Drive train rumble - Ideas welcome (1 Viewer)

[Freeborn]

Ok, time for the Saturday futsing-in-the-garage update…

Part 1: Stethoscope
I tossed the driveshaft back on and put the rear axle on jack stands. I started her up, put her in 3rd gear and let the clutch out. I slid underneath with a screwdriver and listened to the transmission, transfer case, and rear diff. Nothing sounded terrible at all. In fact the diff was almost silent.

Part 2: GoPro
I took it off the jack stands and tossed a camera underneath looking at the driveshaft and rear diff. I think I see the smoking gun. I’d be very curious to see if others share the same opinion…

 

[Mr. Green]

With axle torquing I could hear something but unsure if that was it? Still thinking it’s input/output angles but let us know what you try next. Shims or maybe confirming retorquing u bolts.

 

[Freeborn]

With axle torquing I could hear something but unsure if that was it? Still thinking it’s input/output angles but let us know what you try next. Shims or maybe confirming retorquing u bolts.

You might have heard something, but that’s a lot of wind noise. I was mostly looking at how much the axle rocks back when my foot is on the gas.

I’ll take a look at re-torquing the u-bolts as an easy first step. Although if they’re loose, they’ve been loose for years. I’ll likely try some small shims also.

 

[pb4ugo]

The movement I see looks minimal. The pinion is going to move on acceleration, de-acceleration that's what leaf springs do. You can add links to help stop the pinion from rotating. I hear periodic metal to metal contact in the beginning of the video when you 1st start moving, like a brake shoe coming in contact with the drum. It could be at the parking brake or rear brake. Did the t/case flange have any movement, up down, in and out? Same with the pinion?

 

[Blue77FJ40]

Does that shock absorber look excessively compressed to anyone else? May be a contributor…

 

[Freeborn]

The movement I see looks minimal. The pinion is going to move on acceleration, de-acceleration that's what leaf springs do. You can add links to help stop the pinion from rotating. I hear periodic metal to metal contact in the beginning of the video when you 1st start moving, like a brake shoe coming in contact with the drum. It could be at the parking brake or rear brake. Did the t/case flange have any movement, up down, in and out? Same with the pinion?

No play on the output shaft or pinion.

 

[Freeborn]

OP Update:

Got 2* shims. Was looking forward to a relatively quick installation to see if they make a difference. Once I had everything off of the leaf springs it was apparent that their bushings were toast - like bad - like seemed unsafe.

So now we wait for the new bushings to arrive along with a 9/16”-18 die to chase the threads on the u-bolts. More to come…

 

[Freeborn]

Update:
Bushings: installed
Shims: installed
Vibration: same as always

I’m thinking the problem is in the transmission. Anyone live in Denver and want to go for a ride to see what you think?