Can really build a race Mini for the road? We examine bodyshell prep and suspension components in a bid to find the answer.
Back in the April 2018 issue we published a beginner’s guide to classic Mini motorsport, looking at costs and how to get involved. We touched upon the contrasts between a race Mini to a road-legal Mini, suggesting that they’re outwardly similar yet mechanically quite different. So how different really is a road car to a circuit racer and what’s to stop you from using race-spec parts on the road, and vice versa? There’s much to cover, so let’s start with the biggest component – the bodyshell…
Aside from the fancy graphics and paint, there’s very little to distinguish most circuit racing Mini bodyshells from their original road-going state, at least upon first inspection. And realistically you could fully prepare a race Mini bodyshell, then use it on the road, but as will be a reoccurring theme, that could be an expensive route for not much gain.
Interiors are fully stripped of all nonessentials and flammable fabrics, the factory bitumen sound-proofing painstakingly removed from the floors, rear wings and roof. All the parts that make a Mini a tad more comfortable and civilised – squishy seats, the radio, heater, sound-deadening pads and carpet – they’re off the menu. The rear seats will no longer be of use, so these are trimmed back midway and the rear companion bins usually removed for roll-cage access.
Where welded-in roll-cages are commonplace, the latest designs form the skeleton of the car and are integral to safety. For a road car, if you fancy a rollcage it’s more practical to opt for a bolt-in design, as it’s easier to remove for future rust repairs. But how safe is any type of roll-cage in road car? On one hand it will considerably strengthen the shell, on the other, it introduces lengths of hard steel tubing all around your head. So harnesses and racing seats come highly recommended alongside a ’cage, making a quick visit to the shop that little bit more awkward. You’ll also need to consider switches and controls, and if you can still reach everything while strapped in.
Lightweight composite panels can certainly be used on both road and race Minis to good effect, although panel fit and vibrations can leave something to be desired. On a racer, it’s beneficial to leave a
large gap around a composite front end to the scuttle panel, for example, as it saves wearing out the paint when it rubs. That’s going to look quite agricultural on the road, plus you have all the road grime to flick up and out. Standard steel front ends are arguably much better suited to a road car – better panel gaps, less vibration, and stronger. Remember that race Minis rely on the roll-cage for strength, not the front end. Another common fitment to race Minis are polycarbonate side and rear windows. Lightweight and shatter-resistant, they’re ideal for competition, but for regular road use, even the fancy coated versions will become scratched in time. Security is also questionable if you go for the sliding hatch front door windows.
Tubbed rear arches are commonplace across all lowered Minis, and done properly make a sensible long-lasting modification, if that’s your thing. Modifying the bulkhead for a large airbox, however, is increasingly becoming a problem at MoT time, so that’s one mod best left to the race circuit, in the UK at least. Rear valance removal, well, that’s only advantageous on the road if you’ve modified the rear cones to accept a hex bar adjuster inside the Hi-Lo suspension platforms. That leads us to…
To adjust the rear right height easily, without jacking the car in the air, the rubber cones have their centres drilled out, through the threads that usually grip into the cone
compression tool up front. The purpose is to be able to more precisely set up corner weights to perfect the car’s balance. On a road car that’s usually in vain as there are so many variables, from passengers to luggage, and to really notice the difference you need to be on the limit of adhesion.
Sure, adjust corner weights on a raceinspired road car if you like, but you needn’t worry too much about adjusting the ride heights in situ, as a ballpark setup will do the trick. Instead, save some work of drilling cones and the front tower bolts by tweaking ride height on the external Hi-Lo adjusters instead. Also consider what’s practical in terms of ride height for the road, where speed bumps and pot holes can give a brutal reminder of low ground clearance on a regular basis. Rubber cones can also sag considerably over time.
Discounting coilover conversions for the road due to their inherent short-spring harshness, you’ll require more supple suspension offered by standard-spec rubber cones. Racers tend to use yellow (full competition) or red spot (race/rally) cones; red can be okay on a fast road car but yellow will likely be far too harsh.
This harshness is also largely dependant on the dampers. Start at the halfway point on adjustable dampers, then work from there to find the right balance. Race dampers tend to feature shorter fully open lengths to reduce suspension droop. They can also cost a small fortune, with billet alloy bodies and anywhere up to four-way adjustability to
control bump and rebound. On both counts, this can be overkill on the road, especially when there are so many affordable single adjustable road damper units to choose from.
Anti-rollbars are certainly worthy of both road and competition Minis, but the level of stiffness required on a heavily sprung aggressive racer is far greater than on country lane weekend toy. It’s a common misconception that race Minis all run both front and rear anti-rollbars – it’s usually one stiff rear bar only, the effect being to reduce understeer by improving front end grip. It promotes lift-off understeer so the car can be balanced on the throttle through each corner, cocking an inside rear wheel in the process. You don’t really want to be experiencing that on the daily commute, so a good tip for the road would be to run the suspension and soft as possible, then invest in small diameter front and rear bars to reduce bodyroll. We’ve tried this setup in the past with Smootha Ride cones and a pair of ARBs and were suitably impressed.
