I recently finished my 66 cpe body on restoration. All suspension is stock. I was told if I want better handling, to get the thickest sway bar GM makes and install it and this will make it handle better in the curves. Is this true? What is the best sway bar to install? Thanks in advance Dean
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Re: 66 sway bar
Dean----
Some folks might feel like you've been told, but I'm not one of them. The selection of the proper sway bar for a particular application is related to factors other than just one's desire to "have the best cornering ability posible". Specifically, the sway bar works in conjunction with and is "matched" to front coil springs, front shock absorbers, vehicle sprung weight, and whether or not the car is also equipped with a rear stabilizer bar.
For a 1966 Corvette with 327 cid engine, the standard front sway bar was a 3/4" diameter bar of GM #3831971. 1966 Corvettes with 427 cid engines used a 7/8" diameter bar of GM #3871318. And, those 1966 Corvettes equipped with F-40 suspension used a 15/16" diameter bar of GM #3831972. All of these bars are long-since GM-discontinued. For 1966 Corvettes, no front sway bars other than those mentioned above was ever installed on a Corvette. Larger diameter bars are available in the aftermarket, but were never originally available.
In addition to the above, 1966 Corvettes with 427 cid engines also used a rear sway bar. This bar was of 9/16" diameter and of GM #3872451.
The largest diameter front sway bar which GM ever utilized on a C2 or C3 Corvette was the 1-1/8" diameter bar of GM #351596 which was used on 75-82 Corvettes with HD suspension. This bar was utilized in conjunction with a 7/16" diameter rear bar of GM #351597. The GM #351596 sway bar is easily retrofittable to your car, but is discontinued and not available in reproduction.
By the way, aftermarket sway bars are usually configured differently than GM bars and may require aftermarket-supplied mounting/connecting hardware which is configured differently from original.In Appreciation of John Hinckley -
Anti-roll bars...
or "stabilizers" in GMspeak are used to limit roll and balance the relative understeer/oversteer characteristics of the chassis. Bigger is not always better. For example, if you increase the size of just the front bar, the car will roll less, but it will also understeer more, and small changes in anti-roll bar diameter can have a big effect on handling because their contribution to chassis roll stiffness varies with the FOURTH power of diameter. If you tell me more about your car (engine, base or F41 suspension) I can give you some hints, but the most important choice to make is tires. With a right choice of tires I can make a C2/C3 handle as well or better than a C5. (I'm not kidding, guys!)
DukeComment
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Re: 66 sway bar
Stabilizer bar design is contingent on a number of contributing factors. The roll characteristics of your 66 is greatly influenced by stabilizer bar size and design. However, the tire size, spring rate and shock absorber rate also contribute to roll dampening. As Joe stated, Chevrolet engineering released several designs for production. If you change only the stabilizer bar without researching the proper spring rate, tire size and shock absorber will modify the driving characterizes of you car. Chassis design is a very complex process and depends on many different disciplines. The inter-action of all systems components define vehicle ride and handling characteristics.
Hope this information was useful.
Best Wishes, Franz EComment
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So, Duke, let's hear it!
Duke,
As usual, you have my interest up with your comment about suspension. I've been chasing better handling on my 65 327 Convertible with HD suspension and bilstein shocks. All components are new, running KOs, 205 75 Michelins, and recently had Dick Guldstrand and Co. "blueprint" the steering box (with really nice results.. never thought it was possible with recirculating ball steering).
So, what is the combination that you have found to work? And how did you decide what to do? This old ME would like to know...
Thanks!
JimComment
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It's all in the tires!
No matter what you do to the suspension you are limited by your 205/75 tires. All of these tires that I am aware of are of the hard, generic, "all season" variety that emphasize ride and tread longevity for sedans and light trucks.
The best tire available is the 225/60ZR-15 BFG Comp T/A R1, a DOT legal racing tire, but it won't work on on your production steel wheels or even knockoffs. It needs at least a seven inch wheel, and a nice one is the American Torq Thrust D, which has been with us since our cars were built and is still available, new.
