Vibration from 22–35 MPH, then disappears

TheBlackPearl

TheBlackPearl

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Oct 4, 2020
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Kentucky
I am getting violent vibration (shaking), beginning at around 22 MPH and continues up until about 35 MPH. The vibration then disappears and Jeep runs smoothly. The vibration seems to be coming from passenger front end but I haven’t tracked anything yet. 1998 TJ with 2.5 4-cylinder, 4.10 gears (open front) and 31” tires.
 
TheBlackPearl said:
I am getting violent vibration (shaking), beginning at around 22 MPH and continues up until about 35 MPH. The vibration then disappears and Jeep runs smoothly. The vibration seems to be coming from passenger front end but I haven’t tracked anything yet. 1998 TJ with 2.5 4-cylinder, 4.10 gears (open front) and 31” tires.
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Check your control arm bolts

Check you track bar bolts and do a dry steering test for play

Rotate tires and see if it changes

Keep us posted .
 
You
TheBlackPearl said:
UPDATE - it’s only under acceleration. Shaking stops when coasting, so that pretty much eliminates an out of balance tire...
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Check your rear control arm tightness...not by hand..with a wrench ..all 4 and examine the bushings .....or you may have a bad/loose rear u joint or pinion angle issue . Pinion angle issues don't just appear though, changed cause that.
 
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You may also have a broke transmission or motor mount.
 
Are your RE control arms fixed or adjustable length? If they're adjustable your vibrations may be from having set the rear axle's pinion angle too high. Vibrations that occur only while accelerating are commonly caused by a slightly too high of a rear pinion angle.

With the factory driveshaft the rear pinion angle must be the same as the transfer case output shaft angle... parallel to.

2joint_angle.jpg
 
The RE control arms are adjustable. I will check pinion angle. The vibration is coming from the front (or so it appears). The dash shakes badly and it shakes more on passenger side.
this is a learning experience. I will check everything that has been noted. I appreciate the support!!
 
Man you need to pull your front drive shaft you could have a double cardan about to fly apart... I forgot you said it was coming from the front.. but be careful there is something wrong with that jeep.

I can't put my finger on what's happening and I can't help but wonder is the steering wheel shaking are you experiencing some form of death wobble... But you've got something going ...I don't know if you rotated your tires but a broke belt and a tire can do some funny stuff.
 
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AndyG said:
Man you need to pull your front drive shaft you could have a double cardan about to fly apart... I forgot you said it was coming from the front.. but be careful there is something wrong with that jeep.

I can't put my finger on what's happening and I can't help but wonder is the steering wheel shaking are you experiencing some form of death wobble... But you've got something going ...I don't know if you rotated your tires but a broke belt and a tire can do some funny stuff.
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X2 that problem could also be related to the front driveshaft. A good way to confirm if it is or is not would be to disconnect the front of the front driveshaft from the pinion yoke and suspend it up & out of the way via straps, strong zip-ties, etc. so it isn't being spun while you drive around to see if the vibrations are gone or still there. Just make sure it's suspended safely so it can't fall down while you drive which could be fatal for the driveshaft and/or the transfer case. Or just temporarily entirely remove the front driveshaft for the test.
 
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Jerry Bransford said:
X2 that problem could also be related to the front driveshaft. A good way to confirm if it is or is not would be to disconnect the front of the front driveshaft from the pinion yoke and suspend it up & out of the way via straps, strong zip-ties, etc. so it isn't being spun while you drive around to see if the vibrations are gone or still there. Just make sure it's suspended safely so it can't fall down while you drive which could be fatal for the driveshaft and/or the transfer case. Or just temporarily entirely remove the front driveshaft for the test.
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And if you do what Jerry says whatever you do don't put it in four wheel drive....
 
Chris.... Jerry just quoted my post. It just feels incredible. I bet the rest of my life is going to be downhill from here.
 
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The tires are good and this Jeep will run highway speeds with zero excessive noise or vibration and tracks straight down the road with no hands on steering wheel at 60-65 MPH. I’m intimately familiar with broken belts in tires. This is not the problem. The weather isn’t cooperating with me today and my garage is taken up by one of my wife’s projects. I may go ahead and pull front driveshaft and take it by my local driveline shop for an inspection and/or rebuild. It is overdue anyway.
 
TheBlackPearl said:
The tires are good and this Jeep will run highway speeds with zero excessive noise or vibration and tracks straight down the road with no hands on steering wheel at 60-65 MPH. I’m intimately familiar with broken belts in tires. This is not the problem. The weather isn’t cooperating with me today and my garage is taken up by one of my wife’s projects. I may go ahead and pull front driveshaft and take it by my local driveline shop for an inspection and/or rebuild. It is overdue anyway.
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all we can do is guess we're just throwing out possibilities.... Keep us posted when you learn we learn.
 
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Hmmm, mine is having a pretty bad shake around that speed as well, also only under acceleration. Though mine also gets quite the shake when I am coming to a stop. My mechanic said he thinks it needs a rebuilt trans, so a friend of mine has been checking it out for me, he is now thinking I need a new torque convertor. As I try and figure out why it's happening for me, I throw it into neutral every time I come to a stop, and whenever the shake starts I throw it in neutral. It seems like it is happening when it is switching from 1st to 2nd, is that the case with yours? Also, if the shaking is happening and you throw it into neutral does it go away?
 
GenericDisplayName said:
Hmmm, mine is having a pretty bad shake around that speed as well, also only under acceleration. Though mine also gets quite the shake when I am coming to a stop. My mechanic said he thinks it needs a rebuilt trans, so a friend of mine has been checking it out for me, he is now thinking I need a new torque convertor. As I try and figure out why it's happening for me, I throw it into neutral every time I come to a stop, and whenever the shake starts I throw it in neutral. It seems like it is happening when it is switching from 1st to 2nd, is that the case with yours? Also, if the shaking is happening and you throw it into neutral does it go away?
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I have a manual transmission
 
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