Wierd Vibration From Underneath Floorboard

Cherokeekid88

Cherokeekid88

Well-Known Member
Joined
Jun 30, 2007
Location
High Point, NC
So I am having this issue where at speeds above 40 or so, I can place my left foot in the center of the floorboard and i feel this slight vibration coming from underneath. The best way I can describe it would be the feeling of an unbalanced front DS. I removed the front drive shaft this morning and I cant really tell if it has helped it or if its just my mind playing tricks on me or not. I can also feel it when I am braking from high speeds. If I move my foot over to the left or to the right of the center of the floorboard, I don't feel it. The last thing I did to my jeep was lift it a little more in the rear when I swapped in the 8.25 with 4.10's, but I shimmed the rear axle to make the pinion angle go up alittle, and I installed some long arms about 3 weeks ago, but this just started about a week ago.
I kind of stumped at to what it could be.
 
either a bad CV head on the front DS (if it has one) or the rear shaft is not running at the correct angle. If the rear has a CV head the pinion on the rear axle should be "pointed" directly to the T-case output, if it's a U-joint style the angle at the pinion and the T-case should be the same to keep it balanced.
 
BIGWOODY said:
either a bad CV head on the front DS (if it has one) or the rear shaft is not running at the correct angle. If the rear has a CV head the pinion on the rear axle should be "pointed" directly to the T-case output, if it's a U-joint style the angle at the pinion and the T-case should be the same to keep it balanced.
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I know that I need to do an SYE. I currently have a T case drop and still have a slight vibe at 30 mph, but would that really cause me to feel a vibe under my feet? Im not under minding your knowledge, just trying to figure this out.
 
A vibrating jeep is a vibrating jeep... Does it increase with speed? If your tcase output and rear pinion aren't parallel then you will get vibes. Get an angle finder and make sure.

That, or you've got alignment issues in the front end. Checked your caster since you did the long arms?
 
braxton357 said:
A vibrating jeep is a vibrating jeep... Does it increase with speed? If your tcase output and rear pinion aren't parallel then you will get vibes. Get an angle finder and make sure.

That, or you've got alignment issues in the front end. Checked your caster since you did the long arms?
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I haven't checked the caster, I need to do so. But I have come to the conclusion that it is either my tires or I need to go ahead and do a HnT on the rear DS. So tomorrow morning im going to get my tires rotated and balanced so I can rule that out.
 
Cherokeekid88 said:
I haven't checked the caster, I need to do so. But I have come to the conclusion that it is either my tires or I need to go ahead and do a HnT on the rear DS. So tomorrow morning im going to get my tires rotated and balanced so I can rule that out.
Click to expand...

Did you ever plate / stiffen the frame at mounts for the long arms, If not, Thats most likely the vid
 
Took my jeep up to discount tire after work this morning and had them balance my tires with weights on both sides. Seemed to eliminate a good majority of the weird feeling I was having from underneath. Now I think with a combo of adjusting the caster and getting my HnT done sometime soon, I think all will be good again.
 
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