Over the last several months I have gathered a ton of information on vibration diagnosis as I worked through each issue on my EX. I didn't see one similiar to this one on this forum and I think it has some really good information on diagnosis of vehicle vibrations, so I thought I would post for others to use.
Vehicle vibration can be caused by:
Tire/wheel unbalance or excessive run out
Defective tires with extreme tread wear
Nylon overlay flat spots (performance tires only)
Incorrect wheel bearing adjustment (if applicable)
Loose or worn suspension/steering components
Certain tire tread patterns
Incorrect drive shaft angles or excessive driveshaft/yoke run out
Defective or worn U-joints
Excessive brake rotor or drum run out
Loose engine or transmission supports/mounts
And by engine operated accessories
Refer to the appropriate Groups in this manual for additional information.

VIBRATION TYPES
There are two types of vehicle vibration:
Mechanical
Audible.
Mechanical vehicle vibration can be felt through the seats, floor pan and/or steering wheel.
Audible vehicle vibration is heard above normal background noise. The sound can be a droning or drumming noise.
Vibrations are sensitive to change in engine torque, vehicle speed or engine speed.

ENGINE TORQUE SENSITIVE VIBRATION
This vibration can be increased or decreased by:
Accelerating
Decelerating
Coasting
Maintaining a constant vehicle speed

VEHICLE SPEED SENSITIVE VIBRATION
This vibration condition always occurs at the same vehicle speed regardless of engine torque or engine speed.

ENGINE SPEED (RPM) SENSITIVE VIBRATION
This vibration occurs at varying engine speeds. It can be isolated by increasing or decreasing the engine
speed with the transmission in NEUTRAL position.

VIBRATION DIAGNOSIS
A vibration diagnosis should always begin with a 10 mile (16 km) trip (to warm the vehicle and tires).
Then a road test to identify the vibration. Corrective action should not be attempted until the vibration
type has been identified via a road test. During the road test, drive the vehicle on a smooth surface. If vibration exists, note and record the following information:
Identify the vehicle speed range when the vibration occurs
Identify the type of vibration
Identify the vibration sensitivity
Determine if the vibration is affected by changes in vehicle speed, engine speed and engine torque.
When the vibration has been identified, refer to the Vibration Diagnosis chart for causes. (see below)Consider correcting
only those causes coded in the chart that are related to the vibration condition. Refer to the following cause codes and descriptions for explanations when referring to the chart.


TRR—Tire and Wheel Radial Run out: Vehicle speed sensitive, mechanical vibration. The run out will not cause vibration below 20 mph (32 km/h).

WH—Wheel Hop: Vehicle speed sensitive, mechanical vibration. The wheel hop generates rapid up-down movement in the steering wheel. The vibration is most noticeable in the 20 - 40 mph (32 - 64km/h) range. The wheel hop will not cause vibration below 20 mph (32 km/h). Wheel hop is caused by a tire/wheel that has a radial run out of more than
0.045 of-an-inch (1.14 mm). If wheel run out is acceptable and combined run out cannot be reduced by repositioning
the tire on wheel, replace tire.

TB—Tire/Wheel Balance: Vehicle speed sensitive, mechanical vibration. Static tire/wheel unbalance will not cause vibration below 30 mph (46 km/h). Dynamic tire/wheel unbalance will not cause vibration below 40 mph (64 km/h).

TLR—Tire/Wheel Lateral run out: Vehicle speed sensitive, mechanical vibration. The run out will not cause vibration below 50 - 55 mph (80 - 88 km/h). Excessive lateral run out will also cause front-end shimmy.

TW—Tire Wear: Vehicle speed sensitive, audible vibration. Abnormal tire wear causes small vibration in the 30 - 55 mph (88 km/h) range. This will produce a whine noise at high speed. The whine will change to a growl noise when the speed is reduced.

W—Tire Waddle: Vehicle speed sensitive, mechanical vibration. Irregular tire uniformity can cause side-to-side motion during speeds up to 15 mph (24km/h). If the motion is excessive, identify the defective tire and replace it.

UAJ—Universal Joint (Drive Shaft) Angles: Torque/vehicle speed sensitive, mechanical/audible vibration.
Incorrect drive shaft angles cause mechanical vibration below 20 mph (32 km/h) and in the 70 mph (112 km/h) range. The incorrect angles can also produce an audible vibration in the 20 - 50 mph (32 -80 km/h) range. Caster adjustment could be required to correct the angles.

UJ—Universal Joints: Engine torque/vehicle speed sensitive, mechanical/audible vibration. If the U-joint is worn it will cause vibration with almost any vehicle speed/engine torque condition.

