GMC K-Series Pick-up

1988 GMC K-Series Pick-up Drive Train / Driveline   

I have a 1988 GMC 4x4 with a manual transmission (4speed w/ OD). It shifts just fine although when I engage the clutch, take my foot off the accelerator, or put it into a gear I hear and feel a "clunk" sound as if there is some sloppyness in the drivetrain somewhere. The transmission was rebuilt 5 years ago. I've been told it may be as simple as a bad CV or U joint or as bad as a tranny on its way out. I don't want to take it in right away as the dealer would love to replace it for a costly rebuilt. Is there some way to rule out the worst-case-senerio. And like I said, it shifts no problem, fluid is up, and there are no other sounds or problems with the drive train.

Hi, My first thought is that the driveshaft for the rear differential might be binding on the transmission output shaft.

There should be a greese zerk to lube the splines and worse case you may need to clean the splines of old grease to get the yoke to slide properly.

Roger

That makes sense a lot of now, Roger. The problem shows up once I've driven a few kms. I went under the truck and there doesn't appear to be a grease fitting anywhere near the yolk, only a rubber sleeve. I'll probably need to take it in for a "yolk and sline" service.

Keep me posted.

To accept my answer please click on OK to finish up.

Roger