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

Ok, so this is how I think this should go. I'll measure runout on the yokes, find the high spot, mark it, then install the drive shaft and measure its runout and measure the high spot, and then remove drive shaft and orient the assy this way. Does this sound right? I know you guys must think I'm plum loco at this point, but if you've been dealing with these vibes as long as I have, and have been dumping money and more money at the problem, you might at least feel sorry for me. I'll take pity at this juncture, lol!

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I don't really know what you mean about the high point of the run out, but it think you only have 4 ways to put on the driveline right? I guess if that was an issue you could just take off one side or the other and spin the yoke 180 degrees and go drive it till the vibration is gone.

1 driveline in
2 driveline turn 180
3 one yoke turn 180
4 other yoke turn 180

Unless I am missing something.

I do pitty you, I wish I had the answer for you. I admire your patience.
 
With a run out gauge installed, I put the gauge needle on the smooth part of the yoke with a little pressure, set the gauge to zero, then rotate the yoke 360* and watch the gauge. The spot where the yoke measures the most (usually in thousands), is what I consider the high point of the yoke. Same for the drive shaft. Say for instance, the gauge peaks out at .006 at the 120* portion of the rotation and does not go any higher, that should be my high point. Sounds good in theory, right?
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Technically, if there is more metal there it may be the heaviest part, but I would be shocked it .006 would make your car shake.

Honestly before I did what I did now, I was an automagician, I did a lot, I mean a lot, of clutches and transmissions(manuals and automatics). I was a transmission guy for Nissan for many years before I was a drive-ability/electric tech at Toyota, Granted I wasn't a specific Jeep guy, but I did do a lot of clutches for an independent for a lot of years. I never marked drivelines and never had any come back for vibrations. I mean think about the worst u-joint you have ever seen. Most likely it gave you a clunk when you shifted gears, but how much did it actually shake your car? Compared to a .006 run out of a solid yoke.

To me it is balanced like your wheel. You don't mark the lug with the holes you put the tire on any which way. I believe your driveline is the same. Or at least in my experience. Now granted you have a weird situation, but I would be hard pressed to believe you could even feel an out of balance yoke. I am not saying never, but it would be a first for me. Plus you replaced them all at one point. That would be amazing if you replaced a bad yoke with another bad yoke.
 
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Yep, it's pretty crazy that these little nuances would make a difference at all. I'm just reaching for the stars here. Keeping in mind, these vibes started as soon as I re-geared the rear axle, without changing anything else except a right rear wheel bearing because the seal was leaking a little and I had it apart, and new clutch pack for the Traclok LSD. Tomorrow after work I'm swapping drive shafts and doing my silly run out experiment, so stay tuned.
 
Rob mentioned some posts back that I could pull the yokes to clock them and I was too stupid to understand until tonight. While I could clock the yokes to match, I can't clock the drive shaft without removing the yokes to clock them how I think they should be. I also took more time to measure run out a bit better, so my previous numbers are bunk. The new drive shaft has very little runout, so I think I improved there. I marked my highs on the yokes(which is tough to measure being that the yoke castings are rough and probably not that round in reality, but I measured none the less. Took it for a spin, thought the vibes were better. Went back and clocked the rear yoke 180* out from the TC output yoke and went for a spin again. Felt about the same. My conclusion about the whole run out scenario, unless you are measuring stupid crazy massive run out, I don't think none of it matters much in this situation. Gonna drive it for a couple days and evaluate the vibe intensity to see if I gained anything. Might try to lower the pinion angle some more and see what I get.
 
bobthetj03 said:
Rob mentioned some posts back that I could pull the yokes to clock them and I was too stupid to understand until tonight. While I could clock the yokes to match, I can't clock the drive shaft without removing the yokes to clock them how I think they should be. I also took more time to measure run out a bit better, so my previous numbers are bunk. The new drive shaft has very little runout, so I think I improved there. I marked my highs on the yokes(which is tough to measure being that the yoke castings are rough and probably not that round in reality, but I measured none the less. Took it for a spin, thought the vibes were better. Went back and clocked the rear yoke 180* out from the TC output yoke and went for a spin again. Felt about the same. My conclusion about the whole run out scenario, unless you are measuring stupid crazy massive run out, I don't think none of it matters much in this situation. Gonna drive it for a couple days and evaluate the vibe intensity to see if I gained anything. Might try to lower the pinion angle some more and see what I get.
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What? You slipped the new yoke in and still have vibes, only slightly better? Okay, so a couple fo days, adjust pinion. Hoping some small adjustments will solve it! It would make my week!
 
When it vibrates does it sing or whine at all or is it a quiet vibration?

Here is a stupid idea. You can put a few hose clampd on your driveline. Both but one at a time. It will essentially unbalance your driveline. The reason I say this is because I am perplexed and it is something I might try. But this way you can see if you get two different vibrations or intensify the one you have. Still may not give you the whole story but one more cheap thing to try..

