noise in drivetrain on decel.

[howlinwolf]

78 k10 350, 3sp tranny with low, and I'm unsure of the transfer case, but from the dash to seat, the selections are 4lo, neutral, 2hi 4hi.

Now, what happens is on the deceleration, or engine braking, there is a loud whining sound that changes with speed. I don't seem to hear it in 1st. Jacky tried low. Also it does it in 4hi, havnt tried 4lo.

It's a little quieter when the transmission is in neutral, but still present. Any ideas?

[Irish_Alley]

transfer case is 205. the 3 speed has L,1,2,3 and R? sm465 if it does, its geared pretty low(well doesnt go above 1:1 which is great for work). do you have auto hubs or manual? disconnect  the front shaft and see if you still hear that noise. when you start hearing the noise? so i take it it doesnt do it in 2wd?

[howlinwolf]

It does it in 2wd . And yes, thats my trans

[Irish_Alley]

has it always done this or this is something new?

[howlinwolf]

Pretty new, over thé last week or so. I have been moving across town

[Irish_Alley]

feels like we are playing a game lol. does it make this noise when you decel but are pressing in the clutch"

[howlinwolf]

Sorry. Been busy. It is quieter with clutch in. But still present. Removed front driveshaft. No change

[Irish_Alley]

manual hubs? where they disingaged? now put the front back in and take the rear off all we are doing is eliminating axles if you take the rear off and it still does it this would point to the trans thinking throw out bearing imo

[howlinwolf]

Yes, manual hubs. And I checked and rechecked. They are disengaged. I give up if it's another rear end.

I put the transfer case in neutral and rolled down a big hill, and there was no noise. Does that matter

[Irish_Alley]

was the clutch depressed when you went down hill? but what im thinking is it is the pinion bearing. since there was no pressure holding it back there was no noise but with pressure (having to turn the transmission) there will be noise. disconnect the rear shaft leave the transfer case in 4 hi and try it see what happens

[howlinwolf]

Pulled the drive shaft and the nut was loose. Re torqued, and no more noise

[Irish_Alley]

how long has it been doing this?

[Irish_Alley]

just reread the post. you should be ok with the time since it was loose. but it might of warn the ring and pinion. same deal if you tighten it too much. others on here know more about the ring and pinion like vile so he should be able to help you more but put some lock tight on the nut. normally we tell everyone to put witness marks on the nut and pinion before they remove the nut because you cant just torque it back down. since there is a crush sleeve thats been crushed to torque specs.