My car wanders all over the road, especially when on roads, with high spots from big rigs and trucks.
It is mostly all oiginal ball joints, and steering components, but I have checked everything, including steering box, rag joint, and power steering valve, but still seems to wander??
I just re did the complete rear suspension last year, and all is tight as can be back there.

 

You have something loose somewhere. Place a jack under the lower control arm and get it off the ground an inch or two. Get someone else to wiggle it side to side and use a board or bar to pry up on the wheel, while you look. Any movement is bad. Also check the wheel hub bearings for slop.

 

Hi Darrentpi, I have the same problem with my 70 coupe (which easily has the worst straight line steering of any car I have ever owned)and have done a lot of reading on the subject looking for a solution. It seems that with the change to modern radial tires is where the issue started JMO from reading up on the subject others opinions may differ. When GM started fitting radial tires they were only running 20 PSI which hinted they were aware the steering got twitchy.
The improvement (I won't call it a fix) if you want to stay with original steering components seems to be to add more positive caster to the steering alinement. This will encourage the wheels to track in a straight line (too much will make the car harder to start turning into a corner though)
Trouble seems to be that you are very limited to how much you can add unless you change the upper A arms for ones that allow this but I see that original looking ones that allow up to 5 deg pos caster are available from a site vendor. The sky's the limit if you want to go non stock looking though. Asking around there are many that are quite happy with their stock steering and claim that their car steers well, I know one owner that has three C3 vettes all with std steering, 2 he says steer poorly but the 3rd is very good, he has not been able to establish what is different about the 3rd car that makes this so. Many forum members have changed out their steering boxes to a modern design to help fix the problem or a rack and pinion system but perhaps they can chime in with how things went. Personally I think it may need a combo of more caster and a better steering system to really fix the issue JMPO and I know we have some steering gurus on the forum who will have the answers.

 

For what it is worth:

IF your car came into my shop and you voiced your concerns in how it handles....and if I looked at it and it looked like 'some of this...and some of that' have been replaced. I would rip it ALL out and re-build the entire front end suspension.

SO...depending on condition...upper and lower control arm bushings... (many types out there so the choice is yours and you get what you pay for). MOOG parts for the upper/lower ball joints and tie rods ends and idler arm.

Possibly needing to have the cradle stretched back otu so the original A-arms with the factory style cross shafts in the upper A-arms may be required IF...repeat...IF you have little to no shims in your upper A-arm shimming points.

Depending on how much play is in the gear box/rag joint also. I know you checked it...but I am still mentioning it. Especially and play you can feel in the rag joint...which is common when the steering wheel is turned all the way in one direction and it stops against the suspension as designed and THEN the wheel is then turned further. It wallows out the rubber in the rag joint and you begin to get play in it...and that is the beginning of the END of that.

I have done NUMEROUS suspension on Corvettes over the years...and regardless if I am still using factory parts with upgraded bushings and such...or factory rubber...I have never had a car that would not track true and straight when correctly aligned. I have NEVER given a Corvette back to the owner that made them drive it with 'white knuckles' when driving it with a lot of SPIRIT!! They MUST have complete control at ALL times. When ALL variables are taken into consideration...the steering and suspension will perform to a very high standard. Just leave a few things as they are because they are 'good enough'...and that is what you will get ...something that is good enough. And if that is what you want...then...you got exactly what you wanted.

Not knowing how or what you did in the rear...I can say that it is REALLY IMPORTANT that this area is CORRECT...because if you do not have it RIGHT...you will have a steering wheel in the rear and the car will be all over the road.

DUB

 

It looks like you've hit most of the common items in you check off list, but one thing you didn't mention was the idler arm. When someone describes their steering as you have the first two items I check (also the two easiest things to address and typically the first two to show excessive wear) are the rag joint, and the idler arm.

Having said that, and based on your other comment regarding the components all being original, I'd agree with Dub, you need to come up with a plan to address all of the front end components (as you've done on the rear) or you'll likely be chasing your tail trying to get it to track straight and true. If the idler arm is bad, changing it first may give you a bit more time to enjoy the car while you work out a maintenance plan.

Good luck... GUSTO

 

Good post Dub. My '69 with rebuilt front and rear suspension, and steering components confirms what you say. It tracks straight and true and handles corners like a new car.

Having said that, at the risk of hijacking this thread, how do you stretch out the cradle so more shims can be used. I have a Speed Direct bolt in spreader bar. I have some tension on it, but I don't think it would take the forces required to really spread the frame.

So how is it done?

Thank,
Pete

 

Which vendor, Haggisbash? These might be the ticket for me.

