2nd Gen Non-Engine/Transmission 70 mph shake

[high rsk]

shake shimmy at 70 or so on hiway sometimes its ok replaced all wheels with another set, no change. Gas shocks and track bar replaced, had it aligned, no diffrent. Raised engine and trans no change. help!!! :--)

 

[DieselTweaker]

Take a look at your driveshaft, check your u-joints

 

[Crowhurst]

As Partsman said. The shop manual at section 3-3 gives twelve possible sources of vibration from the prop shafts and universal joints, together with the ways of dealing with them. If you do not have the shop manual, the possible causes are listed as:

a. Undercoating or other foreign material on shaft.

b. Loose u-joint clamp screws

c. Loose or bent u-joint or excessive runout.

d. Incorrect drive line angularity.

e. Rear spring center bolt not in seat.

f. Worn u-joint bearings.

g. Propeller shaft damaged (bent tube) or out of balance.

h. Broken rear spring.

i. Excessive runout or unbalanced condition.

j. Excessive drive pinion gear shaft yoke runout.



and for the universal joints:

a. U-joint clamp screws loose.

b. Lack of lubrication.



The manual then gives detailed instructions on how to deal with each of the twelve. One interesting section states "Propellor shaft vibration increases as the vehicle speed is increased. A vibration that occurs within a specific speed range is not usually caused by a propellor shaft being unbalanced. Defective universal joints, or an incorrect propellor shaft angle, are usually the cause of such a vibration.

Good luck in your hunt.

Nick.

 

[BigPapa]

I also had a nagging vibration at @70 mph. Swapped wheels, tires, carrier bearing, and u-joints. No change. When I swapped the auto for the NV4500 it magically disappeared. The transmission itself was changed (along with the flex plate/tc for a flywheel/clutch of course) and the front part of the drive shaft. Could've been any of those parts.



Just my . 02.



Scott