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Frank's Suspension, Part 3

Tie-ing down the bum

by Julian Edgar

Click on pics to view larger images

At a glance...

  • New rear upper trailing arms
  • Watts link replcament bushes
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So far on our EF Falcon six cylinder we’ve fitted new springs and dampers (excellent) and adjustable front and rear sway bars (at this stage in the modification process, results only OK). Now it’s time to fit some rear suspension parts pretty well unique to Falcons of this era – revised upper trailing arms and new bushes for the Watt’s link arms and centre pivot.

Compared with the new springs and dampers, or the new sway bars, the bits and pieces looked pretty unimpressive sitting on the workshop floor. But the results were astounding....

The Parts

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The Whiteline trailing arm (upper) conversion kit is cat no KTA101. It comprises two new fabricated trailing arms with polyurethane bushes. The arms are the same length as standard but require new holes drilled in the upper axle bracket, which mounts the rear ends of the arms both lower and further back. Drilling templates are provided, as are two new nyloc nuts. The different location requires scallops in the lower parts of the arms to clear the axle housing. The retail price of the arm conversion kit is $231.

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The Watts link bushes kit is cat no W0892 and costs $73.90. The kit comprises steel inserts and bushes for the centre pivot point on the diff, and four bushes, one for each end of the two lateral arms.

Note: as with all the suspension products provided by Whiteline for the Falcon, these components were made available free of charge.

The aim of the revised suspension parts is to reduce rear-end steering, especially roll-oversteer.

We had Simon of Simon’s Car Clinic install the components. This was a straightforward 2½ -hour job.

Fitting Rear Arms

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Only the upper arms are modified – the lower arms remain untouched.

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Removing the lower arms is as easy as undoing two bolts. Note that the arm replacement should occur one at a time, otherwise the axle can rotate, making it hard to do the job.

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The new replacement arms and the old. As can be seen, they’re very close in length and shape. However, arrowed is the scallop designed to clear the axle housing, needed because of the revised mounting location.

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The provided paper template in place. Simon cut out both holes but it would be better to cut out only the original hole, and centre mark the new hole.

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The new mounting position holes are drilled through the axle bracket. Note that Simon is using an air drill – a conventional electric drill would be difficult to fit into the correct position, especially on the other (right-hand) side of the car.

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The original nut for the mounting bolt is held captive by a bracket. New nyloc nuts are supplied but we found the originals fouled the position of the new nuts. Simon used a thin cutting disc in an angle grinder to remove the old nuts.

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The new arms then easily bolted straight in.

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The new arm in position, with the revised rear mouting position arrowed. Repeat for the other side and then that job is done.

Fitting Watt’s Link Bushes

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The fitting of the Watt’s link bushes was even easier. The centre pivot nut was undone, as were the nuts on the outer arms’ pivots.

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The old bushes were pushed out with a punch and hammer (and they were all in good condition)...

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..and the new bushes greased and then pushed into place.

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The supplied steel bushes when then greased and pushed into the polyurethane bushes.

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The Watts linkage was then reassembled.

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Here the new Watts link bushes and one of the upper semi trailing arms can be seen – job done.

Driving Results

So would these new parts really make much difference, or would it be more a case of I-think-I-can-feel-something that we’ve previously experienced with some bush swaps?

The short answer is that the revised rear end is dramatically better than standard!

Compared with the lurch-and-lean rear that was previously ever-present (yes, even with the new springs, dampers and sway bars), the rear feels absolutely planted. The steering also now comes from the front wheels, not a combination of the front wheels and a wayward rear axle. In fact, to be quite honest, we didn’t think there was anywhere near the potential improvement to be had in the rear suspension – and now that we can see what’s possible, we can retrospectively be even more critical of how it previously was.

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On a viciously tight and bendy road, one where the guard rail is right next to the edge of the road, and where there’re off-camber sections, bumps and dips, the Falcon feels a metre narrower. Not only can you place the front-end far more accurately, but the rear-end is now so much more predictable that cornering lines can be executed with precision previously impossible. In fact, I could go so much faster on this stretch of road that the car was scraping its body on some of the bigger bumps.

The difference is hard to describe because there’s not just more rear-end grip available, there’s also so much more control and precision. The difference is literally so great that if someone had told me that, when the car was in Simon’s workshop, he’d installed a whole new independent rear end, after driving I’d have believed it.

It needs to be kept in mind that in normal, gentle driving, the handling improvement is vastly less. It’s only on a really demanding road, being driven quickly, that the night-and-day transformation is so startlingly clear.

Whether or not such a transformation would have been apparent with stock springs and dampers, and stock sway bars, is anyone’s guess. We’d imagine that the improvement would still be clear, but without having the damping control to keep the tyres in contact with the road, and the bigger sway bars to stop excessive body lean (especially in flip-slop S-bends), the rear end improvements may have been drowned out.

Conclusion

With the addition of the rear-end bits and pieces to the suspension, and engine and brake changes already made, the old EF Falcon is now starting to be able to set point-to-point times on difficult roads that are seriously good. Even with the as-bought budget tyres, the car now turns-in sharply, has a lot of grip, is settled and competent when committed, has razor sharp throttle response and can be edged into understeer or oversteer as wished. Inner wheelspin can still be a problem, but that’s about the only problem I can think of. The transformation from standard handling (which, it needs to be remembered, I didn’t think half bad on bumpy and difficult secondary bitumen roads) is enormous.

We still have a few Whiteline suspension bits and pieces to fit – front suspension braces, front camber/castor kit, front castor rods – and a Mock Motorsport supplied Limited Slip Diff. Now the decision is what to do next. Hmmm, perhaps the LSD...

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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