be a bear. Very thick oil in them can make the rig hard to drive. Driving style needs to change with an LSD setup. Making them fully Open diffs with the "Open shim kit" seems to be popular.
 
Diem Turner said:
Slightly different take but, to my mind, I'd think that spring steel, because of its higher ductility in comparison to HS steel, offers a bit more flexibility (as the name already kind of implies) which, to my very limited understanding of metallurgy and materials application, seems like it would be a better fit for this particular use case. That's just a working hypothesis, I'm more than happy for someone with actual knowledge on the subject tell me why my "logic" is sound or faulty.
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You just gave me an idea’…! Spring steel/piano wire, those are easy and cheap to find in most hobbystores.. I just got my first Arrma ever last week, found a nice k6 exb and took the diff apart before running it just to be shure everything was ok (didnt trust the PO) and when i saw how small those diff parts was compared to my Losi LMT wich is only rated for 3S, I thought holy poop no wonder those diffs explode with 6s! I saw small wear marks on all diff pins and the idear of using hss steel drill or piano wire is perfect!
 
don't have hardly any trouble with my rtr diffs have broke my lsd diffs twice and thats in a talion exb I have the 2018 talion all upgraded to m2c parts and never had any trouble with the rtr diffs at all been running it for years. the car as been regularly serviced in those years also
 
The only thing I have heard go wrong on the RTR diff's is a result from poor shimming, low fluid, cracked diff housing, and weak outdrive pins. All of which seem like an easy fix.
 
Drill blanks are too brittle and will easily shear, put one in a vice and tap it with a hammer. Like a Toothpick

Here’s what you want, toughness. Haven’t broken one yet, I do run vitavon spider/sun gears however so expect the cast ones to become the weak point.
https://www.mcmaster.com/product/2900A239
 
RCbuzz said:
The only thing I have heard go wrong on the RTR diff's is a result from poor shimming, low fluid, cracked diff housing, and weak outdrive pins. All of which seem like an easy fix.
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I always felt user error was the primary issue with the diffs.
Of course it doesn't help that out the factory they are setup poorly, not properly shimmed. And always low on oil.
If you toss the diffs OE Sat and Sungear shims, for a whole set of Mugens instead, use the proper CST oils and fill them up, they are fairly durable.
If you get 20 + hard runs out them no issues, you did well. Then just clean out/service them with fresh oil etc.
And keep rolling. Using the Arrma Metal upgrade diff at the Center is also good to do.
I don't feel the need for them at the front or rear. The center diff is what gets very hot. Like 250F +. The heavier the rig, the hotter they get. Offroading.
I've melted a Plastic OE center diff twice before.
 
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I've had better luck making my own Sungear cross pins from HS drill bit "blanks" or cutting off the drill bit "shanks".
A Dremel and very careful cutting will make sets of them easily. They are stronger.
2.25 x 9.8mm (length size)
Buy 2.25 mm diameter drill bits, and cut to 9.8 mm . Chamfer/round off the ends well.
 
But you are right.
These simple OE crosspins can ruin a wet dream of an otherwise well built diff.
When the stocker pins do bend or snap apart, the Sungear will split apart, shatter, and take out the $whole gearset$. Been there one too many times. I feel it is the most common cause of the RTR diff failures. It was for me at least.
What you want to avoid in the first place. (y)
 
I use cobolt 2.25mm drill bits in some of my diffs not broke one yet not broke a sun gear either
 
SrC said:
If the hardened Cross pins don't bend or snap like the stockers do, the Sungear wont also crack/shatter in pieces.
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Exactly..☝️.. 99% of the time it's the snapped pin rotating in the sun gear bore that snaps them into pieces..
 
2,6mm drill hss drill fits just tight ind the diff, only question now is, is the drill pin as strong as the arrma pins? Will get once tested

IMG_3069.jpeg
 
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