"Clunk" noise at takeoff
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Laughing Gas
Joined: Oct 2004
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From: Brandon Mb
"Clunk" noise at takeoff
My truck has began making a clunk noise when I go to take off from a stop. If I start slowly, it doesn't do it, only if I gas it. Also, if I tighten the drivtrain up (a brakestand without tire spin) it makes the same noise when I let off the gas. It doesn't make the noise when I decelerate though. I recently had the diff apart (2 or 3 weeks ago) Backlash seemed good, and so did gear contact. I haven't noticed it doing this in reverse, but I never stand on it in reverse either. If anyone can give me some advice as to what might cause this I'd love to hear it.
Trevor
Trevor
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Joined: Mar 2002
Posts: 19,402
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From: Bonita Springs FL
Lots of things. U-joints, transfer case slip yoke, sway bushings front or rear, tranny mounts, tranny crossmember, engine mounts, incorrect torque on pinion nut, radius arm bushings... I'm sure there's more, but those are the most common causes.
I currently have the exact same thing going on with my truck, and I'm just about at the bottom of the list.
I currently have the exact same thing going on with my truck, and I'm just about at the bottom of the list.
Thread Starter
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Laughing Gas
Joined: Oct 2004
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From: Brandon Mb
I don't think it will be incorrect pinion torque. The backlash between crown and pinion seemed good, and so did contact between the gears (they go hand in hand I guess). I believe the u-joints are okay (greased recently) haven't looked at tranny mounts, cross members or sway bars. An engine mount would have shown up by the engine trying to jump out wouldn't it? I think it might be inside tranny or transfer case, because it only does it in drive, not in 1st. If it were in the diff, it would do it all the time. So its thrown me for a loop. Gonna get a mechanic friend to check it when I get home. (Don't trust guys I don't know, got burned once.) Thanks for the input though.
Senior User
Joined: Nov 2003
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My mechanic (Ford dealer) said it was in the drive shaft--there is apparently an inner section and an outer sleave, and when they separate, it creates a metallic clunk any time there is torque pressure on the drive shaft--ie. shifting into gear/reverse, or accelerating. He said I could fix it for about $500, or live with it--I decided to live with it. Aside from being annoying, it does not seem to cause any problem driving.
I'm sure there are other things that can make that noise as well. We narrowed it down, by shifting into gear with brakes on, which made a metallic clunk every time, and checking all other components--ie. U-joints, etc.
Hope that helps.
Frank.
I'm sure there are other things that can make that noise as well. We narrowed it down, by shifting into gear with brakes on, which made a metallic clunk every time, and checking all other components--ie. U-joints, etc.
Hope that helps.
Frank.
