Help diagnosing vibrations and wobble

[BassCat976]

I need a little help diagnosing a shake/wobble/heavy vibration that recently started on our TJ. 1997 2.5L 5 speed, in November I added a RC 3.25" lift, which is essentially their 2.5" springs and a 3/4" spacer. We've put about 750 miles on it since then with no issues. Running 31/10.5 R15 on 15x8" rims

2 weeks ago my wife drove it and it started shaking on her, so much for her she actually ran off on the shoulder trying to come to a stop. Called me I was thinking death wobble, so I met her, let her drive another vehicle home and I drove the tj, at that time I could not recreate the problem.

This week I went through and inspected underneath and checked tightness on all components related to the lift, nothing noticeably out of whack, the front track bar did need the axle side bolt retorqued, it was slightly loose. Test drove it and now I can fairly consistently get it to react and shake. Here's what it does:

At somewhere around 45 you can feel a vibration that gets worse as you get closer to 50, its not subtle its pretty violent and will shake yout phone or whatever right off the dash. I feel it mostly in the seat of my pants, almost a side to side like someone is shaking the car. The steering seems to stay pretty steady, the wheel is definitely not getting pulled from my hand.
If I accelerate beyond 50 it goes away 99% there is a slight vibration that feels more like a tire out of balance. I've driven it up to 65 range and that's the only vibe in it.
Upon deceleration it will have that hard shake as it slows through that 45-50 mph range. It does seem more pronounced in 4th gear, but if I slow in 5th to the same speed range it will do it but a little less dramatic as its really lugging the engine at that point. I have not tried to take 3rd up to that speed.

Could this be a driveline vibration? What could have changed, broke, or loosened to have this start while my wife was driving? We've had it to 70+ multiple times since putting the lift on with no hint if a shaking or vibration issue until now.

I don't think its standard "Death Wobble" it seems more speed related, I've driven Dodge trucks most of my life and this shake is not in the wheel like one of hose truck was. The 4 lane near our house is pretty rough and bumps potholes etc, have not seemed to effect it at all.

Thanks, sorry for the long post but wanted as much info out as possible and be strategic on how I try to eliminate this.

 

[afitzray97]

Were the tires new with the lift? First thing I'd check is maybe a wheel weight somehow came off even though it seems pretty unlikely. Can you get to a tire shop going slower than 40?

After that, and assuming this is really not felt in the steering and thus not typical death wobble, the new lift would be binding the rear driveshaft more than it was before so start there. Maybe you finally put one of the ujoints beyond it's ability and it's failing. If this is the case, you really don't want to drive more than you need to until you figure out what's going on.

To diagnose, completely remove the rear driveshaft (use grease pen to mark everything so you can put it back the same way when you reinstall) and drive just long enough to get it up to 50 in 4wd (using just front driveshaft now). If the problem is still there, reinstall rear driveshaft (go ahead and replace ujoints while it's out) and remove the front. test again.

 

[CharlesHS]

To diagnose, completely remove the rear driveshaft (use grease pen to mark everything so you can put it back the same way when you reinstall) and drive just long enough to get it up to 50 in 4wd (using just front driveshaft now). If the problem is still there, reinstall rear driveshaft (go ahead and replace u joints while it's out) and remove the front. test again.

IF the rear driveshaft is removed and the Jeep is driven; there will be ATF coming from around the transfercase output shaft while driving the Jeep.
IF a SYE or a transfercase drop has not been installed; the vibrations felt are probably caused by the driveshaft angle on the U joint as posted above.

 

[afitzray97]

If you slip the stock driveshaft off the splines from the transfer case, it will leak?

 

[CharlesHS]

If you slip the stock driveshaft off the splines from the transfer case, it will leak?
View attachment 313206

There is a shaft seal inside, but it only seals when the driveshaft yoke is installed.
The rubber bellows only keeps the dirt and dust off the driveshaft yoke slider....

