Driveline vibrations...

[EJD]

I talked recently to one member and got some sound advice but I wanted to make a thread and see what the forum has to say about my specific vibes that i'm experiencing right now.

So I read the thread @Chris made (Is Your Jeep Wrangler TJ Experiencing Vibrations or Death Wobble? READ THIS!), if your experiencing driveline vibes, read this...and I did but i'm still not totally sure where to go with all this. The vibes i'm experiencing seem to have happened after I installed my 1" H&R Springs and more recently after my ZJ Tie Rod Conversion, I feel like i'm getting one more vibration that wasn't there before the install. Not 100% sure.

Anyhow I have tried my best to track the vibrations so I could list them here. First they are kind of minimal vibrations that are more just annoying than anything. I have 2 vibrations, one between 30-35mph, and one between 55-60mph. That 55-60 is the worst of the 2 because its in that sweet spot of speed limit cruising. I have also noticed that I can feel the vibration through the floor with my left foot in the dead pedal area. I would also like to note that the vibrations do go away instantly if you take your foot off the gas pedal while it vibrating.

I have done some visual checks of the front driveshaft u-joints and they look to be intact, though I didn't lift the vehicle to check up/down/side/side movements but all the caps look good from what I can see. I have checked the track bar at both ends for looseness, nothing. And so far visually, the only thing that looks bad at all are the Control Arm bushings, they are dry-rotted pretty good, specifically the LCA bushings.

Are bad Control Arm bushings enough to cause the types of vibrations i'm describing or am I overlooking something? Or should I be checking other things further, would pics of anything be of any assistance? Any help here would be great! Thank you in advance.

 

[Chris]

Well, the first thing to check for obviously is that everything is torqued down to the proper specs.

I'm not 100% sure about bad control arm bushings causing vibrations. I would think they would be more likely to cause slop when accelerating, turning, etc. I wouldn't think they'd cause vibrations.

I know it seems unlikely, but I always think something like this ends up being a tire balancing issue.

 

[EJD]

I know it seems unlikely, but I always think something like this ends up being a tire balancing issue.

I hear that, but can tires just come out-of-balance a year after being in-balance? There was no vibes prior to me doing a few projects but everything was torqued to spec that I personally touched. I'll definitely keep checking things out, I more/less wanted to see if any of my symptoms sound familiar and direct towards a certain area or not...or if certain things may be wearing out that are causing vibrations.

 

[Chris]

I hear that, but can tires just come out-of-balance a year after being in-balance? There was no vibes prior to me doing a few projects but everything was torqued to spec that I personally touched. I'll definitely keep checking things out, I more/less wanted to see if any of my symptoms sound familiar and direct towards a certain area or not...or if certain things may be wearing out that are causing vibrations.

Actually yes, they can. One of those little weights can get knocked off. I am not saying that’s the problem for sure, but most people end up chasing these vibrations like crazy only to find out it was indeed the tires out of balance. 9 out of 10 times that seems to be the case.

The other thing I would suspect would be a u-joint.

 

[EJD]

Actually yes, they can. One of those little weights can get knocked off. I am not saying that’s the problem for sure, but most people end up chasing these vibrations like crazy only to find out it was indeed the tires out of balance. 9 out of 10 times that seems to be the case.

The other thing I would suspect would be a u-joint.

So hypothetically, if a tire were out of balance and i'm feeling it up front, if I rotated the tires (front to back) the vibration would potentially go away? or to the back...that would mean my tires are for sure out of balance, but if I rotated the tires and the vibration was still there...then its something else. Right?

 

[bobthetj03]

Explain your vibration a little more in detail. You say you feel it in the floor with your feet? What's going on with steering wheel feel? Do you also feel it in your seat? Is the vibe heard, or heard and felt? Why do you think it's a driveline vibe?

