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Re-geared, now I have a vibration above 50 mph

JMT

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Compromise. I feel like I'm married to this hunk-o-junk!

For Sale:
2003 Wrangler Sport
A whole bunch of cool shit on it
33's re-geared, SYE, DCDS
3" lift with 1/2" butt crack
Extra special back massaging feature above 65(priceless)!
I’ll take the SYE, DCDS and last but not least, the 1/2” butt crack. You can keep the vibes, but hey, that’s what women want, so don’t sell out!
 
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bobthetj03

bobthetj03

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Today was all for not, but got some routine maintenance done. The plan, change engine oil, change TC oil, drop skid, replace input yoke, install front ds, rotate tires. After dropping the skid I find out they sent me the wrong yoke. I'm 90% sure the yoke isn't the problem, but it would have been nice to rule that out. I moved forward and changed the tc fluid. It was pretty black and hadn't been changed since the SYE install 25K ago. Went ahead and checked the torque on the tc input yoke, and front diff yoke, again, just to be sure. Ran out of time to play with front pinion angles, so wrapped it up and drove home. front pinion is 0.7* higher than ds. No change. Vibes at 65+.
 

Alex01

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Today was all for not, but got some routine maintenance done. The plan, change engine oil, change TC oil, drop skid, replace input yoke, install front ds, rotate tires. After dropping the skid I find out they sent me the wrong yoke. I'm 90% sure the yoke isn't the problem, but it would have been nice to rule that out. I moved forward and changed the tc fluid. It was pretty black and hadn't been changed since the SYE install 25K ago. Went ahead and checked the torque on the tc input yoke, and front diff yoke, again, just to be sure. Ran out of time to play with front pinion angles, so wrapped it up and drove home. front pinion is 0.7* higher than ds. No change. Vibes at 65+.
Axle yoke or t-case? Sounds like you got a good amount done atleast. At this point it's really starting to seem like manual hubs are the way to go.
 
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bobthetj03

bobthetj03

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Axle yoke or t-case? Sounds like you got a good amount done atleast. At this point it's really starting to seem like manual hubs are the way to go.
I already had the front axle yoke replaced. The tc input was still the factory piece. Yep, manual hubs seem to be the answer, or re-gear up to 4.10. Manual hubs is the no brainer, but costly.
 
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bobthetj03

bobthetj03

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Bit of an update. I decided to try and lower the t-case skid to see what would happen. I've done this before when I had the factory skid on, with no positive results. With this Barnes skid being thicker and one inch higher, I decided to put my 3/4" OME pucks on, thus lowering the drive train said amount, and obviously changing the pinion to ds relationships. Up to 70 mph I'm 80% vibe free. I still get a low faint rumble from 55 up, but I no longer get the massage in the seat and steering wheel. I re-adjusted the rear pinion angle today to get it back to 1* lower than the rear ds. The front pinion angle is now 1* higher than the front ds. At this point I'm not sure why lowering the t-case improved the vibes, other than the operating angles at the t-case improved by the lowering enough to see improvement. With only a 3" suspension lift I just don't get it! There are TJ's out there with 4" or more lifts and drive smooth as glass to 80 mph. I'm on the search to see if I can find a shop in the NorCal area that can do active balancing of the ds like what @psrivats had done, which cured his vibes. I still haven't replaced the input yoke on the t-case yet, so that is still looming in my head.
 
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psrivats

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Last post I read said he had a bad font axle shaft and a bad rear driveshaft yoke. And replacing those cured his vibes...
It was a combination of everything. I actually had replaced the yokes very recently and the axle shafts were brand new Yukons that were put in during the regear. I had gotten them checked as well. I am still not sure why the shop decided to replace those specific parts. Still waiting for an explanation.
 

AndyG

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I had a bent rear axle flange , barely , that made mine vibe at 66 after I regeared .

I agree that one thing, or the cumulative of several , and vibes can start .

Parts changing is hit or miss, and active balancing must require some knowledge on the diagnostic side .

I’m glad these issues are being recognized and resolved , it’s gonna help a lot of people.
 
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bobthetj03

bobthetj03

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I had a bent rear axle flange , barely , that made mine vibe at 66 after I regeared .

