I read a post about this a little further down. I too get play when i wiggle 12 and 6 on my rear wheels. When i look to see what's moving, it appears as if the whole trailing arm as well as the differential side yokes are moving. I get a very quiet whine when i'm on the highway, and when i'm on it really hard going through the gears i get a click click click click every once and a while. What causes the diff yokes to do this? What is involved in fixing it?

 

The side yokes wear into the differential cross shaft in the posi unti. 1/8-1/4" of play is ok, any more and I would start to get ready to tear the rear end down. I reshim my yoke for autocross racing on a yearly basis (due to posi clutch plate wear.) Tom's Differentials has the best cross shaft (better than GM's!)

 

The end of the yoke inside the differential is worn. That is something that they do after years of use. There should be almost NO in-out movement on the side yokes. They will wear into the snap rings if you let them go. Later sharks were very soft so the problem is more common. I real PIA to change.... you have to remove the half shafts, spring and the differential to do it. And then you have to re-align the rear.

 

1/4" PLAY IS not ACCEPTABLE... .025" would be too much...

 

It's not the cross shaft that wears. It is the ends of the yokes and I feel 1/8th to 1/4 is far too much play. I don't know what is the upper limit of play but when I do them I try for a few thousands.
Some yokes are still hard on the end and the groove can be adjusted to take up play. If the end of the yoke is soft then the only way to fix that yoke is by replacing or installing a tool steel button.

 

The Yoke dimension from the end of the yoke to the snap ring groovve is .187"(3/16) If you are checking the yoke end play on the car, I like to remove the 1/2 shaft. It's NOT necessary but you'll get a true reading and can also check the U-joints. The yoke are softer then the posi pin and were probably only case hardened so once you get to .034-.040" they may start wearing out faster. If you find under .050" play with them in the car leave the differential in the car for a while if everything else is ok. If you remove the differential for other service then replace them. It makes no sense to pull out the rear end and try to save a couple of bucks,unless you like that job You have to look at the wear on the pin too,it will wear even though it's hardened.
If you get the rear of the car in the air,level the T arm with a jack and see where your play is, could be a combinatin of bushings,yokes,and Bubbafication.
Gary

 

Too bad you're on the left coast, I had a couple of cool forum guys in today to open up and inspect a differential.
Gary

 

My trailing arm is not moving at all. It seems like the bearing to me. I have to get in there and investigate. If the 1/2 shaft is moving in and out you have worn side yokes.

 

I also have play in my trailing arms due to worn side yokes, and it's many times 0.025". I autocross and track the $hit out of my car and it seems there's no ill effects on handling. On a street car it wouldn't make a damn bit of difference.

Eventually I'm going to do something about it to make it right, but it's not so pressing on my mind that it's no. 1 on my list.

 

,Somewhere I read that some guys actually removed the snap rings to allow for more play.......I installed new side yolks when I bought and refurbed the rear I'm using now, the play was less than .025" when I re installed it...

 

geez why would they do that???????

 

Are you sure he wasnt running a 6 link? I think you have to remove the c-clip in order to let the axle drift in and out.

 

I guess I should clarify my answer, 1/8-1/4" AT THE WHEEL is FINE for any Corvette! I have serviced cars with over 1/2" of play at the wheels that were driven for may thousands of miles without problems (tended to be owned by NCRS and "car show" types.) You cannot really measure the yoke endplay on a freshly "built" differential at the side yoke. If during the rebuild you installed a new posi clutch plate set, you will find that after about the first 1000-5000 miles there will be 1/16" to 1/8" of wheel movement at the wheel in the Vette differential (along with a buch of really NASTY metallic clutch plate particles in the rear end lube.) On the other subect of what is wearing, I find the cross shafts tend to be the most common wear item on the Vette differential on the 15-20 or so that I have serviced and re-built in my carrer (maybe you have done more?) The yokes can wear and when they do, I would replace them with International Axel Company side yokes and not the others (rebuilts) that are unknown parts with inserts installed. You can talk to any good Metalurgist and they can tell you how the axels in a car take a "set" during use; if you swap sides, they will be WAY MORE prone to failure then if they go back into the same side they were removed from. I also know that I probably subject my LT-1 to much more severe useage than most posters on this forum with the 3000RPM drag launches (12.28@117MPH with slicks) and autoX useage (1.4G lateral acceleration by my data recorder with "sticky Hoosier tires.)

 

Mine wore almost to the snap ring. In that condition the rear cannot be aligned (camber wise) Even at max travel of the eccentric there would still be a few degrees of negitive camber. "Bubba" bends struts to fix it. Anyway with that amount of wear the outer edge of the flange actually was hitting the differential housing. One sid dug a groove in the carrier from a U-joint bolt. I don't understand how people say it's ok to leave them alone.

 

i'll crawl under there and take some measurements tomorrow. I drove the snot out of it today and it didn't make the clicking noise once, and I only noticed the whining for an instant at 80mph.

 

I am in the process of new bushings and spring in the rear. I checked the end play and found that I had .125 on each side. It looks like a rebuild is on the way. Would you go with a rebuild from a vendor or have it done at a local shop? What questions do you ask a local shop about the rebuild? I have called and priced ring and pinion sets and found that in the posi unit, there is a couple of choices beside the stock replacement. Any suggestions on this? The car is just driven on the street 2,000 to 3,000 miles a year with a 350 horse 350 and a four speed.

Thanks, Garson

 

You need to find a local Corvette club and inqure there, there must be some club in Southern Oregon. My friend Dave at Corvette Repair in Mountain View, CA (650 969-5351) is THE BEST differential/drivetrain mechanic I know of, Dave does stuff for many of the L-88 vintage racers with 600+HP Vettes and all are satisfied customers (but those rearends/parts don't come cheaply at around $1500 for a rebuild to live/last at those HP levels and you still need to tear down and check parts on a yearly basis for them to be reliable.)