another possible drive line vibe question

desertrunner said:
So the drive line guy in town said he can't spin the stock shaft. His equipment doesn't hold that style shaft and he said he doesn't know of anyone near me that can.

So still spitballing ideas here knowing that I did not have the vibe before the re gear. The shaft is the same the pinion angle is the same so assuming that isn't the issue, my thought is something in the rear diff. When I pull the rear shaft the vibration is gone so I can only imagine it has something to do with load on the diff and on the drive side of the gears.

I guess I can pop the rear cover again and check the tread pattern on the gears and make sure it was set up correctly in the first place?

I also could pull the carrier and spin the bearings on the carrier and pinion and see if anything is obviously messed up with the bearings?

One issue I'm seeing with pulling the carrier is the idiots that did my re gear routed the locker line right in front of the ring gear instead of over the top so I kinda risk popping a hole in that line by bending it more....
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You can spin the pinion without removing the carrier. If you want to check the gear pattern, clean things up and add some marking compound, then spin use the pinion to move the ring gear and take a look at the mesh. Things should look nice and centered.

(Check here if you need a visual)

https://wayalife.com/showthread.php...d-Thread/page8?p=686341&viewfull=1#post686341

As for the locker line, that's suspect. I would have them make that right. What a pain. But honestly, so long as they changed the bearings with quality components, and the gear mesh is right, I wouldn't pull the carrier out at all. Worst case, I'ed get some adjustable rear control arms and clean up the pinion angle... that way even if it doesn't solve the vibration, your pinion is set and you can upgrade the rear driveline at that point.

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DWiggles said:
You can spin the pinion without removing the carrier. If you want to check the gear pattern, clean things up and add some marking compound, then spin use the pinion to move the ring gear and take a look at the mesh. Things should look nice and centered.

(Check here if you need a visual)

https://wayalife.com/showthread.php...d-Thread/page8?p=686341&viewfull=1#post686341

As for the locker line, that's suspect. I would have them make that right. What a pain. But honestly, so long as they changed the bearings with quality components, and the gear mesh is right, I wouldn't pull the carrier out at all. Worst case, I'ed get some adjustable rear control arms and clean up the pinion angle... that way even if it doesn't solve the vibration, your pinion is set and you can upgrade the rear driveline at that point.

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I think just for piece of mind sake I might just pop the cover again and check the gear pattern just to make sure.

As far as the bearings go they were all replaced with the master instal kit that came with my trail leader package from dynatrac. HOWEVER when the shop was doing the instal they noticed that the pinion bearing was bad. They brought it out and showed me when they spun it it had an audible clicking and kinda ratcheting feeling to it. They had one in stock to use instead. I'd like to give them the benefit of the doubt that they wouldn't have put bad bearings in it on the carrier too but if 1 was bad maybe the others were too. Or the pinion bearing they had in stock that they used was bad or shitty quality who knows.

If I'm already pulling the cover to check the tread pattern would spinning the diff by hand give me any indications that the bearings are bad? Might I be able to hear clicking or anything that might clue me in?

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desertrunner said:
I think just for piece of mind sake I might just pop the cover again and check the gear pattern just to make sure.

As far as the bearings go they were all replaced with the master instal kit that came with my trail leader package from dynatrac. HOWEVER when the shop was doing the instal they noticed that the pinion bearing was bad. They brought it out and showed me when they spun it it had an audible clicking and kinda ratcheting feeling to it. They had one in stock to use instead. I'd like to give them the benefit of the doubt that they wouldn't have put bad bearings in it on the carrier too but if 1 was bad maybe the others were too. Or the pinion bearing they had in stock that they used was bad or shitty quality who knows.

If I'm already pulling the cover to check the tread pattern would spinning the diff by hand give me any indications that the bearings are bad? Might I be able to hear clicking or anything that might clue me in?

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It's possible, but ideally, you would need to spin it under load to know for sure, especially with the pinion bearings...

I would check the gear pattern, and photo document it. *do not pull the carrier

If the gear pattern isn't "perfect" I would put everything back together (driveshaft included) and head back to the shop that did the regear. Hold them 100% liable until it's right.

I hate when this kind of B.S. happens. To me, the inconvience on me is worth it to insure the shop does not fuck me over. I work hard for my money, and I'm sure you do as well.

EDIT: I would be back there just for the locker line if it were me... even if everything else checked out.

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desertrunner said:
I think just for piece of mind sake I might just pop the cover again and check the gear pattern just to make sure.

As far as the bearings go they were all replaced with the master instal kit that came with my trail leader package from dynatrac. HOWEVER when the shop was doing the instal they noticed that the pinion bearing was bad. They brought it out and showed me when they spun it it had an audible clicking and kinda ratcheting feeling to it. They had one in stock to use instead. I'd like to give them the benefit of the doubt that they wouldn't have put bad bearings in it on the carrier too but if 1 was bad maybe the others were too. Or the pinion bearing they had in stock that they used was bad or shitty quality who knows.

