Clunk When Lifting Off Light Throttle
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4wd Low
Joined: Dec 2022
Posts: 14
Likes: 2
From: Alberta
Clunk When Lifting Off Light Throttle
I daily a 1977 F150 RWD 3speed-Auto supercab longed, that has starting to make a clunking sound.
When applying light throttle, 30% or less, and lifting your foot off, there is a clunk. Sometimes this clunk is immediate, ans sometimes this clunk is delayed by a second or two. This clunk sometimes feels like it's comin from under your butt (middle of the cab) , and sometimes almost feels like it's coming from the front driver's side. It's more recently been feelin the latter.
I should also add, that when shifting into R from P, after havin er sit, it shifts quite nicely. However, after driving the truck, and shifting D to R, N to R, P to R, it is quite a hard shift into R. I have read that this is just an ol Ford auto thing, but im also thinkin the clunk could be related to this.
I have worked on numerous vehicles, old n new, but am new to Dentsides. In my mind, I think of ujoints and Im also thinking kingpin, just because it sounds like its coming from the front? Does that make sense, or is there something else I should be lookin at/for?
Any help would be appreciated!
When applying light throttle, 30% or less, and lifting your foot off, there is a clunk. Sometimes this clunk is immediate, ans sometimes this clunk is delayed by a second or two. This clunk sometimes feels like it's comin from under your butt (middle of the cab) , and sometimes almost feels like it's coming from the front driver's side. It's more recently been feelin the latter.
I should also add, that when shifting into R from P, after havin er sit, it shifts quite nicely. However, after driving the truck, and shifting D to R, N to R, P to R, it is quite a hard shift into R. I have read that this is just an ol Ford auto thing, but im also thinkin the clunk could be related to this.
I have worked on numerous vehicles, old n new, but am new to Dentsides. In my mind, I think of ujoints and Im also thinking kingpin, just because it sounds like its coming from the front? Does that make sense, or is there something else I should be lookin at/for?
Any help would be appreciated!
Laughing Gas
Joined: May 2015
Posts: 931
Likes: 392
From: Port Orchard, WA
It sounds like U joints to me. If you can, slide under the truck and try and move the driveshafts around near the u joints. If they’re really bad, you’ll get movement at the u joint itself. If none of them move, you may still have a bad u joint. Sometimes they will look fine but are actually binding and heating up while driving. If you have a laser thermometer you can sometimes pinpoint a “hot” one after driving.
Hotshot
Joined: Feb 2004
Posts: 10,785
Likes: 2,595
From: The Shenandoah Valley
My'77 C-6 auto will do it if I've just gone up the hill to the intersection in 1st, then 2nd after exiting my driveway, and then before it goes in third, I let off because of the stop sign, it shifts into 3rd ... and it could be described as a clunk. Not a hammer or metalic type clunk, just a firm clunk under no load.
It's normal ... now for over30 years. It got a shift kit in the '80s.
It's normal ... now for over30 years. It got a shift kit in the '80s.
Moderator & parts slinger
Joined: Feb 2007
Posts: 50,157
Likes: 5,786
From: S/W Missouri, Polk county
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4wd Low
Joined: Dec 2022
Posts: 14
Likes: 2
From: Alberta
I recently started hearing a mild humming sound coming from the rear middle of the truck when cruising at highway speeds. I purchased a new carrier bearing, and the 3 Ujoints as I mine as well replace them when the whole thing is out.
I wil update with the results!
I wil update with the results!
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