 

[rebelles]

I didn’t see if any info if there was a transfer case drop kit installed or a SYE kit. I installed that same lift on my LJ and had some driveline vibrations. I then installed a transfer case drop kit and eliminated them. Just my experience. There’s several threads on quick/cheap ways to drop that may be worth an initial try to help diagnose (thinking of spacing the skid plate with several washers to see if that changes things).

 

[JMT]

I need a little help diagnosing a shake/wobble/heavy vibration that recently started on our TJ. 1997 2.5L 5 speed, in November I added a RC 3.25" lift, which is essentially their 2.5" springs and a 3/4" spacer. We've put about 750 miles on it since then with no issues. Running 31/10.5 R15 on 15x8" rims

2 weeks ago my wife drove it and it started shaking on her, so much for her she actually ran off on the shoulder trying to come to a stop. Called me I was thinking death wobble, so I met her, let her drive another vehicle home and I drove the tj, at that time I could not recreate the problem.

This week I went through and inspected underneath and checked tightness on all components related to the lift, nothing noticeably out of whack, the front track bar did need the axle side bolt retorqued, it was slightly loose. Test drove it and now I can fairly consistently get it to react and shake. Here's what it does:

At somewhere around 45 you can feel a vibration that gets worse as you get closer to 50, its not subtle its pretty violent and will shake yout phone or whatever right off the dash. I feel it mostly in the seat of my pants, almost a side to side like someone is shaking the car. The steering seems to stay pretty steady, the wheel is definitely not getting pulled from my hand.
If I accelerate beyond 50 it goes away 99% there is a slight vibration that feels more like a tire out of balance. I've driven it up to 65 range and that's the only vibe in it.
Upon deceleration it will have that hard shake as it slows through that 45-50 mph range. It does seem more pronounced in 4th gear, but if I slow in 5th to the same speed range it will do it but a little less dramatic as its really lugging the engine at that point. I have not tried to take 3rd up to that speed.

Could this be a driveline vibration? What could have changed, broke, or loosened to have this start while my wife was driving? We've had it to 70+ multiple times since putting the lift on with no hint if a shaking or vibration issue until now.

I don't think its standard "Death Wobble" it seems more speed related, I've driven Dodge trucks most of my life and this shake is not in the wheel like one of hose truck was. The 4 lane near our house is pretty rough and bumps potholes etc, have not seemed to effect it at all.

Thanks, sorry for the long post but wanted as much info out as possible and be strategic on how I try to eliminate this.

It’s tire balance.

Definitely NOT driveline. The driveline gets faster and faster, so if a vibe starts at 40mph it will continue to increase as you go faster.

Yours occurs under load and not under load. It’s speed related. That’s tires. Get them balanced

Plus, the ~45mph onset is a dead giveaway

 

[BassCat976]

It’s tire balance.

Definitely NOT driveline. The driveline gets faster and faster, so if a vibe starts at 40mph it will continue to increase as you go faster.

Yours occurs under load and not under load. It’s speed related. That’s tires. Get them balanced

Plus, the ~45mph onset is a dead giveaway

Thanks gives me directions to head in.
Tires were not new when lift was installed, I will rotate them and see what (if any) difference that makes. that can be checked on my way to the shop to get the balance checked. It will also be easier to check everything again for wear/tightness or anything broken while its up on a lift.

 

[JMT]

Thanks gives me directions to head in.
Tires were not new when lift was installed, I will rotate them and see what (if any) difference that makes. that can be checked on my way to the shop to get the balance checked. It will also be easier to check everything again for wear/tightness or anything broken while its up on a lift.

Sometimes tires cup or get out of round as they get older. I had that problem with 31's and got DW that I cured to a mere shimmy between 42-50mph. I got the tires re-balanced three times and two different shops and that shimmy would not go away. The day I bumped up to 33" tires the ride was smooth as glass with no other changes. The tires themselves just had issues.

At any rate, switching tires front to rear can be an indicator. If no change then get balanced as you plan. Request a perfect balance due to the front axle and the precession factor (bet they haven't heard of that). Look for a shop that is accustomed to balancing bigger tires (offroad places). They will know more about what it means to get a perfect balance and know you will be back if they are not perfect so it is in their best interest to get it right.

