REAR SWAY BARS

[Dan Baldwin]

Interestingly, the current hot setup in ITS (no V8, but a still-heavy I-6 up front) is stiffer springs in front and NO rear roll bar. Why this works is beyond me, since I run stiffer springs out back (albeit much less stiff than ITS levels at 160F, 200R) with a 1" front bar (adjusted to the stiffer of two settings) and a 3/4" rear bar (adjusted to the softest of three settings).

I LOVE the way the car handles now. It would seem to me that the ITS setup should cause the car to push quite a bit.

 

For every day use, it's probably not a bad idea to remove the rear bar in a V8 Z, given that it should have a lower polar moment of inertia, and could use the additional rear traction relative to an L6 car.

 

If you use a larger-than-stock front bar, you should reinforce the mount to the frame rails. I just ran long bolts up through the rails and used a 1/4" steel backing plate on top of the rails. If you don't reinforce some way or another, a stiffer bar will tear out the mounts. Ugly.

[blueovalz]

The best combo I had for the street (very neutral) was a 1.125 front, and .875 in the rear. worked very well, BUT, I think this very thick front bar was responsible for the frame rails starting to crack near the mounting plates. Anyway, I have nearly the same size front and rear (just larger arms on the rear which is equivalent to making it a smaller diameter bar) on the race car.

[johnc]

There's always more than one way to skin a cat. An ITS 240Z car setup can go two ways and the preferences seems to be based on geography.

 

East Coast

 

300 to 350 lb in front spring rates

250 to 300 lb in rear spring rates

1" front anti-roll bar

no rear anti-roll bar

 

West Coast

 

225 to 275 lb in front springs

250 to 325 lb in rear springs

22 to 25mm front anti roll bar

19 to 21mm rear anti-roll bar

 

Both work well. Maybe it has something to do with the tracks on each coast?

[blueovalz]

I think that the spring rate used front/rear will also have a lot to do with your choice. My rates are the same front and back, and this is most likely why the front and rear bars are closer in size. John's numbers sort of indicate this may be true.

[DavyZ]

Unless you are using an LSD to combat this, JTR indicates that the rear bar causes inside tire to lift, and then the torque of the V8 just spins the inside tire causing loss of traction and producing slower times. So, with an open diff, the hot ticket according to JTR (if you slalom, etc) is to NOT a rear bar. That makes complete sense to me because the inner tire will stay on the ground, thus giving more traction. But wouldn't there be more unwanted chassis twisting going on with only a front bar?? Yes? That would concern me enough to reinforce the chassis some if I was to run no rear bar. BTW, Dan's idea about reinforcing the front bar mount is an excellent one! Gotta remember to do that....

 

Davy

[260DET]

No rear roll bar is the thing to do here, too, even with a LSD.

 

I like mine with bars front and rear. One thing I've found is that the stock '77 mounts are not strong enough, the rear ones particularly allow a lot of flex which means that the bar is not working as it should. So I use beefier aftermarket poly mount bushes and retaining brackets. Plus I've strengthened the stock chassis mounting areas, the stock rear ones being particularly weak.

[Guest HIGHRPM]

Question for everyone. I just read the JTR manual and got to the section on sway bars and now I'm confused about their opinion on removing the rear sway bar. It seems that every article i read, everyone is upgrading front and rear bars, and not removing the rear bar! I would like to hear from people who have both removed the rear bar and those who upgraded their bars to tell me how their cars improved or got worse. And for those that upgraded the bars, which size combination works best for everyday use???

 

74 early 260z v8 daily driver

 

74 early 260z next project - prostreet

[74_5.0L_Z]

I've been autocrossing my car for about 6 months. I'm no expert, but here is my experience thus far. I have 200# springs in the rear and 175# springs in the front. I also have an open differential. The car also has the Suspension Techniques 1.125" sway bar in front and 7/8" in rear. I tried the combination with the rear sway bar attached, and the car easily spun the inside tire. I disabled the rear sway bar, and the rear traction improved dramatically; however, the car now has a slight push. My next step is going to be to go stiffer on the rear springs, and leave the rear sway bar disabled. This is what I suggest for cars with an open diff:

 

250# rear springs

175# front springs

1.125" front sway bar

no rear sway bar