‘94 manual clattering in 3rd gear only

[Yondering]

I could use some thoughts from you experienced Ranger guys.

94 4x4, 4.0, manual 5 speed (I think that would be the M5OD?) This one is a Mazda B4000 if that makes a difference.

All gears drive smoothly except 3rd - it makes a rattling/clattering sound through the shifter, pretty loudly, when under power only. Can’t feel it in the drivetrain, but can feel the shifter vibrating with that sound. Doesn’t do it when I let off the gas, or in any other gear or neutral. It’s a rhythmic noise that’s definitely connected to engine rpm or vehicle speed.

It almost sounds like if the tip of a shift fork was rubbing on a gear tooth or something. Also, it starts to do it if I try to press the shifter into 3rd from a stop without using the clutch (tried that as just another test of what it’s doing).

Any thoughts on what the issue might be? I haven’t even been underneath it yet to check it out; do these have a removable side panel on the transmission to access the internals? Or do they need to be pulled from the motor?

 

[Shran]

While it's making the noise, pull your transfer case shifter slightly to the left (assuming manual t-case.)

The shifter itself rattles on several of my trucks. Could be a lot of other things too.

 

[Yondering]

While it's making the noise, pull your transfer case shifter slightly to the left (assuming manual t-case.)

The shifter itself rattles on several of my trucks. Could be a lot of other things too.

Unfortunately it’s the electric t-case with the push buttons on the dashboard, not a manual transfer case shifter.

 

[Shran]

Hmm. I guess I'd be tempted to pull the trans and inspect it. Maybe someone else will have a better idea before you go to that extreme but since you've ruled it down to one gear in very specific situations, in my mind, that narrows it down quite a bit. I just mentioned the shifter because mine rattles like that only under a load in certain gears but I imagine it's a harmonics thing, not your problem though.

There is a bearing inside 3rd gear itself - part 15 is the bearing, 16 is 3rd gear. It also could be related to part 13/14 assembly too if the springs & keys are missing or damaged. Since you can feel it through the shifter it would make sense in my mind. I guess it could be something broken or loose inside the top cover (shift rail, fork, etc) but that seems less likely.

FYI, there is no inspection port on a M5OD, they are assembled through the top.

 

[Yondering]

Hmm. I guess I'd be tempted to pull the trans and inspect it. Maybe someone else will have a better idea before you go to that extreme but since you've ruled it down to one gear in very specific situations, in my mind, that narrows it down quite a bit. I just mentioned the shifter because mine rattles like that only under a load in certain gears but I imagine it's a harmonics thing, not your problem though.

There is a bearing inside 3rd gear itself - part 15 is the bearing, 16 is 3rd gear. It also could be related to part 13/14 assembly too if the springs & keys are missing or damaged. Since you can feel it through the shifter it would make sense in my mind. I guess it could be something broken or loose inside the top cover (shift rail, fork, etc) but that seems less likely.

FYI, there is no inspection port on a M5OD, they are assembled through the top.

View attachment 91914

Yeah, that was my assumption too; we'll have to tear into it to find out what's up. I was just hoping maybe someone else had heard of the same issue.

Thanks for the diagram, that helps too.

My first thought was a broken tooth on one of the 3rd gear wheels, but for the noise it's making, I think that'd be felt through the driveline too, and it's not. And not the key on the shaft, since it pulls fine in 3rd other than the noise, no slipping. It's definitely something related to the gear, being a regular and loud clack-clack-clack that matches speed. My assumption is that it's whatever the shift fork is contacting when in 3rd; maybe a bad bearing or maybe something on the gear or synchro hitting the shift fork every revolution.