Have an 05 TJ with a 4.5" short arm RE lift on it. CV shaft etc. I
didn't cut any corners. measured pinion angle, adjusted upper control
arms, etc. Been fine for a couple years.

I am wondering what does a vibration feel like? Is it a contant vibe
or pulsing?

I am getting a weird almost harmonic minor vibration around 70mph and
up. About every 2 seconds, for a fraction of a second the harmonic
vibration "pulses". Sorta like "Whoam, Whoam, Whoam, etc".

I am finding it hard to describe. LOL.

Any help?

If you have ever used M/T tires, you will have noticed a vibration due to
the tires at very very low speeds (1-2)mph.
Driveshaft vibrations will feel almost the same, but in higher speeds (~10
mph or above). Because the feel is similar, if you do the lift and switch
to M/T tires at the same time, you won't be able to tell for sure if you
have driveshaft vibrations, unless they are very severe, or you know exactly
what to feel for.

Incorrect pinion angles, will have as a result the driveshaft to increase -
decrease rotation speed, twice per driveshaft turn, or 2*[axle ratio] times
per wheel revolution.
For example, if you have 4.10:1 gears, the driveshaft will pulse 8.2 times
per wheel revolution.

Since the wheels rotate with almost constant speed, the fluctuations of the
driveshaft speed are transmitted to the clutch and crankshaft of the engine,
via the gearbox.
So this will give you the impression that the engine is not running
smoothly.

Yes, just before it pole-vaults the car and you cart wheel down the
road.

"ULB" yahoo.com> wrote in message
news:87941c85-7cb8-444b-9635-b16351a6d3a2@m73g2000hsh.googlegroups.com...

On Mon, 05 May 2008 14:06:46 -0700, L.W.(ßill)Hughes III wrote:

Yes what?

If you don't have a sensible answer -- preferably from experience or
verified documentation -- don't attempt humour. You don't possess a humour
module.

sounds like wheel bearing or badly cupped tires
my bet is its tires esp. if they are bf Goodrich's triple wall tire

ULB wrote: