I’ve covered some of these issues in other post but thought it may be more clear to re start.
Base line.
All chassis rubber- consumable components replaced, recent alignment. Trailing arms where rebuilt. Steering box “blueprinted”.
Recently send the power steering pump, ram and valve off to a reputable rebuilder. This did help with the low speed forces and overall steering.
I raised the back and recheck the trailing arm shims (a member suggested this), they seemed tight.
With the rear raised I noticed the drivers side wheel moved almost 1/4” in the camber plane but non in the toe in plane. The pax side wheel moved about 1/8” in the camber plane and non in the toe in plane. It looks like the bearing moving and not the suspension components. If it was the bearing shouldn’t it move in both planes? The trailing arms were built up by a local mechanic and not a reputable corvette shop.(?)

The issue I’m chasing is the car feels like there is play and a disconnect between where I point the car and where the car tracks. The suggestion to check rear shims (forum member) does sound legit as you could make a steering input, the force would move the trailing arms if not tight cause a slight rear steer. This is kinda how it feels, long post but this is hard to describe if you’re not a chassis person. My long term goal is to have this vette highly dialed in but I can’t even get the basics at this point!
Thanks Gents!

 

I would certainly not discount thoroughly checking the rear shims and the bushings. I know you indicated that the bushings were changed, make sure poly was not installed. If rubber was installed, make sure they were installed correctly. Problems with the shims can make the car feel like it is disconnected from the front when accelerating or steering. Jerry

 

Are the differential side yokes moving in and out of the differential when you move the wheel?

 

When you say camber and toe, you're trying to move the wheels between 6:00&12:00 and 9:00&3:00, right? If so, I'd not be surprised that you don't feel much horizontally vs. vertically. If you think of a rod (bearing) in a tube (bearing race), because of gravity, the rod falls to the bottom with any gap at the top. Side to side is more difficult because the rod is sitting in the bottom of the tube.

Sounds like excessive movement to me. The bearing clearance shouldn't allow 1/8" to 1/4" of free movement. Unless someone more experienced than I thinks otherwise, perhaps the spindle nuts are not torqued appropriately or else the internal shimming is too much. It really does take an experienced mechanic to set these up correctly.

 

I’ll take a look at the side yokes, 67:72, correct on the “indexing” or orientation when checking play. I’m kinda thinking these arms are going to have to come off and be checked by someone who knows what they are doing. Better now than in the middle of the driving season.😖

 

I have a 1968 C3 convertible and its 427 and four speed and 3.36 rear. A few months after we bought the Corvette we took it on a road trip to the 1991 Corvettes@Carlisle about 103 miles from home.
Then the next day in the mid-afternoon while we were driving back to our hotel (off the Turnpike) and it was raining buckets and buckets. As soon as I got on the Pennsylvania Turnpike I felt something was seriously wrong with the tracking of the 4 wheels. In HEAVY Rain and above 35-40 m.p.h. my rear end started to CRAB down the highway with my rear end going to the left. As I slowed down the handling went back to normal and I drove several miles at sub-40 mph to the hotel. This was a very scary experience and only after checking it out did I carefully headed safely back home. The car never exhibited any strange behavior or noises from the rear end but in heavy rain it runs like a normal car. It acted perfect the next morning where it was sunny and beautiful so I went back to Carlisle and on to home without any issues.

Trailing Arms (T.A.'s) are something some guys will take on, I decided to just pay someone to do it right the first time for me. The T.A.'s can be a beast to remove but doing the R&R is very doable in a home garage. I have heard that a bad bearing in a trailing arm can do all sorts of bad things. I don't have the tools or experience to rebuild something like this. I prefer to pay someone now that I am in the "post 60" crowd but I do as much as I am able to do.

The Side Yokesare important to check. These are the parts that are inserted into the differential and they have been known to wear strangely and popping off the C-clip inside the differential. The Side Yoke is the part that attaches your Differential to the half-shafts which connects to the trailing arm. If they move in and out more than a specific amount then you need to address this issue. The yokes were fine on my car, all my problems were tied to the trailing arm itself. After the trailing arms were overhauled the Corvette drove very nicely and tracked perfectly.

 

What are your alignment numbers? These cars like a LOT of caster.

There's nothing wrong with poly bushings, except in the trailing arm, and strut rods.

 

Follow up:
I got time to check the rear end movement out, it wasn’t really what I expected. The passenger side has play in the side yoke and the drivers side is moving inside the trailing arm. The good news is I have a direction and cause for the strange handling. The downside is possible rebuild of the rear differential.

 

You should be able to put a dial indicator on the yoke.
An ideal blueprinted diff will have the yoke move in/out only around .006". Heavily worn-out yokes can move .250"
You can also put a dial indicator on your trailing arm and measure your hub bearing play at the axle hub. These should be very tight, .003" or less
More than that means you need the trailing arm axle bearing rebuilt.
The rubber front trailing arm bushings should only be torqued tight when the cars normal weight is on them and they are at normal ride height. This could easily require some creativity on your part. The rubber bushings "twist" when the T/A goes up/down and if not centered properly at a "neutral" position, they will tear rather easily. Or a brand new bushing would restrict movement, until it tears. You can check that looseness by prying with a crowbar in the shim pocket.
Sounds like you have a direction.

Rebuilding a trailing arm is pretty unusual and very technical. I would not trust a local rebuilder. That should be done by a Corvette shop, or GTR1999, he is the best around. He taught normal machinists.

Good luck!

 

Sounds like sound advice. I’ve already contacted GTR and I’ll probably pull both trailing arms even they have been “rebuilt”. It’s always tough to take steps backward after paying for rebuilds but that is the path forward.

i can tell without measurements that the drivers side yoke is well out of specs, not a full .25” though.

 

Yes if you can see that one move, you can feel it when you drive the car.
Just ask Interpon. He documented that pretty well in his threads.

 

I found a few of his post but couldn’t find the one about yoke play and handling. Regardless, I’ve found the issue with a bit of forum help!
KC

 

good luck!
trailing arm bushings here.. video #10 post..
https://www.corvetteforum.com/forums...nd-advice.html

axle end play with video here.. alignment throughout threads.. and differential advice.. This one surprised me how much it improved turning..
https://www.corvetteforum.com/forums...ay-advice.html

i would DIY if you can.. this forum is awesome.
NOTE to moderators.. i used to be able to see all threads started by me in profile , now it does not allow?

 

I have a spare rear end that I expect to DIY. Having these links is really helpful.

The search feature has been broken for a bit. It affects everything, since searching for your own previous posts/threads uses the same database. I've had to pull threads out of email, or find them with DuckDuckGo.

 

I find Google Search is always the strongest / fastest search engine.

Just start your search with "C3 Forum..."