To run 335s I think you will have to flare the rear fenders, I know they would not fit in my wheel well openings at least.

 

I agree! Depends on what you are looking for and whether you plan on racing or not. I have seen some pretty stock rear suspended vettes that are very quick on a road course! Wheels and tires are VERY important to improving the handling and dollar for dollar will give you a maximum ROI on your money. If rear height adjustability is a concern, than the longer spring bolts are your best bet on a composite spring.

I run in the rear:

255/45/17 ZR summer only tires on SLP rims
3/4 inch OEM type rear sway bar-poly bushings
360 monosprings with poly cushings, would prefer a 420 spring!
Bilstein Sports, not the HD's in the rear
Competition Adjustable Heim Strut Rods-no bushings, rubber or poly

I don't race the car but on the street it's handling for a C3 is hard to beat and it rides better than it ever did when new. A must do BTW would be a spreader bar on the front suspension. I have a completely stock style front suspension as well but with the Spreader bar and a custom/blueprinted rebuilt OEM steering box with poly bushings everywhere. The key to improving the ride and handling is eliminate ANY sloppiness in the front and rear suspension for a terrific riding and handling street C3. Just a thought!

 

I was just thinking. I bet that I can change my rear mono spring for race day including setting the correct ride hieght as fast or even faster than changing rear coil over springs with the new even height adjusting.


Mono is just jacking the rear up and six nuts and bolts with air tools and it is off. Lift the new one in place. and hit the six nuts and bolts.

Coil over rear: jack the rear up and remove maybe just the lower mount position if that is the way the spring comes off. Or maybe take them all the way off. The slow part is the spanner wrench and locking collar. It is hard to compress big spring rates with a little phoney spanner wrench with coil over shocks on a car.


The best setup is a 4 link. I work on race car 6 links and the complexity to dial in them for bumb steer, camber and castor is exponential

 

If you are just looking to make this a good handling street car....then i have to say this, and I don't want to step on any toes here, but...here goes.

Either suspension system will be fine, the coil over offering it a more unique look, and more customization to the ride. But both will handle as well as the other.

Wheels and tires ARE where it's at...however, unlike what G-kull said, I have to advise against going with such large tires in the back on a street car. I wouldn't go above 10 inch wide tires in the back, and I would go above 275s in the front. My reasoning...

The wider the tires, the harder it is to get good alignment. The more dramatic crappy road conditions will be. Especially if they are directional tires. I had wider tires on my car, and it required a lot more of my concentration to keep the car on the road at speed on the highway. Now I run 245s, front, and 275 rear. My next tire purchase will have me with 295s rear, and 275s front. Since the narrower tires, my car is a lot less squirrely on the highway, and lot more predictable on crappy roads. For someone that races on the weekends, my next big purchase will be wheels dedicated to racing, so I can slap 315s on the rears (fattest tires I can run without fender flares), and 295s on the front, and not have to worry about driving them on crappy CT roads.

That's just my opinion, and maybe my situation is unique...Gkull knows a lot more about this than I do, so I'm hoping he'll chime in...

 

You buy tires that give you what is your acceptable traction limits in all directions. If you are happy with 255/15 or more modern 17 or 18s, go for it. Then you adjust your spring rates and shock settings to match your driving style.


Tires make so much difference. Like i've spent the day lapping the track on big sticky slicks and you get into a mind set of where the limit of traction is on a tight turn. Then I bolt on my 335 rears 275 fronts and drive home. NO more late braking and turning in. I pitched the Vette clear sideways on the first freeway on ramp near the track.

The cool factor of 4 corner coil overs

 

Very true that tires are where it's at BUT not everyone is here to race and throw down FTD's at an autocross event. Sure you might be able to change a fiberglass spring out faster than a coilover spring but who cares. Don't most racers prep their car before a race anyways. As a racer, I'm sure your on a budget just like every other racer is. You would probably more incline to spend $150 on two coilover springs vs $330 for a fiberglass spring. Tires alone are enough to put a big hole in your pocket.