If I'm already pulling the cover to check the tread pattern would spinning the diff by hand give me any indications that the bearings are bad? Might I be able to hear clicking or anything that might clue me in?

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If your pinion spins and doesn't feel gritty or rough and has NO in and out play nor play while rocking it, the bearings are likely OK.
As far as the carrier, same thing. It should spin smoothly. If the carrier bearings have proper preload, you should be able to take a pry bar and pry the carrier sideways as hard as you want and it will not move. If the carrier moves at all, it was not set up correctly.
If for any reason you do replace a bearing, use the exact same part # to match what is there. Some bearings (although the exact application for the same vehicle) can have slightly different taper or roller count and will mess with the measurements.
 
Ok guys well I have ideas in my head in what I want to check.

I am going to buy a dial indicator pull the cover and check the gear pattern, check backlash, and make sure the ring gear isn't warped or anything. And check the bearings best I can without pulling the carrier.

(Read some other info on the internet that someone was getting the same vibes I described due to a warped ring gear.)

If all that checks good then I'll try buying some adjustable rear uppers and set the pinion in line with the DS and see if that helps.

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desertrunner said:
Ok guys well I have ideas in my head in what I want to check.

I am going to buy a dial indicator pull the cover and check the gear pattern, check backlash, and make sure the ring gear isn't warped or anything. And check the bearings best I can without pulling the carrier.

(Read some other info on the internet that someone was getting the same vibes I described due to a warped ring gear.)

If all that checks good then I'll try buying some adjustable rear uppers and set the pinion in line with the DS and see if that helps.

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A dial indicator is a great tool to have. If ring gear does end up having runout, also check the flange of the carrier itself. It's possible, but unlikely that the gear wasn't stoned properly prior to bolting on too if the gear has runout but carrier doesn't. This is really uncommon but if there were a machined imperfection on the gear that wasn't filed off, it could cause an untrue mating surface.
 
WJCO said:
A dial indicator is a great tool to have. If ring gear does end up having runout, also check the flange of the carrier itself. It's possible, but unlikely that the gear wasn't stoned properly prior to bolting on too if the gear has runout but carrier doesn't. This is really uncommon but if there were a machined imperfection on the gear that wasn't filed off, it could cause an untrue mating surface.
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Yeah I'm not mad about buying a dial indicator.

Definelty going to check everything I can with the gears and set up and bearings what not. If everything checks out I'll prob end up fixing the DS angle next

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desertrunner said:
Ok so I messed with the pinion yoke and took some video. I don't know if moving the pinion yoke would give me any accurate information about backlash but here are the 2 vids I took. See if anything seems abnormal.

Also no play in or out or side to side with the pinion only rotation.

https://youtu.be/ylQqVxsGNp8

https://youtu.be/yk3NfO8wo9Y

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Neither one of those is an accurate determination of backlash. A proper test can only be done by holding the pinion tight and putting a dial indicator on the drive side of the ring gear tooth. It's a very minimal amount to measure. I think it's .007-.015 IIRC.
 
WJCO said:
Neither one of those is an accurate determination of backlash. A proper test can only be done by holding the pinion tight and putting a dial indicator on the drive side of the ring gear tooth. It's a very minimal amount to measure. I think it's .007-.015 IIRC.
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Yeah. Should be 6 to 10 thousandths. Need to remove axle shafts, hold pinion, set up dial indicator, and rock carrier to check.
 
WJCO said:
Neither one of those is an accurate determination of backlash. A proper test can only be done by holding the pinion tight and putting a dial indicator on the drive side of the ring gear tooth. It's a very minimal amount to measure. I think it's .007-.015 IIRC.
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fiend said:
Yeah. Should be 6 to 10 thousandths. Need to remove axle shafts, hold pinion, set up dial indicator, and rock carrier to check.
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Ok yeah I figured that wouldn't really tell me anything until I check the backlash the correct way BUT I figured I'd toss those vids up and see i anything stuck out to someone.

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desertrunner said:
Ok yeah I figured that wouldn't really tell me anything until I check the backlash the correct way BUT I figured I'd toss those vids up and see i anything stuck out to someone.

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Hard to tell but in your second video it looks like there is some lateral movement in your pinion. If so, something is wrong that needs to be fixed.
 
fiend said:
Hard to tell but in your second video it looks like there is some lateral movement in your pinion. If so, something is wrong that needs to be fixed.
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Pretty sure that's just me shaking the camera while filming, I gave it a good once over in every direction and it didn't budge other than rotate

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I went through this same evolution after my gears were done. I never could find a problem even after 3 driveshafts and two sets of gears. I checked everything I could think of. My theory in my situation is that it’s some sort of resonant frequency issue. I ended up installing a dampener on the T-case that was found on some older JK’s and played with my rear pinion angle until I got the vibration to a minimum. I still notice it just due to all the time I spent working on the issue but no one else notices. Not saying that is your issue, just sharing my experience which sounds very similar. I’m subscribing to this to see where it goes. Maybe I overlooked something. Best of luck.