Rose-jointed (rod end) suspension components are an absolute must on any race car to make the most of the available grip, but on the road you’ll need to balance up how harsh is too harsh. Removing the rubber bushes gives a more precise feel but less give in the suspension. That said, we’ve driven many road Minis with solid-mounted front subframes and Rose-jointed bottom arms and tie-rods, and it’s not anywhere near as hard work as you’d expect. Typically, the harshness comes from overly-stiff
dampers, running the suspension too low or with completely knackered old rubber cones. If you do choose rod-end suspension components, as opposed to those with rubber or polyurethane bushes, keep the joints clean and check regularly for wear. A race car is spanner-checked after every track outing, and there’s usually something worked loose! It’s also worth investing in high quality rod ends from known-good brands, as they’re stronger and more durable than budget-grade items.
WHEELS AND TYRES
The aim of perfecting the suspension setup is to maximise tyre grip, so clearly tyres are a major consideration to the surrounding components and geometry. Setup for a Mini Miglia on slicks varies wildly to a MkI on treaded historic tyres. One thing you’re unlikely to be able to transfer from race to road are the tyres themselves, unless of course it’s a race series that stipulates roadlegal tyres only.
Radial road-going tyres are designed to last for many thousands of miles, and as such tend to be constructed from harder rubber compounds than their racing counterparts. They’ll respond differently to changes in camber, toe and caster, and setup can be altered accordingly. They’re also not available in the same widths, in 10- and 12-inch diameters, seeing as the Mini was originally designed to run on 10x3.5-inch wheels. As a result, if your dream is to run with 10x7-inch Mini Miglia split-rims on the road, the widest 165-section tyres available can become incredibly stretched. That’s not ideal as most tyre makers stipulate maximum wheel widths, so you could be in hot water, insurance wise, if you had an accident. It also doesn’t do the handling any favours to have a tyre hanging half off the rim!
Running with race-width wheels on the road also has a tendency to induce tramlining, where the front tyres follow all the grooves in the tarmac. To allow fitment of seven-inch wide wheels, much negative offset – or ‘poke’ if you’re down with the kids – is required. Mini Miglias get around the physics by some incredibly involved
setup processes up front, the knowledge handed down over many generations, but mainly a lot of time and effort with string, protractors and head scratching.
The other two considerations with regards to using race wheels on the road are maintenance and wheel arch extensions. Many split-rim wheels use polished bare aluminium outers, and that takes some serious dedication and buffing to keep things looking pristine out on the road. Most will also require wide arches and much trimming of the front wings for clearance on any degree of steering lock.
Without going into a full suspension geometry setup feature here, if you fit the same level of adjustable components to a road car, the procedure is going to be the same regardless of the application. Except of course that everything needs to be more precise on a race Mini, and that takes a lot of
time as you can chase your tail, especially when corner-weighting. A full professional suspension setup by a Mini race specialist can take an entire day, for example. There’s nothing stopping you from perfecting road Mini suspension geometry in the same minute detail, but by the time you top up the fuel tank and bump up a kerb or two, everything changes.
So there’s a basic outline of the differences between road and race, and the compromises required. It’s not really feasible to build a competitive race Mini for the road, and nor can you expect a road Mini to perform faultlessly on track, but there’s certainly much cross over between the two. Next we’ll look at your options when it comes to engine, transmission and drivetrain components, and we should probably look at brakes and ancillaries too.
Road and race are two very separate disciplines, so choose wisely when building a fast road Mini – some upgrades are more useful than others.
2 Pushing to the absolute limit on track requires precise suspension setup to perfect the handling.
1 Cutting-edge Mini Miglia build in progress, where the welded-in roll-cage forms the structural integrity of the car.
All creature comforts are removed for safety, weight loss and a professional finish. 4
3 Tubbed rear arches can be useful on all lowered Minis, to avoid tyre scrubbing.
6 Lightweight doors and exterior panels can work equally well on road cars, but weight reduction is less noticeable stuck in traffic.
5 Although recognisable as a Mini, the bodyshells are highly modified for strength, handling and ease of repairs/maintenance.
7 Removed rear valance for easy ride height adjustment.
8 Softer suspension and spring replacements are the way forward for road cars, at the expense of body roll.
10 These rod-end-equipped lower arms from MED are aimed at motorsport use, but can potentially still be used on the road.
9 Fully-adjustable length lower arms and tie-rods are used to perfect the suspension geometry up front.
13 No room for your shopping in here! A flat carbon fibre boot floor with regulation foam-filled fuel cell and integral anti-rollbar.
Racing dampers like these from Quantum are lightweight, highly configurable and rebuildable – beautiful but expensive for a standard road Mini. 11
Many parts on a race Mini are standard by default, or by regulations, whereas others are more exotic, like the split-rims and large rear anti-rollbar. 12