Let's face it, there aren't many C3'ers that are all out racing either. I appaud those that do as it is an awesome experience/time. I'm sure some may do a long track or autocross event every now and than.

I'll bet 90% of the people purchasing these coilovers are not going to change the springs. Same goes for composite guys. But if you did, you would probably be happier knowing that you had to spend $150 vs $330. When we talk to a potential customer about our coilovers or composite springs, the first thing we ask is, "What are you going to do w/the car". If the word race comes out of their mouth, the very next question is, "What kind of tires".

As an added bonus for guys who convert to our coilovers, if they are not happy with the recommended spring rates we provide, we do exchange the springs out one time and customer just has to pay the shipping charge, which we've only had to do 1 time.

If you add up the cost of offsets, adjustable shocks, composite rear spring & long spring bolts, the cost of our rear coilover kit is about $280 off the mark. Both systems work well and we sell a lot of each. I guess it just depends on how much you want to fine tune your car.

 

If your OEM rear suspension is tight you're not going to see "a substantial improvement" by installing coilovers. Not for the kind of limited use you intend. But if that 'coin' is just burning a hole in your pocket and you're going for the 'cool' factor, why not look at Speed Direct's Sharkbite coilover setup?

http://speeddirect.com/index.aspx?nodeID=132

 

I'm not knocking their kit but if your going to do a coilover set up, your most likely to have/want to run a larger tire/tire & rim package. So you may have to upgrade to offsets or relocate the PB bracket depending on the tire & rim selection you choose. Let's say your like most and you want to get the widest tire available in the rear, your probably going to go with offsets. Guess what gets in the way of you doing that after you do that, the sway bar. So your options are, no sway bar or my shortened rear bar. With the way my shortened bar mounts to the t-arm, you can't use it w/their kit.

 

Can I add one thing. To the front of the rear trailing arms, I added steel bushings to replace the rubber. The bushing I am talking about is the one that inserts into the frame where you adjust the toe setting.

Maybe my imagination, but it had a big effect on the trailing throttle oversteer.

 

I appreciate all the feedback and advice. Lots of knowledge here for me to digest before making my decision obviously. My needs are for the street, I don't see myself bring the car to an autox course. The biggest reason being is that my line of work keeps me away from home 8-9 months out of the year.

As the car sits it has BFG's 255/50/15's at all 4 corners. After the rear suspension upgrade this fall, and the engine changeout in late spring I see the next item changing out being rims and tires. I would say its likely I would go with 18's with 275's at the rear with 245's on the front. I might stay with the 255's there though. I will put more thought into this when the time comes though.

In the end I want the best handling C3 I can have. The entire handling package is the sum of all the parts involved front/rear/tires/steering. It was mentioned above about the spreader bar, that is another thing I am going to get. My newer car (Cobra) has this from the factory, as well as an older GT.

Van Steel has been great about getting me the quotes, and I need to contact them direct to finalize any decision and purchase. I also need to contact a member here concerning the differential I would like for him to provide. So far I see a rough estimate for all the rear suspension parts including differential as being over 5K. This is in the ballpark of what I expected for the better than stock setup I am looking at.

I again want to thank those that are providing feedback and advice. Alot to digest still but the information you provide is invaluable to me. I would ask Van Steel this...When it comes time to finalize any decision and order, whom do I need to speak with? I have received quotes via e-mail, and I see them adding to the discussion here as well.

Jeff

 

I have not touched my rear trailing arms since the car was new and plan on having them rebuilt with new bearings somtime soon (65,000 miles) and WAS going to go with rubber on the arms since I have heard that poly is not great in that application. Where did you get a steel trailing arm bushing and do you have any pictures?

 

I've been sitting this one out, but given the above statement conflicts with others feel you need to better nail down your true priorities (for yourself) so you don't end up dissappointed by having made the wrong compromises between comfort and performance. Yes, there is middle ground between those two ends of the spectrum, but it's hard to see spending cubic dollars to get there. My $.02


TSW

 

end up dissappointed by having made the wrong compromises between comfort and performance.

