[nbeddoes13]

Hey all, I've got a 1997 TJ SE. its got the stock Aisin AX-5 manual tranny in it. A loud knock has developed in it, and it only happens in reverse. It is quite loud. The knocking stays on a consistent rhythm, and speeds up as i go faster, so im pretty sure that it is something broken on a rotational part, rather than a loose piece of metal floating around.

I had a friend tell me that it might be a broken spline on my reverse shaft, or something along those lines.

I was just looking for some input and opinions, on what else it could possibly be, or to see if anyone else has had the same problem.

Thanks for the support,
Nick

P.S. oh and i also have narrowed in down to bieng something inside my transmission, rather than something like a U-Joint. I had the vehicle up on jack stands and had a friend run it in reverse while i listened, and the sound was definitly coming from the transmission.

[nbeddoes13]

*bump*

[HandsOn]

Not sure what it might be in the transmission, but I was going to suggest looking at your u-joints and pinion angle and such anyway.
A vibrating shaft is not likely to transmit noise through a chain drive t-case like you have, but I've seen/heard quite an odd assortment of noises in NV3550's attached to gear-drive transfer cases, so thought I'd throw that out there.
And to bump it back to the top again.

On a side note, have you ever changed the lubricant in the tranny? Don't know what the recommended interval is, but manual transmissions do tend to get overlooked sometimes.
When I did that once, I lost the rear output bearing and it made some pretty interesting noises! But then it would go completely quiet again, so not near as consistent a sound as yours sounds to be.

Good luck with the diagnosis. Hope the fix is inexpensive.

Paul

[nbeddoes13]

Originally Posted by HandsOn

Not sure what it might be in the transmission, but I was going to suggest looking at your u-joints and pinion angle and such anyway.
A vibrating shaft is not likely to transmit noise through a chain drive t-case like you have, but I've seen/heard quite an odd assortment of noises in NV3550's attached to gear-drive transfer cases, so thought I'd throw that out there.
And to bump it back to the top again.

On a side note, have you ever changed the lubricant in the tranny? Don't know what the recommended interval is, but manual transmissions do tend to get overlooked sometimes.
When I did that once, I lost the rear output bearing and it made some pretty interesting noises! But then it would go completely quiet again, so not near as consistent a sound as yours sounds to be.

Good luck with the diagnosis. Hope the fix is inexpensive.

Paul

Hey, thank you for your input, i was begininning to think i wasent gonna get any answers

So i am positive that the root of the problem is in the internals of the transmission. i had the jeep on a vehicle lift in our shop recently and had my step dad accelerate it while i listened underneath, and the tranny was definitly the source of the knock.

I also replaced the tranny, Tcase, and differential fluids, when i replaced my clutch last month.

thanks for giving some input though!

nick

[nbeddoes13]

*bump*

[HandsOn]

Hope you get it figured out without too much distress (to the wallet!) or too much down-time. Wish I knew what could make a knocking sound inside the AX-5.
Could be an output bearing maybe? How many miles on the rig? Did it start all of a sudden at full volume? Or do you remember it coming on kind of slow and quiet at first, getting louder as you put more miles on it?

The noise I was talking about was definitely the transmission making the noise too. It just wasn't the transmissions fault.
The "symptom" was inside the transmission. And three Jeep/tranny experts concurred. However, the "fault" was with the driveshaft and pinion angles causing a vibration that fed back into the transmission and sounded like the countershaft/idler was going to fall out. Made a ton of nasty noises similar to a broken internal component.
Re-aligned the pinion and the noise in the transmission completely went away.

In that case though, it was more of a heavy rattling, rather than a knocking.

Good luck.

Paul

[nbeddoes13]

Originally Posted by HandsOn

Hope you get it figured out without too much distress (to the wallet!) or too much down-time. Wish I knew what could make a knocking sound inside the AX-5.
Could be an output bearing maybe? How many miles on the rig? Did it start all of a sudden at full volume? Or do you remember it coming on kind of slow and quiet at first, getting louder as you put more miles on it?

The noise I was talking about was definitely the transmission making the noise too. It just wasn't the transmissions fault.
The "symptom" was inside the transmission. And three Jeep/tranny experts concurred. However, the "fault" was with the driveshaft and pinion angles causing a vibration that fed back into the transmission and sounded like the countershaft/idler was going to fall out. Made a ton of nasty noises similar to a broken internal component.
Re-aligned the pinion and the noise in the transmission completely went away.

In that case though, it was more of a heavy rattling, rather than a knocking.

Good luck.

Paul

oh ok. thank you for the clarification. that makes more sense now. ill have to look into that. and it has been this way since i got the jeep a couple of months ago.

[nbeddoes13]

*bump*

[nbeddoes13]

i figured it out. i took the transfer case and tail end of the transmission off of it, and found a broken tooth on the reverse gear.

thanks for the help and opinions.

nick