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

[DWLJ]

Oh, great all with the same issue and no sure fix. I am having the same issue after re-gear. 05 lj 4speed auto OD. 4" lift, first and got slight vibs, installed SYE and adjusted angle and went down to almost nothing and tolerable. Then re-geared to 4:88 and much worse, pulled front DS and replaced u-joints and had balanced, only slightly better. I have not tried running it in 4 high at 65+ but I will try that next and see if there is any change. This is my first jeep and would really like to find a jeep pro to drive it and see if this is normal after

 

[Greg]

I posted in this thread a few months ago and I’m still having vibes above 65. To recap, I’ve replaced everything in the driveline (d-shafts, yokes, bearings, chain, trans mount) except the front output shaft and the engine mounts, which will probably get done this spring. The vibe is completely gone with the front d shaft out. I rebuilt the transfer case because my front output shaft had some vertical play. The front output pilot bearing that came in my rebuild kid didn’t have a bearing cage to hold the needles in place, the needles just rode in the case next to each other. I did some research and that particular style bearing is only rated to about 4300 rpm. I still had the same vibes after the rebuild so I tore it down again and replaced that pilot bearing with one rated for 8600rpm. Even with the much tighter toleranced pilot bearing I could still feel a tiny bit of play on the front output shaft. The shaft diameter is exactly what it should be on all bearing surfaces, so I’m still stumped. The 8600rpm bearing didn’t fix the issue, but it reduced the vibes significantly, I can actually drive it on the highway with the front shaft in now, I just keep it at 65. I’m wondering if the tolerances in the np231 are just not tight enough to handle the higher rpms of running 4:56 gears on 33’s.

https://www.amazon.com/dp/B007EDPEK2/?tag=wranglerorg-20

 

[bobthetj03]

No resolution for me as of yet. I've replaced pretty much everything except motor mounts, unit bearings, and a left rear axle bearing. I've played with the rear pinion angle, and have it to where the vibes are tolerable. Mostly just a harmonic now until I get above 65 mph, then I can feel it in the steering wheel and the seat. This morning commute to work developed a new noise I haven't heard before. My wife, who commutes to work with me, says she's heard the noise before, but now it's louder, so it is within my audible range apparently. It is a whirring harmonic. It's cyclic and higher pitched. Between the vibes, the noise from my half worn out KM2's, and now the whirring, I am just bombarded with noises. Been just turning up the stereo to drown it all out. Hey @Rob5589 , what say you about my new noise? Think I got a pinion bearing or axle bearing crying?

 

[Mike_H]

I posted in this thread a few months ago and I’m still having vibes above 65. To recap, I’ve replaced everything in the driveline (d-shafts, yokes, bearings, chain, trans mount) except the front output shaft and the engine mounts, which will probably get done this spring. The vibe is completely gone with the front d shaft out. I rebuilt the transfer case because my front output shaft had some vertical play. The front output pilot bearing that came in my rebuild kid didn’t have a bearing cage to hold the needles in place, the needles just rode in the case next to each other. I did some research and that particular style bearing is only rated to about 4300 rpm. I still had the same vibes after the rebuild so I tore it down again and replaced that pilot bearing with one rated for 8600rpm. Even with the much tighter toleranced pilot bearing I could still feel a tiny bit of play on the front output shaft. The shaft diameter is exactly what it should be on all bearing surfaces, so I’m still stumped. The 8600rpm bearing didn’t fix the issue, but it reduced the vibes significantly, I can actually drive it on the highway with the front shaft in now, I just keep it at 65. I’m wondering if the tolerances in the np231 are just not tight enough to handle the higher rpms of running 4:56 gears on 33’s.

That is an interesting find...not one that I think I've heard of, but it instantly "makes sense"

 

[Rob5589]

No resolution for me as of yet. I've replaced pretty much everything except motor mounts, unit bearings, and a left rear axle bearing. I've played with the rear pinion angle, and have it to where the vibes are tolerable. Mostly just a harmonic now until I get above 65 mph, then I can feel it in the steering wheel and the seat. This morning commute to work developed a new noise I haven't heard before. My wife, who commutes to work with me, says she's heard the noise before, but now it's louder, so it is within my audible range apparently. It is a whirring harmonic. It's cyclic and higher pitched. Between the vibes, the noise from my half worn out KM2's, and now the whirring, I am just bombarded with noises. Been just turning up the stereo to drown it all out. Hey @Rob5589 , what say you about my new noise? Think I got a pinion bearing or axle bearing crying?

