Truck makes clicking noise while driving

75 GMC K25, 350/TH350/NP203-unconverted

When driving forward there is a low volume clicking sound from under the front of the truck. Its frequency is related to road speed, not engine speed. My wife described it as sounding like a baseball card flapping in a bicycle wheel spoke, and that's fairly accurate. It started a day after I slowly ran the truck up and back over a curb to pull a trailer into the yard, but I'm not sure that is related.

I've tried jacking up the truck and turning each front wheel by hand, but I can't reproduce the noise in the driveway. When driving it starts out fairly quiet, but then seems to pick up volume. There is no pulling in the steering wheel or any different feel to how it drives. It does not seem to get better or worse while turning. My guess is that it might be a bearing cap on one of the axle shaft joints hitting the hub, but I can't see any rub marks.

Any ideas?

Thanks,

Bruce

Bad U~Joint.

Is there a splined sleeve connecting the tranny out put to the TC? If it is, they click when worn.

I believe there is a splined sleeve from the T case to the transmission, but this noise seems to be coming from farther forward. The NP203 also has a front driveshaft with a Cardan joint on one end, and it has a slip joint. I am going to try to verify that it is properly extending and compressing to keep full engagement when the axle moves. I'm also going to check fluid level in the NP203, just in case low fluid might cause chain noise.

The difficult part of troubleshooting is that I can't reproduce the problem in the driveway. If I drive back and forth or jack it up and move the front tires by hand I don't get any noise. But a half a block after I get out of the driveway I will have a very pronounced clicking noise that matches road speed.

I replaced ball joints last year, so I had the front axle shafts out and and the universal joints looked good then. I also repacked wheel bearings at the same time, so I don't think its likely that they are making the noise. From a driveability standpoint the truck seems complete normal, but just has the noise.

Bruce

Did your best friend put a zip tie on your driveshaft?

About the only way to check U~Joints is to remove the drive shaft and rotate yokes and trunions, remove trunnion caps and inspect the shaft the needle rollers turn on.

That’s not easy to pinpoint, probably joint, in my opinion. Given the noise started after a “peak level” torque event, the CV joint could have failed under load and now is flopping within itself.
Good hunting.

Sure would be funny, but a relief, to find a rock or nail in the tire. Lol

I spent part of my morning with the truck on jack stands and me crawling around under it with a big screwdriver trying to pry on U-joints and check for something loose. My only accomplishment was adding a little oil to the transfer case (probably a couple caps full) and determining that the front axle also needs a little bit of gear oil. I found nothing obviously loose, no bolts missing, and no rocks stuck anywhere.

I think I'll have to just drive it a little more and see if the noise gets loud enough to pinpoint where its coming from. It reminds me a little of the sound of a bad CV joint, but more like a click than the knock you get from a CV joint. It also happens when I'm driving straight ahead, not necessarily just in turns.

Thanks again.

Bruce

SquareRoot said:

Sure would be funny, but a relief, to find a rock or nail in the tire. Lol

Click to expand...

Thats where I would focus nextand hope for an easy fix . I have had an anti rattle clip on my brakes come out and make similar sounds

SquareRoot said:

Sure would be funny, but a relief, to find a rock or nail in the tire. Lol

Click to expand...

Take it to Les Schwab. Seems like a rock in a caliper is always the fix. At least that's what their commercials say...

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MisterB said:

Take it to Les Schwab. Seems like a rock in a caliper is always the fix. At least that's what their commercials say...

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Click to expand...

I think you mean "the culprit"? Lol

Does your truck have rally wheels with trim rings on them. If you do remove the trim rings and see if the noise goes away.

Tmich396 said:

Does your truck have rally wheels with trim rings on them. If you do remove the trim rings and see if the noise goes away.

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Yep,that would do it. I thought that but didn’t see beauty rings in Bruce’s profile pic.

Also , Do you have those wheel weight they stick on the inside of the rim ? I had some that came loose and got caught on my caliper . Not good