RickDett

Can some one tell me the difference between the OEM style rear sway bar links and the Addco style rear sway bar links in regards to performance.

(1969 small block coupe)


OEM http://www.parts123.com/corvettecent...50g&ukey=14567

Addco (the ones show in this kit)
http://www.parts123.com/corvettecent...50g&ukey=49365

jb78L-82

I would strongly urge you to use GM oem type rear sway bar end links. Non factory addco type front sway bar end links will not allow proper rear trailing arm movement when cornering. GM used a unique rear sway bar end link on the IRS of c3's for a very good reason.

redvetracr

the factory bar mounts directly to the top of the t-arm, the addco bar mounts to the t-arm but the bar mounts behind the t-arm a few inches and it doesn`t have a dog leg bend like a factory bar making it (in my opinion) less effective, I happen to have an extra original genuine GM BB 9/16 rear bar with the links if you or anyone else is reading this, slightly more expensive than the addco but it`s genuine GM and it works, send a PM

Alan 71

Hi RD,
WELCOME!
First Post!
Here's a couple of pictures that illustrate how the original sway bar mounted. You can compare it to the aftermarket bar's mount.
You can also see the 'dog-leg' rvr describes.
This happens to be an original 7/16" sway-bar.
Regards,
Alan

RickDett

Humm… I presumed only the hardware mountings links where different. I notice now that the bars are not interchangeable. It looks like the OEM bushings mounts vertical and the Addco mounts horizontal to the bar. I assumed the Addco was an improved updated design.

redvetracr

It`s hard to beat GM engineering

Alan 71

Hi RD,
If you'll notice the aftermarket rear sway bar mounts using a rubber bushing 'link' similar to the way the stock front sway bar mounts.
Obviously GM felt something different was needed for the rear sway bar because of the arc the trailing arm travels in. The mount is a double pivot.
Regards,
Alan

The typical front sway-bar mount with bushed link. Note, no pivot.

RickDett

Now that I realize I can't use the addco sway bar with the OEM style links I guess my question would be is it hard to find an OEM style 5/8" rear sway bar?

jb78L-82

OEM factory rear sway bars were 7/16 inch (SB gymkhana suspension) and 9/16 inch for BB cars. I would suggest the same...I have this 3/4 inch OEM type rear sway bar with my suspension and OEM factory gymkhana front sway bar-1 1/8 inch with all poly bushings which makes the front bar act like a bigger bar with rubber bushings. Not sure if you can get a factory type OEM rear bar of 5/8 inches

http://www.mamotorworks.com/Corvette...le-34-602628-1

What size is your front bar? If it is a stock front bar for a 69 (7/8 inch?) I would suggest a 7/16 inch rear OEM type bar with poly mounting bushings

redvetracr

I have an extra 9/16" factory rear bar, if you or anyone else is interested send a PM

The13Bats

so does that mean the VB like addco is junk?
Damnnit man my donor chassis came with all that VB transverse stuff....

jb78L-82

Here is the issue for me with non factory rear sway bars:

As stated before, since GM purposely did not use the same endlink on the rear sway bars of C3 corvettes with the IRS suspension, I was always very cautious about changing my factory 7/16 inch piece to a larger rear bar with the horizontal endlink arrangement like they used on the front C3 sway bar. In fact, just about every GM car from that era with front sway bars AND a rear sway bar (there were not many)used the horizontal endlink arrangement on the rear bar as well but all of these cars had a solid rear axle suspension. I always thought, "now why would GM design a different endlink for the rear bars of C3's", if not for a very good reason? In the late 70's I added an Addco rear sway bar to my 73 Nova and also used an addco rear sway bar (with the horizontal endlink holes) for my mom's 72 Caprice, both solid axle cars, with great results.

When I was thinking in the early 2000's of upping my rear bar to the 3/4 inch since my 78 still understeered at the limit (documented as well in publications that stock SB C3's understeer at the limit with the gymkhana suspension, NOT oversteer, as many forum members state with aftermarket non factory rear bars), I specifically looked for the OEM design for the reasons stated. ADD that I was reading that forum members often complained about snap oversteer using aftermarket non factory rear sway bars with non OEM endlnks, I seriously began to think more about why GM chose the unique rear sway bars used on the C3's. My 78 with a stock 1 1/8 inch poly bushing bar and the midAmerica OEM type 3/4 inch rear bar with poly mounting bushings does NOT have snap oversteer...in fact it is very neutral handling at or near the limit of handling....made me think about what was happening with the aftermarket rear bar with non factory endlinks that I kept reading about from forum members. In every case that I came across, the C3 either had mismatched sway bars front to rear OR had a rear bar with non factory endlinks.

