Experts Only - Desperate Plea for Help - FJ40 Driveline Vibration. LONG Post.

[Bear Lake Cruiser]

I don't know if a bent axle housing or inner axle would run relatively smooth without the DS connected... but it might be exaggerated with the DS connected.

I wouldn't even know how to begin checking for this. I will put it up on jackstands today and run it. Give a listen thru a piece of rebar or something to various locations. And heavy torque the motor mounts as per @lcwizard . All with my Bro in Law's help.

 

[Bear Lake Cruiser]

Who has a link to the transfer case manual so I can figure out how to adjust/change the output shaft bearing thrust washer as per Georg's recommendation? 1981 model, split case with the smaller diameter idler shaft.

 

[Brownd3max]

When you pop a motor mount it's almost always the driver side. Easy way to tell is put it in low range and pop the throttle. Your shift lever
will tilt excessively to the passenger side and you'll probably hear the fan contact the shroud. Once I went to an Aussie 5speed in the 60
I had to carry a spare all the time. Every other outing on a rough trail I'd lose one. Finally I just drilled through the mount and used a long 7/16 bolt and locknut. Even if the rubber tore, the engine couldn't lift and trash the shroud. Drag racers traditionally used a chain bolted from the block to frame as a safety measure.

"Drag racers traditionally used a chain bolted from the block to frame as a safety measure."[/QUOTE] Ah, you took me back to the '70's, when I did just that to my 427 powered "drag-truck".

 

[lcwizard]

"Drag racers traditionally used a chain bolted from the block to frame as a safety measure."

Ah, you took me back to the '70's, when I did just that to my 427 powered "drag-truck".[/QUOTE]

We both just gave up our age...so many old school tricks that have been forgotten. Did you ever clean the inside of an engine by adding a quart of ATF and running a couple hundred miles....or the water in a spray bottle sprayed into a running, hot intake to clear carbon from the combustion area? What a lot of old time mechanics understood is that everything doesn't always work exactly like the engineers tell you.
The theories of the parallel driveline flanges are merely a good starting point. Trial and error is sometimes the best solution. This is true with
other vibrations and harmonics like "death wobble". So many people believe that just because an alignment shop did the alignment according
to the book, the problem is solved. The specs are a good starting point . From there you leave the tie rod clamps loose and take a drive.
Get it up to 45mph. If everything works, then great. Tighten everything up and go. If there's a wobble, turn the tie rod one full turn either direction and drive again. If it gets better or goes away, you're on the right track. If it gets worse turn the rod back to where it was and keep
going another full turn and drive again.
When it comes to these harmonics, use the specs as a starting reference. Just because everything looks correct by the manual doesn't mean
that formula works for every truck with every possible modification. Don't hesitate to play around with a 2 or 4 degree shim. Backwards , forwards, try it all. Every journey leads to an answer
As Winston Churchill said "
Success consists of going from failure to failure without loss of enthusiasm.

 

[Bear Lake Cruiser]

Ah, you took me back to the '70's, when I did just that to my 427 powered "drag-truck".

We both just gave up our age...so many old school tricks that have been forgotten. Did you ever clean the inside of an engine by adding a quart of ATF and running a couple hundred miles....or the water in a spray bottle sprayed into a running, hot intake to clear carbon from the combustion area? What a lot of old time mechanics understood is that everything doesn't always work exactly like the engineers tell you.
The theories of the parallel driveline flanges are merely a good starting point. Trial and error is sometimes the best solution. This is true with
other vibrations and harmonics like "death wobble". So many people believe that just because an alignment shop did the alignment according
to the book, the problem is solved. The specs are a good starting point . From there you leave the tie rod clamps loose and take a drive.
Get it up to 45mph. If everything works, then great. Tighten everything up and go. If there's a wobble, turn the tie rod one full turn either direction and drive again. If it gets better or goes away, you're on the right track. If it gets worse turn the rod back to where it was and keep
going another full turn and drive again.
When it comes to these harmonics, use the specs as a starting reference. Just because everything looks correct by the manual doesn't mean
that formula works for every truck with every possible modification. Don't hesitate to play around with a 2 or 4 degree shim. Backwards , forwards, try it all. Every journey leads to an answer
As Winston Churchill said "
Success consists of going from failure to failure without loss of enthusiasm.[/QUOTE]
Gotta love Winston!

 

[handcannon]

I had a 69 Camaro back then. The motor mounts in those cars had a problem with coming apart (I wonder why). The solution that GM had? A chain on the motor mount! The repair package I got was a chain and some bolts.

Don

 

[Bear Lake Cruiser]

Ah, you took me back to the '70's, when I did just that to my 427 powered "drag-truck".

We both just gave up our age...so many old school tricks that have been forgotten. Did you ever clean the inside of an engine by adding a quart of ATF and running a couple hundred miles....or the water in a spray bottle sprayed into a running, hot intake to clear carbon from the combustion area? What a lot of old time mechanics understood is that everything doesn't always work exactly like the engineers tell you.
The theories of the parallel driveline flanges are merely a good starting point. Trial and error is sometimes the best solution. This is true with
other vibrations and harmonics like "death wobble". So many people believe that just because an alignment shop did the alignment according
to the book, the problem is solved. The specs are a good starting point . From there you leave the tie rod clamps loose and take a drive.
Get it up to 45mph. If everything works, then great. Tighten everything up and go. If there's a wobble, turn the tie rod one full turn either direction and drive again. If it gets better or goes away, you're on the right track. If it gets worse turn the rod back to where it was and keep
going another full turn and drive again.
When it comes to these harmonics, use the specs as a starting reference. Just because everything looks correct by the manual doesn't mean
that formula works for every truck with every possible modification. Don't hesitate to play around with a 2 or 4 degree shim. Backwards , forwards, try it all. Every journey leads to an answer
As Winston Churchill said "
Success consists of going from failure to failure without loss of enthusiasm.[/QUOTE


Dave to you have any steel shims in stock? And what front bumpers do you have in stock for the 40?

 

[Bear Lake Cruiser]

Finally gave it a good run on jack stands and checked everything out. New drive shaft for the rear does have some tiny play. both front and rear u joints have very minor play in one direction only, north and south on each end. east and west tight. (don't know how else to explain it). Shaft is in phase and when spinning at 40 mph it seems to spin without wobble. The slip joint is tight. Also left front motor mount is sloppy. Not busted all the way but sloppy. Motor will jump but not quite enough to hit the fan shroud but just barely. First stop is back to the driveshaft place that built the shaft. Then all new mounts both front and tranny. It also seems to have some diff noise. Transfer has noise but it sounds like normal gear mesh, etc. Same with tranny. (listening through a long screwdriver). Still runs quiet and smooth on front shaft only with the rear removed.

 

[Bear Lake Cruiser]

Drive shaft shop pulled the shaft and balanced while I waited. it was still good from the day he made it. So then down the road to Tucson Differential. I described it, he heard it and immediately said surely the pinion bearing and maybe some other bearings. He was so sure of it, he ordered the parts while I was there and said it was not necessary to inspect first as he had heard the noise hundreds of times in the past. Will rebuild it a week from Wednesday. Lets see how it goes. I have had others in the past be "sure of things" only to be wrong. I guess we all have. I wish I had a shop..... and more knowledge. I'm still going to change the 3 mounts on motor and tranny.