Testimonial

Banzai Magazine - PB Coilovers Review Part 2

As revealed last month, the superbly quick production and delivery of the revised collar size for the PB coilovers forced my arrangement of the project's new wheels and tyres. After a few weeks of running around on the new arch-filling rolling stock, I've had opportunity to analyse what they're like to livewith, mostly in testing weather conditions. I'm pleased to say that there's been only a negligible loss in steering precision and ride comfort despite the lower tyre profile; and bizarrely, the tread pattern appears to be quieter on the motorway than the original dB series Yokohamas, though I do not have a decibel meter to prove this conclusively.

I wouldn't normally dream of fitting larger diameter wheels without an appropriately lowered ride height, but as the date for my return to Torque Developments International (TDI) for the suspension fitting was in sight I decided to endure the quirky stance. I think the multi-spok design of the Blitz wheel works well against the Euro-friendly shape of the Yaris. But my goodness they are a pain to clean. Because of this I've been doing my best to read the road as far ahead as possible to avoid pressing the brakes and engulfing them in a plume of pad dust. Most of the wheel is accessible by hand with a wash mitt: it's just the inner crosshatch that's proving particularly difficult to clean with anything other than a toothbrush.

Before getting on to the new developments of this month's update, I'd also like to report that the Voris sailed effortlessly through its first scheduled service (10k miles). The work was despatched ell iciently by my local dealer while I waited, the car emerging cleaned and vacuumed throughout. It was an altogether pleasant experience, lubricated with a couple of cups of decent coffee while I watched the morning news.

The work is no less efficient at TDI and the workshop is equally pristine, which is partly why the Essex outfit is my preferred tuning partner. Now that he's well practiced taking the Yaris's suspension apart, workshop manager Dennis Hayes made short shrift of deconstructing the front-end. After removing the original top mount bearings and bellows-shaped rubber boots from the MacPherson struts, they were located over the new collars and secured between the cup-shaped adapters and the car's fixed top mounts. It all went together perfectly.

We hadn't noticed this previously but the two lower mounting holes on the coilover bodies are slightly elongated. This was a fantastic bit of foresight on the part of PB as we hoped it would allow us to marginally increase the front camber values without resorting to shims or adjustable top mounts, thereby helping to tuck in the tops of the front wheels. Remember I'd commented last issue that the arches had looked over-stuffed and that the wheels stood slightly proud of the bodywork. We'd soon discover during the geometry setup if these holes were enough on their own.

The third mounting hole on the coilover body is for the anti-roll bar drop link. The original part cannot be used here as the distance between mount and bar is reduced, so PB has supplied an adjustable version instead. With the car still raised off the ground on its jacking points and therefore no tension being applied to the bar, Dennis bolted on the drop links, ensuring that their lengths were identical and that the gaps between the arms and driveshafts were also equal.

Moving to the torsion beam rear-end - always a much simpler setup - the springs can be removed from their mounts by compressing the coils with your hands, while the shocks come out after loosening just two bolts on either side. Height adjustment in the new suspension setup is provided by an adjustable alloy platform underneath the shortened springs. But unlike other setups I've seen, PB's platform is securely bolted to the vehicle, which makes it highly unlikely that the spring could ever be accidentally dislodged from its location.

After lowering the car to the workshop floor, the ride heights were approximately set and I was ushered out onto the roads of Thurrock to gently settle the suspension. The heights were then checked and adjusted so the car sat as I wanted - as always, equalising the arch gaps and with a slightly nose-down attitude. In terms of measurements, this turned out to be a genuine 40mm drop at the front and 45mm at the rear, with plenty of further adjustment available either side of these figures if necessary.

Instantly, the visual effect of the wheels and sharp-edged design of the third-gen Yaris gelled. and TDI's staff members were genuinely surprised at the transformation this relatively modest drop had made to the car. Its persona suddenly changed from white goods shopping trolley to a small car with a mean streak in its personality. To see what I mean you'll have to wait for the full reveal in a future issue.

A full geometry session followed using TDI's impressive John Bean laser alignment machine, which conclusively proved the worth of those elongated and slightly offset mounting holes - the negative camber they've generated has tucked in the front wheels perfectly. All toe and caster values were then readjusted to within manufacturer tolerances, so there shouldn't be a negative impact on tyre longevity or handling. I'll let you if that proves to be the case later on too.

The PB coilovers offer 30 steps of damping adjustment from a positive-click dial at the top (it's a little fiddly but not impossible to adjust under the front scuttle panel), and the value I'm currently happiest with is an equal 18/30 front and rear. The ride quality has firmed up somewhat but because the damping is well controlled it never feels crashy, harsh or as if the car is bouncing along. Many people have not even noticed that it's running aftermarket suspension, which I suppose is a good thing. The one thing I have noticed, however, is that I appear to have a slight rubbing sound emanating from the nearside rear when the suspension compresses suddenly over a bump. It doesn't appear to be too harsh but needs sorting nevertheless, perhaps with some gentle arch rolling. Still, Toyota's PR man did tell me to make sure I filled those arches.

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