weighed car, and removed swaybars..surprise!!

[blueovalz]

Well, after making all the external changes for a semi-legal street car, I weighed it yesterday. 2321 lbs wet without driver. Funny thing though, I un-linked the swaybar up front (it is the only bar in use) for better weight measurements (571 LF-626 LR-596 RF-530 RR, so the weight needs to be jacked around a little) and driving home, I found my car handles better without any swaybars (first time that has happened). The only thing different than I had before is an increase in spring rates of 225 F & 265 R (from an original 200/200). As the car sits at this moment, I have a 50/50 F/R distribution. This swaybar issue has mucked up everything I ever thought I knew about setting up this car. I am not sure how to interpret the results in regards as to why what seemed to be only a moderate change in spring rates resulted in a such a drastic change in my bar requirement . The front bar was a 27mm bar. Obviously I had the car set up poorly before taking it it??? Any feedback would be appreciated.

[DavyZ]

*bump* John Coffey, any ideas?????

 

Davy

[johnc]

I found my car handles better without any swaybars (first time that has happened).

 

I wouldn't use how the car "feels" as you're driving on the street as a quantitative measurment of how well the car handles. But, assuming you're correct:

 

1. You anti-roll bars may have been bolted up with pre-load - meaning that overtightening or uneven tightening cased that bars to twist as the car was sitting level.

 

2. One or more of your anti-roll bar mounts, end links, or mounting points on the control arms are broken.

 

3. The bushings are shot.

 

4. One or both of the anti-roll bars are cracked or broken.

 

5. Your anti-roll bars are too big for the springs and shocks you're running. If the car "feels" more lively and responsive then this is probably the cause.

 

FYI... when you corner weigh a vehicle you're supposed to disconnect the anti-roll bars before the car goes on the scales.

[74_5.0L_Z]

Hey Terry,

 

Can you define what you mean by handle better? Less understeer maybe? Handle rough corners better?

 

A problem I'm trying to work out is binding associated with the factory style sway bars. In my mind, the only time a sway bar should have an affect is when the car tries to lean. The factory style and aftermarket sway bars that mount like the factory bars bind at the end links as the suspension goes through its range of motion. The end links have to rock in order to accomodate the changing length between the bearings on the frame and the lower control arm, but the factory style links bind. The stock style sway bars also bind at the bearings. This binding doesn't allow the suspension to move smoothly through its motion, and can cause problems (like a mid corner push, and difficulty with rough corners).

 

One solution to the problem is pillow block bearings, and rod-end end links (custom sway bar). A band-aid fix I'm working is the use of spherical bushings(like those used in the aftermarket T/C kits) in place of the delrin bushings of the end-links. This should at least allow the end links to rock without binding.

 

Sorry for the rambling, but I think that the sway bars can perform better, and give expected results if binding is reduced.

 

I have heard of some ITS racers (especially on the west coast ) running stiffer springs, and no sway bars.

 

Dan

[Forrest]

Is there any rule of thumb about what rate springs should be used with what size swaybar, and vice versa?

[auxilary]

I think the general rule of thumb is the higher rate the spring, the smaller diameter swaybar. And vice versa

[Forrest]

Starting at stock swaybar rates and spring sizes?

[johnc]

I have heard of some ITS racers (especially on the west coast ) running stiffer springs, and no sway bars.

 

That's an East Coast thang. They've got those glass smooth tracks out there so they run big fat monster springs and dinky anti-roll bars. Us West Coast folks have bumpy tracks so we use nice compliant springs and bigger anti-roll bars.

[blueovalz]

Well, more background here. The car "drives" better in that, at the limit of traction on a skid pad, the car is very neutral at part throttle (can be steered easily using thottle), and "turn in" is greatly improved. Bar and links are in excelent conditon as are the bushings (actually, they are all heim jointed so there are no bushings and the joints are in excellent shape). Originally the car set-up was very neutral. I then installed stiffer springs all the way around, with more bias toward the rear (265lbs R and 225lbs F), and removed the rear bar, which made the car a bit tight. My next intended step was to use a slightly smaller front bar (still wanted a little understeer in it for the street), but when I disconnecte the front bar in preparation for the corner weighting, I was quite shocked to realize how neutral the car felt on a cloverleafs that I pushed through on the way to the shop. So much so, that I am now re-evaluating what I need to do next. Quite puzzled, but if this works fine, then that's what matters.

[ianz]

As john mentioned, bigger bar in the front makes the car understeer or "push", bigger bar in the rear makes the car oversteer.

 

Suspension setup is about the most subjective thing on a car, especially a street car with an inexperienced driver (speaking for myself)

 

If you are happy with the car's handling without sway bars, no one says you have to use them, there a pain!!

 

you are running really stiff springs for the street (stock rate is 140 lb/in front and rear I think) but if the car is not too twitchy, and you like the way it feels, leave it!!

 

If the car still has more body lean than you want, try using the stock front and rear bars off the 280Z.

 

The motorsport and Sus Tech sway bar kits are HUGE in my opinion and designed to work best with soft springs, so they may be excessive in your case given the spring rates your running.....

 

just my 2 bits......

 

good luck!!