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Frank's Suspension, Part 2

Fitting new adjustable sway bars

by Julian Edgar, photography by Georgina Edgar

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In Frank's Suspension, Part 1 we covered the fitting of new Whiteline springs and dampers to our EF six cylinder Falcon. The result was exceptional: a major improvement in handling and rear-end grip under power, together with a good ride quality. We did the springs and dampers first, because that’s the approach taken by the vast majority of people when upgrading suspension. And, following the same perspective, we fitted the Whiteline adjustable sway bars next.

Whiteline Adjustable Sway Bars

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The front adjustable Whiteline sway bar (anti-roll bar – same thing) has part number BFF35AZ and is 30mm in diameter. The rear adjustable sway bar is 22mm in diameter and has part number BFR35Z. In each case adjustment is made by moving the sway bar links, which comprise S-shaped designs bent from steel bar, so that the effective lever arm length of the sway bar is changed. To accommodate this variation, new brackets are supplied for the car body that allow the links to be moved without unduly increasing their angularity. The sway bar themselves are equipped with flattened ends drilled with multiple holes. The D-bushes, on which the sway bars pivot, and the bushes within the sway bar links, are made from polyurethane.

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Here is the hardware for the front sway bar mounting. From left to right: the new body mount brackets (note the three adjustment holes), the S-links, nyloc nuts, washers, bolts and the D-brackets. The polyurethane D-bushes and also shown, as is the grease to lubricate the bushes.

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The rear hardware follows the same approach.

Note: as with all the suspension products provided by Whiteline for the Falcon, these components were made available free of charge. Retail cost for the front and rear adjustable sway bars is AUD$266 each.

So how does the stiffness of the new sway bars compare with the old? (Note that the Falcon was fitted as standard with the raised Country Pack suspension; AFAIK, this alters only the springs but it may provide different sway bar thicknesses as well.) Clearly, the actual stiffness of the new sway bars depends on where the links are positioned in their adjustment holes, but an immediate feel for the change can be given by looking at the relative diameters of the old and new.

Standard

Whiteline

Stiffness Change*

Front Diameter (mm)

27

30

+52%

Rear Diameter (mm)

22

22

0

*calculated only from diameter change

We chose to leave the rear bar in its softest position and set the front bar to +1 step-up in stiffness. The reason for doing this was that with the new springs and dampers, the Falcon has a tendency to transition to oversteer at higher speeds; we’d prefer it to start pushing into understeer in the same conditions.

Handling and Sway Bars

It’s certainly not always the case, but in general, uprating the stiffness of the sway bar at one end causes the biggest change in handling at the opposite end. So for example, a much stiffer front sway bar will tend to reduce oversteer; a much stiffer rear sway bar will tend to reduce understeer. This is also a function of the fact that the grip of the end of the car with the upsized sway bar is likely to be reduced: the sway bar works by trying to pick up the inner wheel, so the downwards pressure of the rubber on the road at that end of the car is lessened, leading to decreased grip.

Installation

We had Simon of Simon’s Car Clinic install the springs and dampers. This was a straightforward 2-hour job.

Rear Sway Bar

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The standard rear sway bar is heavily curved to clear the diff. It is connected to the rear axle by means of D-brackets and to the car body by short sway bar links, rubber-mounted at each end to allow angularity of movement as the axle moves up and down.

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Removing the rear sway bar was just a case of undoing the D-bracket and sway bar link bolts and nuts...

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...until the old bar could be manoeuvred out past the axle.

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The body brackets for the sway bar links comprise right-angled brackets. These are bolted to the original body mounts.

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With the link brackets in place, the new sway bar could be fed over the rear axle and tailshaft.

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The D-bushes were thoroughly greased and then slipped over the sway bar....

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... before the original D-shackles were bolted back into place.

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The sway bar links were then installed, with the previously chosen stiffness setting being used.

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The finished job.

Front Sway Bar

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The front sway bar has a less complex shape.

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The first step was to undo the links. These use polyurethane bushes as standard.

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The D shackles could then be undone...

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...and the standard sway bar removed.

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Again, right-angled brackets with multiple adjustment holes bolt to the body mounts.

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The process was much the same as for the rear bar, but because of the bar’s bigger diameter, new D-shackles were used in addition to new bushes.

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With the sway bar positioned beneath the bell-housing, installation was easier than for the rear bar.

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The S-shaped links were then fitted.

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A final step was to wipe over the front and rear bushes to remove surplus grease that might attract dirt that can then work its way into the bushes.

On-Road Results

One characteristic of upsized sway bars that few consider is the trade-off in ride comfort.

With two-wheel bumps, like those met when you cross a bitumen filler strip, stiffer sway bars have no affect on ride quality. The sway bar simply pivots in its mounts as the wheels rise together. But in one-wheel bumps, the story is different. In those cases, the sway bar stiffness has the affect of aiding that wheel’s spring, resulting in increased bump stiffness.

And with the Falcon’s increased sway bar stiffness, this change in one-wheel bump stiffness is quite clear. Whereas previously you never went ‘ouch!’ when a front wheel hit a pothole, with the increased sway bar stiffness, in these conditions a jar can now be felt through the car. The quality of the ride with the combination of Whiteline springs, dampers and sway bars is still quite good, but a similar drop in ride quality to that which occurred with the fitting of the sway bars would start to make it borderline. To put this another way: I wouldn’t have wanted to start off with stiffer springs and dampers and have then fitted the sway bars...

However, the reasons you fit stiffer say bars are to improve handling, and tweak the handling balance. And are the ‘bars successful at this? Well, yes and no.

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Even with the rear bar at its softest setting and the front ‘bar at +1 stiffness, the propensity for oversteer is little changed. The car sits flatter in corners (more on this in a moment) but the balance feels, if anything, more inclined to oversteer than it did before. So why not increase the front bar stiffness even further? The answer to that is that I now think trying to tweak the balance is, at this stage of the suspension modification process, not the approach that should be taken. There are still plenty more suspension parts to be fitted and these will further change the handling behaviour.

So, finally, how hard does the Falcon now corner? The answer to that is: considerably better than before. As expected, the car sits flatter. It also has less weight transfer in S-bends and turns-in more sharply. But this also has a downside – in wet conditions the car is more sudden. In wet, slippery urban conditions, the stiffer roll resistance and lack of a rear limited slip diff makes it a bit of a lucky dip at to whether the car will power oversteer or simply spin an inner wheel. This inconsistency is more of a problem than either handling trait - what you want is to know is what to expect!

(Incidentally, we didn’t mention it before but the lowered springs have given the Falcon noticeable front negative camber. That’s probably why we concentrate so much here on oversteer: the front-end grip is very good.)

So would we recommend the Whiteline sway bars? Sure! Their ability to be adjusted for stiffness is extremely useful – although more so at the end of the handling set-up process than part way through. They look well made and are easy to fit. But if this is as far as you’re going with the handling upgrades, we’d suggest buying just the front sway bar, and then seeing whether you can get the results you want by tweaking its adjustment.

Much more so than with the fitting of the Whiteline springs and dampers, there are also trade-offs to consider when fitting stiffer sway bars. Perhaps in retrospect we should have fitted the upgrade sway bars right at the end of the handling upgrade...

Next: more work on the rear suspension

Contacts:

Whiteline Suspension – www.whiteline.com.au

Simon’s Car Clinic – Tamborine (Queensland) – 07 55436155

The Whiteline suspension components were supplied courtesy of Whiteline

Simon’s Car Clinic was paid at normal commercial rates

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