Rattle grinding noise when driving


Jan 29, 2022

So I’ve got something that has progressively gotten worse over the course of the past few weeks and it’s the rattle grinding noise coming from the engine/trans area. The noise is never present at idle but only when in any of the five gears and I’m cruising but on the gas still. Transfer case is new and the engine doesn’t seem to have any issues. Transmission just got new redline Gl5 fluid. Clutch and related throw out and pilot bearing are brand new. Any thoughts? Or a direction I can go in?
First , I’d stop driving it - inspect the drive shafts/u joints (grease loss or reddish powder are clues) but remember a drive shaft can appear ok but be ready to grenade

then put it on jack stands and run it slow -

If none of that reveals anything remove the front shaft entirely and drive it easy and see what happens -

Keep us posted
This is the front driveshaft ujoint. I can’t believe you were right. I had replaced those not too long ago
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I mean regardless if it’s the noise or not that shouldn’t sound like that. Hopefully that fixes it
It likely will- that joint has likely ground up/ lost needle bearings since installed or one fell out at install- the spicer X series really go the distance. My guess is one dropped out when built- that joint is pretty fresh.

I’d pull the shaft if I had to drive it- a front shaft failure can grenade the transfer case and practically total a TJ. Sounds dramatic and boy it is if it happens- especially at the cardan joint.
Thank you for your advice I would have never thought to check the drive shafts since they had new U-Joints. I’ll make sure to put a response soon if it fixes it!
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The front shaft is usually a good suspect for vibes and noises - I start there if I’m chasing one usually -

I’d likely at least unhook it at the front pinion and zip tie it up- just don’t put it in 4wd of you do.

Greasing it might quieten it down short term but that joint is shot.
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Alright. An update in a bit embarrassed to put but maybe it’ll help someone else in the future. Apparently the clamps holding the u-joint to the yoke were loose.. very loose… on the front and rear. Going to go test drive to see if all noises are gone
So just test drove and the original noise is still present. Anyone have any other ideas on what it could possibly be? Maybe it’s normal AX-15 noises but that kind of rattling just sounds wrong to me
I didn't hear anything on the video... Does the noise go away when you press the clutch? I replaced my clutch a few years ago, and the throwout bearing that came in the kit only lasted a few startups, and then the jeep would sound like a diesel with all the rattling it was doing...
I can’t push in the clutch when accelerating. If it’s in neutral it doesn’t do it and it doesn’t happen at idle. I had my throw out bearing blow up on me in a parking lot last year. Everything in there is pretty new. It is only in gear and holding on the gas slightly when accelerating. Otherwise it doesn’t happen but it’s much louder than the video where I can’t solve it with a volume knob without blowing my speakers out. Just worried the transmission might be on its way out. I’m only at 140k and it shifts great. Just put Redline MT-90 in it recently too
There's a few of us here in the area. It's hard to diagnose sounds over the interwebz. If you don't get it figured out on your own soon, you can swing by one of our semi-frequent Jeeps and drinks meet ups to hear first hand. Usually around Gainesville/Warrenton'ish.
I’d love to come to those! It’s just annoying to have this going on. I figure that maybe I’ll put some fluid additive in the transmission and see if it fixes it.
Alright so just to put what I did to fix the issue.. I ended putting the jeep through 4WH and 4WL a few times and then back into 2WH. Still took the driveshaft off to lubricate everything but the noise is gone now! I’m guessing it wasn’t fully out of 4WD or something like that.
You have the original linkage? Might want to invest in a cable shifter. Most swear by Saavy...I have a Stienjager. Makes adjustments invinite and disconnects as simple as a pin removal.

Nice job!