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This is a really common problem with Corvettes and I can't believe it took 10 posts before someone figured it out. The procedure for replacing the yokes isn't really all that bad. The bigger problem is likely to be finding quality replacements.
Originally Posted by Wee
Be careful....Some of the eBay ones are junk. I do not know how to tell the good ones from the bad but someone else might. Brian
There are a lot of really bad "reproductions" out there. If you can, find a machine shop with a Rockwell Hardness Tester and have them check the hardness of the ends of the yokes. Rockwell "C" scale hardness needs to be in the high 40's to low 50's. Anything softer is not worth installing - they will get chewed up and destroyed.
I may have missed the point where we leapt from checking the condition of the bushings in the strut rods to purchasing side yokes because the ones in the rear are damaged.
motogotro, have you actually verified that the bushings in the strut rods are okay?
with Gusto. I replaced my strut rod bushings 2 years and 4000 miles ago. After replacing I adjusted to 0 degrees camber and was pretty well in the center of the adjustment bolt range. The camber creeped further out (negative camber) until I was almost at the end of adjustment on the passenger side. I then thought it was yoke end play or wear so I took everything apart. The left side yoke end play was .027 and the right was .029 which shows some wear but is really good for the original 69 diff. The new strut rod bushings I bought were elongated and worn causing the problem after 4000 miles.... Garbage bushings so I replaced with adjustable rods and it's fine now.
The left side in your pic is out really far at the bottom resulting in big negative camber. Remove the strut rods for a start and no matter how good the bushings might look in place, that has to be some or most of the problem. If the bushings are fine and I would bet anything they are not, you can then remove the half shafts and check for yoke wear. You actually get yoke wear from bad strut rod bushings that allow excess movement of the halfshafts and the yokes in and out.
Last edited by CanadaGrant; 01-27-2019 at 12:43 AM.
I would hope and assume that he's going to check the yokes before replacing them. Bad strut rods/bushings are pretty obvious even to a non-Corvette mechanic working on the rear alignment. The yoke problem is not obvious to someone not familiar with the setup, so it becomes the suspect condition due to how common it is, and how difficult it is to detect for the "average" alignment tech. You will recall from the original post:
Originally Posted by motogotro
They were not able to get the rear wheels to come into spec. They couldn't tell me exactly what was wrong. I've ordered the strut rod bushings although I cannot tell for sure that they are bad.
Pretty good indication that the yokes are moving around...
I took my '81 in to have a 4-wheel alignment but they were not able to get the rear wheels to come into spec. They couldn't tell me exactly what was wrong but when I look at the car from the back the camber is easily visible, the tires lean in significantly at the top. I've ordered the strut rod bushings although I cannot tell for sure that they are bad. I had the car jacked up yesterday and tried to find some slop in the rear suspension but did not find anything excessive. I know there is a busing at the front of the rear trailing arm, is it likely that this bushing is bad as well? Is it replaceable? What else will cause this camber issue with the rear wheels?
If you could take some photos of the underside of the car, lay on the ground and snap some photos, everyone would have a better idea of what is wrong. Maybe photos of Yokes and half shafts, and strut rods and adjusters.
Be careful....Some of the eBay ones are junk. I do not know how to tell the good ones from the bad but someone else might.
Brian
Sounds like the originals are junk as well so if it turns out that I need them, I'm stuck between a rock and a hard place. I assume that the only other alternative to the ebay ones would be used ones from another C3?
Well, we are having a nice day today so I started tearing into this and was surprised to find less play in the yokes than I expected. I'm not sure how much is normal or now much the play I have will affect the camber but it doesn't look nearly as bad as I was expecting. I did find a couple of bad u-joints, a leaking right side yoke seal and it looks like my trailing arm bushings are on the way out if not already out. I also noticed that the strut rods come out of the inboard brackets at an extreme angle, is that normal. They are almost hitting the bracket because of the angle. The car is jacked up by the frame so the suspension is fully unloaded. I attempted to upload two videos showing the play in my yokes but I can't tell if they attached.
Left trailing arm bushing Left strut rod Right trailing arm bushing Left strut rod with half shaft in place. Right strut rod
Looks like you need to do a little bushing work... - unbelievable that an alignment guy would not catch the obvious issues that need to be fixed before attempting an alignment. On the yoke endplay, the ideal endplay in the yoke stub shafts is about one to eight thousands (.001 - .008). From the factory, the Vettes came with anywhere from ten to thirty (.010 - .030). If the yokes are moving in and out more than .050" -ish, they will start affecting the stability of the rear alignment. But you have other issues to correct before worrying about dropping the rear end out... Good job giving it a good checkout!
