Noise under load

[1992gen1_fan]

For about a month or so when accelerating fairly hard, my truck makes fairly audible growl/scrapish type sound, when it makes the noise I can feel a slight vibration in the floorboard. It will do it until I let up on the throttle. Usually just notice it mostly in 4th and 5th gear and it don't always do it.

I was thinking maybe clutch slipping but I tested it on a good hill in 4th and did a 25-50mph hard accel and did'nt notice any slip.

Any ideas?

[RCCUMMINS89]

Natural question would be..........u-joints?

[1992gen1_fan]

I'll look at them. Its hard to tell but sounds like around the trans/engine mount area. It makes me think of a thrust bearing of some sort. I just changed the fluid in the Getrag, looked clean.

[1992gen1_fan]

U-joints look good, the drive shaft its self needs work though. Alot of play where the 2 pieces of the drive shaft meet.

[RCCUMMINS89]

Could be your issue.

[1992gen1_fan]

Today I got a quote to get the drive shaft fixed. Prety sure thats the origin of the sound, can't believe I overlooked the most obvious possibility . I'll report back when I get the repaired drive shaft installed, thanks.

[Matt's'93]

Hey, I had my 1991 that made a similar noise. I was able to buy new rubber mounts that go between the transfer case and the cross member. Mine had become soft and when under load the bolts were able to shift sideways and contact the frame (cross member) which made one hell of a growl/grinding noise. After I installed them it eliminated that sound....
Also my 1993 was making a similar sound and shortly after it made a big bang..... and lets just say the Nv4500 is in the mail
Hope this helps

[1992gen1_fan]

Ok, I'll check out the trans mounts and such. They "looked" ok but who knows. Also I have had the mount plate break before so I'll check that out.

I sure hope this don't end up like your '93, the Getrag still shifts fine and is'nt getting hot or anything. But from what I've read they can give up suddenly without notice or very little notice like yours.

[Philip]

U-joints look good, the drive shaft its self needs work though. Alot of play where the 2 pieces of the drive shaft meet.

Do not go by looks. Remove the drive shaft and move the U-joints threw the full range of motion. Just looking and trying to check for play normaly doesn't show anything.

These trucks have a very narrow range of suspension movement. Every U-joint I have replaced in my truck has had grooves worn into the crosses from the needle bearings. I have replaced U-joints every two years sence 1998 on this truck on the rear shaft.

[1992gen1_fan]

Thats a good point. When I take the shaft down this week I'll look them over real good. I already told the driveline shop to put some new u-joints in while they have it appart since they hav'nt been replaced in a few years.

[m880cummins]

Check/replace U joints, check motor mounts and, if you have a 2 piece rear driveshaft check the carrier bearing for slop. Also if you have a suspension lift, make sure the two piece rear shaft is perfectly straight. You may have to make a spacer to drop the carrier bearing if it isn't.

Charlie

[PToombs]

My truck had a nasty vibration and I suspected the u-joint. I pulled the shaft and looked at the rear joint, it had some dark marks where the roller was working on the yoke. I couldn't feel them with my fingernail, but I changed it anyways. Vibration gone!

[1992gen1_fan]

Dropped off the drive shaft at the driveline shop. Replacing the slip yoke, spline stub, possible 3 u-joints and the carrier bearing assembly. All Spicer parts $$$ I should have it back next week, we'll see if that cures the noise.

[1992gen1_fan]

Check/replace U joints, check motor mounts and, if you have a 2 piece rear driveshaft check the carrier bearing for slop. Also if you have a suspension lift, make sure the two piece rear shaft is perfectly straight. You may have to make a spacer to drop the carrier bearing if it isn't.

Charlie

The truck is stock height, though the drive shaft in the stock setting is not a strait line to the rear diff. Looks like it was to make clearance for a muffler or to keep it away from the fuel tank or something.

[1992gen1_fan]

Picked up the drive shaft, guy said the u-joints were still in good shape. Got the slip yoke, spline stub, and carrier bearing replaced though. I'll see if the noise is still there tomorrow when I can put a few miles on it.