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Ugh. I am moving 1000+ miles on friday(towing a small boat) and my rear end is whining pretty loudly now at 35+mph.

I'm really in a bind here, I have never done any work on a rear end before and wouldn't even know where to start to try to diagnose it or repair anything. I guess I'm going to see if I can find a shop that will guarantee they can have it done in a few days at most.

If anyone has any advice at all, I'm all ears.

This sucks.


1996 5.8L Bronco
 

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Discussion Starter #2
Ugh. I am moving 1000+ miles on friday(towing a small boat) and my rear end is whining pretty loudly now at 35+mph.

I'm really in a bind here, I have never done any work on a rear end before and wouldn't even know where to start to try to diagnose it or repair anything. I guess I'm going to see if I can find a shop that will guarantee they can have it done in a few days at most.

If anyone has any advice at all, I'm all ears.

This sucks.


1996 5.8L Bronco
I found a few posts about tightening a pinion nut, but not sure where this is or what they are referring to.
 

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i'd find out how much a shop wants to look at it/fix it, then compare that to what you can find used. unless you are out in the middle of nowhere, i bet you could find another 8.8 for a couple hundred bucks or less out of another bronco or f150. if the shop wants a bundle (which is often the case to work on differentials) or can't get it done in time, this may be a reasonable option.

either way, good luck!
 

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yo,
Excerpts From 1996 F-150, F-250, F-350, Bronco and F-Super Duty Workshop Manual;
Check Lubricant & Level
A plugged axle vent will cause excessive seal lip wear due to internal pressure buildup. When a leak occurs, check the vent which is located near the top of the differential housing. Make sure the vent hose is not kinked. Remove the vent hose from the vent nipple and make sure the hose is clear of dirt or other foreign materials. While hose is removed, pass a length of mechanics' wire or small diameter Allen wrench in and out of the vent nipple to clean it of any dirt or foreign materials. Install vent hose.

Make sure axle lubricant is to specified level.

Is/Does;
Noise Is the Same on Drive or Coast? above 35 mph
Noise Changes with Type of Road Surface? Road noise. Tire noise

Noise Tone Lowers As Vehicle Speed Lowers? Tire noise. Driveline noise. INSPECT driveshaft, U-joints and rear axle universal joint flange


Noise Most Pronounced on Turns? wheel bearings. Differential side gears and pinion gears

Noise Is Different When Transmission in Drive During Coasting and When in Neutral During Coasting? Axle. INSPECT transmission.


Non-Axle Noise
There are a few other conditions that can sound like axle noise and have to be considered in diagnosis.
The three most common are exhaust, tires and trim mouldings. Make sure that none of the following are the cause of the noise before proceeding with an axle teardown and diagnosis.
In certain conditions, the pitch of the exhaust may sound like gear whine. At other times, it can be mistaken for wheel bearing rumble.
Tires, especially snow tires can have a high-pitched tread whine or roar similar to gear noise. Radial tires, to some degree, have this characteristic. Any non-standard tire with an unusual tread construction may also emit a roar or whine-type noise.
Noise Tone Lowers as Vehicle Speed Is Lowered; REBALANCE or REPLACE tire.

Driveline noise. INSPECT driveshaft, U-joints and rear axle universal joint flange. REFER to Section 05-00. For removal of driveshaft, REFER to Section 05-01

Trim, grille and mouldings can also cause whistling or whining noises.

Analysis of Noise
Bearing whine is a high-pitched sound similar to a whistle. It is usually caused by malfunctioning pinion bearings, which are operating at driveshaft speed. Bearing noise occurs at all driving speeds. This distinguishes it from gear whine which usually comes and goes as speed changes.

Bearing rumble sounds like marbles being tumbled. This condition is usually caused by a malfunctioning wheel bearing. The lower pitch is the result of wheel bearings turning at only about one-third of driveshaft speed. Wheel bearing noise also may be high-pitched, similar to gear noise, but will be evident in all four driving modes.

Because of the severe loads they must handle, rear wheel bearings may require replacement at high mileage. If a rear wheel bearing fails at low mileage, it is usually caused by overloading or a defect in the bearing.



Axle shaft noise is similar to gear noise and differential pinion bearing whine.

Axle shaft bearing noise will normally distinguish itself from gear noise by occurring in all driving modes (drive, coast and float), and will persist with transmission in neutral while vehicle is moving at problem speed. If the vehicle makes this noise, remove suspect axle shafts, replace rear wheel bearings and install a new set of wheel seals. Re-evaluate vehicle for noise before removing any internal components.




Gear Howl and Whine

Before disassembling the axle to diagnose and correct gear noise, eliminate the tires, exhaust, trim items, roof racks, axle shafts and rear wheel bearings as possible causes.

The noises listed on the Road Test Form in this section usually have specific causes that can be diagnosed by observation as the unit is disassembled. The initial clues are, of course, the type of noise heard on the road test and the driving conditions.

Bearing malfunctions will normally be obvious at disassembly. As noted earlier, inner and outer pinion bearings make a high-pitched, whistling noise, usually at all speeds. If there is only one pinion bearing that is malfunctioning, the noise may vary in different driving phases.

Pinion bearings are frequently replaced unnecessarily on axles with low mileage under 24,139 km (15,000 miles) when correcting gear noise. They should not be replaced unless they are actually scored or damaged, or there is a specific differential pinion bearing noise. Examine the large end of the rollers for wear. If the pinion bearing's original blend radius has worn to a sharp edge, the pinion bearing should be replaced.

Remember that the low-pitched rumble of a malfunctioning wheel bearing can also be caused by the exterior luggage rack or tires.

Rear wheel bearing noise might be mistaken for pinion bearing noise. Inspect the rear wheel bearing carefully before tearing down the axle.


For 8.8-inch or 10.25-inch (semi-floating) axles, the rear wheel bearings are pressed into the axle housing tubes, making them more difficult to check. However, the axle shaft is the inner race for the bearing. If the bearing is damaged, the roller surface on the axle shaft may also be damaged. The rollers run approximately on the center of the polished surface.


Chuckle

Chuckle that occurs on the coast driving phase is usually caused by excessive clearance between the differential gear hub and the differential case bore. It can also be caused by a damaged tooth on the coast side of the pinion or ring gear.

Any damage to a gear tooth on the coast side can cause a noise identical to chuckle. Even a very small tooth nick or ridge on the edge of a tooth is enough to cause the noise.

You can often correct this condition and eliminate the noise simply by cleaning up the gear tooth nick or ridge with a small grinding wheel. If the cleaned up or damaged area is larger than 3.2mm (1/8 inch), it is advisable to replace the gearset.

To check the differential ring gear and pinion, remove as much lubricant as possible from the gears with clean solvent. Wipe the gears dry or blow them dry with compressed air. Look for scored or damaged teeth. Also look for cracks or other damage.

If either gear is scored or damaged badly, the differential ring gear and pinion must be replaced. If there is metal broken loose, the rear axle housing must also be cleaned to remove particles that could cause damage later. Any other damaged parts in the rear axle housing must be replaced.
 

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Could be the rear u joint making noise, too. I'd put the truck on jack stands, drop it in gear, and probe the differential housing with an automotive stethoscope and try to ID the problem more closely. The stethoscope costs about 3.00 bucks at O'reilly's.

Additionally, for the cost of gear oil, you can pull the rear cover and inspect the differential internals.
 
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