drivetrain opinions needed (1 Viewer)

[RKTINC]

I have searched a great deal here on the forum but I am not sure this question has been asked in this way:

On FJ80's, please list the most common drive line failure points based upon your experience. I anticipate
"none" and "never had a problem in 400k miles answers, but for those who have had issues or work on these rigs for a living, What are the issue listed from most frequent to rare.

Thanks,

RKTINC.

Here is my guess:

1.) u joints
2.) drive shafts
3.) wheel bearings
3.) rear diff repairs/rebuilds
4.) front diffs repairs/ rebuilds
5.) transfer case? (internals??)

I bought a really good low mile 80 with no issues. I then bought a rough 80 with less than 150k miles for body and interior parts and find that is has a loud roar at highway speeds. Seems to be rear end, but my tech buddy who is getting ready to work on it says he hears front end.

Thoughts?

 

[bugsnbikes]

All items listed are “wear items”. some go 200k......some go 140k....some seem to last forever. part of the problem purchasing a used rig is that you don’t know what service has been done along the way.

For items that require lube and minor service.....if that hasn’t been done at all or neglected you can be looking at things like u-joints or axles worn out and in need of rebuild or replacement.

My guess would be to spend some time investigating the rear axle....drain the fluid and inspect it for metal and color. If it’s goopy black and loaded with sparkle.....you are probably onto something.

Yank on the rear driveshaft near the ujoints and see if there’s any play.

Unscrew the front axles knuckle fill hole and stick a small stick in and see how much grease covers that.

Overall- you may want to search the forum here for all of the 150k p.m. maintenance of wear items and start going down that list.

Or just get that list and have your buddy who is going to maintenance it for you start doing down the list. with any used vehicle recently purchased......it’s much better to go thru it fully checking wear items and catching them before they comepletely fail and result in much more expensive damage.

At a minimum - all fluids should be yanked and inspected from engine trans tcase and axles...and then obviously fix all noisey worn out items that either need a lubing or changeout , rebuild,

 

[BILT4ME]

What year is each truck?

Makes a difference for the drive line and interchangeability.

91-92
93-94
95+

 

[bigredmachine]

I had a u-joint go out and that was it, for some reason one of the passages in the joint wasn't allowing grease out to the bearing cap. I greased them regularly, usually every oil change or two, so even with service wearable items can still go bad.

 

[BILT4ME]

I had a u-joint go out and that was it, for some reason one of the passages in the joint wasn't allowing grease out to the bearing cap. I greased them regularly, usually every oil change or two, so even with service wearable items can still go bad.

When you greased them, did you do it with the driveline "unloaded"? That means: Wheels chocked, transmission in neutral, no parking brake.

This removes all loads on the DS and allows grease to go where it NEEDS to instead of the path of least resistance.

This is a frequent failure of proper maintenance because everyone gets in a hurry.

 

[bigredmachine]

When you greased them, did you do it with the driveline "unloaded"? That means: Wheels chocked, transmission in neutral, no parking brake.

This removes all loads on the DS and allows grease to go where it NEEDS to instead of the path of least resistance.

This is a frequent failure of proper maintenance because everyone gets in a hurry.

it was as unloaded as it would ever be, I had it picked up on my lift at work since I usually do it when I change the oil. im guessing it was more a lack of matainence from the po than anything.

good to know about unloading the drive line, I would have figured the grease would go where it needs to go anyways