A fast whirring could be pinion bearings, especially if it increases when the speed increases. Axle bearings are usually slower sounding and more of a grinding, sometimes increasing when turning and loading up that particular side.

 

[jeepndogs]

I posted in this thread a few months ago and I’m still having vibes above 65. To recap, I’ve replaced everything in the driveline (d-shafts, yokes, bearings, chain, trans mount) except the front output shaft and the engine mounts, which will probably get done this spring. The vibe is completely gone with the front d shaft out. I rebuilt the transfer case because my front output shaft had some vertical play. The front output pilot bearing that came in my rebuild kid didn’t have a bearing cage to hold the needles in place, the needles just rode in the case next to each other. I did some research and that particular style bearing is only rated to about 4300 rpm. I still had the same vibes after the rebuild so I tore it down again and replaced that pilot bearing with one rated for 8600rpm. Even with the much tighter toleranced pilot bearing I could still feel a tiny bit of play on the front output shaft. The shaft diameter is exactly what it should be on all bearing surfaces, so I’m still stumped. The 8600rpm bearing didn’t fix the issue, but it reduced the vibes significantly, I can actually drive it on the highway with the front shaft in now, I just keep it at 65. I’m wondering if the tolerances in the np231 are just not tight enough to handle the higher rpms of running 4:56 gears on 33’s.

I think you are heading in the right direction with this. I had the same issue but chose to do a hub conversion to stop the front shaft from spinning to solve it. I did however meet a guy at a Jeep event recently that was some sort of problem solver wizard for Jeep. Apparently he travels all over the country fixing issues other guys can’t. He also drives a lifted Lj on 35,s with 5.38’s. He took one look at my Lj with the hub conversion and the first thing he asked was if I did that to correct a vibration. After answering him he started to explain what he knew about the problem. He started with anything over 3in of lift starts to exceed the angle of the front cv joint. It’s not at its max but it lowers the RPM it can spin at without vibration. The gearing starts to exceed the joint RPM and causes the shaft to spin almost in an oval. Then the tolerance stacking starts to come into play. The shaft diameter isn’t large enough to prevent deflection so that starts to flex, then the front output of the TC starts to move around. The TC is mounted to a big flat pan and once the harmonics are transferred to the skid plate it resonates up into the tub causing the harmonic noise that is heard in the Jeep.

He claims the only way to stop it is to reduce the angle of the CV joint, slow the joint down, or stop it from spinning. He had raised the TC and said it actually decreases the angle of the front CV without adding too much angle to the rear. Absolutely no clue if any of this is really true but he sure sounded like he knew what he was talking about and I went for a ride in his Lj and there were no vibes and or noises at 75+ except for the tire noise from the MT’s

 

[lowranger]

I think you are heading in the right direction with this. I had the same issue but chose to do a hub conversion to stop the front shaft from spinning to solve it. I did however meet a guy at a Jeep event recently that was some sort of problem solver wizard for Jeep. Apparently he travels all over the country fixing issues other guys can’t. He also drives a lifted Lj on 35,s with 5.38’s. He took one look at my Lj with the hub conversion and the first thing he asked was if I did that to correct a vibration. After answering him he started to explain what he knew about the problem. He started with anything over 3in of lift starts to exceed the angle of the front cv joint. It’s not at its max but it lowers the RPM it can spin at without vibration. The gearing starts to exceed the joint RPM and causes the shaft to spin almost in an oval. Then the tolerance stacking starts to come into play. The shaft diameter isn’t large enough to prevent deflection so that starts to flex, then the front output of the TC starts to move around. The TC is mounted to a big flat pan and once the harmonics are transferred to the skid plate it resonates up into the tub causing the harmonic noise that is heard in the Jeep.

He claims the only way to stop it is to reduce the angle of the CV joint, slow the joint down, or stop it from spinning. He had raised the TC and said it actually decreases the angle of the front CV without adding too much angle to the rear. Absolutely no clue if any of this is really true but he sure sounded like he knew what he was talking about and I went for a ride in his Lj and there were no vibes and or noises at 75+ except for the tire noise from the MT’s

Did he say that was a good call on your part to do the hub conversion to stop the vibration? Did he suggested that as another option to stop the vibration?

