I've aligned my suspension and it turns great, doesn't have bump steer, but follows the ruts in roads bad. Not overly darty any more, but does a tad. After posting on it, most say its the 245/45/17 front tires and 275/40/17 rear. These are not large tires by today's standards. New C5 don't wonder.
So, why can't I have a great handling C3 that will even handle like my 99 VW jetta?
1) There are after market A arms with better geometry. Spreader bars to stiffen the A arms.
2) There are coil overs
3) There are the composite monoleaf fronts
4) Modern tires and rims
5) Steeroids steering systems
What is stopping these C3 from handling like a C4 with fat tires?
If we can have better A arms and coil overs etc to add caster, camber, etc. what is holding it back?

 

Stock camber settings are good for stock sized tires or slightly larger. The wider you go with the tires, the more you need to dial in negative camber to prevent the outer edges of the tire from catching on ridges in the roadway, and steering the car for you.
We had this with a Monza that ran 12" fronts....dialed in more camber and the dartyness went away. I hope this helps....

 

Won't more camber chew your tires? Not sure as those old VW bugs had huge camber in the rear tires.

 

....

 

Much as I love the C3, it admittedly has some geometry issues inherent with its decades old design (blame the bean counters, not Zora); in particular among others with front scrub radius, front bump-steer, rear camber curves, and even more so with rear toe-steer. I'm not crazy about the C4, but it did offer some improvements on these fronts. However, as for the issue of "wandering" in ruts, my '92 did too. The General actually reduced front tire width in '93 due to complaints (proof to this viewer comfort was becoming more and more the priority of the buying public).

Assuming there's nothing actually wrong with your C3 chassis, whether or not this characteristic is of any consequence is more often than not a matter of preference/tolerance than of being a real problem, and IMCO this isn't something for which I'd compromise an otherwise sound alignment.

FWIW (and not to flame you), if you think it's a bother on street tires, you're in for an eye-opener should you ever find yourself on wide road racing slicks.


TSW

 

I agree with what "TheSkunkWorks" is saying and will just add that you can expect that "wandering" from aggressive low profile tires and that the newer cars "mask" it better so you don't notice it quite as much. I have a couple of Hot Rods with performance oriented suspension and modern tires and they both do it. I also had a '86 C4 with Yoko 008Rs on it and they were sticky tires (80 wear rating) and it was noticable on that car too.

 

Take it on a known smooth highway and see if it handles correctly, if it does move to a city that has better roads. Mine handles fine around were I live except on one road that huge trucks use and therefore big ruts in in the road, my PT Cruiser does the same as does my work truck

 

I like your way of thinking...

 

its great. keeps your arms muscly. enjoy it

 

TBH you can't go putting 40 profile tyres on a 40 year old car and expect it to work.

Manufacturers design a suspension system as a unit, that means everything from the road to the chassis.

Tyre width, sidewall stiffness, geometry, springs, dampers and bushing.

I would strongly suggest not dialling in loads of negative camber, this will only make your 'tram lining' as we call it, worse.

Additional negative camber is normally a work-around for excessive positive camber due to body roll or poor geometry.

I would suggest you look at your scrub radius and castor.

 

I have 245/45/17 ZR's in the front and 255/50/17 ZR in the rear on my 78 and found that two changes to the suspension, assuming everything is completely up to snuff in your suspension, made a BIG difference in the car's former wondering state:

1. In the front, polyurethane control arm bushings, upper and lower-this change dramatically reduced the movement in the A arms and greatly improved this condition to the point that it is very similiar to the rut effect that I experience with my 2008 Chrysler 300 with 245/55/18 ZR's in place of the OEM 225/60/18 tires. Very big change.

2. In the rear replaced the OEM strut rods that HAD poly bushings with competition strut rods with Heim joints which completely eliminated any movement from the strut rods under load. Heim joints do not alllow any bushing deflection (there are no bushings) and the much heavier strut rods will not flex like the OEM rods.

