I'm trying to diagnose a metal splintering noise coming from my front driveline this weekend and I suspect it may be a shredded spline somewhere in the front diff. Since I've tried before to loosen the front diff input spindle nut with no success, I'm planning to run it up the road to a mechanic about 3/4 of a mile away to have them hit it with the airgun and then tighten it back to a more manageable torque before driving back home to disassemble everything. Will that be safe or do I risk shredding the spider gear/carrier? Alternatively I could pull the axle shafts and just bolt the wheels back onto the hubs so the spindle would never turn, but then there wouldn't be much resistance when loosening the bolt. Ideas?

 

don't just pull your axle shafts and drive it. you need to have at least the stub shafts tightened to your hubs to keep them from coming apart.

why not just tow it? find someone that has caa/aaa and use their card, or simply invest in your own membership. it's cheap and handy for all jeepers.

 

I've got towing coverage through my insurance but seems an unnecessary expense if there's no risk driving it back to the house. Just want to make sure that the pinion gear won't damage the spider if it's at, say, 80 ft-lbs torque rather than the 150-200 it must be at now.

 

What's the issue? You can't loosen the axle nuts?

 

Not the axle nuts, those I can manage. It is the nut on the back of the pinion that connects the front diff to the front driveshaft yolk.

 

Um, impact wrench?

That said, are you SURE it's in your diff? All u-joints check out?

I wouldn't start messing with the diff AT ALL, unless you are SURE it is the issue, and if it is, do you have the resources to fix it yourself? I'm guessing no, if you can't even get the pinion nut off the yoke...when it comes to differential work, you don't want to screw around with it if you don't know what you're doing. You can REALLY screw things up bad, and it will end up costing you a **** ton of money.

I highly suggest you VERIFY what it isn't first, then if it comes down to pointing to something internal to the diff, take it to someone who can do it right. Just trying to save you some time and headache here, man...

 

Fair point. No, I do not know for a fact it is the pinion, though I am fairly confident it is not u-joints as there are no other signs of a u-joint issue. I'll get the carrier out and inspect the splines on the gears that mate to the axle shafts, and if there's no damage there then I'd be inclined to think it is the yolk-pinion or the front ds output shaft at the t-case.

And do answer your other question, no, I also do not have all the tools to measure and set the run-out and backlash of a new pinion and gearset if I needed to. I was under the impression that I could put it all back together without any of the special tools if the pinion checks out fine. I'm guessing from your concern that this is not the case though. I appreciate the input.

 

While you are taking the axle shaft pay close attention to the u joints as metal sounds are typically u joints. A stock jeep will rarely break the ring and pinion.

 

Although this guy rants, he does know some stuff 😋 listen to him.

OP. Open the diff COVER first, drain and inspect by rotating and you can see if there are metal shavings. If there is an issue with grinding, they'll surely be shaving in the diff fluid if its bad enough

 

Bingo. INSPECT first. If you're talking about pulling the carrier out, you better be ready to put it back right...otherwise you're in for a lot of time and expense...

 

Thanks for the continued opinions. Just for some background, I only get this sound when in 4-Low starting from rest, so the highest torque possible on the driveline. I also have diff fluid leaking out the drivers side, which leads me to believe something inside sliced up the seals (though I know it could be general wear & tear too). I pulled both axle shafts a few weeks ago when I first noticed the noise and all those splines look good. U-joints are fairly new and I just rechecked with no signs of hang-up during rotation. Also, I've had the carrier out a few times before, namely when changing the inner axle oil seals, so I'm confident in my ability to remove it and I know how to set the bearing caps correctly. If it does end up being one of the carrier gears that is causing the issue, is it possible to replace just one of the cogs without replacing the entire carrier?

Thanks again.

 

Good and bad - after further inspection, I found nothing, but the noise remains. By nothing I mean that one of the eyes of the axle inner half-shaft had stretched and the U-joint was in there really loose, but after replacement of the joint and half-shaft I still had the noise. Axle and carrier splines were all in great shape. Diff oil had lots of glitter, a few flakes, but no shards. I'm guessing the oil leak was caused by the wobble in the axle from the loose connection at the u-joint.

So what does that leave me? All the bushings at the sway bar are in good shape and clean. Something with my control arms? Motor mounts?

 

Take your front drive shaft off, drive around the block with it off. If the noise isnt there, you have a bad u joint on the shaft. If it is, you have a more in depth problem

 

Before I took the diff apart, I rocked the jeep back and forth in 4-Low with the front shaft out and no noise. I played with all three U-joints for a while on the shaft, and though I didn't inspect under the bearing caps everything rotated smoothly. I know it's still possible a DS U-joint is the problem, but seems unlikely with that information.