 

[Chris]

So hypothetically, if a tire were out of balance and i'm feeling it up front, if I rotated the tires (front to back) the vibration would potentially go away? or to the back...that would mean my tires are for sure out of balance, but if I rotated the tires and the vibration was still there...then its something else. Right?

If it’s an unbalanced wheel, the vibration isn’t going to go away with tire rotation. It will still be there until the wheel is rebalanced.

 

[EJD]

Explain your vibration a little more in detail. You say you feel it in the floor with your feet? What's going on with steering wheel feel? Do you also feel it in your seat? Is the vibe heard, or heard and felt? Why do you think it's a driveline vibe?

I say I feel the vibration in the floor with my left foot, as its always on the floor and its most noticeable there, but its the whole area under the pedals that I can feel it in. Anywhere between 55-60mph its most noticeable, and only noticeable while accelerating. If it's happening and I take my foot off the gas, the vibration stops immediately, then if I hit the gas again it vibrates again (otherwise smooth sailing). The steering wheel doesn't really vibrate like I feel it in the floor but you can feel the slightest vibration in it while its happening. Do not feel it in the seat at all, and the vibration is heard and felt. I thought thats what all vibrations while driving/accelerating were called...dunno, guess it could be another type of vibration than driveline. Though after reading that thread up top, it sounded like what it was called.

If it’s an unbalanced wheel, the vibration isn’t going to go away with tire rotation. It will still be there until the wheel is rebalanced.

I didn't mean the vibration would go away permanently, I meant it in the sense that it would feel/sound weaker or different than in the front. If the vibration is felt up front and not in the back it would imply one of the front wheels would be out of balance, and not a rear wheel, correct? So if you rotate front to back, and the vibration follows, that would help single it out.

 

[Jeepaholic]

The part that makes me say not a tire out of balance is the vibe goes away when throttle is released. This is a power train vibe to me.

 

[Chris]

The part that makes me say not a tire out of balance is the vibe goes away when throttle is released. This is a power train vibe to me.

X2 to this. If the vibration goes away when you release the throttle, it's drivetrain related. Sounds like it could be a u-joint possibly.

 

[EJD]

The part that makes me say not a tire out of balance is the vibe goes away when throttle is released. This is a power train vibe to me.

Good point.

A few folks have mentioned u-joints as a possibility and i'll have to do some homework on that topic and see whats the best way to check those and narrow things down more.

 

[JMT]

It showed up when you put the 1” H&R springs. All our TJ’s are different. I would not expect a 1” SL to cause vibrations. HOwever, check your real lift by measuring the front and rear springs. Stock front is 12” and rear is 8”. Anything over that is your true lift. It’s a free check and it will be interesting to see what we learn from your situation. I suspect that if you do a TCase drop, maybe just 1/4” with some washers, you’re vibes will go away. It is causally related to your SL and only under acceleration, so a driveline issue.

 

[EJD]

It showed up when you put the 1” H&R springs. All our TJ’s are different. I would not expect a 1” SL to cause vibrations. HOwever, check your real lift by measuring the front and rear springs. Stock front is 12” and rear is 8”. Anything over that is your true lift. It’s a free check and it will be interesting to see what we learn from your situation. I suspect that if you do a TCase drop, maybe just 1/4” with some washers, you’re vibes will go away. It is causally related to your SL and only under acceleration, so a driveline issue.

Yeah, its hard to remember if I noticed it right after the H&R spring install, but the suspension, steering, and cooling system upgrades are all i've done up front. So its either something was affected by one of those things and changed something or something is going bad from normal wear and tear.

What will the lift check do? Give you the amount to drop the TC? Also check this at full droop i'm assuming?
I could also throw it in neutral at the same time and check the driveshaft for any play, right?

 

[Jeepaholic]

I have a similar vibe, kinda buzzy but barely felt, and goes away when throttle is released. I actually just took my rear drive shaft out today to inspect as there was no movement by grabbing it while installed. One u joint had a bit of wetness around it but that's it. Is that bad?