Keep in mind that these two changes were dramatic and I still need to have the OEM steering box (32 years old now, 65,000 miles) rebuilt and blue printed by GTR1999 on this forum (I will not buy a rebuilt aftermarket box or even a new one since build quality and steering box adjustment are sometimes dubious) and I still need to replace the rear control arm bushings (again 32 years old). I was shocked at the improvement in the wandering with these two changes. The car tracks very close to a more modern car with these changes and with the tires mentioned above. Ther modern ultra high performance tires mentioned above alone made a big difference over the OEM 255/60/15 tires which have soft sidewalls and tend to deflect easily over rutted roads. The key to eliminate the wandering is to minimize anything in the suspension that will deflect and move around. BTW-the ride with 550lb front springs, a 360 monospring in the rear, and Bilstein HD shocks is really quite good, not harsh at all. Hope that this helps!

 

If your car 'wanders', it's probably due to one [or more] of three problems: your [front wheel] alignment is set with positive or zero toe-in; you have some loose/worn components in your steering system (rag joint, steering box, links, joints, and/or bushings); or you are driving on well-traveled truck routes with rutted-out road surfaces. You can't have straight-line handling with 'wash-board' roads.

 

I agree with all the above, EXCEPT to note that with any stock p/s control valve in that position you have a necessary looseness that is greatly accentuated with modern rubber, and is the most important thing I noticed when going to rack/pinion steering in '01-02 winter....the car is tight as can be now....I have all the other changes now, but the U/Inner bushings are wearing after 15 years...ya THINK??

anyway, I find any conversions that eliminate the p/s control valve from the OUTPUT on the cross/relay rod at end of pittman arm to be a huge positive, wether rack or Jeep box conversion....not only that but 2.7 turns vs 3.7 turns L-L is much superior for handling...no longer handles like a bus.....smaller steering wheels from later sharks help too....

 

I agree wholeheartedly with your comments about the OEM steering on the C3 vettes but I was referring to folks that do not want to deviate from the OEM steering for whatever reason. In my case, just about every change, anywhere on my car, is geared more to optimizing the original systems rather than change to a different design, including the steering system. I can tell you with my setup right now with the ultra high performance tires, the complete OEM steering system, and the OEM original trailing arm bushings in the rear that it is pretty darn stable right now with the other changes of made over 25 years. I have spoken with GTR1999 personally as well as other forum members about his work, and from what I can gather a blue printed rebuilt box by him is far superior to any other OEM box and even the steering on brand new C3's back in the day since he hand adjusts every one of his rebuilt boxes, something that never happened at the factory. I am fairly confident that with a blue printed box and new trailing arm bushings, my car will be far superior than what came from the factory, it is already right now-especially steering response, handling, and ride!

 

I under stand the worn parts, but even those that have everything new/better, still have wandering issues.
What does the MFG do to "mask" the wandering?
I have new off set trailing arms (4,000 miles)
New steerioids
Alignment is set at:
Camber: old left -.2 rt -.3 Now -.3 and -.3
Caster: old 3.0 / 3.4 now 3.3 and 3.4
Toe: Old -.2 /-.23 now .27 / .24 Total old -.42 now +.5

Rear:
Camber: old -1.1/-1.2 now -1.0/-1.1
Toe: old -.13/.0 now +.14/+.13
Total change rear: Toe old -.13 now .27 (shouldn't the rear have tow in???)


Much as I love the C3, it admittedly has some geometry issues inherent with its decades old design (blame the bean counters, not Zora); in particular among others with front scrub radius, front bump-steer, rear camber curves, and even more so with rear toe-steer.
But if it's geometry issues, why don't aftermarket A arm fix it? Is it not the a arms?
What is scrub radius and rear camber curves?
Can't an alignment fix toe-steer or a set of poly bushings?


TBH you can't go putting 40 profile tyres on a 40 year old car and expect it to work.
Why if we can change just about every aspect of the car?
Manufacturers design a suspension system as a unit, that means everything from the road to the chassis.
Which is true. So what size tire significantly reduces wandering? Even people with stock tires report wondering.
Tyre width, sidewall stiffness, geometry, springs, dampers and bushing.
But geometry, springs, dampers, bushing and all can be changed with minimal effect on wondering.

I was expecting an answer like, the physical distance between the upper and lower a arms are too close or a arms are too short. Things that we cannot fix. Otherwise it would have been remedied already.

