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No, it's definitely too loose.Guys, does this look/sound good?
With the old 4S system it is quite easy to bend the motor mount, causing it to not be parallel however, this K4s V2.5 has a center differential and new power module, it’s quite different. The old slipper clutches move side to side a good bit, really no need to shim them up. I’m sure it doesn’t hurt. I ran my V2 slipper clutch like that with a 6s system without any problems other than smoking the clutch all the time. Which is why I went to the new power module. Now I’m having problems keeping the spur gear on the center diff.
Clean out & replace the fluid. Some of that is the grease, it broke down. I've had mine do that especially in the composite diff cases. The grease gets hot & wears out & turns black. Common.Is it time to replace the diff oil? This is how it looks after 2-3 months or so. Or it's fine to use as is for another few months?
That's right! (Although I don't usually clean loctite off screws, seems to have a better hold that way)@Glitch I've never done this process before, so bit scared to mess it up. But it looks like a good time to try it.
I believe those two big-headed bolts (that are used to adjust the mesh) must be thread locked. Looks like the process would be:
Will be doing it tomorrow. Need to buy two bearings that hold the diff. One of the old ones is almost non-functional.
- Take out those bolts, clean them
- Apply Loctite, partially screw them in
- Fully assemble the module
- Adjust the mesh through those special holes and tighten everything up
Sooo. I've:
Made a test, 2 battery packs. The car feels more responsive to the throttle trigger and accelerates a bit more "wildly", so to speak. I believe this is due to everything being tightened up in the center diff module.
- Installed new stainless steel grub screw to hold the pinion gear. Made sure it's sitting tight.
- Made sure the spur gear is held tight
- Adjusted the mesh to be tighter
Sadly, the strange sound did not disappear, so I'll have to dig deeper. The sound can be describe as a slight whine when I take my finger off the throttle and the car rolls passively. Also, when the throttle is somewhere around half pressed, a high-pitched whine appears. Something resembling Formula 1 from the 90's
The car itself feels fine to drive. Not sure what to make out of it. I guess I'll need to disassemble and look into front/rear diffs as well.
Could it be that the motor itself got damaged somehow?
Anyway. More wrenching and testing to do Gladly it's not a relic from the previous century and all the parts can be replaced. Oh, except those that are out of stock until Feb 31st 2026.
Great thoughts, thank you! I'll keep digging.The strange whining sounds could be from a bearing.. either elsewhere in your drivetrain (hopefully)
or back in your motor (that's would be a bit more challenging to replace)
Should be simple to isolate..
Just disconnect the Center driveshaft
and go drive your rig around like normal (in basically RWD mode) and see if it makes the noises.
If so , then you know to focus on the rear of the vehicle..
Ah, that little plate - what I do is shove a flathead screwdriver into the gap (the same place you put the zip-tie) and twist it a bunch while pulling it towards you. I can post a vid later if you like. This also works remarkably well for getting out the power module - just gently slide it into a crevice and give it a twist.Thank you guys! Will tighten all up and check the diff fluid.
Also, lifehack. The diff "holder/blocker" part did not want to move. Zip tie to the rescue! Super easy to pull that part out.
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