Remotely. My brothers are 1,200 miles away. The truck is a 2004 Ford F250 4x4 with an automatic and a limited slip diff. They had a rear u-joint replaced. They noticed a vibration after the repair. It starts around 55-70 pmh and only upon deceleration. They also replaced the gear oil with Mobile synthetic 75W-140. I'm thinking its the rear u-joint, but could it be coincidence? Any way to diagnose it before bringing it back to the shop? There are limited options as far as shops in Montana.
Make sure the front U-joint isn't binding. That can cause all sorts of problems, up to and including cracking the transmission case from vibration.
Usually a u joint would bang first on deceleration.
Twice I've had weird deceleration vibration, once it was a ujoint that was super worn and machined an oblong hole in the caps and only floated to the middle on deceleration/no input. It also locked up in park.
The second was a motor mount failing, the engine pulled up under acceleration, but settled down onto the bad mount when you let off the gas. It was an old Ford truck
Do you think it's coincidental that the hum started right after the u-joint replacement?
Drive shaft reassembled out of phase?
Just told them to check that. We'll see.
Don't rule out a bad Ujoint. Some of the parts store gems are hideously awful.
outasite said:Drive shaft reassembled out of phase?
How can that be? The yokes are welded on. The phase is fixed.
I've put the shaft 180 degrees off from original and had a weird harmonic show up.
Curtis said:outasite said:Drive shaft reassembled out of phase?
How can that be? The yokes are welded on. The phase is fixed.
If it's a 2-piece drive shaft it can be assembled out of phase. If it's a 1-piece drive shaft it has to have a slip joint and it could have been pulled out and slipped back in out of phase.
Driveshaft center support bearing.
Apparently the shop used a gorilla high on PCP to tighten the bolts. They didn't have the ability to loosen them so they took it back to the shop.
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