M5od-R2 Grinding in 4th and neutral

[kstank01]

Hi everyone, a couple years ago, I did a 302/M5od-R2 swap into my 1983 Ranger. The engine/trans/transfercase were all rebuilt before being installed. Recently it started making a grinding/rattle sound while in 4th gear with little to no engine load (goes away when I give it gas), and the same noise while coasting in neutral above 35 mph, as well as a really bad, vehicle bouncing, vibration below 35 mph. Also hard to get into 1st and reverse when hot.

I pulled the trans and did a rebuild (all new bearings, syncros, shift forks, 5th/reverse slider, pretty much everything but the gears and shafts). Found a bad 4th and 5th gear bearing, and a bad 1st and 2nd gear shift fork. Put it back yesterday and did a test drive today. Shifts great, no more vibration, but still has the same noise. I'm not sure where to go now.

Just wondering if anyone had any ideas of what could cause a grinding/rattle sound coasting in neutral above 35 mph or in 4th gear under little to no load?

Have been using the Royal Purple Syncromax.

 

[85_Ranger4x4]

Gears looked ok though? It is about all that is left.

 

[kstank01]

Yes. Gears were all good. I'm thinking at looking more at something in the linkage. Possibly play in the shift fork rails.

 

[85_Ranger4x4]

Were they pretty loose? I would think they would still detent to the correct location.

 

[kstank01]

No. They weren't lose at all. They looked almost brand new. I'm going t pull it back out this weekend and take a look.

 

[85_Ranger4x4]

If it is 4wd you might check the t-case when you have it out too. Might be a resonance thing with a loose chain or bearing in that.

 

[kstank01]

Good point. Will definitely look at that.