Intermittent gear grind from front axle

Sorry boys, but I have a lot of questions to ask and maybe some info to share about my YJ. So this thing has a vacuum actuated locker which I think might be the culprit. When I take off slow and drive like a turtle I never hear this sound, but if I try and keep up with the other rats in the rat race I hear a slight grinding noise like the noise you would hear trying to put a manual in reverse while going forward and it lasts for about a second. This is when i am in 2wd, when im am on the dirt in 4wd i never hear it. I feel like maybe the diaphragm is not holding vacuum to keep the slide in place or letting the front axle attempt to lock while i am moving. Any help would be much appreciated. Thank you

machoheadgames said:

It’s not a locker, it’s an axle shaft coupler. All it does is free up energy spent on turning the front axle by allowing the front driveshaft to sit still.

It uses vacuum in one direction to disengage the motor in 2WD and then in 4WD it reverses the vacuum to engage the fork and coupler. You might have a cracked vacuum line or something else handicapping the system’s ability to stay engaged.

Also very likely is the cheap junky aluminum fork in the CAD has wallowed out and no longer holds the coupler firmly, possibly causing the grinding you’re experiencing (from the coupler moving around) . A heavy duty cast iron fork from the aftermarket world is a much better option.

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Thank you for the info, I will check those hoses for a leak. Thank you for your time.