rear driveshaft/ ujoint question

[galeo7171]

I'm trying to track down the loud noise coming from the rear of my truck. At certain speeds I can hear a continous loud metal on metal knocking noise. It sounds like somene is taking my tow hooks and banging them against my bumper. It seems to be worse if I put it in neutral and coast down the road) I put it in neutral (1986 CUCV blazer) and set the parking brake and checked the ujoints. The rear ujoint has some play in it and I noticed when I grabbed the rear drive shaft and rotated left to right, the shaft moved about 2-3 inches left to right at rear axle pinion. Is this normal amount of play normal. The axle is a 10 bolt, and has 120k miles.

 

[1stDeuce]

Whoa, on first read, I thought you were saying that you could shake the pinion around... 1/4 turn or so in the driveshaft is "normal" for a 10 bolt chev axle. If there's play in that U-joint, you need to replace it before it grenades and takes out the yoke and driveshaft... There is pretty good angle on that joint to begin with, so it is possible it could be making some good racket when you drive it.

In the event your Gov-Lock is starting to come apart, you might get some banging from inside the rear diff... Usually any failure inside the diff makes an external appearance in short order... If you really don't think it's a wasted U-joint, pull the diff cover and check it out. A few quarts of 90wt and some RTV to seal the cover and at least you got a little PM done!

C

 

[galeo7171]

Whoa, on first read, I thought you were saying that you could shake the pinion around... 1/4 turn or so in the driveshaft is "normal" for a 10 bolt chev axle. If there's play in that U-joint, you need to replace it before it grenades and takes out the yoke and driveshaft... There is pretty good angle on that joint to begin with, so it is possible it could be making some good racket when you drive it.

In the event your Gov-Lock is starting to come apart, you might get some banging from inside the rear diff... Usually any failure inside the diff makes an external appearance in short order... If you really don't think it's a wasted U-joint, pull the diff cover and check it out. A few quarts of 90wt and some RTV to seal the cover and at least you got a little PM done!

C

What exactly does shaking the pinion around? I pushed up and down on the rear driveshaft near the rear ujoint and noticed that the ujoint itselft would move up and down and I could hear a clicking noise. When i twisted the driveshaft left to right it would move around 2-3 inches...so this twisting is normal? but the ujoint needs to go right?

 

[maritimer]

replace the u-joint asap, it really sucks when the let go and do major damage lol