 

[Greg]

I think you are heading in the right direction with this. I had the same issue but chose to do a hub conversion to stop the front shaft from spinning to solve it. I did however meet a guy at a Jeep event recently that was some sort of problem solver wizard for Jeep. Apparently he travels all over the country fixing issues other guys can’t. He also drives a lifted Lj on 35,s with 5.38’s. He took one look at my Lj with the hub conversion and the first thing he asked was if I did that to correct a vibration. After answering him he started to explain what he knew about the problem. He started with anything over 3in of lift starts to exceed the angle of the front cv joint. It’s not at its max but it lowers the RPM it can spin at without vibration. The gearing starts to exceed the joint RPM and causes the shaft to spin almost in an oval. Then the tolerance stacking starts to come into play. The shaft diameter isn’t large enough to prevent deflection so that starts to flex, then the front output of the TC starts to move around. The TC is mounted to a big flat pan and once the harmonics are transferred to the skid plate it resonates up into the tub causing the harmonic noise that is heard in the Jeep.

He claims the only way to stop it is to reduce the angle of the CV joint, slow the joint down, or stop it from spinning. He had raised the TC and said it actually decreases the angle of the front CV without adding too much angle to the rear. Absolutely no clue if any of this is really true but he sure sounded like he knew what he was talking about and I went for a ride in his Lj and there were no vibes and or noises at 75+ except for the tire noise from the MT’s

Very interesting. Thanks for posting this. It does make sense that raising the t case will reduce your front cv angle since the fulcrum is on the engine mounts. I’m thinking it would be pretty easy to do a quick experiment to see if I get any significant change in vibes by bringing the t case up a bit. I wonder if any guys running belly up skids are having these vibe issues?

 

[jeepndogs]

Very interesting. Thanks for posting this. It does make sense that raising the t case will reduce your front cv angle since the fulcrum is on the engine mounts. I’m thinking it would be pretty easy to do a quick experiment to see if I get any significant change in vibes by bringing the t case up a bit. I wonder if any guys running belly up skids are having these vibe issues?

Well the hub conversion falls into the category of stopping the shaft from spinning. I fought this for months and spent way more than doing the conversion trying to solve the issue. After sucking it up and doing the conversion I drove it to the Jeep Jamboree in Wisconsin where I met the guy. I averaged 75-80 for 5 hours each way and there was no vibrations. I have $1600.00 in the conversion not including the rims. I opted to go with the big bolt pattern that is 5x5.5. But you can do it and keep the 5x4.5 as long as your wheel has a 108mm bore center.

 

[bobthetj03]

Well the hub conversion falls into the category of stopping the shaft from spinning. I fought this for months and spent way more than doing the conversion trying to solve the issue. After sucking it up and doing the conversion I drove it to the Jeep Jamboree in Wisconsin where I met the guy. I averaged 75-80 for 5 hours each way and there was no vibrations. I have $1600.00 in the conversion not including the rims. I opted to go with the big bolt pattern that is 5x5.5. But you can do it and keep the 5x4.5 as long as your wheel has a 108mm bore center.

So if I understand what you're saying, raising the TC helps with the angle of the front DS?

 

[jeepndogs]

So if I understand what you're saying, raising the TC helps with the angle of the front DS?

Yes, the entire driveline slopes down towards the rear of the Jeep. If you look the front TC output shaft actually points up. Since the pivot point is the motor mount when the back of the tail shaft is moved up it actually makes the front TC output move down which decreases the front CV joint angle. From what I was told the TC output pointed up from the factory was the reason the CV joint was used from the factory. That was how they took care of the front driveshaft angle.

What he said made sense to me. Basically the TC points up, and the front shaft angles down. From the factory that angle was 8-9 degrees or something like that in total. When we lift over 3in that increases the downward angle of the driveshaft which changes the total angle of the CV to 12-13 degrees(could be wrong on the exact angle he said) Spicer rates the joints for RPM based on angles, at the 12-13 degrees the joint is approved for around 3500 RPM of driveshaft speed, after that it apparently can’t cancle out the vibrations. With a 33 ( which usually measure around 32) and 4.56 and higher gearing the driveshaft will hit 3500 around 60-65.

I spent several hours with the guy talking about this. He either really knew what he was talking about or he could bullshit with the best of them. Considering his Jeep has absolutely no vibration and he has apparently driven it from upper Wisconsin to Moab a few times I assume he knew what he was talking about.

I myself never attempted to raise the TC to see if it helped because I had already done the hub conversion and the vibration was gone. I do have a tummy tuck planned at some point and for the hell of it I will test his theory when I do it.

