Noises when unloaded.

[eric67m]

On my 67 4x4, 465/205 14 bolt there is a rattely gear noise when I get off the throttle. I just recently got my truck back on the road. I mainly notice this noise in 3rd and 4th gear when I get to speed and let off the throttle. I was suspecting transmission or transfer case until yesterday. I loaded the truck with 1-1/4 yard of beauty bark. The noise is now gone with the weight in the truck. I suspect the noise is from one of my u joints or from my center bearing of my 2 piece drive line. Could it be shocks or the rear end?

What should I check for what is causing this noise?

Thanks in advance, Eric
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[odog]

Mine does this when unloaded, it took me awhile to figure it out. I have overloads and when I get up to speed and hit a bump they touch, causing a clattering noise. NOn noise when I have a load on because the overloads are in constant contact. Just an idea.

[flyingtim01]

Mine does this too, though it doesn't matter whether it's empty or loaded. Whenever I let off the throttle at speed and coast, I can hear this knocking/clatter. I know my 465 needs an input bearing at the very least, so my brain is telling me that when it's coasting the input shaft isn't under any tension, so to speak, and so its knocking around a bit.

I might be way off, because I haven't taken it all apart yet, and I suppose it could be just about anything. Although, I have a one piece driveshaft, and I've done the U-joints in them, so I can eliminate that. Maybe it is your carrier bearing though, if you load up, make the driveshaft angle less severe, and it quiets down?

[burnin oil]

Mine does it also. I believe it is the throwout bearing flopping around a little bit as it is not a constant spin design.

[classicundercar]

I had a similar problem and my rear drive shaft (as in the splines) was shot. u joints didn't fix it, but replacing the driveshaft did.

[LONGHAIR]

Another thought is that the noise is still there, but the load muffled (absorbed or blocked) it?

[eric67m]

I do have overloads but I do not recall the noise happening along with bumps.

My u joint at the rear end is new. I think the other two do not have too much time on them. My center bearing has been replaced. The two piece skip joint has a 1/4" section of a tight pipe section that fits snugly over the splines but possibly should be moved to under the cap that is on the splines.

I have thought of removing my front drive line or replacing it with another one. I have removed my shifter boot and watched the front drive line. It randomly turns but does not seem to have any relationship with the noise.

I have not yet tried the transfer case in any different gear than 2wd to see if it would effect the noise.
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