Drive train vibration; u joints, rear end or carriage bearing?

A grinding noise suggests a bearing at fault or perhaps worn pads on the brake rotor.

However, the clunking noise you mention could also point to a problem with the drive shaft or differential.

The first thing you should do is to get under the vehicle and try twisting the propshaft back and forth. If there's any movement this points towards a worn universal joint on the propshaft. A worn universal joint can cause a clunking noise - particularly when pulling away. The vibration caused by a worn universal joint can also damage bearings in the differential and also to the splined ends of the axle shaft.

You're also going to have to remove the wheel from where the noise comes from and examine the end of the axle shaft/bearing.

The link below is of images of the rear axle:

land rover discovery rear axle Google Search

go to the magicmechanic website and send him this--hes the best there is and will rply

Hello,

If problem only occurs 'under power' sounds like a u-joint (driveline - rear wheel drive) or a cv-axle (front wheel drive). Check for excessive play, fluid, boot tear and breakage.

Rob, assuming this is a 4X4? Sounds like a bearing. They can vibrate, snap, clunk, all kinds of terrible noises or vibrations.
Axle u joints will also do this. Is it all wheel drive?

look for out of round tires or a bent axle.

GET IT TO A MECHANIC!! Something is loose or about to collapse! Remember that vibration and noise can travel away from the source so get the mechanic to start in that corner.
You need to get the following checked!
-Prop shaft mountings at transfer box.
-Prop shaft mountings at differential.
-Prop shaft bearings.
-Differential condition and oil level.
-Drive shafts at differential end.
-Drive shafts at the wheel end.
-All flexing joints in the system including UV joints and CV joints.

Check your driveshaft joints for excessive play. If it's bad enough to clunk into gear, usually if you have someone watch from the side underneath you can see the one that is worn when you go from drive to reverse. (do not lay in the path of the wheels when doing that ) Another way of checking is with both rear wheels safely supported (on flat ground) and the trans in neutral to unload the driveline...then try to move the driveshaft by hand. When replacing the bad joint, check the opposite end as well for any binding or play.

Much of the symptoms you describe sound like a CV joint. I would take it to the dealer and insist that it be fixed... What is bothering me though is under normal operating conditions, CV joints and boots are engineered to last upwards of 150,000 miles. Some go the distance, but a lot reach the end of the road far short of their design life. According to one major aftermarket supplier of replacement axle shafts, CV joint shafts are typically being replaced at anywhere from 70,000 miles to 130,000 miles.

Read this and see if you agree...
SYMPTOMS OF CV JOINT FAILURE
Bad boots are not the only thing you need to look for. You also need to listen for noise or complaints that might indicate a CV joint problem. These include:

• Popping or clicking noises when turning. This almost always indicates a worn or damaged outer CV joint. To verify this condition, place the vehicle in reverse, crank the steering wheel to one side and drive the vehicle backwards in a circle (check the rearview mirror first!). If the noise gets louder, it confirms the diagnosis and the need for a new CV joint or replacement shaft assembly.
  
• A "clunk" when accelerating, decelerating or when putting the transaxle into drive. The noise comes from excessive play in the inner joint on FWD applications, either inner or outer joints in a RWD independent suspension, or from the driveshaft CV joints or U-joint in a RWD or AWD powertrain. The same kind of noise can also be produced by excessive backlash in differential gears. To verify the condition, back the vehicle up, alternately accelerating and decelerating while in reverse. If the clunk or shudder is more pronounced, it confirms a bad inner joint.
  
• A humming or growling noise. Sometimes due to inadequate lubrication in either the inner or outer CV joint, this symptom is more often due to worn or damaged wheel bearings, a bad intermediate shaft bearing on equal length halfshaft transaxles, or due to worn shaft bearings within the transaxle.
  
• A shudder or vibration when accelerating. May be caused by play in the inboard or outboard joints, but the most likely cause is a worn inboard plunge joint. Similar vibrations can also be caused by a bad intermediate shaft bearing on transaxles with equal length halfshafts, or by bad motor mounts on FWD vehicles with transverse-mounted engines.
  
• A vibration that increases with speed. This symptom is rarely caused by a failing CV joint. An out-of-balance tire or wheel, an out-of-round tire or wheel, or a bent rim are the more likely causes.

remove the rear shaft from a 1990 full size gmc van (g-van) make sure the one you select has the scew on sleeve at the front of the rear section of the shaft
this will be the right lenght
take the rear yolk off your old shaft cut of the ball socket now get the same u-joint your truck calls for and mount the rear yolk (the section of the shaft that bolts to your rear end) to the new shaft
this works ive done it
you eliminate 2 of the 4 u-joints and lighten up your shaft this releives strain on you tranny and rear end when these u-joints and ball bearings fail they cause the vibrations which ruin the rest of your drive train also you gain 10hp
i spent 300 bucks rebuilding the OEM shaft and got no where so for 25 bucks i did this

Probably a bad u-joint.