??? Diff trouble ???
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Joined: Feb 2018
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??? Diff trouble ???
78 F150 4x4, 400, C6, NP205. Engine, tranny, and transfer case have been rebuilt. I have a weird rumbling noise, but only in certain situations. It always happens when I let off the gas and take the load off the drivetrain, or when I just started adding load to the drivetrain. When cruising steadily there's no noise whatsoever.
Hubs unlocked, 2 wheel drive: barely noticeable
Hubs unlocked, 4 wheel drive: barely noticeable
Hubs locked, 4 wheel drive: holy hell! Sounds like it's coming from transfer case, but everything is new in there and tight.
I know the rear diff has a lot of backlash, but now I'm wondering if it's the front diff. I should point out that I figured it was the transfer case before, which is why I rebuilt it. Wheel joints on front are new as well. Any ideas from the Ford gurus? Thanks in advance!
Hubs unlocked, 2 wheel drive: barely noticeable
Hubs unlocked, 4 wheel drive: barely noticeable
Hubs locked, 4 wheel drive: holy hell! Sounds like it's coming from transfer case, but everything is new in there and tight.
I know the rear diff has a lot of backlash, but now I'm wondering if it's the front diff. I should point out that I figured it was the transfer case before, which is why I rebuilt it. Wheel joints on front are new as well. Any ideas from the Ford gurus? Thanks in advance!
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Joined: Jul 2005
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If you have access to a frame lift, pick the tires up off the ground, and put it in 4WD and lock the hubs, and fire it up and put it in gear, and then go around the truck with a stethoscope or something like that.
It would probably work better with someone in the driver seat modulating the throttle, and tapping the brakes, and making steering inputs, to try to simulate the condition.
My first thought was a front wheel bearing or something loose in the front brakes, but I really don't know...
It would probably work better with someone in the driver seat modulating the throttle, and tapping the brakes, and making steering inputs, to try to simulate the condition.
My first thought was a front wheel bearing or something loose in the front brakes, but I really don't know...
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God I wish I had a frame lift. That would be just the ticket. Wheel bearings are good...recently replaced along with new rotors and calipers. Pretty sure the PO used it as a plow truck cause I have seen/fixed a lot of worn and busted parts. When I rebuilt the transfer case, something I should have noticed before popped up...the rear driveshaft u-joints were not phased properly. So I fixed that and inspected/repacked u-joint caps with grease.
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Yes they were, MeanGreen! LOL. I thought about dropping the rear driveshaft out and driving in 2 wheel front only to see if it happens. Thanks!!!
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