 

[bobthetj03]

Yes, the entire driveline slopes down towards the rear of the Jeep. If you look the front TC output shaft actually points up. Since the pivot point is the motor mount when the back of the tail shaft is moved up it actually makes the front TC output move down which decreases the front CV joint angle. From what I was told the TC output pointed up from the factory was the reason the CV joint was used from the factory. That was how they took care of the front driveshaft angle.

What he said made sense to me. Basically the TC points up, and the front shaft angles down. From the factory that angle was 8-9 degrees or something like that in total. When we lift over 3in that increases the downward angle of the driveshaft which changes the total angle of the CV to 12-13 degrees(could be wrong on the exact angle he said) Spicer rates the joints for RPM based on angles, at the 12-13 degrees the joint is approved for around 3500 RPM of driveshaft speed, after that it apparently can’t cancle out the vibrations. With a 33 ( which usually measure around 32) and 4.56 and higher gearing the driveshaft will hit 3500 around 60-65.

I spent several hours with the guy talking about this. He either really knew what he was talking about or he could bullshit with the best of them. Considering his Jeep has absolutely no vibration and he has apparently driven it from upper Wisconsin to Moab a few times I assume he knew what he was talking about.

I myself never attempted to raise the TC to see if it helped because I had already done the hub conversion and the vibration was gone. I do have a tummy tuck planned at some point and for the hell of it I will test his theory when I do it.

It may help the front, but won't it do the opposite effect with the rear DS and make the angles worse? I too am planning a TT, so we shall see. Probably won't help my scenario cause my vibes are coming from the rear DS.

 

[jeepndogs]

It may help the front, but won't it do the opposite effect with the rear DS and make the angles worse? I too am planning a TT, so we shall see. Probably won't help my scenario cause my vibes are coming from the rear DS.

Don’t know for sure but I’m thinking the rear is pointed down and the front was up from the factory, raising the rear may level them both? Like I said, never tried it but it sounded good coming from the guy and his didn’t have the vibe.

 

[bobthetj03]

Don’t know for sure but I’m thinking the rear is pointed down and the front was up from the factory, raising the rear may level them both? Like I said, never tried it but it sounded good coming from the guy and his didn’t have the vibe.

Wouldn't that be just awesome sauce if a TT cured it? I'd be in jeep heaven!!!

 

[jeepndogs]

Wouldn't that be just awesome sauce if a TT cured it? I'd be in jeep heaven!!!

Sounds like you have a new project to get started on! Lol!

 

[bobthetj03]

Sounds like you have a new project to get started on! Lol!

Yep, First part of it is already ordered.

 

[DWLJ]

Yep, First part of it is already ordered.

Whats involved with the TT? I have looked for a thread but maybe not looking in the right spot?? Is there other options I should be looking at to raise the TC? I am willing to try anything at this point to get rid of the vibration.

 

[bobthetj03]

Whats involved with the TT? I have looked for a thread but maybe not looking in the right spot?? Is there other options I should be looking at to raise the TC? I am willing to try anything at this point to get rid of the vibration.

Quite a bit actually.
Adjustable rear control arms
Slip yoke eliminator/DC drive shaft (Rubi models just DC drive shaft).
Body lift
Some say motor mount lift, but I'm gonna try without it.
TC shift linkage(not sure if I'll be able to adjust it without going the cable shifter route).
Exhaust modifications. Cat or muffler is gonna be in the way.
I'm sure there's more, but that's the jist of it.

 

[DWLJ]

Quite a bit actually.
Adjustable rear control arms
Slip yoke eliminator/DC drive shaft (Rubi models just DC drive shaft).
Body lift
Some say motor mount lift, but I'm gonna try without it.
TC shift linkage(not sure if I'll be able to adjust it without going the cable shifter route).
Exhaust modifications. Cat or muffler is gonna be in the way.
I'm sure there's more, but that's the jist of it.

ok thanks,
I have the adjustable RCA, and the SYE, DC drive shaft, just need to do the body lift, ( i was hopping not to but if I have to I will )

 

[bobthetj03]

ok thanks,
I have the adjustable RCA, and the SYE, DC drive shaft, just need to do the body lift, ( i was hopping not to but if I have to I will )

Depends on how much tuck you want to do. You might be able to get away with a mild tuck without a BL. Just need to crawl under there and do some measuring.

In vibe related news, crawled under the jeep yesterday to check the rear drive shaft bolts. They were tight. However, one of the jam nuts on my left upper CA was loose, really loose. These vibes are knocking shit loose, or I didn't tighten the jamb nut tight enough.