 

Bias ply tires are WIeRD , after you are used to modern radials.

Firestone repops are awful for wandering over imperfections as you describe. I hate mine on the Camaro . They just suck the big one.

 

I had a local expert corvette repair specialist align my car. It darted and wandered terrible.
After too many scary near crashes I called a local corvette expert and asked where he gets his cars aligned. No part changes just different spec settings. Car handles great now.

 

While your at it, check the rear end for loosness / bushings, attach points, etc.; obvious odd ball tire wear is a good indication.

 

I also forgot to comment on the power steering control valve ( if equipped). Though the control vale is supposed to allow the taper stud to move that goes into your pitman arm. I have dropped down so many steering center links and noticed that the taper stud has so much side to side play.,..that you can have EVERYTHING new in the front end and NOT take this into consideration and still wonder why you feel like your are steering a boat. This amount of side to side play that the taper stud has can be adjusted....and I have broken down control valves and have seen the worn parts and when I get new and or rebuilt ones in...the amount of side to side play in the tape stud is MUCH less than the worn out part that I removed. This stud is designed to move forward and backwards due to the sweep it has to take to make the steering move...but the side to side play in this stud can be excessive. Something to consider. ALL IT TAKES is a little bit of play in many parts and you have a steering/suspension that is loose. A little bit of play might not seem like much...but it can add up...quickly.

I am also curious if your did trailing arm bushings. These are critical to get correct.

Pete,
This requires a frame machine. Pushing up on the bottom of the engine cradle...while pulling out CAREFULLY at each upper control arm mounting point. Thus bringing the frame basically back to where it should be. Then a VERY CLOSE inspection of all welds....due to as we know...these frames are not the best built part ever made. I have had to go in and actually weld up broken spot welds and such BEFORE the pull began. I DO NOT take any of the weld point for granted.....I REALLY, REALLY look at them VERY WELL before I begin doing anything. Roughly a 30% chance that the Corvette will have to have some initial repairs before the pull starts. From my experiences.

The spreader bar only will hold what you have and does NOT have the MOXI to push the upper control arm mount points further apart. I have never seen one that is that stout that can do this without beginning to bend under pressure.

Obviously..COMMON SENSE comes into play here and know what to release pressure on can make this go easier. Because when it comes to frame pulling...you have to 'over-pull' so when the steel springs back...it goes to where you want it. RARELY does the frame stay put where you stopped the pull.

DUB

 

I had the same issue (all new sus parts frt & rear) with good year radial GT tires back in day. I've had BFG T/A ever since and run them NO MORE than 26 psi. if I inflate them to 30psi or more they get a little "darty". I've driven the car for 30yrs like this and gone on road trips with out any issues. FYI, I have 245/60R-15's on the front & 255/60R-15 on the rear.

I noticed in your photo, It appears your rear tires camber (at least the LT) is Negative. The alignment HAS to be SPOT ON and if you have driven some time like that, the tires will need to be replaced!

 

The C2/C3 steering is pretty good when everything is in good condition but there are a number of areas where improvements/upgrades can bring the car's steering up to modern standards. I have yet to see a C3 that will steer like a modern car with 100% factory steering components and suspension pieces. Why is that? Well some of the design elements of the factory suspension limit certain alignment specs as mentioned as well as too much movement from factory parts or design limitations of the factory steering system. Another issue is tires-forget the bias ones and the radial 255/60/15's have a sidewall that flexes like a marshmallow causing the car to bounce all over the road-less so with the factory 225/70/15's. With a BB car, the issues are magnified by the weight of that engine.

You mentioned that some of your suspension parts are original and been checked. How many miles on those parts? My experience is that unless a suspension component is really worn, it is not always possible to visually or statically find an issue with suspension parts-you need to change parts sometimes even if they look "OK", especially on a C3. I have owned my 78 L-82 67,000 miles on the car and I have changed just about every single suspension part over 32+ years. The key to modern ride and steering is ELIMINATE/MINIMIZE ALL unwanted suspension/steering movement. So here is what I have learned over those 32 years about the C3 suspension and steering:These are highlights of problem areas and what to upgrade

Front:

