hello i want to race my 1974 c3 on some vintage racing Events here in Europe.
i have this suspension Upgrades:
vbp 550 front springs
vbp 420 rear spring
1-1/8 front sway bar
no rear bar
bilstein Sport Shocks
avon cr6zz 275/55-15 classic racing tires

i want to go with an 1-1/4 front bar and an 5/8 rear bar,ist this ok?
what do you guys think?
thank you and greetings from Vienna,Austria

 

Assuming the OP (or subsequent viewers) might have been looking for advice on how to go about the actual sorting process...

First rule of chassis setup/tuning: Only make one change at a time. Otherwise you won't know what changes actually improve things and you can easily get lost.

Second rule: Only make changes based on diagnosis drawn from testing. Bypassing this step and simply throwing a catalog at your chassis WILL leave a good percentage of untapped potential on the table, however glowing may be the reviews of any particular set of kit. So, bear in mind that what works for someone else (myself included) isn't necessarily going to best suit your individual circumstances (car/purpose/rules/skill...). And, guessing without having a decent grasp of what you're doing can turn into a recipe for ending up in the Armco. I would urge anyone truly serious about actually sorting their chassis for tracking to study up on the basic fundamentals, to develop a sensitive backside, and learn how to evaluate tire temps with a tire pyrometer (an IR type will do in a pinch).

Third rule: Don't confuse how a car seems to handle at less than 10/10ths of its limits with what its actual handling and drivability characteristics will be on the edge. A car with final oversteer will often feel like it is on rails right up until it bites you.

My basic setup philosophy, vastly oversimplified:
Work from the tires up.
Stiffen the frame and reduce suspension compliance.
Reduce weight without compromising safety, and work to improve weight distribution and lower the CG.
Get the suspension geometry right, not only including static alignment and ride heights, but to also minimize bumpsteer, rear toe-steer, scrub, and to optimize roll centers and camber gain.
Use as much spring rate as practical/tolerable to balance the car and control roll (notice I didn't say "eliminate roll"), as well as dive and squat, while being careful not to install more rear spring than absolutely necessary, and only relying on bars (think of them as crutches) as secondary or fine tuning tools. You do NOT necessarily need a rear bar, despite what people try to sell you.
Shocks aren't just for controlling unsprung weight, but also for tuning how a car transitions into and out of corners by regulating the speed at which weight transfers.

There is much more, of course, but the above will hopefully give you a basis from which to work. My $.02, no charge.


TSW

 

Is your 73 a 4 speed car? I'm big on adjustability. Many years ago I went to a road racing track in my 79 with your kind of setup. The VB&P street & Slalom kit. I do believe in the rear Smart struts with poly or steel hiem end joints.

As I went faster I found all the serious short comings of our vettes. Brakes are the first failure point. I took off the front and rear dust covers or shields for more air flow and used 600 degree brake fluid. As I went faster the brakes boiled and failed and the 550 front springs are inadequate. Some people here on the forum manage to use stock brakes with air ducting. I had 17 inch wheels so I went to bigger rotors and calipers.

front height adjustability is a big thing so i went to a semi coil over QA-1 set up. Depending on how much grip your front tires have determines the required spring rate. Probably in your case I would jump right to 650#

 

yes,its a 4 speed car,my brake upgrade is:wilwood d8-6calipers front with epc yellow brake pads and motul 660 racing brake fluid

 

I use the Wilwood BP-20 pads 13.25 GT1 rotors and Superlite 4's with Thermloc pistons. I had destroyed the front rotors in one race weekend and never had a hint of brake fade.

These are 700# front springs



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adjustable end links front and rear on my sway bars. It gives the wheel vertical free movement before the sway bars come in. Old picture with 420# rear

 

looks great!!!

 

I use 295 slicks fronts

 

I use 295 slicks fronts

 

VP&B dual mount front & rear with a Drag Vette 6-link in the rear.





QA1 dual adjustable shocks, Steeroids R&P, Willwood caliphers& rotors. T

 

What are you cooling with the rear fan?

 

Badvette, Good luck with your venture! What's the sanctioning body rules on modifications you can make to the suspension, brakes and drive train?

 

the rules are:only 15" wheels(i use avon cr6zz 275/55-15),stock Diameter brake Rotors(i use wilwood d8-6),no coilovers,drivetrain:4 Speed only

 

My kind of thread

 

The differential itself. Had an Auburn center section and after a every track session temp exceeded 300F and the clutches locked up, with gear oil spewing out. I went back to the Eaton center section and put the cooler, pump, filter assy. Temps at 160F now. Also allows for more oil in system 5 quarts total. T

 

I always considered a rear cooler. My rearend would get so hot that you couldn't touch it for a half hour after a 30 minute event. I went to 85W-140 Valvoline Synpower. It was a 4.11 rear. It now runs much cooler with 3.55 gearing. I only use 2-3-4 gears of my 5 speed. The big jump to .064 OD was too much. Local track I only get up to the mid 150 mph with my 434 ci on the main straight. Miller race track in Utah has a 3000 foot main straight and those crazy Moto GP bikes were doing 208 mph on the main straight. I need to go to an event there.

 

Now that is a problem.

 

Running a 355 with 3.73, 5 speed. gkull you're right, no power in fifth with the .68od. I top out at around 145, right on the chip in fourth. Was thinking of 3.42s or 355s to get more speed. I run at Road America. The front straight is almost 7/8 mile in length. Also working on moding the engine with a Vortech. Are factory gears good for 600hp? {have a set of 3.42]. Now all I need is AFR heads, cam, blowthrough carb, and fuel system. T Another question gkull, how are you attaching the cooler ducts to the caliphers?

 

like to hear more about this setup.


Drag Vette 6-link in the rear

I'm dropping a bb chevy in my 68 and want to get it to hook and handle better

the vette brakes and van steel stuff look great take a look at what danny popp does to his car to handle, works very well!!! I'd like to emulate that car to the extent my wallet will allow but I'm going with a BB which puts quite a bit of weight up front so handling will take a back seat to traction and straight line speed. looking to lighten the car up as much as possible too.

 

I used 3 inch aluminum tubing. round on the air side and hose clamped on. The brake side I made more oblong using a vice and then I welded on brackets to hold it onto the caliper mounts. Blowing into the aluminum hats center to flow through the rotors

I've always had Richmond or now US gears in the rear and they never seem to wear

 

I wouldn't over-estimate the impact of the BBC's additional weight on handling. A BBC with alum heads (money well spent), intake and water pump is less than 100# heavier than an L82 SBC, and that weight is behind rather than above the front axle. IMOE this can be fairly readily compensated for with some BBC-appropriate chassis tuning and a little weight savings elsewhere. And, if you'll strive to control rear roll with the spring rate you can avoid the traction penalty on corner exit acceleration had by running a rear bar, which means you can pick up the throttle earlier. I'd also suggest that you wait and see just how much you actually need to reduce rear camber gain before spending money on drag strip oriented kit (per the "2nd rule" in my earlier post).