If your experiencing a high speed vibration from the driveline when cruising...it may be pinion bearing failure in the rear axle. Just got my rig repaired after almost 2 years of trying to find the source. Noticed symptoms when "coasting" in the 60 to 70 mph range. 98 F 150 supercab, 4x4, 4.6l, AOD, 3.55 open.

 

How was it determined to be the pinion bearing and what was the repair bill???

 

I have same vibration in a 2002 SC. 60-67 mph. It has done it since new with 300 miles on ododmeter. Ford had local tire store rotate and balance tires with less than 2000 miles. Not much difference. Dealer said its a truck, it has a rough ride. My 98 SC didn't do this. Truck has General AW tires.

I normally have a plastic insulated cup in the cup holder at all times and the ice rattles in the cup and drives me crazy. Also zippers on my briefcase rattle constantly.

Help a brother out. I spend 5 to 6 hours a day in this vehicle. I thought about going to the dealer and shaking the guys desk and chair for 5 - 6 hours a day to let him know what I'm having to endure.

 

The Ford dealer where I purchased the truck new finally found the problem and repaired. I have owned the truck for about 2 1/2 years...vibration started at about 26k miles and gradually got worse. When I took a Ford tech for a ride at 64k miles he was finally able to verify the noise. Paperwork shows they found backlash out of spec, and had variance in the backlash. Appears they replaced all the bearings, and the ring and pinion set, readjusted backlash. Ford asked for "participation" from me in the form of $80.00..total repair cost was estimated around $850.00.

The wierd thing about this vibration was that it only showed up when the driveline was "unloaded", or "coasting" in the 60 to 70 mph range. If accelerating, or engine braking, there was no noise or vibration. I would imagine the speed range might change for trucks with different tire sizes and gear ratios.

I've read, in this forum, of other problems that cause vibrations..you might want to check out...torque converter stutter, tailshaft bushing failure, driveshaft out of balance or not lined up properly when installed to name few I remember..good luck.

By the way, the seals on the axles had to be replaced as they were leaking already....thats right, 2 years old, 64K miles and the seals were shot...more "built Ford tough" quality..

 

Excessive backlash is usually caused by incorrect set-up of R/P (which should have whined from day# 1) or derbis in the housing (such as casting sand that wasn't removed from axle housing, head section, in the manufacturing process).

Any contamination in the diff. assy. or excessive abuse will open up the backlash (distance between the ring & pinion).

From all the problems I've read on this board, I think FOMOCO may have some problems with workers not cleaning all the casting before they go to differential set-up and assembly.

 

gearman,

Strange but true..this rear axle never "whined" at all..just vibrated when in the 60 - 70 mph range. If you've ever driven a car with an out of balance driveshaft, that was what it felt and sounded like.

I've put about 700 miles on since Ford repaired..no noise yet...keepin' my fingers crossed.

Since Jan. 7 its been in the Ford shop 3 weeks for the 4.6l head gasket problem (they finally had to drop in a new motor) and the rear axle rebuild.. This week its in for the driver door crack repair..hot damn, I'm just enjoyin' the heck out this truck!! I know most of the guys at the Ford shop by their first names now !!!

I'm actually very pleased with the way the local dealer has responded to the problems...just disappointed that $30,000 doesn't buy much in the way of quality from Ford these days.

 

Do yourself a big favor and have your driveshaft checked for straightness, balance, and that the U-Joints are properly 'timed'.

Pinion bearings don't normally wear out unless the improperly serviced (like when changing a pinion seal), running drastically low on axle lube, or by excessive loading from an out-of-balance driveshaft.

 

Guys there's a TBS on this issue in the Transmission forum under "BLOWING SEALS The problem is well known by Ford...

 

Printout the TBS and take it into Ford and tell them what you're experincing..If you don't get results from that dealer, go to another. I went to 2 before I got results..