Strange behavior in OD
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Junior Member
Joined: Jan 2003
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Strange behavior in OD
There seems to be a lot of expertise here so maybe someone has encountered this problem. I will try to describe best I can.
I own a 2000 F150 GVWR 7700 with 5.4 automatic. It has 25,000 miles.
On occasion, cold or warm, when in overdrive at normal cruising speed, lets says 55mph, the transmission gives a strange clunk. This occurs when I gently back off on the gas pedal (lets say when following a car for example) and then gently again get back on the gas. When I get off the gas, it almost feels like a standard transmisson where engine compression slows the truck, then upon applying gas again, there is a loud clunk sound and associated jerking sensation.
This does not always occurs, sometimes I try to replicate it with not luck. There does not seem to be any pattern, except that it seem to occur only in OD. There are no codes I beleive since the OD light does not flash.
Any ideas? Is this normal behavior for the 4W700R?
I own a 2000 F150 GVWR 7700 with 5.4 automatic. It has 25,000 miles.
On occasion, cold or warm, when in overdrive at normal cruising speed, lets says 55mph, the transmission gives a strange clunk. This occurs when I gently back off on the gas pedal (lets say when following a car for example) and then gently again get back on the gas. When I get off the gas, it almost feels like a standard transmisson where engine compression slows the truck, then upon applying gas again, there is a loud clunk sound and associated jerking sensation.
This does not always occurs, sometimes I try to replicate it with not luck. There does not seem to be any pattern, except that it seem to occur only in OD. There are no codes I beleive since the OD light does not flash.
Any ideas? Is this normal behavior for the 4W700R?
Senior Member
Joined: Aug 2002
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From: Starkville Mississippi
my truck kind of does that but its normal for the truck to shift out of overdrive even at 70mph when you let off the gas. For some reason when letting off the gas it downshifts out of overdrive and kind of clunks and the engine revs higher from the lower gear until it shifts back into OD.
Just my .02 but im pretty sure i know what your talking about,
Just my .02 but im pretty sure i know what your talking about,
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Junior Member
Joined: Jan 2003
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Thanks for the reply
You may be right, I never noticed if the revs actually jump up has I get off the gas, but they are definately not higher than 1500rpm while coasting before getting back on the gas. It almost seems like something stays locked up, then suddenly unlocks, or maybe the other way around.
Also, there is no big jump or drop in revs when I get back on the gas, just this loud clunk. The revs stay constant it seems throughout all this.
Also, there is no big jump or drop in revs when I get back on the gas, just this loud clunk. The revs stay constant it seems throughout all this.
Last edited by MustangSVO; Jan 28, 2003 at 01:34 PM.
Senior Member
Joined: Mar 2000
Posts: 1,740
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From: SE Florida, USA
It won't shift out of overdrive at closed throttle. It does unlock the torque converter, though.
The clunk is all the backlash in the drivetrain. When you go to closed throttle the lash all loads in one direction. When you get back on the throttle all the lash has to move to the other direction. When it takes up the lash there is a clunk.
If the torque converter stayed locked at closed throttle the clunk would be much worse. I've tried doing that. It's ugly!
The clunk is all the backlash in the drivetrain. When you go to closed throttle the lash all loads in one direction. When you get back on the throttle all the lash has to move to the other direction. When it takes up the lash there is a clunk.
If the torque converter stayed locked at closed throttle the clunk would be much worse. I've tried doing that. It's ugly!