Wow, I've sure been there and done that! It then became difficult to admit to myself that it was a mistake and make the change to something else.

I like the adjustability of the QA1 coil over system; ride height, spring rate, and shock damping. Plus it greatly simplifies and cleans up the rear suspension. If you're still running the steel leaf spring, the coil over system removes a ton of weight. It also eliminates the conflict between the hot exhaust pipes and a composite spring.

Just my .03
John

 

Jeff,
You can ask for me (Dan) or Paul. Either of us can help you out and answer any additional questions you have.

 

Jeff,

I can tell you that no matter which way you go, Van Steel is the place to work with. I've used them for all my suspension parts, and even visited their shop. Dan and Paul were very accomodating, they really know what their doing and have great parts (and prices too!). They'll give you good advice so you get what your looking for.

I have an 81 that's had some modifications done. For the suspension, I needed a stronger rear suspension and wanted better handling while keeping the street manners of the car. I don't intend to race it, but you never know if I might try an autocross course now and then. Here's what I did. I kept the TA's in stock configuration. I used a 71 differential (because it's iron vs. aluminium) mounted to the 81 batwing and used Van Steel smart struts (that don't work loose by the way). I'm running a 5/8ths stabilizer bar, bilstien gas shocks and BFG 255R60 15 tires all around. I also went with larger half shafts, and had to change from yokes to flanges.

The front basically got a stock rebuild, with control arm bushings, ball joints and other misc. standard type parts. I also replaced the steering control valve.

Now I realize that this is far from what some guys have done, but it will bounce you hard from side to side in the seat, you certainly need the seat belts so you stay put! The car handles flat, doesn't have a harsh ride and doesn't really understeer or oversteer under "spirited" street driving. Now if I push it hard enough it will oversteer and come around in a hurry, especially if it's a bit damp out, but to me that's part of the fun.

Here are some pics of the rear:







Like I said, not for racing, but it's fun, better than stock, and it didn't break the bank either...

 

I agree that poly is NOT great in that application. I got mine from Guldstrand.

 

From the BTDT files, a word of caution to anyone running a setup on the street which results in final oversteer at the limits, as such leaves little/no margin for error should an unexpected traffic or hazard situation present itself at the wrong moment. Thing is, you don't have to be driving at 10/10ths for TTO to induce a spin. I've been fortunate to have gotten away with it on a couple of occasions, thanks to God above and to years of on track experience. Your results may well vary.



I'm planning on stepping up to the sphericals or perhaps even doing the Johnny Joints. Also, like the threaded toe adjusters, but looks like a body-off task.

 

Cottoneg-Thanx.

Theskunkworks-Sphericals like on the strut rod heim joints and what are johnny joints?

I would rather not use a rubber trailing arm bushing when I get the arms rebuilt.

 

Heims on the camber struts, sphericals or Johnny Joints on the TA's.

 

If you go for the fully adjustable (compression and rebound) coilovers you will have so spend some time at a track to set up the suspension.

Then the suspension may need to be altered for streetdriving..

Dont think that a general setup will be anything but just "general" and will not give you full performance out of your suspension at "all times" or at all surfacecs.

Driving on a track is a lot different from driving on the road when it comes to sideforces and tarmac temperatures etc.

To get full advantage of a fully adjustable system one have to work a lot with it, set it up for each track and so on.. Well thats if your interested in getting the most out of it of course..

But there is several huge differences between a mildly modified road hotrod and a racecar.
A racecar ONLY se racetracks, a hotrod streetcar (like my own) taste tracks only a couple of times every year and need different settings.

On my -72 i went for the dualmount fibersprings front and rear and i can tell that they work wery well, both on the track and at the street.

One can adjust the settings depending on if your on the road or on a track but its a compromize.. -Just as the rest of the car.. -Just as how im using it..

If you choose the fully adjustable coilovers make shure to take your time to understand the system and set it up properly, there are an suprisingly large amount of drivers both on bikes and cars that buys expensive gear for the looks and then cruises around with crap setting.

//Ricky.