1. In the front, polyurethane control arm bushings, upper and lower-this change dramatically reduced the movement in the A arms and greatly improved this condition to the point that it is very similiar to the rut effect that I experience with my 2008 Chrysler 300 with 245/55/18 ZR's in place of the OEM 225/60/18 tires. Very big change.

2. In the rear replaced the OEM strut rods that HAD poly bushings with competition strut rods with Heim joints which completely eliminated any movement from the strut rods under load. Heim joints do not alllow any bushing deflection (there are no bushings) and the much heavier strut rods will not flex like the OEM rods.
Thanks those sound like easy and relatively cheap fixes.

P.S. I 99% sure the car already has the VBP Street and Slalom system in it. Visual inspection shows all the same components, shocks, springs, sway bar, Smart strut bracket, HD camber strut rods. I cannot verify spring rate though. It even has the off set trailing arms.
Someone, previous owner, dumped some $ in this car.

 

i also have the heim joints.
and
trailing arm front polyurethane bushing kit.
Learning how to do alignment yourself at home is a big plus. better to drive/adjust/drive 'til u like it.

 

I am not really sure what else to say here other than you only mention your tire size but nothing about their speed rating, who makes them, ultra high performance etc which is why I specifcally mentioned the whole tire construction issue above. Can you fill me in on those facts? Also, I see above you mention all your alignment settings but don't mention if you have upper and lower poly control arm bushings-I found that the poly bushings in the front especially helped alleviate some of your issues and Smart struts are not heim joint competition struts. To minimize the wondering you are experiencing assuming everything else is perfect, you have to minimize any type of suspension bushing deflection which I did with polyurethane bushings just about everwhere so far. You are correct that a 40 year old suspension design cannot compete with a C5/C6 outright but there is MUCH that can be done to close the performance gap and it is not very hard to do if you are handy! Tires are VERY IMPORTANT in the whole equation! Many people would be shocked at how a C5/C6 would handle with 1970's tire technology in a 255/60/15 S rated tire on one of those cars-Believe me it would be all over the road! A great deal of the handling in many modern cars is directly attributable to the greatly improved tires! I must admit that your problem sounds like something is wrong some where since what you describe on your car is almost totally absent from mine.

 

I'd have to disagree with that, if you mean geometry as tweaking camber and tracking, then no, it's not going to make huge improvements, you need to look at the setup as a whole.

To start with I'd be looking at the ET of those alloys you've got compared to stock and what your scrub radius is.

The tyre sidewall is a spring, shock absorber and insulator. To go from a 60 profile tyre to a 40 means a massive increase in sidewall stiffness.

The increased sidewall stiffness means that every minor rut in the road is picked up by the wheels, pulling the steering. Couple that with the fact that with 40 profile tyres, your springs may now be soft, your dampers too soft and you bushing have too little, too much or not progressive enough 'give'. You can soon end up with worse steering than stock.

 

Sorry for the lack of info. I just got the car so don’t know everything about it. It has BF Goodrich G-Force T/A 275/40 ZR17 98w M&S, 400 treadwear, and Traction AA. The front are the same but 245/45/17.
What do you mean by “ET fo those alloys”? Sorry, trying to learn a lot here.
I don’t know what the scrub radius is, but will google shortly.
I don’t know if the front has poly. I’m just assuming and you know what that means. How do I tell? It’s all new stuff. The previous owner put a lot of $ in the suspension, and it looks like the VBP street/slalom setups with same shocks, sway bar dimensions, and new coil springs, smart struts etc.
What tools are needed to do your own alignment? I’d love to play and experiment!
Thanks guy also for spending time to help answer some questions. Your experience is a big help.
I have to order some Hemi joints for the rear and figure out some how if the front has poly or not.

 

FWIW - my 98 C5 (130,000 miles) recently started following a 'groove' in the freeway at one area where they moved lanes with painted lines. I am attributing it to the current, worn, run flat tires - plan to put on new rubber very soon and I expect it will go away (if not will check my front bushings). Note that my 79 w/ BFG 60 series 15 inch tires, poly bushings, ... - does NOT follow this same 'groove'.

How is the tread on your BFG T/A tires?