Noisy Drive Train (1 Viewer)

[Raven361]

Howdy everyone!

It's been a while since posting, but I have a question for you all. I have an 86 FJ60 with a Chevy TBI, NV4500 transmission, 34mm split t-case, stock front axle, and a FZJ80 rear. Front has a ARB air locker and the rear has an Aussie locker.

The question is, when I am driving down the road in 3rd and 4th, it sounds like marbles are rattling around some where in the drive train. I have not yet put a stethoscope anywhere on the drivetrain while on stands yet - but my hunch is either the t-case or the rear end gears. The noise gets worse in 4th, and even worse in 5th but 3rd still has it. Also, the noise only comes when I am going from load to no load, once I am coasting with my foot off the throttle, it subsides. The noise does, however, persist when the trans is in neutral and coasting at any speed.

Things that I am going to check are:
1) put trans in neutral, t-case in 4wd and see how much play is in the t-case gear box.
2) put on jack stands and run in 3rd, 4th, 5th and use a stethoscope to find where noise is coming from
3) ?

Thanks for any input!
Cheers.

 

[OSS]

Low oil level or old oil or wrong oil in transmission.

Or

Worn bearings in the transmission. Usual suspect for "marbles rolling around below" is front bearing.

Even a brand new transmission can get wrecked if it's run low on oil.

If it was a rear end or transfer problem, the racket wouldn't change when in different gears.

 

[Raven361]

Thanks OSS. I didn't feel like the rear end was the issue and felt more like it was the trans or t-case. I will check the oil level and report back!

 

[kirvesmies]

Low oil level or old oil or wrong oil in transmission.

Or

Worn bearings in the transmission. Usual suspect for "marbles rolling around below" is front bearing.

Even a brand new transmission can get wrecked if it's run low on oil.

If it was a rear end or transfer problem, the racket wouldn't change when in different gears.

i'm tending to agree with @OSS 's last statement. i can't give any insight as to possible mechanicals internally as i'm not at all versed on the nv4500

 

[Raven361]

Well, oil was good in both. Put transmission in gear and wiggled the driveshaft up, down, side to side, and rotated it, transmission is tight. Did the same thing with the t-case in 4 hi. Ran out of time to check all gears, but did it in 1st and 4th with no change. Going to do the same thing all over again with it up in the air to eliminate the diff gears (which may be a little loose).

I'm starting to think that it might be the pilot bushing or the input bearing on the transmission - but only time will tell when I can drop the trans.

Thanks for the input so far!

 

[Raven361]

After some digging and narrowing down, I found that it is a damn u-joint... I am kicking myself in the a$$ as I rebuilt everything from the clutch back (sans the u-joints of course). The happy note is that the pilot bearing was shot and I had a pretty bad leak on the t-case seal, so all in all it had to be done anyway. That all said, the major issue is that my pinion angle plus the horizontal angle from yoke to yoke is causing the u-joints to fail. So, it looks like I need a double cardan to correct the pinion angle and attempt to move the drivetrain to the drivers by about 2 inches to eliminate the horizontal deflection. Oh boy.