Also, make sure your tire pressures are not too high. I don't remember what tire size you have, but 31's 28psi, 33's 26psi, 35's 24psi.

A DIY alignment may also be in order. It's very easy to do and you could do it when you swap the fronts and rears.

https://wranglertjforum.com/threads/how-to-align-your-jeep-wrangler-tj.85/

 

[SvtLdr]

Tires was my first instinct as well. Aging tires will start to do funky things on the road. Any idea how old they are?

 

[BassCat976]

Tires was my first instinct as well. Aging tires will start to do funky things on the road. Any idea how old they are?

No but they are several years old. I believe the Jeep sat for a year or so before we bought it at the end of the summer.

I checked and rotated the tires when I got home, they will certainly need balanced. They all have sticker weights on them, other than one that was on the rear and it’s pretty obvious that one has thrown them, and I’m sure it needs weight.

The shake is obviously still there, but now with the week with no weight on the front, it is a little more pronounced and easier to get it to start.

Plan is to take it to the shop(my brothers) on Monday, try to get the wheels balanced out and throw it on the alignment rack to double check things.

 

[Dom 97 TJ]

It’s tire balance.

Definitely NOT driveline. The driveline gets faster and faster, so if a vibe starts at 40mph it will continue to increase as you go faster.

Yours occurs under load and not under load. It’s speed related. That’s tires. Get them balanced

Plus, the ~45mph onset is a dead giveaway

Death wobble:
The death wobble usually has multiple conditions that initiate the wobble. This could be one or multiple parts causing the wobble. Take the time to inspect all of the suspension, steering, and tires.
Steering: With all four wheels on the ground. Have your wife turn the steering wheel left and right with medium force (do not have to turn the wheel very far). While you lie under the front end watch the pitman arm, tie rod ends, drag link, and steering box; watch for any worn parts. Inspect steering stabilizer for leaks.
Suspension: Lift the front end and use a block of wood (4x4) and pry bar under the tire. Force the tire up and down watching the ball joints to ensure they are not worn.
I am suspicious you will find the root cause of the death wobble in one or more of the components listed above. Good Luck! Dom

 

[JMT]

Death wobble:
The death wobble usually has multiple conditions that initiate the wobble. This could be one or multiple parts causing the wobble. Take the time to inspect all of the suspension, steering, and tires.
Steering: With all four wheels on the ground. Have your wife turn the steering wheel left and right with medium force (do not have to turn the wheel very far). While you lie under the front end watch the pitman arm, tie rod ends, drag link, and steering box; watch for any worn parts. Inspect steering stabilizer for leaks.
Suspension: Lift the front end and use a block of wood (4x4) and pry bar under the tire. Force the tire up and down watching the ball joints to ensure they are not worn.
I am suspicious you will find the root cause of the death wobble in one or more of the components listed above. Good Luck! Dom

I’m not the OP and I don’t have DW. The OP ‘s wife had DW, but they can’t recreate it after tightening the TB to spec.

OP now has a shimmy ~45mph that goes away about 50mph. Needs tires balanced first since precession is the trigger of DW. All components could be fine, or they could have issues. Either way he needs to start with tires.

 

[AndyG]

It’s tire balance.

Definitely NOT driveline. The driveline gets faster and faster, so if a vibe starts at 40mph it will continue to increase as you go faster.

Yours occurs under load and not under load. It’s speed related. That’s tires. Get them balanced

Plus, the ~45mph onset is a dead giveaway

It is amazing how 45 mph is the magic number-ate dinner thursday night with an XJ guy- 45 mph , it goes wild.

You can watch the forum- you will see 45 mph pop up- I have no clue why, except it must create enough of a harmonic -

 

[JMT]

It is amazing how 45 mph is the magic number-ate dinner thursday night with an XJ guy- 45 mph , it goes wild.

You can watch the forum- you will see 45 mph pop up- I have no clue why, except it must create enough of a harmonic -

Sufficient centripetal force for tire imbalances to start showing up is around 40mph