 

[JMT]

Yeah, its hard to remember if I noticed it right after the H&R spring install, but the suspension, steering, and cooling system upgrades are all i've done up front. So its either something was affected by one of those things and changed something or something is going bad from normal wear and tear.

What will the lift check do? Give you the amount to drop the TC? Also check this at full droop i'm assuming?
I could also throw it in neutral at the same time and check the driveshaft for any play, right?

Just check spring measurements with it on the ground. Easy peasy. Only thing it will do is tell you your true lift. Buying a 1” lift doesn’t necessarily mean you will get 1” of lift. If you’re closer to 1.5 or 1.75, driveline issues would just be more likely in my mind. But, there have been stranger things. Mostly it’s for all of our benefit in knowing what could happen to our TJ’s.

Let’s just see what the lift is. Then try a small TC drop (1/4-1/2”) and go from there.

 

[EJD]

Just check spring measurements with it on the ground. Easy peasy. Only thing it will do is tell you your true lift. Buying a 1” lift doesn’t necessarily mean you will get 1” of lift. If you’re closer to 1.5 or 1.75, driveline issues would just be more likely in my mind. But, there have been stranger things. Mostly it’s for all of our benefit in knowing what could happen to our TJ’s.

Let’s just see what the lift is. Then try a small TC drop (1/4-1/2”) and go from there.

True lift here is 3/4" up front currently. Which kind of makes sense since when I installed them and I measured the difference (before and after) and only got 1" or a 16th under. Since then i've installed aftermarket bumpers and have a winch on there too, so makes sense that the lift would drop a touch more. However that sucks too because now I think I need the 0.75" spacers.

Also your mention of the TC drop got me thinking, i've had a frame repair too (safe-t-caps) both center skid plate sections. I'm wondering since those particular sections of the frame (which are what the TC skid mounts to) is now higher or lower than stock. Does that make sense?

It would be great if I took that measurement before hand to rule it out, but if I had someone else that could measure from the top of the frame to the top of the stock TC skid plate, I could check that against mine to see if I already have a TC drop or lift in effect and didn't even know it.

 

[JMT]

True lift here is 3/4" up front currently. Which kind of makes sense since when I installed them and I measured the difference (before and after) and only got 1" or a 16th under. Since then i've installed aftermarket bumpers and have a winch on there too, so makes sense that the lift would drop a touch more. However that sucks too because now I think I need the 0.75" spacers.

Also your mention of the TC drop got me thinking, i've had a frame repair too (safe-t-caps) both center skid plate sections. I'm wondering since those particular sections of the frame (which are what the TC skid mounts to) is higher or lower than stock. Does that make sense?

It would be great if I took that measurement before hand to rule it out, but if I had someone else that could measure from the top of the frame to the top of the stock TC skid plate, I could check that against mine to see if I already have a TC drop or lift in effect and didn't even know it.

I think I know what measurement you're asking for. I'd whip out and do it now, but I'm at work till 7pm CST. Probably, hopefully, someone will beat me to it. If I get a chance at lunch I'll track down a measuring tape here at work and post up w pic to make sure I'm measuring what you're interested in. Strange to me the frame repair would change the height of the TC skid mount though, but I don't know much about frame repairs.

 

[EJD]

I think I know what measurement you're asking for. I'd whip out and do it now, but I'm at work till 7pm CST. Probably, hopefully, someone will beat me to it. If I get a chance at lunch I'll track down a measuring tape here at work and post up w pic to make sure I'm measuring what you're interested in. Strange to me the frame repair would change the height of the TC skid mount though, but I don't know much about frame repairs.

Yeah, i'm not 100% sure if it does change anything but it got me wondering if it did and I didn't even realize it.
If you or anyone else can, that would be great and thank you in advance! I would maybe need a measurement at the front and back of both sides if possible.

Also for my rear compressed spring height should be 8" at stock height?