Arrma LSD differential gasket missing..common?

KnowAir

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I just pulled my front diff from my K6EXB for the first time. I've been running for almost a year now, never checked them out of the box. I know most recommend a teardown right out of the box, and I get it. I figure if something is a miss, it'll let me know. The diff has worked flawlessly, no clicking or skipping, just freewheeling a bit more than it used to..well, surprise, no oil. Wet, but no actual fluid. I should mention that both output shafts were pretty wiggly, alot of side to side movement. So, being the minimalist I am, fill and reassemble. Simple, right? Well, after doing so and tightening down the ring gear to the cup, it's bound up tight, weird, it was fine, all I did was fill with fluid and put it back together?
After taking it back apart, I find that there is literally no gasket between the ring gear and cup..they must've left the screws loose from the factory,LOL. That allowed the diff to work, and what little fluid that was in it leak out?
Interestingly, now that it's been sitting on the bench with 7k fluid in it, it's leaking out the bottom past the o ring.. simple refill eh?🤣🤣
 

Oopspoops

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Note sure about gaskets, but I got a Mojave EXB recently, and my rear diff was missing one of the LSD plates. I'm glad I checked.
 

KnowAir

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Note sure about gaskets, but I got a Mojave EXB recently, and my rear diff was missing one of the LSD plates. I'm glad I checked.
TBH, I haven't dug that deeply.. who knows what all else is missing!!🤣🤣
Can't be much, it's been driven pretty hard for a year..
 

KnowAir

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Possibly, I haven't seen any remnants, but also have run for a year without maintenance. I really can't complain. If I had the money, I'd just buy a complete diff from JRC and toss it TBH.
 

morrjr71

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When I checked the diff fluid level in my Kraton 6s after running it for a couple of months, I found a torn diff gasket from the factory. The gasket never leaked, and since I didn't have an extra gasket at the time, I reinstalled the original one. That torn gasket hasn't leaked in over a year, but I did buy a package of extra diff gaskets to have on hand in case there was a leak. The new gaskets are still in the unopened package.
 

Dan B.

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Hmmmm…. I ordered a pair of diffs from JRC to rebuild my NOTO a little while back. Disassembled them to check fluids and shim. One went back great, one was locked up. I moved on to something else without figuring out, but I’m going to check now to see if there is a gasket missing! It never occurred to me that’s what it might be. I don’t recall checking for the gasket. Mine are usually stuck to the housing and I don’t move them so the holes continue to line up. If that’s the case it would certainly explain it!
 

KnowAir

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Uh, found it!! @Rolannd was right, it was there, inside, shredded to bits and pulp by the gears. LOL Maybe it had been out of position during assemblu at the factory, not sure. My bad for being lazy and impatient and not checking from new. I'd say lesson learned but I'm NAS in that regard🤪
What I also discovered, and why the fluid was leaking out (besides the misplaced gasket) is the diff cup is broken. Seems to be where the steel sleeve that the bearing mates to is molded into the cup. Once I removed the crown gear and pin, the cup fell apart. I'm guessing the shims, pin and gears were the only things holding it together..
Kinda glad I didn't have any gaskets on hand as I would have just slapped one in and reassembled. 🙄
I have had quite a few 1/8 rc's over the years and have become accustomed to the gasket being nearly invisible and almost permanently bonded to the ring gear. Tends to happen after hundreds of heat cycles and time..enough so that I didn't even look for the gasket initially, LOL.
So now, I need gaskets and a cup at minimum. Funny, I'm the idiot who always says I don't need an LHS..😔🤔🤪
Might just order a complete diff from JRC at this point. Not sure.
Thanks for the help as always!! The best group of rc car/truck enthusiasts is all right here on AF!!😁😃😉🍻
Hmmmm…. I ordered a pair of diffs from JRC to rebuild my NOTO a little while back. Disassembled them to check fluids and shim. One went back great, one was locked up. I moved on to something else without figuring out, but I’m going to check now to see if there is a gasket missing! It never occurred to me that’s what it might be. I don’t recall checking for the gasket. Mine are usually stuck to the housing and I don’t move them so the holes continue to line up. If that’s the case it would certainly explain it!
Yup!! A couple months back I decided to service and delete the lsd plates in my mojo exb diffs.. I literally spent multiple sessions over a couple days trying to get them shimmed out..every time I tightened down the ring gear, it would lock up!? Holy $hit!! I'm an idiot!! I'll bet anything that the gasket in the rear diff is missing!!🤔😬🤬🤣🤣
 
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