Rear sway bar

[frank mccracken]

Is there any physical or visual difference between a rear sway bar for a C2 and one for a C3?

[Joe L.]

Re: Rear sway bar

Frank-----

Yes, there is a difference. The configuration of the bends in the bars are different, although it's hard for me to describe the difference. The 65-67 bar was GM #3872451. The 69-74 bar was GM #3967713. Both bars are 9/16" OD. The GM #3967713 will fit and work on the 65-67 applications, though.

[frank mccracken]

Re: Rear sway bar

Thanks Joe.

[Jack layton]

Re: Rear sway bar

A 1965-67 bar just sold on e-bay for $451. They are pricey!

[Henry J.]

Joe: Re: 68 Rear Sway Bar

Joe, until your post, I never considered the possibility that the 68 rear sway bar may be unique (by now, I should have known better). Yes, indeed, the AIM calls out number 3923676. Can you describe how it differs from those you have identified and which others may fit in its place? Thank you.

[Joe L.]

Re: Joe: Re: 68 Rear Sway Bar

Henry------

Yes, the 1968 rear sway bar is GM #3923676. Exactly how it differs from the 69-74 rear bar, GM #3967713, I've never been able to positively determine. Some authoritative information sources seem to indicate that it was a 7/16" bar. Others, including some observations by 68 owners with, apparently, known-original bars, indicates that it was a 9/16" bar.

I tend to think that it was a 9/16" bar since the frame mount bushings used with it, GM #3923675, were also used for all of the 69-74 applications. If the bar had been 7/16", I would expect that a different bushing would have been used. That's not a 100% sure deduction, though, since these bushings are a "compress-to-fit" type of thing and, theoretically, it's possible that the same bushings were used for both size bars. The 1975-82's with FE-7 and a KNOWN 7/16" bar used a different bushing, though, so that would indicate that GM thought that a different bushing was needed for 7/16" bars.

The GM #3923676 bar was also used for early 1969 applications. I don't know when the change to the 3967713 occurred. My expectation is that it happened in early calendar year 1969. I would expect that all 1968-built 69 models, with big block, of course, had the 3923676 bar.

Aside from the possibility of an OD difference in the bars, I think that the only way to tell them apart would be to see the blueprint drawings or compare KNOWN examples of the 3923676 and 3967713 side-by-side.

[Henry J.]

Thanks once again, Joe! *NM*

[Paul L.]

Joe: FE7 Bar on a 1967?

Joe, I have an FE7 7/16" bar that I purchased for my former 1979. It became a round-to-it and is still in my basement. Would that fit on my 1967 SB Coupe?

[Joe L.]

Re: Joe: FE7 Bar on a 1967?

Paul-----

Yes, I believe that it would fit although, of course, it wouldn't be correct. It's hard to say if its installation would improve or detract from the car's handling performance. Also, your SB car frame may or may not have the weld nuts on the frame for installation of the bushing retainers.

[Paul L.]

Re: Joe: FE7 Bar on a 1967?

Joe,
I understand and appreciate the comment re correct. But sometimes I deviate from the standards I am afraid. The weld nuts are there (see pic). The front bar is 3/4". I will try to get a reading from suspension folks on what a 7/16" rear bar will add, if anything. If nothing, I will sell it. It has been re-done with new GM bushings (thanks for those numbers a little while back) and will be of use to some C3 owner.

[Duke W.]

Re: Joe: FE7 Bar on a 1967?

Adding a rear anti-roll bar where non-existed before will increase rear roll stiffness, which will bias the handling to less understeer, which would likely cause excess oversteer in a '67 since the base suspension already had minimum understeer and they can transition to oversteer at the limit.

The FE7 SB suspension from the seventies included HD springs, a 1 1/8" front bar, and a 7/16" rear bar. If you install the 7/16" rear bar on a '67 you will need the larger front bar. Also consider that the redesign of the C3 strut rod bracket lowered the rear roll center, which reduced inherent roll stiffnes due to the springs, so even with both FE7 bars a '67 might be biased to oversteer.

Duke

[Paul L.]

Re: Joe: FE7 Bar on a 1967?

Thanks Duke. I am happy with the handling as it is. The FE7 GM bar will go on EBay. Too bad, I put so much time and money into it with those new bushings suggested by Joe. Live and learn I guess.