Help me figure this one out

a_kelley said:
Pull both shafts and run it in 3rd. I am not too very familiar without looking at a diagram but you said it vibes with front shaft only, rear shaft only, and on stands. Swapped case, no change. Definitely not in front/rear gears or the TC. My money is on the trans..... Before gear swap, it was high 3rd and 4th. After gear swap it was still 3rd. Worth a shot but it won't be loaded like with a shaft in, keep in mind... I have a good yj axle pair if you can get them down there, but I bet it's in the trans.. idk how but that's the only thing that hasn't been tested or changed.
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Infamous1 said:
The trans was pulled and gone through...
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Yes sir, the trans has been completely gone through and rebuilt.
 
No chance they missed something in the rebuild though? I mean if it does it with both shafts out and on stands, you know it must be in the trans since none the rest of it is moving..... And he had the problem before the regear so it is something that hadn't changed with any of the repairs done since you got into it...
 
a_kelley said:
No chance they missed something in the rebuild though? I mean if it does it with both shafts out and on stands, you know it must be in the trans since none the rest of it is moving..... And he had the problem before the regear so it is something that hadn't changed with any of the repairs done since you got into it...
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It doesn't do it with both shafts out at the same time, just with one or the other or both installed.

The re-gear just moved when the vib came in, before it was in 4th, now in 3rd, but roughly at the same speed.
 
It sounds like it's gotta be in the tranny, something the rebuild didn't touch. Tweaked case, output shaft, something along those lines. Maybe pull the transfer case off and run it with a dial indicator on the tranny output?
 
Have you taken a look at the clutch and pressure plate since it came back?
 
Well, I may have just had a break through. On my 2 post lift the backlash is perfect, however on jack stands over a 1/3 of the gear has ZERO backlash. Likely a loose tube I would presume.

Per Jody Treadway's advice, I'm going to open up the back lash on the tight side and test it.
 
Oliver's said:
Well, I may have just had a break through. On my 2 post lift the backlash is perfect, however on jack stands over a 1/3 of the gear has ZERO backlash. Likely a loose tube I would presume.

Per Jody Treadway's advice, I'm going to open up the back lash on the tight side and test it.
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Then why does it have vibes with only the front shaft installed? (assuming rear is where the backlash issue is)
 
jeepinmatt said:
Then why does it have vibes with only the front shaft installed? (assuming rear is where the backlash issue is)
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When road tested with just the front shaft, there is still load on the rear end, with or with the rear shaft installed. I see what you are saying though. I should have tested it on jack stands on all four corners with out the rear shaft in.
 
...and nothing! Some damn vib, 3rd gear 40mph. ***raises gun to head*
 
Take the afternoon off and go fishing. Park jeep down hill facing lake. Forget to set the parking brake. Stray dog/cat/etc. jumped in jeep and knocked out of gear... oh no.
 
If you have a go pro, mount it on the axle facing forwards. If the vibration is that bad, you should see something moving. Just an idea.

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Oliver's said:
It doesn't do it with both shafts out at the same time, just with one or the other or both installed.

The re-gear just moved when the vib came in, before it was in 4th, now in 3rd, but roughly at the same speed.
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Axle shafts straight? Warped wheel flange? I've seen a few shafts bend right at the flange but it takes a good hit to do it. You ran on stands without front driving and it still vibes right? If so that eliminates front axle issues.
Agreed it's not in trans if the gear changed but vibe was same at same speed in different gear. Also precludes it being the flywheel pressure plate since if it were that, it would vary corresponding to engine rpm not road speed.
 
Can you post a line by line recap of what you have tried? I tried reading back through, but its too scattered and interrupted.
 
If putting it on jackstands changes the backlash, why not put a different axle assembly in it? Bc if you know it's got an issues with that housing it kind of dumb to keep chasing this vibration without fixing it. I still think it's a ring and pinion issue and read through the last few pages to see if you had check it in 4 spots. Which you mentioned a variance. When I was working for Ford they were having major issues with explorers and f150s with crappy ring and pinions. And the trucks were built so solid you'd feel that vibration all the way though the cab.


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iwaxmyjimmy said:
If putting it on jackstands changes the backlash, why not put a different axle assembly in it? Bc if you know it's got an issues with that housing it kind of dumb to keep chasing this vibration without fixing it. I still think it's a ring and pinion issue and read through the last few pages to see if you had check it in 4 spots. Which you mentioned a variance. When I was working for Ford they were having major issues with explorers and f150s with crappy ring and pinions. And the trucks were built so solid you'd feel that vibration all the way though the cab.


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If its an R&P issue. ANd if the issue is present with either drive shaft removed and the tires off the ground, it would have to be a both sets of R&P are bad.
 
Has the front been checked?


Edit: I understand the gears up front are new, but eliminating the rear vibration first then focus on the front, is my reasoning behind it. Not try and tackle both at one time.
 
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