How critical is the rear sway bar?
 

I am restoring a '77 and have found that the rear sway bar is missing. How important is it to install a new sway bar?

I haven't had one on any of the C2/C3 Corvettes I've owned. So not important would be my answer.

Not certain that the 77 came with a sway bar, at least my 77 doesn't have one. I don't see where one has been installed either.

Hi Dave,
Since you posted the same question on each Forum you'll need to check the other post too.
Regards,
Alan

I noticed that. But only answered here.

Starting in the earlier mid 70's (1974?), SBC C3's only came with a rear sway bar IF the car had the sport/gymkhana/F41 suspension-that held true through 1982. All BB's in the early 70's (not sure the year it started having the rear bar) had a rear sway bar. If you are looking for maximum handling, obviously, GM felt that the rear sway bar was necessary for best handling versus the non sport suspended cars.

Rear bars can induce sudden over-steer.

depends on what size front bar you have

Poor driving induces oversteer…not factory rear sway bars.

GM would never have put a rear sway bar on C3 corvettes if in fact the rear bar induced sudden oversteer, especially after the Ralph Nader fiasco with the Corvair. My factory 78 L-82 4 speed with the optional 255/60/15 tires directly from the factory with the 1 1/8 inch front bar and 7/16 rear bar (with the proper GM end links) UNDERSTEERED at the limit and was well documented by automotive publications of the time…all GM vehicles were designed to understeer. My personal experience with a GM style rear sway bar is that a properly matched GM rear bar to the front sway will not induce sudden oversteer…33 years of experience now.

NON FACTORY rear sway bars not properly sized to the front sway bar can induce oversteer..just to be clear.

The sway bars in the late C3s was 7/16". Yes I did have one for my 1979 but never installed it.

The 7/16 inch rear GM bar with the GM end links on the SBC C3's were matched with either a 1 inch front bar on the earlier 70's C3's or a 1 1/8inch front bar started in 1978 on cars like my C3 with the sport suspension. 1974 and earlier BB C3's had a 9/16 inch rear bar and I do not know what size front bars the BB cars had but the BB C3's had more front weight bias 51/52 F 49-48% rear versus the later C3's like my 78 with a rear weight bias (48%F:52% rear) thus a smaller rear bar (7/16). A 78 Sport suspension car would still understeer at the limit even with the 1 1/8 inch front bar AND the 7/16 inch rear GM factory bar, not aftermarket bars with the wrong type of end links which inhibit rear trailing arm movement.

The key point is that a factory style rear bar with the proper GM end link is critical to not having an oversteer situation arise unexpectedly as long as it is matched to a proper front bar that compliments the rear bar. It is going to be pretty difficult to neutral balance a street C3 without a GM rear sway bar unless you go to a rear spring with a very high rating 400-420 lbs/in which in that case will make the car ride extremely hard. Every decent handling car in the last 40 years has had both front and rear sway bars…front engine/mid engine cars ...even FWD cars have them..think about that fact. You cannot effectively balance the car with just a front bar..it will understeer badly at the limit.

I think you both mean 7/8", not 7/16" which is less than 1/2"......:thumbs:

They mean 7/16".

Uhh... the 7/16" "swizzle stick" holds true. I left mine off after doing a rear coil over swap. Gotta admit, I had to laugh at the cute little thing...:rofl:

Rear sway bar discussions always are interesting since it appears there is so much misunderstanding about the bar effect and operation as it relates to a C3 with the IRS suspension.

Paul 74, of course, you are not going to have any problems not running a rear bar on the street…the car will just understeer more without a rear bar ( in conjunction with a front bar) -most SBC C3's without the sport suspension (all the BB did in later years), did not have a rear bar to maximize the handling from the factory.

The SBC C3's had the 7/16 inch rear bar and the BB had a 9/16 rear bar….they are there for a reason folks. As for the small size of that bar, the purpose was to dial out more of the inherent understeer of the cars that ran just a front bar…this is not hard..and even then all GM cars back then still understeered from the factory (safety..much easier to control understeer versus oversteer for the novice driver) including the sport suspended C3's with a rear bar..The small rear bar is small but I can assure you that bar does do something and needs to have the GM style end links. I went about 15 years ago a to a 3/4 inch GM style rear bar with the factory front 1 1/8 inch bar with poly bushings all around (which makes the front bar act like an even bigger bar) and the all understeer is dialed out of the handling…I have never had the rear come around on me unexpectedly.

Here is something else to think about…the C6Z06 is VERY twitchy, tail happy, and difficult to control at the limit..street or race driven. My 2010 Z06 has a pretty beefy Stock GM rear sway bar..using the logic/theory of many, GM should have used a much smaller rear bar or no rear bar, and the Z06 would be much more driver "friendly". Why didn't GM do that? There are lots of reasons but GM knows that the quickest way around a road course/street driven is for the car to be neutral balanced..on the limit..go beyond that limit and you will get oversteer. This fact has been around for ever..not new.

The bottom line is that if you want a very safe, predictable handling C3 that is just a cruiser, by all means, leave/forget a rear bar..but this demonizing of the rear sways bars as evil handling, unsafe, etc…is simply not true and why I defend its use whenever this discussion comes up.

Exactly correct jb. That's why I posted that rear bars "can" induce over-steering. When an inexperienced or non-professional driver pushes his normally under-steering car a little past his limits, he will suddenly be traveling backwards away from the corners apex.

There are a few who understand the operation of the rear sway bar on a c3:thumbs:

Ouch......learned something today.
How could GM think that a 7/16" bar would work?
lol

Where did you get the 3/4" bar? Is it a custom?

No joke..it works!