Drivetrain noise
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Drivetrain noise
Hi all,
I have a F150, standard, 4WD, 4.9, 100k miles, 3:55 limited slip, with a noise that is new to me.
I first thought I dad an exhaust leak echoing off the floor boards. When I drive on the highway it sounds like the exhaust of a dump truck driving along side me. When I take my foot off the gas and slow down, the noise slows down with the speed of the truck. As I approach a complete stop, the noise lessons, and I roll to a stop with a thump, thump, thump that I can feel throughout the truck. This happens even with the engine shut off and the transmission and transfer case in neutral. I have checked the brakes and the drive shaft seems tight. I also rotated the tires and they look good. I have changed the gear oil in the differential and added the correct modifier. Driving with the truck in gear, the noise is a little worse when I take my foot off the gas than when accelerating. Front wheel bearings are OK.
When I jack up the back end and turn the tires by hand, with each revolution I go through a tight and lose spot every 180 deg.
With the rear end up and in gear, the wheels rotate smoothly.
Its got me stumped, but I 'm sure I'm not the first who's heard this noise.
Thanks,
Ringwood
I have a F150, standard, 4WD, 4.9, 100k miles, 3:55 limited slip, with a noise that is new to me.
I first thought I dad an exhaust leak echoing off the floor boards. When I drive on the highway it sounds like the exhaust of a dump truck driving along side me. When I take my foot off the gas and slow down, the noise slows down with the speed of the truck. As I approach a complete stop, the noise lessons, and I roll to a stop with a thump, thump, thump that I can feel throughout the truck. This happens even with the engine shut off and the transmission and transfer case in neutral. I have checked the brakes and the drive shaft seems tight. I also rotated the tires and they look good. I have changed the gear oil in the differential and added the correct modifier. Driving with the truck in gear, the noise is a little worse when I take my foot off the gas than when accelerating. Front wheel bearings are OK.
When I jack up the back end and turn the tires by hand, with each revolution I go through a tight and lose spot every 180 deg.
With the rear end up and in gear, the wheels rotate smoothly.
Its got me stumped, but I 'm sure I'm not the first who's heard this noise.
Thanks,
Ringwood
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vooter61
Clutch, Transmission, Differential, Axle & Transfer Case
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Dec 3, 2001 11:49 PM
