I know there is a problem with wear on the older cars had it been fixed by 82? What is an unacceptable amount of movement and can the be replaced without a a complete over haul?

 

I just torn down the rear end on my '80 which is the same as yours. The car sat a lot over its lifetime and it was leaking very badly from all three seals so I figured it was toast. To my surprise, the bearings, clutches, and gears looked fine as well as the half-shafts and all were within tolerances. So I put in fresh seals and buttoned it back up. I have two others as spares and I intend to rebuild one of them for later, but for now I'm happy to drive it as is. That rear end is fine as long as the car was treated civilly during its life but it is not known to be as durable behind a high horsepower engine as the earlier ones.

There should be very little movement in and out of the short driveshafts. I don't know the exact amount allowable, but any more than a barely noticeable amount can be trouble and will require a tear-down and repair.

 

with the wheels up i can take the top of the tire and watch the halfs move in and out apprx .04-.05" but have no leaks. When i let off the throttle i can hear a chunking sound that will vary with speed. all ujoints have been replaced.

 

That's normal. Look elsewhere.

 

I am old and forgetful i did replace the seals when i first got the car and recall the ends of the stub shafts being worn. If i was semi intelligent i would have thought of it sooner. Must be the ends of the shafts hitting whatever is inside there..... duh. Well if its made to move in and out as the car rolls down the road is this considered a wearable item ?
Crap i hate to take it out again.

 

They don't move in and out as the car rolls down the road even if worn. The suspension geometry forces them inwards with approx. 300 lbs static load.

 

Thus the reason it wears?

 

Exactly. The earlier C3s had deeper case hardening on the end of the yokes, later cars had less.

 

And even if they are early or late side yokes from the factory...the Rockwell hardness value was weak(low) ...versus what they offer now in the aftermarket....unless something has changed and I was not informed. As I was told by the company who manufactures the hardened ended side yokes. The new side yokes are safely under the point that they found that would cause the end to split or shatter due to being too hard...but still hard enough to outlast the original specs. If my memory serves me correctly...originals were at 26 Rockwell hardness...and the new ones are made with a low to mid 50's Rockwell hardness rating.


FOR WHAT THIS MAY BE WORTH TO YOU:
Before you install new side yokes.

I believe that you might want to check your clutches in your differential...you use a torque wrench with the rear wheels raised in gear and set the torque wrench to 40 lbs/ft and tighten a lug nut. If the wheel turns BEFORE the torque wrench "clicks"...the clutches are worn out.

The pinion shaft is more than likely damaged/worn....which is the part that the side yokes press against....so if you go in and put new smooth ended side yokes in...they will begin to wear immediately due to riding/wearing on a rough surface.

Lastly....Side yokes with a .040"-.050" run-out is normal and expected fora n aged car...but achieving a .008" side yoke run-out when the differential is completed is what I am expecting/would like to see....if at all possible. Even though I have not found any text to clarify this measurement for a 63-82...I do know for a FACT that the differentials on the 84-96 specify this measurement in written text in the service manual when side yokes are serviced/replaced. And figuring that the differentials are basically the same design being an independent rear suspension....and talking with others who do differential overhauls who have a good reputation....I feel it is safe to try to get the side yokes to this measurement.

Also...it is NOT uncommon that your 1982 will have the heavy duty side yokes in it for a manual transmission Corvette...even though it is an automatic. GM seemed to use up all they had in stock and I have serviced numerous 82's that had the heavy duty side yokes in them. The bolts are different..much larger than the automatic side yokes. If the bolts that hold the u-joint straps to the side yokes are not the same as the bolts that hold the drive shaft to the pinion flange...then you have the heavy duty side yokes. Also..if they are the heavy duty manual yokes...the bolts are an inverted Torx headed bolt to hold the straps. The automatic yokes are either 12 point 1/4"( factory) or 6 point (replacement).

Best of luck to your repairs.

DUB

 

Thank you all for the information sounds like i can get 1 more year of cruising out of it before its due. My yokes are automatics those little 12 pt bolts stink.