1. Obviously every single suspension component needs to be in like new condition for optimal ride and steering control-this is a given-idler arm, tie rods, springs etc.
2. Ball joints especially the lower ball joints that have a much greater load than the uppers-double down for a BB car
3. Control Arm Bushings. I know that many don't like poly upper and lower control arm bushings but they are great at minimizing unwanted suspension movements and do NOT hurt the ride much at all. I have had mine for 10 years now.
4. Frame Flex between the shock towers-get a spreader bar to stop the C3 frame from flexing-double down for a BB car again with that weight.
5. Steering Box/rag joint-A BIG ONE. the stock recirculating ball steering even when new by its basic design will have play which gets much worse with age and mileage. I have a custom blue printed/rebuilt box that has an olite bushing on the shaft internally that totally eliminates any and all steering play. The only way to achieve modern steering is with a custom rebuilt stock box, borgeson system or rack and pinion-no way around this issue.
6. Tires-BIG ONE-Stock factory tires and sizes are just not optimal for ride and handling-too much flex in the sidewall. I switched to 255/45/17 ZR tires several years ago from the stock 255/60/15's and could not believe the difference. The car tracks perfectly, no wandering, minimizes bump steer, enhanced steering response.

Rear Suspension:

1. Trailing arm bushings. If these are worn/shot, the car will never ride correctly over bumps or handle. It will rear steer. Rubber is preferred in this location due to the twisting action of the arm. mine are rubber, not poly.
2. Steel rear mono leaf spring. The fiberglass composites are much preferred here since they have MUCH better ride quality, react quicker, never sag, and take 40 lbs off the rear suspension. I have had a 360 mono spring since 1986 on my car and would never go back to steel. There is a reason every corvette since the C3 has had composite springs-C4,C5, C6, and now the C7. Hands down superior.
3. Rear Strut Rods-BIG ONE. The stock strut rods are kind of a nightmare since the rods themselves flex under load and the rubber bushings allow too much movement even when new, forget as they age. The hands down winner are adjustable competition struts with heim joint ends-no bushings and thus zero flex and rear suspension movement. For about $200 these are one of the best upgrades you can make to the rear suspension. The rear feels really planted with these struts and no they do not noticeable effect the ride-slightly stiffer and one of the best upgrades you can make to the rear suspension.

My C3 truly rides, handles and steers like a modern sports car but folks it is going to take some changes to make a C3 behave that way.

Hope that helps!

 

Lots of things can cause the car to wander: ball joints, A-arm bushings, steering link joints, ragjoint slop, and trailing arm bushings.

But, even with those things ALL in good condition, the car will still wander, unless the alignment on the front wheels has just a bit of toe-IN. Anything from 1/16" to about 1/8" of toe-in will prevent a good, tight steering system from wandering over those road ruts. 3/32" toe-in would be ideal.

 

That is correct and I failed to mention above-alignment needs to be done correctly

 

As to both your coments, thankyou for the advice.. I did a complete trailing arm rebuild, done by VanSteel. They shipped me back to brand new ones, as well as i had diff, half shafts, spring, everything re done. I did the Re and Re myself, as I am a mechanic. As far as rear camber, I did not get an allignment, however when I removed the trailing arm shims, I correctly matched them up with exact stacking size of shims, as what was originaly on the car.. The rear worked out perfect, no issues.
As for the front, the only thing done was lower ball joints changed, so time ago, as the guy at the shop says in most cases upper do no wear out, correct me if I am wrong??
What should be some of the tests I should do, to find the problem, should I be testing back and forth play, when the car is running, up on jack stands?
How can I tell if that rag is in good condition, of course it looks old and worn, but it seems to be tight.

I have decided I am going to do the complete front end rebuild, even control arm bushings, and every moving part up front, this winter, but would still like to find this issue regardless.

Who in the buisness sells the best usa made front end components for this car? as this car is 95% original, even re using all my original nuts and bolts

 

Thanks for all the posts! I will post some pictures this weekend of closer look at that camber issue, to see what you guys think, as well as rag joint

 

A set of radial tires are much better than those junk
whatchamacallits that came on the car or those modern duplicates...... as they do perform the same condition and handling situation you described....Mine has wandered and even all most switched lanes from new or day one

I went to some good radials and solved my handling conditions

 

I hate to write this...but regardless if you put the shims back in the same locations for the trailing arms...I would have alignment heads put on it and have it checked.

Just because they are new trailing arms means nothing except they are new arms...when it comes to an alignment. I hope that the inner sleeves of the trailing arm bushings were ground or filed flat so the shims rest against a flat surface...versus the protruding sleeve that occurs when it gets staked.... as designed.

I truly hope it is perfect...but the odds are stacked against you. Just 'saying'.

DUB

 

Hi jb78L-82,

Do you use the linkage-booster power steering setup still? I want to get my car steering better, but am not too keen to move away from the factory setup. I have got a correct GM rag joint and have a steering box that Gary R blueprinted for me. I want to keep the power steering system - if you still use it where did you find a "good" PS valve?

Regards,
Matt