I honestly don’t believe it is a drive line or yoke issue. You have replaced them and it didnt change at all. I also have a hard time believing your angles are causing it either. Only because you keep messing with it with no difference. I cant believe as maticulous as you are that you are not close enough.

I know you said this happened after the gear change, but what does that change. Everything that spins spins faster now.

I once had a customer with a camaro that had a slight vibration with a whine. I totally rebuilt his transmission and nothing changed. I took that one in the shorts. In the end it ended up being a wheel bearing. He got a free trans overhaul and a wheel bearing.

Since i cant hear it or feel it, i have to suggest things like exhaust shields rubbing on the body or something vibrating on the firewall? Transmission mount?

It is killing me not being able to fix your Jeep. I know you know that feeling too.
 
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ac_ said:
When it vibrates does it sing or whine at all or is it a quiet vibration?
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It's a low pitch hum mostly just heard as soon as I reach 50 mph. It's not a howl or whine like a wheel bearing or pinion bearing going south. At 65 mph, the low pitch hum becomes felt in the seat and a tiny bit in the steering wheel. My mud terrains make noise too, so they aren't helping matters, but I know the difference between a mud terrain howl and what I'm experiencing after the regear.

ac_ said:
I honestly don’t believe it is a drive line or yoke issue. You have replaced them and it didnt change at all. I also have a hard time believing your angles are causing it either. Only because you keep messing with it with no difference. I cant believe as maticulous as you are that you are not close enough.
It is killing me not being able to fix your Jeep. I know you know that feeling too.
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I haven't replaced the rear diff yoke, but after checking run out twice, I'm pretty sure I can rule the yokes out. I also checked both yokes for play while I had the drive shaft out, and no movement whatsoever. Now with that said, after a drive to work this morning and a fresh perspective on the vibes, I definitely have noticed a difference in the vibes both felt and audibly. I can still hear them coming on at 50, but a lot less pronounced. At 55 it's almost livable, but still not right. At 65 the harmonic wave portion of the vibes is almost gone, and is replaced with a less severe, constant vibe the can be felt and heard. I feel like I'm gaining some ground here, but still not out of the woods. What I didn't tell you about yesterday's events is I removed the rear drive shaft at morning break(I'm getting quite efficient at drive shaft removal), and drove 14 miles at 55 mph to take my wife lunch. With the rear drive shaft removed and running in 4hi, the vibes are very slight and almost gone. I still feel the front drive shaft causing a very slight vibe, but would be totally livable, so If I can get to that point with the rear shaft installed, I'd call it good to go. This leads me to believe the vibe issue is still rear shaft or rear diff related.

ac_ said:
I know you said this happened after the gear change, but what does that change. Everything that spins spins faster now.
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That is literally the only thing that changed once I regeared the rear diff.

ac_ said:
I once had a customer with a camaro that had a slight vibration with a whine. I totally rebuilt his transmission and nothing changed. I took that one in the shorts. In the end it ended up being a wheel bearing. He got a free trans overhaul and a wheel bearing.
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I've checked and double checked the unit bearings and ball joints. I've also yanked the trany mount around to see if it has separated or something and it seems fine, but I have a new one ready to install once I find time to drop the skid and replace it.

I've also checked the exhaust system for rubbing, exhaust shields, etc. Nothing seems to be rubbing.

I'm going to revisit my rear pinion angle. It's 0.5* lower than the drive shaft right now, so I'll drop it 1* at a time until I get a change in something and go from there. @mrblaine, have you ever had to adjust the pinion higher than the drive shaft angle to cure a vibe?
 
IamBR549 said:
Have you tried changing gear oil just to see if it changes sound any? I did that to mine and noticed a change after first oil change. Not sure why


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I've changed oil twice in the 20K miles I've put on the new gears, once after break in, and then again a few months ago to inspect the gears. Does anything look out of ordinary?
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Honestly I never had vibrations in any of my jeeps. Although this is my first TJ and it is not lifted yet and you are scaring me a little, but my old YJ had a 6 inch (spring over + 2.5 OME springs) and it had a 8.8 ford so the pinion was slightly off center. I did to a sye but I actually did it after the 2.5 lift but never changed the driveline after the spring over so my driveline was over extended and off to one side and it never vibrated. I mean I ran the old style KM'2s 33's at the time and you could of course feel those, but it was at all speeds not at any certain speed on the freeway and it was slight. Like you said obvious the tires.

That is why I question this 4 link suspension, because the 4 leaf spring. I had bent springs and my rear pinion wasn't centered and the angle wasn't perfect but it drove fine. Also thinking about it. I removed the front and rear track bars so my axles were only bolted to the leaf springs. I keep forgetting about that because that was one of my first mods was throwing those in the garbage. I know we can't do that with the 4 link, but they weren't necessary in the YJ. CJ's didn't have them.

