Project: In over my head (again)

[venominjected]

Actually, I just did the math. the original drive train weighted ~875lb and the new one is ~1200lbs. the stock springs might be ok with and extra 300lbs on them

It's looks just fine with my Cummins... (engine = 1100 dry, ZF5 175lb, np205 140 lb). (1415 dry without fluids)... my guess by the time alternators, yoke brakes etc I'm 1500+ lbs of powertrain

[12998]

It's looks just fine with my Cummins... (engine = 1100 dry, ZF5 175lb, np205 140 lb). (1415 dry without fluids)... my guess by the time alternators, yoke brakes etc I'm 1500+ lbs of powertrain

Mine "was" fine too.
Started to warp after a couple of years and 8000
miles or so since I put the 7.3 in.
Looking at possibly rebuilding them or getting a new set.
Just saying I would consider leaving all the leafs in if
you have a heavy drivetrain ...

Paul

[teking]

For balance issues you need this. I have them on my truck with HMMWV wheels and tires from Trailworthyfab.


http://www.centramatic.com

For wobble you also need a VERY good single steering stabilizer or a double. Usually if you are over 35" tires you should get a double.


Sent from my SM-G781V using Tapatalk

[Old_Red_Jeep]

I was thinking about getting a steering stabilizer to help with the front. the problem is, you can feel it coming in from all corners. and one of them was bad enough, that people have stopped me to ask about it because they could watch the tire wobble. my old NDT's never had issues like that. and they were 50yrs old!

[teking]

That sounds like more than a tire and balance issue. If they can see the tire wobbling. Bent rim or front-end issue.

BTW those new tires are sweet! If they are a good as you say I might have to look into them as well. $$$??

Sent from my SM-G781V using Tapatalk

[Old_Red_Jeep]

That sounds like more than a tire and balance issue. If they can see the tire wobbling. Bent rim or front-end issue.

BTW those new tires are sweet! If they are a good as you say I might have to look into them as well. $$$??

Sent from my SM-G781V using Tapatalk

yeah, I had the same thought. but I never had any wobbles with the original NDT's and the axles are still original. I did get the wobble to follow tires so I am hopeful that this works. I also did a rudimentary runout test on my brake drum surfaces and they were flat. wheel face was flal, but the outer wheel rim wasn't. The idea I was told was if the tire bead didn't get seated properly, the tire would be on the wheel kind of wonky, creating the wobble.

This is where I got the tires. I thought they were a great deal! Especially for the size and the fact that they are all brand new.

https://csmarmytires.com/%e2%80%8bbf...12-5x16-5-235/

[Old_Red_Jeep]

I got the tires mounted and boy do they perform! I 100x quieter ride and pretty sticky so far! We'll see how they age.



The downside is 2 of my wheels weren't made correctly. Luckily Trailworthy is replacing them for me. The wheels themself are out of whack and are the reason two of mine have wobbled bad. Even with that wheel, the truck is riding muuuuch nicer!

[gonz]

Those tires look great!

[teking]

I got the tires mounted and boy do they perform! I 100x quieter ride and pretty sticky so far! We'll see how they age.



The downside is 2 of my wheels weren't made correctly. Luckily Trailworthy is replacing them for me. The wheels themself are out of whack and are the reason two of mine have wobbled bad. Even with that wheel, the truck is riding muuuuch nicer!

Wheel issue for wobble yep.

Sent from my SM-G781V using Tapatalk

[Old_Red_Jeep]

Long time no update but this is a good one!

A little background and refresher with some of this info being in the thread. I've always struggled with vibration issues on this truck since I "finished" it back in 2020. There's been one major issue after another that we've found and resolved but the truck still had a vibration of some sort.

Here's the summary:
1) wheels. 2/5 wheels had the centers welded in incorrectly and were not true at all. big vibration there
2) Rear axle / locker, there was a lot of what I thought was excess play and when slowing down. the axle would shudder / jackhammer the driveline ~10mph. replaced axle sans locker, good to go
3) tires, went from ancient goodyears to nice BFG's. large improvement

But despite all of this, the truck persisted in a horrific driveline vibration above 55mph. I initially chalked it up to "max speed 55mph" on the dash and assumed that it was some sort of mechanical limit of the original truck. But that started to make less and less sense to me over time. This past summer I started wondering if my rear driveshaft was out of balance, or maybe the ujoint angles were bad? Maybe the driveline brake wasn't true'd or out of round? So a month ago once I finished checking the brakes for the winter I decided to look at the rear driveshaft. I tested the axle side ujoint, nice and tight. Then I went to the tcase side and the whole thing had tons of play! It looked like the rear output bearing on the tcase was smoked!

I then wondered if it was the vibration? If it failed due to the vibration? Did it fail from age (it was the original bearing from 1983)? Did I mis-install something?

We got the NP205 out this weekend and were quickly greeted with the cause of the vibration! The output flange was just plain loose! there was too much fore-aft movement! We took it apart a bit and the bearing and seal looked great (against my expectations)!
Attachment 3969

Attachment 3970

So we cleaned it all up, re-attached, and torqued the snot out of the output nut to ensure that it wouldn't loosen! We took the truck out for a test drive and were very pleasantly surprised that there is now 0 vibration! We even took the truck on the highway at 75mph! (and found out that the engine is spinning at 2800rpm at 70mph. not terrible!)

So it was fixed but one question remained: why was it loose? Was it the jack-hammering of the old locker that loosened it? The torque from the V10? The engine braking? My own improper install?

That last one stuck out to me so I went back through old photos of when I first rebuilt and installed the tcase. It was there that I found my smoking gun. In this picture of the drivetrain installed in the truck for the first time, you can clearly see the inner threads of the output flange retainer nut... NOWHERE near tight enough... Either I really failed at hitting the 130-150ftlbs or torque or, more likely, I forgot to tighten it! And I assume the pressure from the driveshaft kept the thing installed!

Attachment 3971

So, I messed up. But fortunately nothing worse happened and the truck is solid now! I'm honestly impressed that it held up for 5yrs and 16,000mi! I guess that shows the toughness of the NP205.