Now, the big issue is that they may not fit your car without t******* the horizontal portion of the wheel lip. I had to trim my SWC 32 years ago to fit 205-15 Pirellis on '68 wheels. So if you want to buy a set of proper performance tires and suitable wheels, I can give you some hints on how to "tune" the suspension to optimize the new wheel/tire setup. The 225/60s will not interfere as much as 225/70s (depending on the wheel) because they are nearly two inches shorter, but I expect the lip will need to be trimmed. Our Corvettes are good handling cars, for sure, but they will just never generate more lateral g than a Camry without modern performance rubber.
I've had reasonably good luck with Bilsteins including them honoring the original purchase warranty (I still had my receipt.) to rebuild a 20 year old set after one had failed, but the trouble with Bilsteins is that the damping rates are fixed. I've recently become a fan of Spax because they have 14 way adjustable rebound damping, and they can be adjusted while on the car (unlike Konis), which really allows you to get the damping dialed in for your drivng style, suspension set up, and tire characteristics.
DukeComment
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Re: It's all in the tires!
Duke ,I have always liked the American Torque Thrust D wheels. Currently I have 255 by 60 15 BFG Comp TA mounted on stock wheels. I don't believe American Racing makes these wheels in the 15x8 corvette offset, they do make them in 15x7. I have seen a BFG banner showing a C-3 corvette with these wheels, what width and offset are they? I have tried to get this info from BFG unsuccessfully. The tire and wheel combination currently don't rub and fit the wheel well right I would like to be sure the American wheels would do the same.Comment
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"American Mags"
Chuck - American has an excellent online catalog. I've listed the link. Click the "classics" page. They show a 15x8.5 Torq-Thrust D with 3.75 inches backspacing, which yields an offset of -24mm. I think these will work on a C3. They've also brought back the 200S as of this year, but it is fully polished. If you've got any questions you can e-mail them directly. (Isn't the internet great?)
Duke
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Re: It's all in the tires!
Chuck -
Is your car a C2 or C3? If a C2, what is the year, and are your stock wheels knock-offs or standard steel wheels?
Mike
(NCRS #33053)Comment
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Torque-Thrust "D" - won't fit!
The new Torque-Thrust D mags are not an exact copy of the ones available in the 60's (spoke shape is slightly different) and will not clear midyear brake calipers (not sure of Sharks) without machining the back of the wheel or adding a spacer. If you search the archives you'll find a pretty detailed thread on this subject.
Alex '66 A/C Coupe #22298Comment
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Re: It's all in the tires!
Mike- Mike my car is a "73". With the sizeable investment involved with purchacing these wheels you can understand my concern about them fitting right with the tires I currently have on the car. I think I will go the "E" mail route as Duke suggested. To add my two cents worth to the sway bar discussion, I have installed a 1 and 1/8 bar on the front and big block bar on the back and found a dramatic inprovement over the standard 7/8 bar on front and no bar at the rear. The car feels better to me but I am not a chassis engineer.Comment
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Re: Torque-Thrust "D" - won't fit!
Gentlemen: I agree that the torque thrusts are the second best looking wheels you can put on a C1, C2 or C3(C3 aluminums are the best) but if originality is second to performance, why mess with outdated 15" wheels?Comment
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Anti-roll bar diameters
The important thing to remember is that if you increase the roll stiffness of the front suspension (stiffer springs or bigger bar) you must increase the rear roll stiffness in equal proportion to maintain the original understeer/oversteer balance, assuming that you were satisfied with it in the first place. There are ways to calculate this, but it requires taking a lot of on the car measurements which can be tough to do. I usually just use my intuition as a starting point and then adjust the bar size in 1/16" increments on either the front of the rear to get the balance I want. Front and rear alignment settings can also be used to fine tune a car's dynamic response. So you did the right thing by going to the big front bar and adding a rear bar, but I expect that you might have less understeer than the OEM set up, so it might be a little too tail happy at the limit. Don't know if you've every really rung the car out, but if it does oversteer, install the next lower size rear bar.
Another observation is that for a given chassis setup the more tire grip you have the less it will oversteer. I know I've finally fried a set of tires from too many heat cycles when the car gets all loosey goosey. It can actually be fun, but lap times go to hell. Also, if I set the car up for DOT legal racing tires to be neutral, it will pick up a bit of oversteer with HP street tires.Comment
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