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Vibes got worse after SYE??

DanMan2k06

DanMan2k06

NAXJA Forum User
Location
Damascus, MD
'99, aw4, rugged ridge sye

Well I'm a little confused here. I put in an sye about 2 months ago, and my vibes now are worse than they were before? I still have a 1" t-case drop installed as well as shims (not sure what degree, they came with the pack). It's not so much a vibration as it is a serious hum. Seems only on acceleration, and at speeds upwards of 40mph. I first heard it as soon as I did the sye and swapped the front shaft into the rear. I was naively hoping in the back of my mind that it was my tires, but after installing the shackle relocators it's definitely worse. I netted about an extra inch from them.

Any ideas? Worn cardan joint? Bad u-joints, cv slip joint?
 
First of all, go pick this thing up from lowes:
h-af006m.jpg


and make sure your pinion angle is in line (or a couple degrees below) the angle of your driveshaft. Before you do this, remove your TC drop since that is no longer needed. It sounds like you need different shims.
 
sorry to hijack, but while on the subject, is 4* down from inline with the shaft too much? i have a light vibe when i let off the gas around 40 mph in 4th or 5th gear
 
put the angle finder on the dshaft, record angle, unhook dshaft and turn yoke so that the widest part is vertical and lay the angle finder across the "ears" of the yoke and record the angle. the yoke measurement should be inline or slightly down from the dshaft angle
 
No need to remove the driveshaft,just put the angle finder on the back of the housing where the 'case spreader" would go.
 
RCP Phx said:
No need to remove the driveshaft,just put the angle finder on the back of the housing where the 'case spreader" would go.
Click to expand...

these are not always perfectly perpendicular to the pinion. it is more accurate to measure from the pinion yoke directly.
 
DanMan2k06 said:
'99, aw4, rugged ridge sye

Well I'm a little confused here. I put in an sye about 2 months ago, and my vibes now are worse than they were before? I still have a 1" t-case drop installed as well as shims (not sure what degree, they came with the pack). It's not so much a vibration as it is a serious hum. Seems only on acceleration, and at speeds upwards of 40mph. I first heard it as soon as I did the sye and swapped the front shaft into the rear. I was naively hoping in the back of my mind that it was my tires, but after installing the shackle relocators it's definitely worse. I netted about an extra inch from them.

Any ideas? Worn cardan joint? Bad u-joints, cv slip joint?
Click to expand...

X2 get rid of the tcase drop. No need for it with a SYE. I've also learned to never assume the shims that are on the leaf packs are right. Most companies send aluminum shims and are prone to cracking down the road anyways. Get things lined up as suggested above and if you still have vibes. Rotate frot DS to rear to get you by and get DS rebalanced.

stroked88 said:
sorry to hijack, but while on the subject, is 4* down from inline with the shaft too much? i have a light vibe when i let off the gas around 40 mph in 4th or 5th gear
Click to expand...

4* below is to much and gives the typical vibes you discribe because of it. Shoot for about 2* below
 
Last edited:
Well guys I thought I'd update here instead of starting a new thread about my findings. I installed my sye about 2 or so months ago. Since then, the front driveshaft has been out. Well I put it back in today and had a heart-sinking realization: my jeep has been driving in 4hi for the past 2 months. No wonder I have freakin vibes....

On top of that, once I put the shaft in I couldn't for the life of me get it to shift out of 4wd. I tried every possible trick in the book. Reversing, adjusting linkage, removing linkage and doing it by hand, gravel, on a lift in the air, everything. It shifts totally fine with the lever, but it's obviously not engaging inside the case. I can go between 4hi, neutral, and 4lo like a dream but when I shift to 2wd it just doesn't want to disengage. I'm gonna pull the case back apart tomorrow. What should I keep an eye out for?

This means that last week I drove over 1000 miles around 80mph to and from charleston SC, in 4wd :(
 
It sounded like some minor driveline vibes. That, and still having the t-case drop in with shims in the pack led me to believe the pinion angle was too high, instead of too low like before. It still handled and cornered like normal 2wd cuz the front shaft was out.
 
since the shaft was out, you didnt hurt anything. the only reason it is bad for them to be driven on hard dry surfaces in 4wd is from drivline bind on the chain. its all good!
 
Ok good. I'm guessing the vibes are because the gears in the case are still under a slight load (in 4wd) rather than coasting like when in 2wd? It's totally bearable under normal driving, but on my trip I did a WOT rip and right around 88-90mph they got REALLY bad. More of a howling. Of course I backed off and didn't do it again but it sure didn't sound good.

Are there any springs that normally wear out? Or that could have fallen out of place when I was putting the halves back together?
 
just drive it like a jeep and not a sports car?
 
sounds like a the mode fork is un pinned from the shift rail, or something along those lines.
 
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