I got bad vibes, man- FIXED. Go to page 9

Jody Treadway said:
The gears have been installed since July with zero issues at all. Same vibe it always had after being lifted, just at a lower vehicle speed.

Now it's totally different.
I wasn't clear earlier.
The vibes are totally different now with the SYE and DC shaft. Before (with 3.73 as well as current 4.56) it was a run of the mill lifted Jeep driveline chatter. Same as my mildly lifted 01 XJ. Tip in throttle, floating throttle vibe. Nothing to sweat.
Now with the SYE and DC shaft, it's literally like riding on rumblestrips from 55-60. Not throttle sensitive, not Accel/decel related.
Once you hit that speed range, the vibes come alive.
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No play side to side at all in the driveshaft right? Have you got another shaft to throw in there and try for the time being?
 
iwaxmyjimmy said:
No play side to side at all in the driveshaft right? Have you got another shaft to throw in there and try for the time being?
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No side to side play. Dave at Oliver's has already sent me a second one, just in case, with no real change. This was a couple weeks ago.
My front shaft will interchange as well. Swapped it to the rear with no noticeable difference either.
 
Jody Treadway said:
No side to side play. Dave at Oliver's has already sent me a second one, just in case, with no real change. This was a couple weeks ago.
My front shaft will interchange as well. Swapped it to the rear with no noticeable difference either.
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I wouldn’t go any further then having a dial indicator on the pinion yoke and the output flange of the tcase to ensure there isn’t a huge variance. Maybe index the yokes/flanges and see what happens.
 
I installed a 242 hack n tap from iron rock a month ago in my xj, along with a new front driveshaft. Perfectly smooth at all speeds.
 
I made a diy tcase drop bracket that made my vibes on the 96zj disappear it was on a 4” lift, I ended up making a 1 1/4 drop bracket but not long after my 42re went out, so can’t say for sure it wasn’t that on mine! I can say after new trans never vibrated again tho!
 
I thought about this as was laying in bed waiting on a fat dude to break into the house last night.
The vibe/noise certainly has a strong resonance aspect to it. I'm wondering if it isn't due to the style of Hack n Tap yoke...
The IRO yoke has like 2.5 of spline with a 1/4" of open behind it. Even though it is bolted to the output shaft, I wonder if the yoke is moving up and down at higher speeds?
That would/could explain the severity of the vibe.
It would be easy enough to cut the yoke shorter so it would have less engagement on the output shaft. That *should* allow for less potential for movement and resonance.

@ghost I know you NAXJA geeks :flipoff2: have good success with the IRO kit. On an XJ application the output shaft is cut shorter to allow use of an XJ front shaft in the rear. This is what got me thinking thisnmay be a solution to my issue.
 
I didnt mention this earlier, but your comment about shortening the replacement yoke made me think of it. I did cut the output shaft to the minimum Iron rock recomend, then had to cut the yoke to fit.
Maybe that would help on the zj? Not sure if the driveshaft you have would still work.
 
junkxj said:
I didnt mention this earlier, but your comment about shortening the replacement yoke made me think of it. I did cut the output shaft to the minimum Iron rock recomend, then had to cut the yoke to fit.
Maybe that would help on the zj? Not sure if the driveshaft you have would still work.
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The ZJ front shaft is about 2" longer than an XJ one. So you only cut about an inch off the rear output. Doing so gives you a lot of spline engagement but I'm thinking that is the issue.
That much engagement also allows for the weight of the rear shaft to lever against the yoke. My vibe is really like a very heavy resonance. Resonances are always due to looseness and/or cylindrical issues.
I'm going to cut the yoke so I only have like 1-1.25" of spline engagement.
My wife rarely even uses 4wd so strength isn't an issue in this case.
We'll see tomorrow afternoon if it helps...
 
Jody Treadway said:
The ZJ front shaft is about 2" longer than an XJ one. So you only cut about an inch off the rear output. Doing so gives you a lot of spline engagement but I'm thinking that is the issue.
That much engagement also allows for the weight of the rear shaft to lever against the yoke. My vibe is really like a very heavy resonance. Resonances are always due to looseness and/or cylindrical issues.
I'm going to cut the yoke so I only have like 1-1.25" of spline engagement.
My wife rarely even uses 4wd so strength isn't an issue in this case.
We'll see tomorrow afternoon if it helps...
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IIRC iron rock recomend a minimum of 1.25" of splines left on the output shaft, that's what I cut mine down to.
Not sure if that would matter with the wife's zj, as you said strength isnt an issue.
 
junkxj said:
IIRC iron rock recomend a minimum of 1.25" of splines left on the output shaft, that's what I cut mine down to.
Not sure if that would matter with the wife's zj, as you said strength isnt an issue.
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I saw that. I'm really thinking the excess yoke length is a contributor. If not, I'm out like 20 minutes work to cut it short.
I've encountered typical driveline vibes many, many times over the last 20+ years of doing this. This one is weird with the severity that occurs at such a specific speed and the fact that multiple angle settings has little to no effect.
That's what makes me think it's less an angle issue and more something else.
 
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If it occurred before the hack n tap and gear change, but at a higher speed, then I’d think it would be something that predated the hack n tap. The gear change and hack n tap have just made it more noticeable and at a lower speed.

I don’t think the yoke is helping but I’d look elsewhere for the prime culprit.
 
rockcity said:
Hurry up. This is like a lotto draw where you are holding out like forever on announcing the last number. :D
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I know it’s bugging the shit out of me too. I still think output shaft is bent. Hell just throw some hose clamps on it and see if you can change the vibration.
 
If the gear swap moved the speed at which it occurs, I would think the source is somewhere upstream from the gears.
 
Can you clarify a few things for me? They may have already been stated but I've found myself lost in all the comments.

1) The output shaft of the TC is cut square
2) The output shaft bottoms out in the yoke
3) The taped hole is concentric and square with the output shaft
4) The hole for mounting the yoke to the output shaft is concentric with the yoke

With the yoke installed on the output shaft (no driveshaft), what's the run out? What's the run out with the driveshaft installed?
 
adamk said:
Can you clarify a few things for me? They may have already been stated but I've found myself lost in all the comments.

1) The output shaft of the TC is cut square
2) The output shaft bottoms out in the yoke
3) The taped hole is concentric and square with the output shaft
4) The hole for mounting the yoke to the output shaft is concentric with the yoke

With the yoke installed on the output shaft (no driveshaft), what's the run out? What's the run out with the driveshaft installed?
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1) The output shaft of the TC is cut square Without a doubt
2) The output shaft bottoms out in the yoke Definitely
3) The taped hole is concentric and square with the output shaft Yup
4) The hole for mounting the yoke to the output shaft is concentric with the yoke 'Tis indeed my friend

With the yoke installed on the output shaft (no driveshaft), what's the run out? What's the run out with the driveshaft installed? Haven't checked yet. I plan to this afternoon when I get time.

I drove it to work today and paid close attention to everything. It's smooth as glass up to 50. Then you can just start to feel and hear the resonance begin. It gradually gets louder and more noticeable and from 56-60 is unbearable. At 61, it all but goes away. When it's doing it, you can feel the resonance in the e brake handle but not the transmission shifter. You *can* feel it a little in the transfer case shifter. It's bad enough to cause the image in the rear view mirror to be completely distorted. It really feels like driving on the rumble strips.

Tip in and tip out of throttle has no bearing on it. This absolutely rules out anything in the differential(s). Placing it in neutral doesn't change anything either. That essentially rules out driveline angle.

I'm really thinking it is something with the IRO adapter yoke. Maybe it's loose on the splines just enough under just the right load conditions to chatter.
 
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