I'm trying to upload videos of the end play but not having any luck. I'll stick a dial indicator on them and see what it reads.
So the angle of the strut rods is okay or is something not right there? Seems odd that they would design the system this way, the bushings will be in a bind from the moment they are installed.
Be glad the alignment shop didnt do the bubba fix.
Unless you plan on jumping the car, the worn stubs arent a huge problem, but with that being said, all of the metal that wears off the end of the stub isnt exactly good for the other parts in the diferential.
There are many threads on this topic including some that the clip groove was completely gone with no drivability issues. Eventually, the stub comes in contact with the diif housing which will ruin the housing.
Well, we are having a nice day today so I started tearing into this and was surprised to find less play in the yokes than I expected. I'm not sure how much is normal or now much the play I have will affect the camber but it doesn't look nearly as bad as I was expecting. I did find a couple of bad u-joints, a leaking right side yoke seal and it looks like my trailing arm bushings are on the way out if not already out. I also noticed that the strut rods come out of the inboard brackets at an extreme angle, is that normal. They are almost hitting the bracket because of the angle. The car is jacked up by the frame so the suspension is fully unloaded. I attempted to upload two videos showing the play in my yokes but I can't tell if they attached.
Left strut rod
Yes, the extreme angle you are seeing is because the rear suspension is at full droop. If you raise the rear control arm up toward it's normal position, you'll see less and less angle.
Once you replace the worn out bushings in the strut rods with new, you may find it necessary to raise the suspension to be able to insert the second bolt in its' end of the strut rod. I would insert the shock mount through bolt first.
I'm trying to upload videos of the end play but not having any luck. I'll stick a dial indicator on them and see what it reads.
So the angle of the strut rods is okay or is something not right there? Seems odd that they would design the system this way, the bushings will be in a bind from the moment they are installed.
You are correct in that the strut rod mounts are slightly offset from each other. It's normal and was designed like that. This provides constant pressure on the rods even in a neutral position to remove any slack. When you put the rods back in with the new bushings don't tighten up the bolts until you have both ends installed as they can sometimes be a bit hard to push into position. By the way, that last strut rod pic of Rusted40's with the huge bend in it is an old Bubba trick. When there is no more adjustment left and still too much negative camber the "technician" bends it up with a BFH to shorten the rod instead of actually fixing the real problem....
Last edited by CanadaGrant; 01-27-2019 at 04:45 PM.
I put a dial indicator on them today and I have .012 in the left yoke and .014 in the right so I think my yokes are okay which is good news. I'm still toying with the idea of pulling the diff to fix the right side leak. I'll already have the trailing arms off so I think now is the time to do it if I'm going to do it but I haven't fully decided if I'm going to do that yet. I have the strut rod bushings on order already but will get the trailing arm bushings and u-joints ordered asap. I have my fingers crossed that fixes my camber issues. Thanks again to everyone for the tips and suggestions.
Good news on the yokes! I got to where you are now, and decided to live with a bit of a leak, rather than miss a month of driving waiting for differential parts. Absolutely everything else got rebuilt or replaced.
I would strongly recommend heim-jointed strut rods now that you've gotten this far, and have a much better idea about how your car works, but it seems that some new bushings may get your alignment back in spec and you back on the road!
Good news on the yokes! I got to where you are now, and decided to live with a bit of a leak, rather than miss a month of driving waiting for differential parts. Absolutely everything else got rebuilt or replaced.
I would strongly recommend heim-jointed strut rods now that you've gotten this far, and have a much better idea about how your car works, but it seems that some new bushings may get your alignment back in spec and you back on the road!
I've already ordered bushings for the OEM rods so I'll try that first and if I can't get it to come back into alignment I'll try the adjustable rods.
I got the trailing arm bushings kit in today and I see that there are some shims in the kit. I've watched some videos for installing the bushings and it came with a kit to stake the center pin but I haven't seen or read anything that talks about the shims. They don't look like the ones for adjusting the toe so I'm assuming they are somehow used to shim the preload on the bushings? Can someone explain where they are used and how I determine how many I need to use?
I put a dial indicator on them today and I have .012 in the left yoke and .014 in the right so I think my yokes are okay which is good news. I'm still toying with the idea of pulling the diff to fix the right side leak. I'll already have the trailing arms off so I think now is the time to do it if I'm going to do it but I haven't fully decided if I'm going to do that yet. I have the strut rod bushings on order already but will get the trailing arm bushings and u-joints ordered asap. I have my fingers crossed that fixes my camber issues. Thanks again to everyone for the tips and suggestions.
.012" is fine. Unless it's leaking really bad, I would wait till it needs a rebuild. My 2 cents.
01-26-2019, 10:04 PM
