81VETTOM

my 81 was, I think for a stock gm sway bar, they should be, mine bolted right up.

ED DINAPOLI

Rick,
The frame is predrilled and tapped, the trailing arms have the access holes prepared for the stabilizer bar.
Ed

dtvett

The holes are pre-drilled. I would suggest purchasing the rear sway bar from Vette Brakes in Tampa Florida. Please note that you want to put a smaller bar on the rear than in the front or you will get poor handling.

redvetracr

RC,
If you or anyone else is interested I have a brand spankin new factory GM 7/16 rear bar (bar only) for sale $100+UPS please e-mail direct
redvetracr@msn.com

sb69coupe

Just an ignorant question here: will adding a rear sway bar without changing any of the rest of the suspension make the car handle better or worse? Seems like GM designed the small block cars with a specific spring rate for front and rear that were "tuned" to work together without a rear sway bar. Shouldn't you also change the springs and the front sway bar to end up with a properly setup suspension? If you don't change the springs, what will the effect be of adding the reaer sway bar alone?

Just curious and wanting to learn.....

dtvett

No, you do not have to change the springs. However, you must make sure that the front bar is significantly larger than the rear bar or you will get handling problems. Remember that the sway bar will increase your spring rate since it puts pressure to the other side when you lean in the turn. However, it will not apply this pressure if you hit a bumb with both wheels since it should then move independently. All big blocks came with the rear sway bar because of the increased weight.

sb69coupe

Right, but didn't big blocks use heavier springs and and a larger sway bar in the front? Why the rear sway bar when the weight added is up front? I assume that the heavier springs were due to the additional weight from the motor. So what happens to the handling of Rick's car if he just puts a rear sway bar on without changing out the front bar to the larger size? Understeer, oversteer?

LT1driver

springs for big block and small block same IF you got the F-41 HD suspension in 60-70s. 70 didn't have the F-41 for small block even if car was LT-1 71 up did get it, not reason why GM did this that I know of.

flynhi

When adding rear bar, start small and work up. Too large a rear bar will cause gross oversteer - as in spin.
See the Addco web site for a chart that compares percentage increase in resistance for increase in diameter. For example, changing from a 5/8" rear bar to a 3/4" rear bar will more than double the roll resistance.
IMHO, a rear bar that is too large effectively converts the IRS to a straight axle which is not what Zora had in mind.......

Tom73

You have to balance the suspension front and rear. Just adding a rear sway bar will more then likely hurt the handling unless the front is adjusted to balance the addition of the rear sway bar.

Get with someone like Vette Brakes and discuss your handling needs and see what they recommend. Usualy if you add a rear bar you need to go to a thicker front sway bar.

Balance, that is the name of the game :D

tom...


[Modified by Tom73, 8:27 AM 10/29/2002]

Smokehouse69

Rick,
Listen to Flynhi. I had a grossly oversized front and rear solid link sway bars on my car when I got it. At first I though it handled like a dream, until I came out of a fairly mild corner and applied just a little too much power. Then I got a nice 360 degree of the scenery at 60 mph. Spinning out on dry pavement is not a fun experience.
I started experimenting and found that at even fairly low speeds the stiff springs and huge sway bar very quickly overpowered the ability of the tire to maintain traction.
I removed the huge rear sway-bar and the handling improved greatly. I now have a stock front and rear sway bar, I have not driven the car since I installed them so I don't know what effect they'll have, but I hope that I see even better handling.

V8yunkie

I can only agree that I would be very carefull in adding a rear swaybar - the car will definitely tend to oversteer!

If you want to improve handling, do not modify BUT replace everything (A-Arm bushings, idler arm, lower and upper ball bearings, tie-rod ends, steering gear, steering gear rag-joint, springs, front sway-bar bushings) with new components. Maybe replace rubber-bushings by polyurethane bushings - this is the only mod I would do.

If you ever drove a car renewed like this, you will be amazed how well they handle. You know, to tune a chassis take a team of experienced engineers WEEKS. So should we really try to "improve" a well-designed chassis by adding any items every here and there?

sb69coupe

Rick, I don't want to sound rude, but are you listening to what people are trying to tell you? If you add a rear sway bar without either changing the front bar to a larger unit, you're not going to "improve the handling of the car". Cars that had the stock rear sway bar have a larger front sway bar to keep the suspension "balanced". It sounds to me like you'll end up with handling like Steve describes, where the rear end wants to come around in oversteer more freely. If that's what you want to achieve, go ahead and install the rear bar.

I just looked under my '69 and you'll definitely have to drop the spare tire tub to make your "upgrade".


[Modified by sb69coupe, 12:13 PM 10/29/2002]

ED DINAPOLI

Rick,
You need to listen to what has been said here on the balance of the front and rear components. You dont want to create a oversteer conditon.
My 74 has a rear stabilizer bar of original size. I have a 1 1/8 " bar in the front. The spring rate in the front is original. I upgraded the rear spring with a fiberglass spring with a 360 pound rate. All the bushing in the front and the rear have been replaced. I also replaced the shocks with blistiens that matched the rear spring. This combo works very well and the ride is very comfortable. I cant tell you enough that the suspension needs to work as a package. Do your homework before you start adding parts. You do need to drop the rear tub before you install the rear bar. You can also install it upside down. This will cause interference with the tub.
Ed

Frank75

Dropping the front bar is no big deal. Contact Vette Brakes for a kit.