Side Yokes?

[t4bz]

Hello all...and now for my next question!

I was at the tire store today and they had my '79 on a lift. The garage guys wanted to show me that there was quite a bit of back and forth play when you pushed and the tops of both sides of the tires (up around the wheel wells). The mechanics admitted that they were corvette illiterate, but felt that the play was too much. I kinda thought the same...

Should there be any play at all?

When it came down fromt the ramp, I looked at the camber, and noticed that the driver's side in particular doesn't look all that great; it looks like it is a bit too much inward.

I looked in my trusty Chiltons, but didn't find much worthwhile. What about the side yokes? It is my understanding that these can wear and cause camber problems. If it is the yokes, is this a difficult repair?

Once again...thanks so much. This board is fantastic...everyone is a tremendous help. I'm trying to overcome my own corvette illiteracy.

 

[t4bz]

Uh-Oh

Just reading the posts about side yokes...sounds familiar and doesn't look good...:confused

 

[tomtom72]

T4bz, I was looking for something the other day at Fast Corvette's web site. In the trailing arm section at the bottom of the page they have "alignment school" button. I clicked it and they had a page on fr/r alignment. I don't know if you might find something useful there. Just a thought. Good luck. tt72

 

[mike weyman]

wheel bearings seem to be more the culprit, but you would have to have it checked.if you need to tackle the rear end,you may want to wait till winter if possible.mike

 

[t4bz]

Thanks...

Thanks...I think I'm going to take it in and have it checked out. There is actually a good 'vette mechanic in my area. I just talked to him for quite a while about my problem.

He told me that he has seen the "stub axles" (he had no idea what side yokes are) go bad on this year a few times. His opinion was that when the springs wear, this puts undo pressure on the stub axles and causes them to wear. He said that most 'vettes this old actually sit way too low. Looking at mine, I thought that it looked okay, but the way he describe it, you should be able to put your hand between the wheel well and the tire, on end. I don't think I can do that!

I'm not sure about the bearings...again I'm an extreme novice, but I was able to see the stub axles moving when he shook the tire. I believe he's going to look into everything, though.

I asked him if it would be a good idea to replace the springs at the same time if in fact it is the stub axles (or side yokes, whatever you'd like to call 'em), and he said you could, but then you'd also have to think about doing the front springs, too, etc. etc. etc. One of those never-ending deals!

I just thought this was interesting information. I'm not certain its my problem, but I'll find out soon I suppose.

 

[tomtom72]

Don't dispair, these are old cars and you have to expect this. You can work out a plan of action so you could do it over the winter. It maybe worth while to go to the book section on this site and find someone who is making reprints of the original Assembly and shop manuals and make the investment. If not so you can do it yourself, so you can be knowledgable about what has to be done. If you have fair mechanical ability with the manuals you can do most of it yourself. Good luck. tt72

 

[78SilvAnniv]

...good vette mechanic in my area...(he had no idea what side yokes are)...

My mouth literally dropped open! I am very surprised that a vette mechanic does not know what side yokes are. Shocked, actually. :eek
The side yokes are where the half shafts are connected to the rear end to drive the rear wheels. It runs between the pumpkin and first set of u-joints.
Hopefully, the mechanic was just not familiar with the term...:confused...I suppose anything is possible.

I have two things I want to comment on;

First, when you observed the excessive toeing-in on your vette's rear tires immediately after lowering...this is not an accurate picture!
Every corvette, when lowered from a lift will do this because of how it is set up, the independent rear end, trailing arms and shocks/springs cause everything to hang to the lowest point and when it sets down, the tires will be closer together.
Roll it backward and forward several times/feet and the tires will settle into their correct riding position, then observe whatever you wish to observe about how they are riding.

The next item is the side yokes. My side yokes went bad on my 78 about 10 years ago, and it was a costly ($1300) repair because I needed to replace the rear gears. I kept changing out the u-joints but that was not the problem, and if the side yokes are worn (and worn badly like mine were) you will have at least these signs:
My rear end made a horrible moaning, groaning noise when starting from a stop and making slow right angle turns. I think this was because of too much play in the side yokes affecting the gears. My tires were too camped out to the outside at the bottom. This meant that I had excessive tire wear on the inside tread of the rear tires.

