Hello:

For about the past 500 mile I have noticed a strange sound (doesn't happen every time) when I take off from a dead stop. It is a metallic "KA-*****" sound coming from the rear of the truck. A very sharp, metallic sound. Seals in the rear diff we replaced by mechanic about 10,000 miles ago and I have the rear diff fluid changed *** needed. Is this something in the diff or driveshaft or trans?

Thanks in advance!

Rick

 

Check your rear U-joint

 

Thanks for the reply!

Where/what would I be looking for?

Rick

 

Put the truck in neutral, lock the parking brake, chock the tires, and climb under the vehicle. The u-joint is the flexible joint between the drive shaft and the rear end. They go out all the time on trucks. Wiggle the drive shaft and attempt to rotate it to check for slack in the U-joint. It will cost <$15 if you replace it yourself and should be <$50 if someone does it for you.

Grim

 

if the u-joint check is satisfactory you may want to consider this. When you come to a stop the rear end lifts and the driveshaft extends out of the transmission. The splined shaft can bind in that position as long as it is static. It returns to normal (slightly forward of your "stopped" position ) once the drive shaft begins to rotate again under power. I am told this is a problem on Chevy trucks and if I was informed correctly Chevy recommends dropping the driveshaft and applying lithium grease to the front of the drive shaft where it enters the tranny( I assume on the splines).
I talked to one driver who told me if he didn't service his regularly an innocent passenger would think he left his transmission at the stop sign.
I have a similar problem on my truck (although mine doesn't have a hard mechanical sound) and when I asked was told extravagant tales about "spring wrap" and the like until finally a mechanic who knew more than how to just swap parts told me what the problem likely was, and he was right.
So,if your u-joints check out (which sounds like the likely problem unless this came on rather suddenly) then at least you have another option to consider.

 

Make sure you check the joints at each end of the shaft, not just the diff end.

$15 for ujoints is a pretty good price. Mine cost $35 ea, heck I can't even get ujoints for my D28 axle shafts for less than $25 ea.

 

Thanks for the good info everyone! I plan to check it out on Saturday. It had stopped doing it for a few days (or I didn't hear it) and started up again yesterday. How hard is it to change the u joints? I am pretty good mechanically but have never messed with the driveshaft before.

Thanks!

Rick

 

I had a sound like this and for me it was the parking brake sticking slightly inside the drum in the rear rotor when stopping. The metallic sound was made by the backing plate when the brake freed itself from what I can tell. I adjusted/lubed the parking brake mechanism and it went away. This COULD be your problem if you find that the other things aren't the problem.

 

The verdict is in fellas...it was the damn parking brake! Thanks for all the tips and info!!!

Rick