Rear Stablizer Bar

[Robert C.]

Does anyone know of any small block 63-67 Corvette option that has a rear stablizer bar. Only Big Block 65-67s? Not aftermarket kits........ Bob

[Wayne M.]

Re: Rear Stablizer Bar

Bob --- Only big block C2's had them. There might be a few random mouse motor cars produced with them, but only because they pulled the frame from the wrong stack, or temporarily ran out of the BB frames. Recall, the sway bar bracket attaching nuts inside the frame box section had to have been welded in place BEFORE the fabrication was completed.

[Joe L.]

Re: Rear Stablizer Bar

Wayne and Bob-----

It may be that a few, some, or many 65-67s small blocks wound up having the frame weld-nuts for the stabilizer bar brackets. However, I doubt that the presence of the weld nuts would have influenced the factory to go ahead and, consequently, install the bar, too. In any event, for 65-67 the rear sway bar was aprt of the big block "package"; it was not supplied with option packages installed on any small block, including F-40/F-41. For 63-64, of course, no rear sway bar was supplied on any Corvette.

[Robert C.]

Re: Rear Stablizer Bar

Thanks Wayne and Joe for your expertise. FYI, my small block 65 has the frame nuts but, of course ,no bar, I have looked at many small block mid-year cars and all late 65s-67s have the nuts in the frame.... I believe later small block cars had the rear bar. I owned a 72(very original)LT-1 air car that had a rear stablizer bar.I'm not sure about 68s and up. Maybe Joe knows.

[Duke W.]

Re: Rear Stablizer Bar

I researched this recently (for Wally Wyss upcoming book) and found that the first factory equipped small block rear anti-roll bar ("stabilizer" in GM speak) did not appear until 1975 with the FE7 option. In fact, we discussed it on the Board. The nice thing about having a small block with a big block frame with the weld nuts for a rear bar is that you open up some easy suspension tuning options such as increasing the size of the front bar and adding a rear bar to bring the roll stiffness distribution back to near original to maintain neutral dynamic response. (A larger front bar only will reduce body roll, but increase understeer.) By this technique you can enjoy crisper steering response and less body roll without having a significant effect on ride quality because the two-wheel bump ride rate remains essentially unchanged.

Duke

[Duke W.]

Hmmmm

Well, Bob, you and I posted our responses at the same time. The parts manual does not show a small block rear bar until '75. If the frame has the weld nuts it's easy to add a rear bar using all factory parts, so it would look original to most observers. The '72 AIM and perhaps '72 Judging Manual could shed some more light, but I'll bet that rear bar on your erstwhile '72 LT-1 was not as original as you think.

Also, one of the posts mentioned a small block and big block frame. Is this correct or were all the mid '65 and up frames equipped with the weld nut in case it ended up with a big block? Seems to me the minor cost of four weld nuts does not justify an additional part number and inventory requirement for a second frame configuration. The assembly manual for those years should indicate if there was a different frame part number for big blocks.

Duke

[Robert C.]

Re: Rear Stablizer Bar

You are right , Duke. I thought that the ZR-1s had the bar. They have the F-41 package without the rear bar. F-41 was only available on Zr-1 small-blocks in 1970 and 1972. You could order F-41 option on any 71' Corvette. The big blocks all had the bar ,but I think a larger diameter if the F-41 package was ordered with a big block car. Confusing, HUH! Also to add to the info,original small block trailing arms did not have mounting holes for the rear sway bar bracket. Today , if you order the trailing arms, all of them have the holes.

[chuck]

Re: Rear Stablizer Bar

The mechanical part of the corvette hobby intriges me the most. My 73 small block had weld nuts in the frame and drilled trailing arms (I installed a big block sway bar on the back), on the front I added a 1 1/8 bar.

[Roberto L.]

Re: Rear Stablizer Bar

Interesting ZR1 references. In some literature it is mentioned that ZR1 were found with and without rear stabilizer bar in 70. I can only read about it, not verify.

All best, Roberto, NCRS #30019, RMC

[Joe L.]

Re: Rear Stablizer Bar

Bob-----

Actually, VERY FEW 68-74 Corvette with small blocks had rear sway bars. Many also have the frame weld nuts (my 69 doesn't, though), but the only 68-74 Corvettes with small blocks that I am aware of that have the rear sway bars are, possibly, "some" 70-72 ZR-1s. You didn't let one of those go unknowingly, did you?

Beginning in 1975, Corvettes with FE7 HD suspension package were equipped with rear sway bars. This bar was GM #351597 and was approximately 7/16" diameter. These cars also used a special front stabilizer bar, GM #351596, which at nearly 1-1/8" diameter, was the largest bar ever installed on a 63-82 Corvette. Both bars are GM-discontinued, though.

[Duke W.]

'70 to '72 ZR-1s

I just read the blurb in the 2000 Black Book about ZR-1 rear bars. Hey, can anyone with a 70 to '72 AIM tell us what it says about rear bars on the ZR-1? Being as how they are considerably rarer than L-88s (total of 57 from '70 to '72), I don't think I'll ever have the pleasure of personally inspecting one.

Duke

[Duke W.]

Re: Rear Stablizer Bar

So how does it handle, and what kind of tires are you on? As Joe said the '75 FE7 package had a 1 1/8" front bar and a 7/16" rear bar, and they also had considerably stiffer springs. The "big block" rear bar is 9/16", so I expect you might have a bit of oversteer.

Duke

[bruce]

Re: Rear Stablizer Bar

I have a 2 owner 72 LT-1 from Canada. It has the original frame/ trailing arms. The frame came with the weld nuts installed, the trailing arms were already drilled for the holes. The ONLY small blocks that came with rear stab. bars in 70-72 the ZR-1s. Ihave seen 5 ZR-1's, they all had the small 7/16" bar

[Joe L.]

Re: '70 to '72 ZR-1s

Duke-----

There are no UPC sheets for the ZR-1 option in any of the 70-72 AIMs. As far as whether any of these cars were originally equipped with rear sway bars, who knows? I have seen numerous references that indicated that some were and some were not. However, in the world of Corvette lore, an undocumented "rumor" gets started and then it's picked up and repeated in other refernces. The next thing you know, it becomes "fact" because "EVERYONE" SAYS SO. It is very possible that the ones that "appeared" with sway bars had them added at some point in their life. Since, there is no way that vehicle documentation could establish this one way or the other, it will be hard to really prove unless some Chevrolet records surface.

[Joe L.]

Re: Rear Stablizer Bar

Bruce----

Interesting observation on the ZR-1s. As far as I know, there was only one, and possibly two, 7/16" diameter rear bars ever made for Corvettes. The first one, which is completely unconfirmed, applied to 1968 Corvettes with big blocks. These cars used rear sway bar GM #3923676, a one-year-only part. Information that I have received from some 68 owners indicates that the bars on their cars are 9/16". However, I also have it from what I consider to be totally authoritative and reliable source that these bars were, indeed, 7/16" bars. If the 1970-72 ZR-1s used a 7/16 rear sway bar, it would have had to have been this part, assuming that it was a 7/16" bar. The only other 7/16" rear sway bar, GM #351597, did not enter production until 1974. I SERIOUSLY doubt that GM had a special bar made up for 57 cars over 3 model years. Especially since, apparently, if they ever existed NONE entered SERVICE parts channels. Suppliers for these bars just don't work that way.