My understanding of the mechanicals of these vettes is very basic, but I do think I know enough to be dangerous. Because I was so shocked about your vette mechanic not knowing the term "side yokes" I would recommend taking your vette to another known vette mechanic for a second opinion.
Good luck and I hope the fix does not cost you an arm and a leg.
Heidi

 

[tomtom72]

Hi all, Side Yokes = stub axles. Most Mechanics use that term because they are kinda like a live axle. A clip holds them into the carrier. On a IRS set up the stub axel is held into the carrier via a clip just like a std live rear car's axle. Same part just different names. Good point about the hanging suspension just off the lift, looking at that for the first time could give a 1st time owner a cardiac!!! tt72

 

[78SilvAnniv]

Egg on my face!

Hopefully, the mechanic was just not familiar with the term...:confused...I suppose anything is possible.

How the tables have turned, now it was ME who wasn't familiar with the 'stub axle' term!
Heidi

 

[tomtom72]

I would say no egg on anyone's face. I remember when I saw that term side yoke and I couldn't get it right away. Only I didn't say anything cause I did know what everyone was talking about. Then it hit me side yoke = stub axle. The shop manuals I had way back when referred to them as stub axles, as did most mechanics back in the 70's. I just hope that t4bz gets a straight deal from the mechanic. If the axles are moving that much I would like to know what else is worn out in the rear....can anyone say rebuild time??? I did mine because everything up to that point was so beat up(starting at the front of the car) so I figured why would the rear not be smoked too! tt72

 

[t4bz]

Stub yokes? Side axles?

Hey everyone...thanks! I think it was more of a deal where the mechanic didn't like the term side yokes...and was more familiar with the old stub axle term. I'm hoping it isn't too severe...I'm thinking about taking it in tomorrow to let someone have a look...then holding my breath. I can do quite a bit...but I'm just a bit intimidated by rear ends.

My '79 has about 64K on it now, but the previous owner let it sit for quite some time. From receipts he had, it looked like he drove it about 1500 miles in the last six years or so. So I'm hoping it isn't a lot more than the stub axles / side yokes.

My plan, if it is in fact that, is to let him do the side yokes and put a rear spring in myself. That looks like a job I can handle.

What do you think about the theory of undue pressure on the yokes due to a weak spring?

And if I do put in a new rear spring, should I put in fronts, too, or do you think that can wait a bit until I can replenish my savings?

Thanks everyone! What a fantastic board! Travis

 

[t4bz]

and another thing or two...

The camber on the wheel that looks off is still that way after the drive home. I may have given the impression that it was merely after the car was taken off the rack.

Also, I've tried to listen closely, and I haven't heard any sort of odd noises coming from the back. The car is a pretty well-mufflered (is that a word?) L-82, so it isn't too extremely loud, so I would think that I could hear an odd-rear end noise. No groaning or moaning or the like. From what I've heard, the side yokes can be varying degrees of bad...if you let them go too awful long they'll wreck your rear end; others are merely bad and need to be replaced. Obviously, I'm hoping its the latter.

I'm sure there is something wrong back there...because there was just too much movement with the wheels. Thanks again everyone. Hopefully I learn enough to post an intelligent reply of my own in the future! Travis

 

[Bob Chadwick]

What do you think about the theory of undue pressure on the yokes due to a weak spring?

And if I do put in a new rear spring, should I put in fronts, too, or do you think that can wait a bit until I can replenish my savings?

I would think the combination of t-arm, shocks and strut rods should keep the thing together. Those are all parts that are torqued in place and provide structural rigidity. The spring end bolts have no such structural purpose.

I would think you can replace the rear spring, if necessary, without replacing the front.

 

[tomtom72]

hi t4bz, I will say up front that there is a thread in C3 section on side yokes(stub axles). It was written by a chevy dealership top tech. who is a member here. It gives the in 7 out play #'s, do a search. I'm just an amature, my car was raced before I bought it si I just did everything over. That said Trailing arm bushings, Camber rod eccentrics(bolts @ camber rod plate under center of spring), camber rod ends bushings, all that stuff back there makes a difference. IMHO you could wait & do fronts later or vice versa, but it might be interestering in the meantime! I don't think it would be a unsafe car to drive, it might be unsafe to drive like a corvette. If I had to make a choice, I would fix the differential 1st, survey both end's suspension needs, cost both out, and then let urgency(saftey) be where to start. If neither end is unsafe, then I would do the end that has the greatest risk of damaging any new parts just installed. If there was no risk to new parts, then start where I could do the most myself to save $$$. tt72. The half shafts I believe form the upper link in the rear suspension. The stub axles a C-clipped in place to limit axle movement in & out, without the C-clips the half shafts & stub axles could move out to alter rear toe adjustment(see Fast Corvettes web site 'alignment school'). I think I have the theory correct. tt72

