Asuga Leaky Diffs

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ridgehead44

ridgehead44

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Good morning, all!

Do the Asuga/Kagama models have a known issue with leaky diffs? I went to change my center diff fluid the other day and the differential was bone dry. 🦴
I filled it with 500K, which should be a bit viscous to easily leak. But I do have thinner fluids in the front/rear. I'll check them this week.
Has anyone else experienced leakage? If so, do the all-metal upgrades generally solve this issue? Thanks in advance!
 
Yes, my center diffs also leak(ed). It does help to sand/polish the red aluminium under the gasket until it’s grey. I also run two gaskets. It seems to help. Sometimes the oil leaks through a screw hole if the screws slowly loosen themselves (locktite).
The plastic front/rear diff cases don’t seem to have leakage problem the center diff has.
 
I place extra shims behind pin, removes play from drive cup, oring seals better & internal gear mesh set better. Need to replace gaskets too from time to time they don’t last forever

IMG_8812.webp
 
Had these in the Kagama 6s for ages now and not a drip of fluid has come out of the rear diff and the rear was always leaking with the naff plastic housing.
Even changed out the centre diff case as well to the xtreme version 🤙 even less leaking but still leaks but wayyyyy less enough that I don't worry about what leaks as it minimal leakage from the outdrive cups :)

Seems Corally put two gaskets on the rear and front diffs from looking at the online kagama 6s manual.

https://corally.com/en/product/C-00...-anodised-black-front-rear-made-in-italy-1-pc

https://corally.com/en/product/C-00...hard-anodised-black-center-made-in-italy-1-pc
👆
The xtreme 🤙 centre diff needs shorter pins to work but on the link it tells you what is needed.

I run 30k Front, 20K rear, 500k centre.


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I was building my Asuga last night & noticed the front diff had 2 gaskets not something I’d seen before on corally myself. But with double gaskets you’re actually affecting how mesh is set on the gears also so not sure I’m a fan of it.
 
I was wondering that with the two gaskets might effect mesh plus not had any problems with rear or front leaking from the ring gear gasket, only leaks on rear diff case from the little steel sleeve side on the plastic case.

Same happened on the syncro 4 rear diff would leak all the time then jammed a bigger o ring in the bugger and that stopped it 😃 . Lasted well over a year then noticed around January this year the rear was leaking really bad, took it out new o rings etc fitted refilled then left it on the shelf few days later the thing is pissing diff oil out. Its the same thing that happened on the Kagama 6s I think the steel sleeve got warped and wont seal correctly anymore.

Got a new metal diff case for the syncro 4 going try the adu ones this time, as cannot stand working on diffs so going full metal like the Kagama less time me getting diff oil everywhere 🤣.
 
Nelson.81 said:
I was building my Asuga last night & noticed the front diff had 2 gaskets not something I’d seen before on corally myself. But with double gaskets you’re actually affecting how mesh is set on the gears also so not sure I’m a fan of it.
Click to expand...
I find the the diff cups have too much play, but if I put an additional shim under the sun gear the mesh it too tight. An additional gasket fixes that, so combined they fix both issues.😎
 
Sandracer_NL said:
I find the the diff cups have too much play, but if I put an additional shim under the sun gear the mesh it too tight. An additional gasket fixes that, so combined they fix both issues.😎
Click to expand...
Ohhh 😃 going try that when I rebuild the syncro 4 diffs.
 
Sandracer_NL said:
I find the the diff cups have too much play, but if I put an additional shim under the sun gear the mesh it too tight. An additional gasket fixes that, so combined they fix both issues.😎
Click to expand...
How thick are your shims I can usually get 2x 0.1mm without issues with the mesh with a corally diff. But with the Erik van Ravenstein diff cases if I add 1 shim my mesh is to tight so his diffs are set to finer tolerances. I wrote a post about itbefore on fb he commented how he sets them that way.
 
Nelson.81 said:
How thick are your shims I can usually get 2x 0.1mm without issues with the mesh with a corally diff. But with the Erik van Ravenstein diff cases if I add 1 shim my mesh is to tight so his diffs are set to finer tolerances. I wrote a post about itbefore on fb he commented how he sets them that way.
Click to expand...
I think I usually have 0.2mm or 0.3mm of shims on both sides of the diff. I believe stock is a 0.1mm shim on both sides.
 
ADU Racing has gaskets for differentials, I'm going to buy them and test them, and I'll also check and add shims if it is necessary.

I actually run 40k front, 20K rear, 500k centre.
 
I was thinking, but didn't ask at first..

Where are peoples diffs leaking from.?

Gaskets leaking, tighten bolts in cover (maybe replace gasket)

Drivecup leaking, use AE green slime or equivalent when building the diff..!!

I have never had to put extra shims in a Corally diff from my memory and I have 4 rigs, that's 12 diffs..!!
The diffs and drivetrain are the best part of Corallly's (they put Arrma to shame.!!)
 
I solved a leaky drive cup by replacing the stock silicone o-rings with slightly thicker slightly smaller diameter viton (FKM fluoroelastomer) one. The toughness and low friction of the viton offset the tighter fitment so the friction didn't change much change it just makes a better seal.

Also the Corally manuals actually lie about the sizes of basically all of the o-rings, you have to experiment a bit to find the real sizes. The listed sizes are close but less than the actual size needed.

DO NOT expose viton / FKM o-rings to acetone they will immediately swell up and they will turn hard once the acetone they have soaked up evaporates. They are tougher and lower friction than silicone and buna-n o-rings but acetone is their Achilles heel.
 
Atomic Skull said:
I solved a leaky drive cup by replacing the stock silicone o-rings with slightly thicker slightly smaller diameter viton (FKM fluoroelastomer) one. The toughness and low friction of the viton offset the tighter fitment so the friction didn't change much change it just makes a better seal.

Also the Corally manuals actually lie about the sizes of basically all of the o-rings, you have to experiment a bit to find the real sizes. The listed sizes are close but less than the actual size needed.

DO NOT expose viton / FKM o-rings to acetone they will immediately swell up and they will turn hard once the acetone they have soaked up evaporates. They are tougher and lower friction than silicone and buna-n o-rings but acetone is their Achilles heel.
Click to expand...
Can you share link to the o-rings and specify the size?

Thanks!
 
22044.webp

Fitted a fresh one of these in my centre diff and the leak I had went away. The original one had a tear.

Assembled with my EVR diff parts and Corally internals - it's bullet proof. And smooth.

The offending O-ring is here: note the tear.

111.webp


Fresh oring inside the EVR diff = zero leaks.

98.webp


Corally o-rings work perfectly well, provided they're not physically damaged. The one I took out had been in that diff for 5 years. Not a bad innings. 🤣

It doesn't owe anyone anything.

Common issue is oil getting into screw holes. When that happens, loctite doesn't work and screws back out. So in that case, oil spews out all around the screw holes and where the spur fits to the case.

If oil is seeping out from the diff outputs near the bearings - it's the o-rings.
 
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