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View Full Version : Sway bar with coilovers?



fishtail8
10-13-2007, 08:15 AM
Just checkin to see how many people run swaybars with their coilover setups. The way mine is right now, the springs are stiff enough that the car doesn't body roll at all. For those who haven't been following threads, it's a 50Pontiac with a MII front, tubular arms and QA1's. Matter of fact you can't even bounce the front of the car. I have a set of scales I can borrow so we can weigh it and figure out exactly what rate of springs to put in. The shop that picked the springs initally happened to be wayyy off on what they thought the car was going to way. They figure it would be at least 34-3500.... but when I ran it across a friends scale at his elevator... It's actually at 3000-3100 w/o driver. So do you run a bar with coilovers?

class67
10-13-2007, 09:00 AM
It can't hurt!

GBodyGMachine
10-13-2007, 05:21 PM
I run a huge bar in the back of mine on coilovers
Jeff

fishtail8
10-15-2007, 07:28 PM
Only two guys with answers..... wow... that's a shocker...

SDMAN
10-15-2007, 08:27 PM
I had the QA-1 coil over setup on the front of my 70 A-body(GTO), and I also used a front HO sway bar (1.375"). I always had 2 complaints with the QA-1 setup. Both could have been resolved, but I sold the suspension to help pay for a completely different setup.

First, they were oversprung. Problem is (was), the spring rates for that setup are extremely limited. Might be better today, but there used to be 2 springs....to lite or to heavy.

Second was the shock valving. For street use, half of the 12 positions were worthless. Same deal. Either way to stiff or way to loose. There is a re-valving kit available that makes the sweet spot larger, but I never got around to installing them.

Having said all that, the car did handle pretty good, and ignoring those 2 nits, I did enjoy driving it. I recommended to the new owner he install the re-valve kits and I believe he intends to do that.

Norm Peterson
10-16-2007, 04:32 AM
The need for a sta-bar depends on the rate of the springs and any limit that you might place on roll angle, not the fact that the springs might happen to be coilovers. Having coilovers goes into the choice of C/O spring rate, which you more normally select with some ride frequency target in mind (which comes around to knowing things like the springs' overall motion ratio, the car's weight and how it is distributed, etc.).

I see those current springs as being about 13% stiffer than what might have been chosen had the weight been known a little more closely. That's not nearly enough stiffer to warrant the elimination of the sta-bar unless it was a pretty thin one to begin with. Most front suspensions for rear drive/stick axle cars rely on the sta-bar for at least 60% of the front roll resistance. I'm not sure whether the MII itself was originally delivered with a front bar or not - a few cars from that era still did not, but they weren't exactly built to conform to the preferences of a Pro-Touring sort of buyer.

If the shocks are new, don't overlook seal friction as an effect that limits motion, particularly at the low speeds that are all you can manage in a "push down on the fender" sort of test. Way too easy to confuse this with spring stiffness.

From inside the car, roll angle typically looks less than it actually is, so this sort of anecdotal observation isn't a very useful measure. No flame intended, as I'm constantly amazed by the amount of roll any of my cars achieve during an autocross as it shows up in pictures taken from outside - at least double what I'd guess based on the view from the driver's seat.


Norm

fishtail8
10-17-2007, 07:32 PM
Thanks for the answers guys, Norm I had to read yours a couple of times to make sure I understood you correctly. You sound like you know your way around suspension. I'm going to scale the car then choose some new springs. There isn't an aftermarket sway bar avaliable for the front end, so there's going to be some time spent at the wreckers with a tape in hand. The rear will have to be a universal one from Comp Engineering to work with the 4-link. There's still lots of shaking down to be done yet, so let the learning curve continue...