One more piece to this mystery is that almost every car maker today uses sway bar endlinks with the vertical sway bar endlink type design in both the front and rear bars since this design allows more suspension movement compliance without increased ride harshness (more suspension movement). My 2010 C6Z06, 2008 Chrysler 300, 2012 Lexus IS350 F Sport, and my 2001 Pontiac Grand Prix ALL use rear sway bar endlinks with the vertical C3 designed rear sway bar type endlinks AND coincidentally ALL have independent rear suspensions.

None of this choice is by accident....just my opinion and thoughts after 35 years with suspension experience.

zwede

I used to have a 5/8" VBP bar w/ aftermarket end links. Yes, the was prone to sudden oversteer when I autocrossed it. I never liked the aftermarket links and then I found that the long link bolts were bent. Obviously the design does not have sufficient compliance for the rear suspension.

I have since switched to a 9/16 OEM bar with OEM links. Haven't autocrossed with the new bar but I'm fairly sure the handling problems are solved.

jb78L-82

RickDett

My setup: I rebuilt my suspension completely including steering box 2 years ago with poly bushings throughout. Differential mount cushion rubber. Reused the stock 7/8 front sway bar, no rear sway bar. Upgraded 460 lb Grand touring front springs. I limit changes to one item at a time. Originally used new AC Delco shocks I have since switched to Bilstein Sports all around I like the sports in the rear but I'm currently back to using the AC Delco on the front. Replaced the original 9 leaf with a new standard 9 leaf rear spring which was too soft I currently am using a 7 Leaf rear spring. SB 350 a/c coupe. Everything else on suspension currently stock.

I am upgrading the sway bars because I seeking more of a sport suspension out of the vehicle. I know balance is a factor so I try to keep my changes to a minimum at each step. Knowledge here on the forum is abundant. I am looking for guidance or recommendations whom have experience with this and/or run a similar setup.

I am leaning towards trying 1-1/8 for the front and 5/8 for the back. (Now OEM style links)

9/16, 5/8 or 3/4 rear bar which would be a better starting point for balance?

The13Bats

so if VB rear sway bars are junk I have to question every product they make like the front and rear transverse springs on my car...it all might be trash....

redvetracr

I have an extra 1-1/8 front bar also, factory rear bars came in two sizes and two sizes only.....7/16 & 9/16

Jason Staley

Most of the products I've purchased from VB have worked very well. Only two things I won't buy from them again are steering joints (tie-rod ends, etc.), and their rear sway bars.

I've had their transverse springs on my car for ~20 years with no issues, and the car handles quite nicely with them.

jb78L-82

I am like you making suspension changes one at a time over 30+ years so I can accurately access the difference before and after.

Here is what the car has today having started in 1986 (put on the VBP 360 spring) as a totally stock gymkhana suspension L-82 4 speed:

Front:

Custom blueprinted/rebuilt OEM steering box by Gary Ramadei

550 springs 1 inch shorter than the stock gymkhana springs with 1/2 coil cut in 2015 after the L-82 rebuild...my 550's are probs 600lbs now with the 1/2 coil cut

Poly upper and lower control arm bushings

Speedirect spreader bar

Bilstein HD's with poly bushings

OEM factory 1 1/8 inch front sway bar with poly endlinks and mounting bushings

255/45/17 ZR ultra High performance summer only tires

Rear:

360 composite spring with poly cushings (they squeak though). Would probs go 420 rear spring if I ever have to replace

Competition adjustable strut rods with heim joints from MidAmerica

Bilstein Sports

3/4 inch OEM type bar...Originally 7/16 inch bar..both with poly mounting bushings.

255/45/17 ZR tires

I would suggest either 7/16 or 9/16 OEM bar (don't think there is much difference between the 2) as a starting point for your setup since you have 460 front springs with a gymkhana rear spring. If you had 550 fronts, I would say definitely to start with the 9/16 OEM bar. I would reserve the 3/4 inch OEM type bar like I have after you access the handling..If it was me, I would go 550 front springs with Bilstein HD's with a 360 composite in the rear with Bilstein Sports with a 9/16 inch rear bar. With this setup and the 7/16 or 3/4 inch OEM rear bar, my car rode more on the comfortable softer side than firm....it was that good. With the 550 front springs cut slightly, the ride is definitely firmer but not harsh one bit.

My 78's ride, steering, and handling is SO MUCH BETTER than the stock gymkhana setup....pretty much like a modern sports car but no match for my 10 C6Z06, of course...it certainly can hold it own against a modern 4 door sports sedans like my modified (suspension/brakes) 2008 Chrysler 300 and stock 2012 Lexus IS 350 F Sport

RickDett

Assuming the 1969 F41 big block suspension front 15/16 and rear 9/16 setup was neutral regarding balance. Then the same set up with a small block would tend to be loose. So then increasing the front to 1-1/8 will be more balanced with a rear 9/16 bar (and OEM links.)

I’m going to start there. I’ll post an update when completed.