Drivetrain Slack Clunking
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Cargo Master
Joined: Aug 2002
Posts: 2,117
Likes: 8
From: Over Yonder, MN
Drivetrain Slack Clunking
I posted this down in the 6.7 forum, but it's probably more pertinent up here. I've been having what I feel is drivetrain slack. Every time I let off or get back on the gas there is a clunk/jerking. It doesn't do it from a stop. I took some video of the clunking while cycling between drive and reverse. I was thinking backlash or something in the diff, What do you think?
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Elder User
Joined: Jun 2011
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I have this same problem on my 99. I think it is in the drive shaft. It it happens when I change from reverse to 2nd also 2nd to reverse. I'll be watching this thread. I was planning on doing the u joints soon. But it hasn't got any worse.
Post Fiend
Joined: May 2009
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From: Pea Ridge, AR
Slip joint regreasing
FTE Leadership Emeritus
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From: Stephensville WI
Fleet Mechanic
Joined: Nov 2011
Posts: 1,825
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From: Land of Taxes
PN for the Teflon ford specific grease is XG-8. My dealer charged $7.92/tube. If you decide to do this repair I also have a step by step in another thread. Search driveline thunk or put my email address in the search box. I was able to reuse my clamps that hold the boot on so the total repair was the grease + my time. Though your symptom sounds a little different that the slip joint thunk, why not start simple.
Postmaster
Joined: Jan 2012
Posts: 2,693
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From: West of Chicago
My 07 E350 box truck (5.4) does the exact same thing. I bought it new with 30 miles on it and now has 58,500 on it. I took it to 3 ford dealers and they couldn't find anything wrong with it. Mine "clunks" at about 15 mph and once I come to a stop again it "clunks" and will actually push the truck foreward a few inches. I would bring it back to the dealer if still under warranty and tell them what it's doing and show them if possible. My truck Is now out of warranty from ford but this un-resolved rear end issue Is the reasion I got an aftermarket warranty. Keep us posted as I'm interested to know how this turns out. Good luck!
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Elder User
Joined: Jun 2011
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My drive shaft is one piece. Looks like the slip joint is towards the rear axel. My pop sounds like its comming from the front of the drive shaft toward the transfer case. There are 2 universal joints with a link in the center. Think its popping there. I can't feal any play when I get down under there and twist by hand.
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Cargo Master
Joined: Aug 2002
Posts: 2,117
Likes: 8
From: Over Yonder, MN
Well I think it's in the transmission... maybe. Got under the truck today and rocked the driveshaft back and forth. There is definitely a noise coming from the transmission, or maybe the transfer case, but i'm leaning towards the transmission. It's hard to tell though if it's whats causing the clunking or if I just wasn't able to turn the driveshaft hard enough to cause the real clunk to show itself.
Elder User
Joined: Jun 2011
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Well I think it's in the transmission... maybe. Got under the truck today and rocked the driveshaft back and forth. There is definitely a noise coming from the transmission, or maybe the transfer case, but i'm leaning towards the transmission. It's hard to tell though if it's whats causing the clunking or if I just wasn't abel to turn the driveshaft hard enough to cause the real clunk to show itself.
Post Fiend
Joined: Feb 2009
Posts: 8,773
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From: Texas Coast
Sure seems like the transmission to me as well. I notced some scoring on the DR-shaft towards the front. Or at least I thought I did. whats that from. LOL if its there.
When does it do this. Only on a incline, not on a incline, when going from dr to r etc?
When does it do this. Only on a incline, not on a incline, when going from dr to r etc?
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Cargo Master
Joined: Aug 2002
Posts: 2,117
Likes: 8
From: Over Yonder, MN
I only hear the clunk when shifting out of park and when alternating drive and reverse like that. I can feel it at speed though, especially when abruptly letting off the gas or getting back on it.
Post Fiend
Joined: Feb 2009
Posts: 8,773
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From: Texas Coast
Next time it does it notice if its only in a specific gear that is does it.
Kinda sounds like a differential issue. I would be tempted to drop the plate and see.
do you ever hear a whining noise when backing up or at about 40 mph?
Kinda sounds like a differential issue. I would be tempted to drop the plate and see.
do you ever hear a whining noise when backing up or at about 40 mph?
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Cargo Master
Joined: Aug 2002
Posts: 2,117
Likes: 8
From: Over Yonder, MN
No whining noise ever. Tonight I noticed its louder after driving awhile, when its been sitting it's actually pretty quiet. If, when rocking it, I pause in neutral for a sec, it will not clunk. I agree it seems like a differential issue. Think tomorrow i'll have a buddy come over so I can listen to it while they rock it.