 

[curtis]

my 2 cents. Seems to me the wheel could only wobble or be wiggled while on a lift only if the lug nuts or bolts are loose or the bearings are worn out. these are the only things that hold the wheels on the trailing arms. other than the bolts going thru the bearing carrier. I would start there, especially if you do not know how many miles on the wheel bearings since last serviced and set up.

 

[t4bz]

Laundry list

Just got all of the horrid news:

1. Right rear control arm needs replaced
2. Rear spring
3. Stub axles
4. Strut rods
5. Left control arm bushing

Not to mention the bushings in the front. I'm thinking I might just take it home and wait for winter, then go through the entire thing. Yikes.

 

[t4bz]

I meant the control arm bushings. I'm debating with myself right now if it is a job I'm capable of.

 

[GTR1999]

Is the control arm rusted or bent? new ones can be had for about $100 now.

rear spring- steel aftermarket ones will raise the rear of the car you'll need 8" bolts. 'glass springs cost more,need shocks, and break.

Stub axles should be replaced if you have more then .060" endplay. To replace you have to drop the rear end out. then you may find you have other issues in there.

strut rod s can be reused if you only need new bushings, they aren't hard to replace. If someone bent them doing an alignment then replace them. Some shop heat and straighten them but I don't like that idea too much.

Control arm bushings - rear ones are hard to relpace because the bolt is usually rust welded to them. Once you get the arm out then you have to flare the tube to hold them together. you have to buy,make or have someone do this part. If using poly bushings they are not flared.

 

[Chris Kennedy]

One thing I have always found is that most mechanics, whether they be professed "Corvette" mechanics, or people like at your tire shop, will take every opporunity they can to point out EVERY imperfection in your car. Then you will get the speech as to why you must do something about this. So, you let them do the "something" and either nothing changes or the so-called problem is worse, then they either say "that's normal" or say something else must be wrong. Recently, I had my car in for some work where the part at issue was contracted out a second time. I had foolishy fallen for the "you know..." line earlier, and the part came back worse than before, and it wasn't really a problem to begin with before I stupidly fell for "the line". While I was waiting for the subcontractor to fix, again, something that didn't need to be fixed the first time, the mechanic said "you know, your power steering control valve is leaking....". I replied two things: "Yes, it has been leaking a bit on and off for about 89,000 miles. I simply top the fluid level off about every 8,000 to 10,000 miles. Big deal. Second, let's get the work the car is in for done right this time, first, before we start messing around with things that aren't really an issue." The car was back on the road that afternoon. Anyway, the point of this is just to say that lots of things can be technically "out of spec." on our cars yet not really be a problem that requires everything to come to a halt while the problem is (maybe) fixed for many thousands of dollars. As long as the "problem" is not dangerous, I am finding that it is frequently better to leave things alone. Often, the parade of horribles doesn't happen at all, and if things do degenerate you definately can pinpoint the problem, saving unnecessary repairs and money. Also, you can enjoy the car, and not have it held hostage at a shop.

--Chris Kennedy

 

[t4bz]

Point well taken

Chris-

Thanks for your reply. I understand what you mean. I made the decision to have some work done on the rear because my camber was so obviously bad off that I feared excessive tire wear. He did point out some front end problems, which I'm choosing to wait to repair until winter; when I can't enjoy the car. That way she'll be ready to go for spring. Also, I'm going to try to do the front myself...I think with this board's help, it should be too incredibly difficult.

I DO have a leaky ps cylinder...funny you mention it as an example! But I would estimate a ton of our sharks have the same problem. Right now, I'm "treating the disease" with lucas stop-leak. Down the road, I'll throw in a remanufactured unit, probably, just so my shark doesn't leave her mark on my friends' driveways.

Your point is well taken, though. I have a bit of confidence in the mechanic I've taken my car to (different than the tire shop) because he's listed as recommended by the local Corvette Car Club. He's also been forthright with me about what is absolutely necessary and what can probably wait. I'm certain my ride will never be perferct, but boy is it fun!