Larger Front Sway Bar Only / Suspension Balance Question

[FlatBlack]

The Suspension setup in my 1978 280Z:

 

* Flat Top L28, Stock '78 5 Speed

* Stock '78 R200

* Tociko 185/200 Springs, HP Struts

* Stock Caliper/Drum setup

* NO Bump Steer Spacers

* New Ball Joints

* Polyurethane Bushings all around

* Rota RB 15x8s with 225/50/15s, on 1/4" spacers [only in the front]

* Larger Front Sway Bar - Size ??? [i purchased this from a member and did not ask the actual size, here is the link: http://forums.hybridz.org/showthread.php?t=145663&highlight=front+sway+bar]

* Stock Rear Sway Bar

* Rear Strut Tower Brace

 

My Problem:

 

I have been going on 'Sunday Cruises' with several car buddies the past couple of weekends. We have been going on local two-lane roads that wind and twist and rise and fall, very good for driving.

 

Last Sunday, I had the same setup as listed above, but with the stock front sway bar. The car felt pretty well balanced, but I was noticing the bumpsteer. Otherwise, the front did not plow out at all and the rear felt fine.

 

I installed the new front sway bar this Saturday, and we went out again yesterday on a different route. The roads were somewhat smoother, and I did not notice much bumpsteer. I can't tell you if that was due to the smoother roads or the sway bar. Before we left, I took a couple of hard 90* turns in the city at about 15-20 MPH. The back end came out a bit. Definitely controllable, but this usually didn't happen.

 

While on the cruise, the Z's rear seemed a bit more loose than usual. It only came out twice, both we off-throttle downshifts into turns. THe first time I was on a downhill hairpin 60* turn to the left, and when I dropped into second at about 40 MPH the back slid out. Once again, controllable, but not what I want.

 

I took most of the turns that day at higher speeds but was driving conservatively because I was unsure of what the rear was going to do. I took it to a large open parking lot afterwards and ran the crap out of it. I was worried about the rear coming out at speed on a corner, so I would get up to about 30, start turning, and then yank the wheel. The rear did come out once or twice, but only a little, and it was easily brought back in.

 

Questions raised/solution possiblilities:

 

* I am wondering if I am reading too much into what I am feeling from the suspension, I never once felt the car leave my control.

 

* Would anyone recommend removing the stock rear sway bar and running nothing, or putting a thicker one in? I have talked to people about this and have got mixed reactions. I want the car to be more stable in high speed turns.

 

* I could also go back to the stock front sway bar, but the new bar has reduced body roll and I would like to keep it. I would love to hear all suggestions though.

[johnc]

From your description above your car is no where near loose and the few back end stepping out events appear to have been driver induced.

 

The roads were somewhat smoother, and I did not notice much bumpsteer. I can't tell you if that was due to the smoother roads or the sway bar.

 

Due to the smoother roads. The anti-roll bar (ARB) has nothing to do with steering kickback.

 

Before we left, I took a couple of hard 90* turns in the city at about 15-20 MPH. The back end came out a bit. Definitely controllable, but this usually didn't happen.

 

At that low of a speed you're getting so little load transfer that the suspension isn't taking any kind of set. You cannot make any balance determination from that test.

 

It only came out twice, both we off-throttle downshifts into turns. THe first time I was on a downhill hairpin 60* turn to the left, and when I dropped into second at about 40 MPH the back slid out. Once again, controllable, but not what I want.

 

That's absolutely normal behavior and is a result of weight transfer forward under decelleration. Downshift in a straight line, not in a corner. You also need to use the brakes to slow the car down, not the gears. Lifting off the throttle should let the rear of the car step out in a controllable manner and it sounds like that's what you've got

 

I want the car to be more stable in high speed turns.

 

Not to be a jerk, but based on the speeds mentioned above you haven't gotten close to a medium speed corner, let alone a high speed corner.

 

Unless there's something mechanically wrong with the car, it sounds like the balance and handling is very normal for a slightly modified S30. You want the back of the car to be responsive to the throttle.

 

Spend your money on yourself. Go to an autocross. Go to an open track day. Spend money on driving schools.

[FlatBlack]

Thank you John. I do appreciate the input. I will keep the current setup and get more drive time on it. I know my driving could use some improvement, and I need to know the upper end of the car's abilities and characteristics.

 

I need to search more thouroughly - My buddy said that there is a thread on larger rear SBs and or removing them.

[johnc]

Because of where you sit in a S30, you feel rear end movement a lot more then in other cars. The car feels like its loose when its really not. That's why its important to explore the car's limits and go beyond them in a controlled environment.

[EvilC]

That's why its important to explore the car's limits and go beyond them in a controlled environment.

 

Exactly! I will say when I first drove my Z on the street "hard" it felt like it always wanted to break loose and I was at the limit of the car but when I tracked it.....I found out I was mistaken. I believe it will take years to fully understand and learn what I am "feeling" in the car. I spoke to Johnc once on the phone about sway bars and suspension setups and it was great help! Silly enough, I have forgot the specs my car was in before I took it apart....and few people including 1 tuff z has driven my car and says it tracks a lot nicer than his car.

 

On a side note, when I was building my car...I changed one part at a time to understand and "feel" what each one does. With that, you learn the new limit or the behavior of the car.