You definitely have me nervous to lift mine, especially because I am planning the same lift as you plus a SYE.
 
ac_ said:
Honestly I never had vibrations in any of my jeeps. Although this is my first TJ and it is not lifted yet and you are scaring me a little, but my old YJ had a 6 inch (spring over + 2.5 OME springs) and it had a 8.8 ford so the pinion was slightly off center. I did to a sye but I actually did it after the 2.5 lift but never changed the driveline after the spring over so my driveline was over extended and off to one side and it never vibrated. I mean I ran the old style KM'2s 33's at the time and you could of course feel those, but it was at all speeds not at any certain speed on the freeway and it was slight. Like you said obvious the tires.

That is why I question this 4 link suspension, because the 4 leaf spring. I had bent springs and my rear pinion wasn't centered and the angle wasn't perfect but it drove fine. Also thinking about it. I removed the front and rear track bars so my axles were only bolted to the leaf springs. I keep forgetting about that because that was one of my first mods was throwing those in the garbage. I know we can't do that with the 4 link, but they weren't necessary in the YJ. CJ's didn't have them.

You definitely have me nervous to lift mine, especially because I am planning the same lift as you plus a SYE.
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I've had this lift on for 10 years. Owned the jeep for 12 of those 10. Once I lowered the TC skid 3/4" after lifting it, I never had any vibrations. Drove it that way for 10 years and 3 sets of different mud tires. Drove smooth as glass up to 80. Didn't need to go any faster than that. It wasn't till I did the re-gear that this whole fiasco started, and that was before installing a SYE. Don't be scared to lift yours. My situation is obviously a unicorn.

Adjusted pinion angle three times today. Went from 0.5* to 1.5*, then to 3.0*. Put it back to 1.5*. No change. Gonna compare vibes on the way home tonight from the 3.0* setting to see what my butt dyno feels. I haven't tried going the other direction yet to where pinion angle is higher than the DS.
 
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hehe "Butt Dyno"

Ya I just put new tires on mine a couple of months ago. Smooth as class to 65 then vibrates like an old 70's motel magic finger mattress for till 70 then smooths out again. It is really annoying because the speed limit her is 65 so theres that. I have had it to two discount tires shops in my neighborhood and they can not even change it. No matter what they do same vibration, but I took off old cupped worn out K02's and it was smooth as glass up to 80. Not sure passed there as that is about where it tops out.

We don't have any good ma and pa 4x shops here so really all I have to work with is Discount tire and other retail tires stores like it. I happened by a Pep boys tire center just to see what they had to say and they said if Discount can't get the tires balance they wouldn't be able to either and didn't even want to try lol.

I am considering buying some aluminum wheels at 4wheel parts and see if they can do a better job balancing than Discount Tire, I am pretty frustrated. I have 31x10.5x15 Duratracs that are really about 30. I don't know if the tires are bad or if Discount Tire is, but Google tells me others have smooth balance with Duratracs, so not sure where to go from here. My Girlfriend doesn't think I should buy my own tire machine and balancer, but I can't seem to find anybody that uses theirs right haha.

Don't really want to lift it till I get that sorted out.

I posted the question in the geography section and a couple people responded about discount tires on the other side of town so I may try those first as they will be free, but super inconvenient.
 
ac_ said:
hehe "Butt Dyno"

Ya I just put new tires on mine a couple of months ago. Smooth as class to 65 then vibrates like an old 70's motel magic finger mattress for till 70 then smooths out again. It is really annoying because the speed limit her is 65 so theres that. I have had it to two discount tires shops in my neighborhood and they can not even change it. No matter what they do same vibration, but I took off old cupped worn out K02's and it was smooth as glass up to 80. Not sure passed there as that is about where it tops out.

We don't have any good ma and pa 4x shops here so really all I have to work with is Discount tire and other retail tires stores like it. I happened by a Pep boys tire center just to see what they had to say and they said if Discount can't get the tires balance they wouldn't be able to either and didn't even want to try lol.

I am considering buying some aluminum wheels at 4wheel parts and see if they can do a better job balancing than Discount Tire, I am pretty frustrated. I have 31x10.5x15 Duratracs that are really about 30. I don't know if the tires are bad or if Discount Tire is, but Google tells me others have smooth balance with Duratracs, so not sure where to go from here. My Girlfriend doesn't think I should buy my own tire machine and balancer, but I can't seem to find anybody that uses theirs right haha.

Don't really want to lift it till I get that sorted out.

I posted the question in the geography section and a couple people responded about discount tires on the other side of town so I may try those first as they will be free, but super inconvenient.
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Have you tried rotating the tires front to back and see if anything changes?
 
bobthetj03 said:
Have you tried rotating the tires front to back and see if anything changes?
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No because it has been laid up for the last month getting the custom switches in the dash put in, and messing with the front bumper, but I did notice that the rear wheels have considerably more weight on them. I will try that to see if it calms down, but my guess is it will shake my steering wheel. but ya I should try that just in case it is better.
 
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