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desertrunner said:
Ok yeah I figured that wouldn't really tell me anything until I check the backlash the correct way BUT I figured I'd toss those vids up and see i anything stuck out to someone.

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From the videos

Video 1 (the rear diff) definitely has MORE backlash than the front... :twocents:

But how much more is the question.
 
DWiggles said:
From the videos

Video 1 (the rear diff) definitely has MORE backlash than the front... :twocents:

But how much more is the question.
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The videos are both from the rear. The first is how much the pinion spins before it starts to turn the axle shafts the second is just the play in the pinion before it meets any resistance. Neither of which is really any accurate measurement of backlash.

The more and more I read on line I keep finding info about bigger gears making the drive shaft spin so much faster than before that it causes vibes. I'm running 4.88s with 33s up from 3.21s so I can't say that I'm all that surprised. I do still plan to pop the cover and check backlash and tread pattern just for my piece of mind but my bet is it has something to do with the pinion angle.

I might just end up buying a set of rear uppers to set the pinion directly in line. Even if that isn't the issue at least it will be set up for later if I go 1350.

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desertrunner said:
The videos are both from the rear. The first is how much the pinion spins before it starts to turn the axle shafts the second is just the play in the pinion before it meets any resistance. Neither of which is really any accurate measurement of backlash.

The more and more I read on line I keep finding info about bigger gears making the drive shaft spin so much faster than before that it causes vibes. I'm running 4.88s with 33s up from 3.21s so I can't say that I'm all that surprised. I do still plan to pop the cover and check backlash and tread pattern just for my piece of mind but my bet is it has something to do with the pinion angle.

I might just end up buying a set of rear uppers to set the pinion directly in line. Even if that isn't the issue at least it will be set up for later if I go 1350.

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The factory shaft should not produce any vibes regardless of the pinion angle pending it is properly balanced. I’d be more concerned with the balance than getting the pinion angle dialed in. I suspect it’s neither of those things. Just my two pennies.


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desertrunner said:
The videos are both from the rear. The first is how much the pinion spins before it starts to turn the axle shafts the second is just the play in the pinion before it meets any resistance. Neither of which is really any accurate measurement of backlash.
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Got it, disregard my previous observation, I was misinterpreting.

desertrunner said:
The more and more I read on line I keep finding info about bigger gears making the drive shaft spin so much faster than before that it causes vibes. I'm running 4.88s with 33s up from 3.21s so I can't say that I'm all that surprised. I do still plan to pop the cover and check backlash and tread pattern just for my piece of mind but my bet is it has something to do with the pinion angle.

I might just end up buying a set of rear uppers to set the pinion directly in line. Even if that isn't the issue at least it will be set up for later if I go 1350.
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so, if you now have a vibration starting at around 40mph with the new gears, your driveshaft was previously spinning at the very nearly the same speed (assuming tires didn't change) at ~((4.88/3.21) * 40mph) or 60.8mph... wouldn't you have felt the same vibration prior to the regear from that logic? only at 61+mph before the regear vs 40+mph now that the gears were changed? :idontknow:

If the only thing that could have changed is the regear, then I would naturally suspect something with that to be the issue... I could see getting an unknown vibration at 60+ mph after regear as the driveshaft would be spinning about 1.5x faster than it ever had before, but in this example that simply doesn't appear to be the case. :hmm:

If we think this through, there are only 2 options:
(1) SOMETHING changed causing the driveshaft to get out of balance or;
(2) there is some issue with the regear that is causing a vibration IN the driveline
*since pulling the driveline eliminates the vibration this could point to a possible pinion bearing/preload/crushsleeve issue perhaps, OR see (1)

I would focus on finding someone who can get the driveline balanced, or barrow one from a friend to test, if a KNOWN good rear driveline still vibrates, then it HAS to be something with the regear, and the shop that did the work should be held liable... :twocents:
 
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So that vibe I had at 45 in my original post got remedied with getting my front driveshaft dialed in. The one I'm fighting now is the one at 60+ so the driveshaft is spinning much faster than it ever was with the previous gears.

I do still plan to pull the cover and check the gears and set up to hopefully rule out a bad gear set or a shitty set up. I'd like to give them the benefit of the doubt but they did not impress me during the instal.

I'll be able to get working on this in the next few days and post up my findings

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desertrunner said:
So that vibe I had at 45 in my original post got remedied with getting my front driveshaft dialed in. The one I'm fighting now is the one at 60+ so the driveshaft is spinning much faster than it ever was with the previous gears.

I do still plan to pull the cover and check the gears and set up to hopefully rule out a bad gear set or a shitty set up. I'd like to give them the benefit of the doubt but they did not impress me during the instal.

I'll be able to get working on this in the next few days and post up my findings

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Unless you were doing 90+ mph before the regear of course...

Sounds good, keep us posted. I'm subscribed and will help where I can :thumb:

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