Kraton Arrma Metal diff case arrived yesterday

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Justintime

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Arrma RC's
I ordered 1 to start. Time to get the other 2! Quality seems great. Easier to assemble. Alot less slop.
 

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Justintime

Did you have any problem installing the spur gear? I got mine all put together and got to the last step of screwing on the spur gear but found out the four holes did not match up between the cup and spur gear. They are off just enough I could only get two of the four screws installed. I messed with it quite a bit using different combinations with the screws but could only get two screws in, i could never get two screws to go in opposite each other, Did you have any issues getting yours all put together? Thanks!!
 
Justintime

Did you have any problem installing the spur gear? I got mine all put together and got to the last step of screwing on the spur gear but found out the four holes did not match up between the cup and spur gear. They are off just enough I could only get two of the four screws installed. I messed with it quite a bit using different combinations with the screws but could only get two screws in, i could never get two screws to go in opposite each other, Did you have any issues getting yours all put together? Thanks!!
No issues. Sorry to hear that.
 
Yeah, x pin inserts are always awesome... most of the time you can get away without them, so we’ll see.
 
Interested to know how the weight is compared to the HR version too..

Someone, anyone we need specs..!! ??
The Hot Racing diff case itself is 14.3 grams, with the screws included from Hot Racing the weight is 16.8 grams. Hope this helps..
 

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Too bad they didn't machine it to still use the X pin steel inserts. Aluminum wears, so having the steel inserts in there would have made them last a lot longer.

Totally agree, didn't really think about until i saw your post.
 
Too bad they didn't machine it to still use the X pin steel inserts. Aluminum wears, so having the steel inserts in there would have made them last a lot longer.
Correct me if I am wrong,but I thought I saw on a different thread that there are spacers that go on the outside of the cross pins with these. That would effectively take the place of the inserts. I would hope that they are a good enough quality shim to hold up as a somewhat replacement.
 
Has the internal volume of diff fluid increased like m2c version?
My plastic diff oe setup consistently gets up to 258 F.degrees. then the diff starts to weep oil and sling all over the spur and pinion. Looking for an aftermarket solution myself.
Yeah, x pin inserts are always awesome... most of the time you can get away without them, so we’ll see.
X pin design creates a non rotating component. Actualy two. Tekno does it this way also.
 
Has the internal volume of diff fluid increased like m2c version?
My plastic diff oe setup consistently gets up to 258 F.degrees. then the diff starts to weep oil and sling all over the spur and pinion. Looking for an aftermarket solution myself.

X pin design creates a non rotating component. Actualy two. Tekno does it this way also.
Exactly, they don't rotate so I don't see it wearing the aluminum much, if at all. It's not like the pins are spinning a groove into the cup. That said, I'd still prefer the pin anchors but we'll see how it works out.
 
Correct me if I am wrong,but I thought I saw on a different thread that there are spacers that go on the outside of the cross pins with these. That would effectively take the place of the inserts. I would hope that they are a good enough quality shim to hold up as a somewhat replacement.
They come with 4 shims. Dry fit was almost perfect. Requires 2 shims on each spur gear to get correct mesh.
Has the internal volume of diff fluid increased like m2c version?
My plastic diff oe setup consistently gets up to 258 F.degrees. then the diff starts to weep oil and sling all over the spur and pinion. Looking for an aftermarket solution myself.

X pin design creates a non rotating component. Actualy two. Tekno does it this way also.
Yes it holds more. Space of x pin reduction.
 
Great info. Thanx for sharing that.
Justintime

Did you have any problem installing the spur gear? I got mine all put together and got to the last step of screwing on the spur gear but found out the four holes did not match up between the cup and spur gear. They are off just enough I could only get two of the four screws installed. I messed with it quite a bit using different combinations with the screws but could only get two screws in, i could never get two screws to go in opposite each other, Did you have any issues getting yours all put together? Thanks!!
Since it is an open case on both sides versus a cup design, perhaps the spur is indexed to one side only and the other side gets the steel cover opposite side. Just a thought. Try reversing the spur and opposite cover if you haven't already.
Just a thought.
Btw, did you get two gaskets with the parts?
I think that I would use Red thread locker on the screws. I feel the center diff. is by far the hottest running component. Mine at high 250's 99% of the time. That heat transfers to the motor/mount considerably.
 
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The Hot Racing diff case itself is 14.3 grams, with the screws included from Hot Racing the weight is 16.8 grams. Hope this helps..
My parts got here early. For the stock cup I weighed just the cup. For the Arrma alum. I weighed the body, cover, 1 gasket and 4 screws, (everything that makes just the cup.)
Stock=10 grams
Arrma Alum.=24 grams


So the Arrma alloy cup is quite a bit heavier than the HR version..!!
I would be interested to know if the weight difference between the stock Arrma plastic cup and the two options we now have make any actual difference in acceleration or rotating mass..?

I see the new Arrma cup doesn't use those metal inserts like the plastic one so that's one less thing to wear out.?
 
So the Arrma alloy cup is quite a bit heavier than the HR version..!!
I would be interested to know if the weight difference between the stock Arrma plastic cup and the two options we now have make any actual difference in acceleration or rotating mass..?

I see the new Arrma cup doesn't use those metal inserts like the plastic one so that's one less thing to wear out.?
The cover isn't aluminum and puts in a good chunk of the weight. Also, it would be that much less weight without those anchors, not that they're all that heavy.
 
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