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KDubya 10-13-2009 10:55 AM

Pulsing Vibration
I tried doing Searches for pulsing and vibration but could not find anything that matched my "problem".

I notice it at around 40-50MPH. It is a vibration that is not steady, but pulses about twice every second, and i feel it most through the floors/pedals.

By 40-50 MPH it is typically while cruising at these speeds under acceleration it does not do it, or i can no longer tell that it is happening. Does it both when the A/c / heater are on or off

2005 TJ 33" tires, small suspension lift(i didn't put it on, and dont know how many inches) , no body lift.

It does have a slight case of death wobble, only happening once every few weeks.

If anyone is familiar with this, or know what it is and/or what causes it, I would love to hear from you.


mrcarcrazy 10-13-2009 11:09 AM

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any sound with it? a vibration that occurs 120x per minute would be just about constant.

First thought is check tires for odd wear, any deformations, check toe setting, and entire front end linkage.

KDubya 10-13-2009 11:21 AM

I'd have to agree that 120 times a minute is pretty constant, haha. I was just trying to put a little emphasis on the fact that its not a steady hum.

As for the sound, it's just the vibration being enough to actually hear it, as well as feel it.

Next time I get I chance i'll give a good listen and feel to see if it does it while moving slower, or even in park.

I'll also give the front a good once over like you suggested. and maybe find the cause of the wobble while I'm in there.

Nice avatar, btw... i nearly peed my pants when i first saw it. :rofl:

KDubya 10-14-2009 11:57 AM

I gave it a once over and didn't find anything that I thought to be abnormal.

I experimented with the vibration some more and found that it only does it while applying a small amount of throttle (enough to maintain speed, but not accelerate) If I let of the throttle completely and "coast" it does not do it.

mrcarcrazy 10-14-2009 12:06 PM

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You know it sounds like driveline vibes to me (they seem to have the on/off via throttle.) But I'm confident someone else here could say for sure (as my jeep is stock height, and I've only worked on 1 lifted jeep.)

Does your jeep have a Transfer case drop on it at all? or is the TC skid as it was from the factory?

I saw this Avatar on another forum and about died laughing @ work one day, after that I had to use it.

KDubya 10-14-2009 12:18 PM

Skid has about 1.5" of drop to it.
You can kinda see in the pictures i posted... Looks like a miniature body lift for skid plates...

Jeepzcb09 10-14-2009 12:24 PM

sounds like you droped your vibrator under the pedal.................jk lol!!!

KDubya 10-14-2009 12:32 PM


Originally Posted by Jeepzcb09 (Post 459275)
sounds like you droped your vibrator under the pedal.................jk lol!!!

:rolleyes: I guess i'd better put it away before the wife finds it...

Jeepzcb09 10-14-2009 01:05 PM

been there done that!!! LOL

jdhallissey 10-14-2009 03:03 PM

Kdubya- you have auto correct? If it has overdrive turn it off so the truck stays in 3rd gear at that speed and see if it happens. Some auto's just vibrate at that range. Try it real quick give feedback! Once you get above 55 then kick it into overdrive.

KDubya 10-14-2009 07:04 PM


Originally Posted by jdhallissey (Post 459363)
Kdubya- you have auto correct? If it has overdrive turn it off so the truck stays in 3rd gear at that speed and see if it happens. Some auto's just vibrate at that range. Try it real quick give feedback! Once you get above 55 then kick it into overdrive.

Had to wait until the drive home, but turning off the overdrive stopped the vibes.


jdhallissey 10-14-2009 07:41 PM

Yep yep glad you can keep your fillings in your teeth now!

Jerry Bransford 10-14-2009 07:51 PM

It sounds like a u-joint vibration from an excessive driveshaft angle caused by a tall suspension lift. If the previous owner had to install a 1.5" transfer case drop, it sounds like he was trying to cure the vibes from a pretty tall suspension lift, like 4" or maybe taller.

One thing about such vibrations... they can take out seals, bearings, and/or u-joints so drivetrain vibrations are not something you can just live with. I'd find a good local 4x4 shop and find out what they recommend. You may need to install a SYE (slip yoke eliminator) kit and aftermarket CV (constant velocity) driveshaft to completely get rid of the vibes, which will also allow that 1.5" transfer case drop kit to be removed. The SYE and CV driveshaft completely eliminates the steepened driveshaft u-joint vibration problem caused by a suspension lift height once you get at or near 4". :)

KDubya 10-14-2009 08:11 PM

Hmm... perhaps looking into it further.

From what I researched a while back SYEs aren't cheap. But if i remember correctly that was for a whole TCase assembly as well. I'll have another snoop around to see what i can find.

jdhallissey 10-14-2009 08:23 PM

Kdubya I truly believe the issue lies in the trans. I ran a 4in lift that was more like 5 and no sye I had no vibes and no issues. Some trannys vibrate in that range. Can you post a picture of your driveline?

KDubya 10-14-2009 08:35 PM

Yeah, that leak is a problem too...

jdhallissey 10-14-2009 08:40 PM

I really have no clue how that would vibrate from the drivetrain IE driveshaft. IF you find time wouldn't be hard to jump under and check to see if those u joints are bad. Grab the center section of the u joint and try to wiggle it if it doesn't move your u joints are pretty much good.

nicolas-eric 10-14-2009 09:38 PM

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Since I have teh belly-up skid I have the same vibes (only with O/D on) around 50 mph and then around 75 mph.

little1989jeep 10-14-2009 10:02 PM

a jeep can go 75?!?!?!? my jeep is bone stock and it just shakes all the time

nicolas-eric 10-14-2009 10:16 PM

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When my Jeep was stock it had a max. speed of 110 mph. Now with the 35" tires and lift itīs only 100 mph fast.

jdhallissey 10-14-2009 10:21 PM

^ lol your nuts!

nicolas-eric 10-14-2009 10:42 PM

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why? we donīt have a speed limit here..

with my mercedes a170 i drive 130 mph when there is no traffic. my fastest speed was 180 mph with my fathers sl600.

jdhallissey 10-14-2009 10:49 PM

Speed is not an issue. I love driving fast in my mustang I have record 168 on gps with it. Any speed over 80 in a jeep I feel is suicide lol.

nicolas-eric 10-14-2009 10:53 PM

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It doesnīt feel dangerous to me. But I do that only with the TJ when there isn't much traffic. Most of the time I drive the TJ with cruise control at 120 kph (75 mph).
When you get used to drive fast on the road thatīs no problem IMO. But it makes more fun with a sports car than with a Jeep.

Jerry Bransford 10-14-2009 10:59 PM


Originally Posted by KDubya (Post 459606)
Yeah, that leak is a problem too...

Perhaps it's just from the photo but that rear pinion angle looks too high, like someone raised it. The rear pinion angle is supposed to be parallel to the t-case output shaft, no higher. If the pinion angle is too high as it looks to be, that will cause a drivetrain (u-joint) vibration.

nicolas-eric 10-14-2009 11:05 PM

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Perhaps he has non-stock rear CAs that have the length for a SYE and CV driveshaft.

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