DSY—Drive Shaft and Yokes: Vehicle speed sensitive, mechanical/audible vibration. The condition will not cause vibration below 35 mph (56 km/h). Excessive run out, unbalance or dents and bends in the shaft will cause the vibration. Identify the actual cause and repair/replace as necessary.

WB—Wheel Bearings: Vehicle speed sensitive, mechanical/audible vibration. Loose wheel bearings cause shimmy-like vibration at 35 mph (56 km/h) and above. Worn bearings will also produce a growl noise at low vehicle speed and a whine noise at high vehicle speed. The wheel bearings must be adjusted or replaced, as applicable.

AN—Axle Noise: Engine torque/vehicle speed sensitive, mechanical/audible vibration. The axle will not cause mechanical vibration unless the axle shaft is bent. Worn or damaged axle pinion shaft or differential gears and bearings will cause noise. Replace the defective component(s) as necessary.

SSC—Suspension and Steering Components:
Vehicle speed sensitive, mechanical vibration. Worn suspension/steering components can cause mechanical vibration at speeds above 20 mph (32 km/h). Identify and repair or replace the defective component(s).

EA—Engine Driven Accessories: Engine speed sensitive, mechanical/audible vibration. Vibration can be caused by loose or broken A/C compressor, PS pump, water pump, generator or brackets, etc. Usually more noticeable when the transmission is shifted into the NEUTRAL position and the engine speed (rpm) increased. Inspect the engine driven accessories in the engine compartment. Repair/replace as necessary.

ADB—Accessory Drive Belts: Engine speed sensitive, audible vibration. Worn drive belts can cause a vibration that produces either a droning, fluttering or rumbling noise. Inspect the drive belt(s) and tighten/replace as necessary.

DEM—Damaged Engine or Transmission Support Mounts: Engine speed sensitive, mechanical/audible vibration. If a support mount is worn, noise or vibration will occur. Inspect the support mounts and repair/replace as necessary.

ES—Exhaust System: Engine speed sensitive, mechanical/audible vibration. If loose exhaust components contact the vehicle body they will cause noise and vibration. Inspect the exhaust system for loose, broken and mis-aligned components and repair/replace as necessary.

 

I ran across this and thought it might be helpful to others. Thanks Christina!

 

Great! Thanks for bring this fine post by Christina back to our attention. Reps

 

That's some pretty detailed info! I just might have to print that out and put it in my files! Reps sent.....oops, in rep jail!

 

Holy crap, Christina posted this back in 2012 but it musta contained some stealth coding in it because I don't remember ever seeing it, and the first reply to it was today, so there is no other explanation!

Thanks for the heads up, Mec-Man and yes, I agree, a "must add" for the tech folder.

Stewart

 

Really? No one saw this for 3 years, I forgot I even posted it but I use it all the time.

It is a great chart.

 

Nope.

And when I revamped the tech folder thread, I did a search on all threads started by you (looking for your tech help threads), and this one didn't come up in the results.

Stewart

 

It wasn't named with the "dummie" tag...

 

'Cuz we're not all dummies, that's why I asked the Stew-man to add it to the tech Folder.


https://www.ford-trucks.com/forums/1...l#post15090593

 

so what do I do for TLR? This has helped me diagnose my issue but how do I fix it?

 

This chart is killer, but my issue doesn't seem to clearly fit into any category.

When I am at highway speeds, and heavily apply the brake, my X shakes up and down in a fashion that feels like what I would guess re-entering the atmosphere is like. The it stops when I get down to 40MPH.

opinions greatly appreciated.

Chad

 

Cementite on front rotors, check the tech thread.

https://www.ford-trucks.com/forums/1...ke-rotors.html

 

Start a new thread and give us more info about your Ex such as 4x4 or rwd, tires, last time brakes were done, when the vibration started, tires, any recent work done.

 

i really needs some advise. I have a 1992 Ford E150. I notice a vibrations right around 70 mph like on the expressway yesterday i felt the vibrations around 70 mph but when i let off and keep it around 65 mph i don't feel the vibration. This chart is so confusing for me cause i need it broke down like im a five year lol. I mean im not smart as many of you are but i clearly need some advise because every time i take my van i feel they take advantage of me. I know how to do a lot of things due to my father showing me a lot of stuff when i was a child while other kids was watching cartoons i was outside helping my dad bleed the brakes and me being a girl they look at me like she is boo boo the foul. but i just need some guidance on this. I have a Florida trip coming up and i got to get my van good to go so i wont break down or whatever. Please any help is helpful but awesome help is awesome. ty KJ