I agree that one thing, or the cumulative of several , and vibes can start .

Parts changing is hit or miss, and active balancing must require some knowledge on the diagnostic side .

I’m glad these issues are being recognized and resolved , it’s gonna help a lot of people.
How did you test to find out it was a bent flange? Did you pull the rotors/drums spin it up to speed on jack stands and measure runout? Mine runs vibe free with the front ds removed, so maybe I bent a front axle ear when I replaced the axle ujoints before the re-gear and now after the re-gear the increased speed the vibes become active? I'm really about out of ideas. I'm still miffed as to why the vibes decreased when I lowered the t-case skid 3/4".
 

AndyG

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How did you test to find out it was a bent flange? Did you pull the rotors/drums spin it up to speed on jack stands and measure runout? Mine runs vibe free with the front ds removed, so maybe I bent a front axle ear when I replaced the axle ujoints before the re-gear and now after the re-gear the increased speed the vibes become active? I'm really about out of ideas. I'm still miffed as to why the vibes decreased when I lowered the t-case skid 3/4".
Here is what's weird , and you will likely cuss me for this ...

My vibe would go away with the front shaft out . For real . Left rear flange bent , and vibe goes away pulling front shaft .

I found out about the issue when I started hearing a brake noise at low speed with light pedal .

It was evident it was the left rear.

My shop likely ran it with no brake disk and made a dial indicator out of something in a fixed position ..like a screwdriver clamped to the rack , or it was evident to the eye .

Thanks , hope this helps.

Incidentally, the shop I use pulls the front shaft first on all vibe issues .
 
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bobthetj03

bobthetj03

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Here is what's weird , and you will likely cuss me for this ...

My vibe would go away with the front shaft out . For real . Left rear flange bent , and vibe goes away pulling front shaft .

I found out about the issue when I started hearing a brake noise at low speed with light pedal .

It was evident it was the left rear.

My shop likely ran it with no brake disk and made a dial indicator out of something in a fixed position ..like a screwdriver clamped to the rack , or it was evident to the eye .

Thanks , hope this helps.

Incidentally, the shop I use pulls the front shaft first on all vibe issues .
Hey, at least it's another thing I can look for that won't cost a bunch of coin.
 

AndyG

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Hey, at least it's another thing I can look for that won't cost a bunch of coin.
Cool...I think to some degree the big spongy tires we run mask some of the issues that might become apparent with smaller tires.

I can't get my mind around how removing the front shaft resolved that issue on mine and I was almost embarrassed to say that it did.

Keep us posted man and don't give up.
 
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S.McArthur

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Well, I installed some spring spacers to level out the Jeep, it was 1.5” lower in the front, now it’s even.
Went for a drive to get a second opinion on what’s causing my vibrations and hit some train tracks. I believe I experienced death wobble and it scared the living crap out of me. Had to damn near stop to get it to quit. Measured toe, 1” difference, made it 1/8-14”, somewhere around there. Hesitatingly I drove home on highway without issue.
Vibration is insane, I really think I have some tire issues and I’m going to drop the TC and see if that helps.
I need a break from wrenching for a few days though, I’ve had enough laying on concrete, and I’m really regretting putting 5.13s in this Jeep.
Whine fest over .
 

S.McArthur

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After a good sleep, I'm calling myself out; I had Firestone put he Jeep on their rack after my re-gear to get numbers and saw my thrust angle is -0.92*. (I bought the lifetime alignment thing, good to have as an extra tool) Completely overlooking this number, I need to make sure my axle is square. Recalling my axle install, I can't %100 say I measured from the axle to a known spot on the frame for reference. I know I set the axle at full bump to be side/side center, but not square.
If a pinion angle makes a vibration difference, a bad/not square angle should be the same...at least that's my thinking.
I got my jeep going as fast as I could yesterday evening and when I coast, the vibration is present, but it levels out to a constant lighter vibration rather than in/out rattle your teeth.
The Jeep is going on 4 jack stands and I'm not putting it down until I have I am at 0 or 1/16" square.
So, shame on me, I accept all potential taunting.