Kagama Occasional screeching noise

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These are the first of my images taken on my brand new Google Pixel 10 Pro XL.

Blinkin' o-rings. FFS.

The joy of transferring everything over 🙄

And why is this damn thing so slippery - it's literally like hanging onto a bar of soap. A very expensive bar of soap at that! 😅

Hope this case arrives soon - I don't trust myself not to break it. 🤞🙏
 
Add some m6x12x0.1mm shims here

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So, after some inspection and changes I took it out for a spin other day. I changed out the center diff fluid with 250K. No Screeching as of now. However I wasnt as trigger happy as other runs but for now seems to have helped. Still need to check front and rear diffs for proper levels. Have considered change the weight just not sure what direction to go with that
 
Wait, silicone seals with silicone oil?! That's not good silicone oil invades and gradually destroys silicone rubber seals. You want buna-N with silicone oil not silicone rubber.
 
Atomic Skull said:
Wait, silicone seals with silicone oil?! That's not good silicone oil invades and gradually destroys silicone rubber seals. You want buna-N with silicone oil not silicone rubber.
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C-00180-182 - O-Ring - Silicone

Are the o-rings are specifically designed for the use in the silicone filled diffs.

I'm not sure if the description of them details their material specification, or whether (more likely) it outlines their intended use.

If they are actually made out of standard silicone, that would explain why our diffs need regular O-ring replacement!

Safe O-ring Materials for Silicone Oils
  • Viton® (FKM): Offers excellent resistance to mineral oils, fuels, and various silicone fluids.
  • EPDM: Known for its resistance to silicone oils, water, and other chemicals.
  • Nitrile (NBR): Provides good resistance to silicone fluids, mineral oils, and hydraulic fluids.
  • Fluorosilicone (FVMQ): A variation of silicone with improved resistance to mineral oil products, making it a good choice for a wider range of applications.
Materials to Avoid (Generally)
  • Standard Silicone (VMQ): While it's the best choice for some silicone-based applications, especially for low-temperature use or in the food and medical industries, standard silicone rubber can degrade when exposed to petroleum-based lubricants or oils.
 
I think the reason why RC companies select silicone o-rings is because they're the smoothest, lowest friction option - especially for shocks.

If o-rings are installed with green slime, it helps preserve the silicone.

Diffs are constantly being whipped in and out for oil changes/tuning on race rigs, so I guess nobody questions the longevity of the seals. 😅
 
Horatio said:
I think the reason why RC companies select silicone o-rings is because they're the smoothest, lowest friction option - especially for shocks.

If o-rings are installed with green slime, it helps preserve the silicone.

Diffs are constantly being whipped in and out for oil changes/tuning on race rigs, so I guess nobody questions the longevity of the seals. 😅
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Viton is a fluoropolymer and should be lower friction than silicone.
 
Atomic Skull said:
Viton is a fluoropolymer and should be lower friction than silicone.
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Ultimately, I suppose this boils down to availability and ease of obtaining the right sized o-rings. With a part number, end users are able to order the right size part, without ever really knowing dimensions or material considerations.

Modern shock packages are great - rarely leak unless dirt gets in or a shock shaft gets bent.

The Corally diffs are the only ones I've had leak through the output bearings, past the Orange o-rings. With the centre diff, it was evident the O-ring had torn slightly, which is indicative of debris or a burr having damaged the seal.

Now I have 10 of these - I can find out if the o-rings inherently leak due to chemical leaching, or if (as I suspect) - they'll be perfectly suitable for the job at hand.

Bearing in mind the XTR is 4 years old, to be honest I don't think any of the o-rings owe anyone anything. 😅
 
My Kagama and Spark both have 1 swollen and 1 worn diff o ring depending on which side we are talking about. I'll be moving over to buna N because they are cheaper and easier to find. Both cars threw the stock diff fluid all over the inside of the car after a handful of runs and before I did a diff service.
 
danl said:
My Kagama and Spark both have 1 swollen and 1 worn diff o ring depending on which side we are talking about. I'll be moving over to buna N because they are cheaper and easier to find. Both cars threw the stock diff fluid all over the inside of the car after a handful of runs and before I did a diff service.
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Look forward to hear results after a little time. Just opened my front and rear diffs and orings seemed fine for now, albeit both diffs were low on fluid from factory. Only appox 13 packs thru it. The center diff orings totally smoked and replaced already with oem's
 
Went for a first run yesterday after filling the front and rear diffs up and already had a run on the center diff with 250k and had no screeching, albeit wasnt being a knucklehead with the throttle on pinned. However I did have an event where the remote cut out. everything was on but no worky. Turned off and back on and all good. I guess I have the transmitter issue others have mentioned. Also managed to bend a rear dogbone. Small jumps and pretty mild driving go figure. Droop is set as well.

I may go back to 100k or maybe 150k ish in center diff, not liking how it is handling entirely. takes bumps and rough terrain great though
 
I tried replacing the silicone o-rings in the rear shocks on my Asuga with 4x8 75 durometer viton o-rings on the theory that they'll last longer and I found that they also increased the shock rebound somewhat probably due to the tighter fitment (one of the shocks had blown a seal so they needed to be rebuilt anyway)
 
Atomic Skull said:
I tried replacing the silicone o-rings in the rear shocks on my Asuga with 4x8 75 durometer viton o-rings on the theory that they'll last longer and I found that they also increased the shock rebound somewhat probably due to the tighter fitment (one of the shocks had blown a seal so they needed to be rebuilt anyway)
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The increased rebound is air in your shock. This will go away once the shock is bled correctly. 👍
 
Horatio said:
The increased rebound is air in your shock. This will go away once the shock is bled correctly. 👍
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I replaced the oil and bled it as per the manual. I think I'm using the wrong term, what I mean is that the time it takes the shock to fully extend after being compressed has increased (not by a huge amount but noticeably) probbaly due to the tighter viton O-rings increasing the resistance to the shaft moving.

EDIT so I just measured and Corally lied about the size of their shock seal o-rings they are 4x7mm not 4x8, no wonder the viton ones were so tight. The seat for the o-rings is also 7mm ID so I think maybe a slightly smaller o-ring is in order instead of a 4x8mm one.
 
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Atomic Skull said:
I replaced the oil and bled it as per the manual. I think I'm using the wrong term, what I mean is that the time it takes the shock to fully extend after being compressed has increased (not by a huge amount but noticeably) probbaly due to the tighter viton O-rings increasing the resistance to the shaft moving.

EDIT so I just measured and Corally lied about the size of their shock seal o-rings they are 4x7mm not 4x8, no wonder the viton ones were so tight. The seat for the o-rings is also 7mm ID so I think maybe a slightly smaller o-ring is in order instead of a 4x8mm one.
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What is it with Corally and their part numbers, and/or dimensions - always being wrong? 🤭

Personally, I set my shocks for little to zero rebound.

Wait for the bubbles to rise up out of the oil. It helps when shock caps have bleed screws, but when they don't, the cap can be loosened as the shaft is pressed up into the shock body and then tightened back up before releasing the shaft. It's one of those jobs where it feels like you could use a third hand!

Getting each pair of shocks the same is more important than zero rebound IMO.

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According to AI, slightly pull the shaft up before tightening the cap to create a slight vacuum that compensates for compression. This ensures zero rebound.

As for o-rings, obviously, unless they are exactly the right size, stiction will alter the feel of the shocks and essentially change the damping.

My understanding is that silicone o-rings are known to be the lowest friction option. Use of green slime helps ensure longevity and reduce leakage.

My Baja's IRC shocks have umbrella seals, which are known to be extremely tough and leak proof, but they're not as smooth.
 
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