AX-15/Tcase Noise (Update)

[Slim]

Video here:

‘97 - 4.0 and AX-15 - 231 with a SS SYE

The tcase I know to be in good shape. Shifts clean and ran through every drive.

AX 15 is old…200k miles, and no known service history. No metal in fluid.

Noise happens primarily when I’m off the accelerator, but not exclusively. I could be mid-rpm’s down the freeway and I’ll get the noise out of the blue.

Also, shifting into/out of reverse is quiet, but engaging gear is noisy. Similar to the noise in the video.

At a loss…am tempted to just say screw it and buy a new AA AX-15 and a use it as an excuse for a new tcase.

 

[CharlesHS]

Hard to hear much in the audio other than exhaust (muffler) noise while driving.
The noise sounds like the beginning stages of a throwout bearing going bad.

 

[Slim]

Thanks — the noise is right at about 3 seconds, if that changes anything...the muffler is quiet then.

I don't think it can be a throwout bearing — my foot isn't on the clutch here.

 

[Slim]

Thinking out loud here for a sanity check, and for future people searching — I've noticed that I could be going down the road just fine, and if I hit a bump. that can make it start the grinding.

So I've got grinding mostly in these scenarios, all of which change geometry or slack in the system:

1. Initial take off in 1st
2. Coasting in any gear and letting off
3. Hitting bumps

So could it be something as simple as the front yoke being set too far "out" of the tcase (either it backed off, or wasn't installed on all the way, which I definitely could have done in a hurry). That would make sense, as it sounds like gears skipping to engage. So the spinning front shaft is manipulating the yoke under load/slack change, which misaligns the output gear and chain, which causes the noise.

I can't get out there to check it tonight, but that's the prevailing thought for now.

 

[macleanflood]

My vote is on the TOB and with your mileage and no service history you probably need a clutch anyways.

I put a Luk kit on my 97. Reasonably priced on Amazon.

-Mac

 

[Slim]

Updating here, and still looking for some help. Hoping to find a solution here and then post up because there are a hell of a lot of threads all over the web about similar issues.

Brand new AX-15 from @NovakConversions went in last week (awesome shipping and product, just first-rate). With that, a whole clutch job (Luk kit).

I still have the same noise. I notice it worst when starting (under power) in reverse and first (which makes sense as no synchros for the AX15), but it also occurs in any gear while coasting.

Grasping at straws here:

• The slave cylinder is likely 250k old. I don't have issues with the clutch pedal...nothing sounds crunchy or grinding in the cylinder itself.
  • HOWEVER, given its age and the fact that the piston was semi-caked in old oil/gunk (I cleaned it), I'm wondering if maybe the valve is shot, and it can't maintain the position of the clutch fork. That could allow the fork to slop enough to move the TOB into a position where it would grind.
    • This would make sense, as road bumps tend to bring up the issue. Bump allows the fork to move because of a lack of sufficient pressure from the slave, and we have the noise.
• As I type, I realize I haven't pulled the rear drive shaft to make sure that the rear diff and tcase are 100% not the issue, but i seriously doubt it here since those are both fresh rebuilds.
  • I further doubt these are the issue, because the grinding stops the second I actuate the clutch. Correct me if I'm wrong, but the clutch in wouldn't reduce the load on the diff or tcase provided by the engine. They'd still be under load from the road/speed.

Welcome any thoughts.