Axle F
One standard axle + 3 x factory horsepower = recipe for disaster. Having done the sums, We’ve come up with an elegant – and manufacturer supplied – solution to the equation.
Catch up on the whole story here.
Since you last joined us, we have been racking up some enviable road mileage in the couth coupe. With a brand spanking BEAMS 2.0 litre engine under the bonnet, progress is now rapid, to say the least. Problem is, it’s also way more than the stock diff and tyres can even try to cope with!
With a final drive ratio of 4.1, the original ST back axle is perhaps a little too high for the needs of this project. Also, rather more worryingly, the actual diff itself is a little on the fragile side, being a teeny little 6.7 inch unit that was only ever meant to cope with around 70 bhp coursing through its planetary gears. So far, our big chief, Peter, has been taking it very easy on the road, applying gradual and gentle throttle openings under load and making sure that no heavy demands were being made on the easily overwhelmed back axle. But where’s the fun in that? After all, we’re trying to create a genuine modern day useable classic that can show most hot hatches a clean pair of treads.
Addressing these issues however was relatively easy. Thanks to the superb job recently carried out at Lepsons on the OEM Supra alloys, we had the perfect answer to the rolling stock problem. A set of 215/60 And 235/60/14s were duly sourced and fitted up to endow the Celica with a suitably 70’s lofty rubber stance and literally twice the footprint of tyre on the road surface.. Should help improve traction, which up until now had been practically non-existent.
The rear axle was a similarly simple affair to sort, thanks to Toyota themselves offering a much beefier 7.5”version in the GT version of the same car. Benefitting from a 3.9 final drive, not only are the internal driveshafts considerably thicker and stronger, but also the diff and casing itself is far more substantial and can cope with significantly more power. It’s a genuinely simple bolt out / bolt in upgrade that requires zero head-scratching and importantly on this project, looks just right should anybody choose to have a squint under the rear of the car.
As an added bonus, and impressively for the vintage of the donor car, The GT axle also comes with a factory fitted limited-slip diff and even a teeny little roll bar (albeit one seemingly made from coat hanger wire!) So it has all the ingredients to allow some controlled tail-happy antics in the future and will finally let Pete full exploit the power that he has been so carefully nursing for all these months.
After having the unit carefully shot-blasted, a few coats of red oxide primer and then chassis black to keep the elements at bay will be later be applied, but even lying the unit on the workshop floor under the original, it was clear to see that it’s a far more substantial unit.
Unsurprisingly, the wheels bolted straight on, immediately endowing the Celica with a far more aggressive stance and really filling out the arches for a much more business like appearance. Although the wheels and tyres now look truly spot on, their increased size only serves to highlight the fact that the car is still sitting at a vertigo inducing ride height, with a decidedly unsexy set of arch gaps. Fear not, this is something that will be addressed in the very near future, with the obvious aesthetic and dynamic benefits.
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Join us next month when we get the new axle back in and start taking a proper squint at the handling. See you then!
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